,, 陈海云, 汪晖武汉大学基础医学院药理学系,发育源性疾病湖北省重点实验室,武汉 430071The role of miRNA in kidney development
Xiaoqi Zhao, Ying Ao,, Haiyun Chen, Hui WangHubei Provincial Key Laboratory of Developmentally Originated Diseases, Department of Pharmacology, Basic Medical School of Wuhan University, Wuhan 430071, China通讯作者: 敖英,博士,副教授,硕士生导师,研究方向：肾病的发育起源及药物防治,肾脏发育毒理。E-mail:yingao@whu.edu.cn
编委: 陈帅
收稿日期:2020-07-16修回日期:2020-09-30网络出版日期:2020-11-20
| 基金资助: |
Received:2020-07-16Revised:2020-09-30Online:2020-11-20
| Fund supported: |
作者简介 About authors
赵晓琪,在读硕士研究生,专业方向：肾脏发育毒理。E-mail:
摘要
MicroRNAs( miRNAs)是一类内源性小非编码RNA (约19~25个核苷酸),主要通过与靶mRNA中的互补靶序列结合,在转录后水平负调节基因表达。miRNA在包括器官发育在内的广泛生物过程中发挥着重要作用。最近研究表明,某些miRNA在肾脏高表达,并与肾脏发育及肾脏疾病密切相关,提示miRNA为肾脏生理学和病理学中的重要调节剂。本综述重点介绍了miRNA在肾脏发育调控中的研究进展,探讨了miRNA在肾脏异常发育的发生发展中起到的作用,为肾脏发育相关疾病的诊断和研究提供参考。
关键词：
Abstract
MicroRNAs (miRNAs) are endogenous small non-coding RNAs (19-25 nucleotides) that negatively regulate gene expression at the post transcriptional level by binding to complementary target sequences in the target mRNA. miRNAs play an important role in a wide range of biological processes, including organ development. Recent studies have shown that some miRNAs are highly expressed in the kidney and are closely related to kidney development and diseases, suggesting that miRNAs are important regulators in kidney physiology and pathology. This review will focus on the research progress of miRNA in kidney development, and discuss the role of miRNAs in the occurrence and development of renal dysplasia, which will provide a reference for the diagnosis and research of diseases related to kidney development.
Keywords：
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本文引用格式
赵晓琪, 敖英, 陈海云, 汪晖. miRNA与肾脏发育. 遗传[J], 2020, 42(11): 1062-1072 doi:10.16288/j.yczz.20-112
Xiaoqi Zhao.
自发现一种非编码RNA (non-coding RNA, ncRNA)可以特异性沉默秀丽隐杆线虫(Caenorhabditiselegans)的基因功能以来,科学家对ncRNA的研究不断深入。MicroRNA (miRNA)是目前研究最多的ncRNA。到目前为止,已报告有近200种物种中存在超过28,000种miRNA[1]。据估计,有多达1/2的转录本受miRNA调节[2]。miRNA介导的基因表达调控作为一种较为保守的基因调控方式被证实参与大多数生物过程,如细胞分化、细胞凋亡、肿瘤发生和转移等[2]。一些在肾脏中高表达的miRNA被认为在肾脏生理和病理中扮演重要角色,可能成为肾病的一种新的诊断标志物和治疗靶点[3]。目前,一些与肾脏发育相关的研究表明,miRNA在肾脏发育中起关键作用。本文综述了miRNA与肾脏发育相关研究进展,探讨了miRNA在肾脏发育及其相关疾病中的潜在作用。
1 miRNA
miRNA是在真核生物中发现的一类内源性、长度约19~25个核苷酸的非编码单链RNA片段。miRNA具有多样性、进化保守性、组织特异性和时序性,在多种组织和器官的发育过程扮演重要角色。miRNA作为调控因子在真核生物体内广泛存在,通过与靶mRNA结合而在基因沉默和翻译抑制中起作用[2]。1.1 miRNA的形成和功能
miRNA一般是由基因间DNA序列编码。在细胞核中,基因组DNA在RNA 聚合酶Ⅱ(RNA Pol Ⅱ)作用下产生长度为数千个碱基对的初级miRNA转录本(primary transcripts miRNA, pri-miRNA)。pri- miRNA在细胞核内被RNase Ⅲ核酸酶Drosha和DGCR8蛋白组成的微处理器复合体(DGCR8-Drosha)切割加工,释放为大约70个核苷酸的茎环结构,称为前体miRNA (precursor-miRNAs, pre-miRNA)。继而,pre-miRNA在RNA-GTP依赖的核质/细胞质转运蛋白exportin-5的作用下,形成复合物从核内运输到细胞质中。在细胞质,pre-miRNA被RNase Ⅲ内切酶Dicer识别并切割,释放出长度为19~25个核苷酸的二聚体miRNA：miRNA*(双链miRNA)。后者在RNA解旋酶作用下解聚,生成单链的成熟miRNA[4](图1)。图1
新窗口打开|下载原图ZIP|生成PPT图1miRNA的形成和功能 miRNA基因被RNA聚合酶Ⅱ
转录为初级miRNA(pri-miRNA)转录本。微处理器复合物(DGCR8-Drosha)将pri-miRNA加工成前体miRNA (pre-miRNA),然后通过转运蛋白exportin-5将其输出到细胞质中。Pre-miRNA被Dicer切割以产生成熟的miRNA。成熟的miRNA识别各自的靶标mRNA,募集RNA诱导的沉默复合物(RISC),并通过翻译抑制,腺苷酸化和/或增强mRNA降解来介导其靶标的转录后抑制。
Fig. 1The formation and function of miRNA
大多数的miRNA充当基因表达的负调控因子。miRNA通常靶向结合在信使RNA (messenger RNA, mRNA)的3′非翻译区(3′-untranslated region, 3′-UTR),导致基因降解或翻译抑制。内源miRNA的抑制活性取决于其是否加载到RNA诱导的沉默复合物(RNA- induced silencing complex, RISC)中。单链miRNA被载入Argonaute (AGO)蛋白,形成RISC复合物。复合物靶向结合到与互补的mRNA的3′-UTR上,进而调控靶mRNA的表达[3]。miRNA的作用方式与其与靶基因的互补性有关。当miRNA与靶mRNA之间完全配对互补时,可能影响靶mRNA的切割和降解[1]。当miRNA与靶mRNA之间不完全配对时,miRNA可能通过抑制翻译或促进mRNA去腺苷酸化和衰变来抑制蛋白质合成[5]。动物中大部分miRNA与靶mRNA之间不完全配对,故多为此种方式影响蛋白表达水平。然而,在某些情况下,一些miRNA能促进特定靶mRNA的翻译。例如,miRNA可通过与AGO2等蛋白质结合形成特定的复合物,在不同的静态(G0)细胞中激活靶基因的翻译[6]。
1.2 miRNA表达的调控
miRNA的生成和降解受到严格的调控,以保证特定的miRNA能在特定的时间、细胞表达适当的水平。一旦失调,将会引起下游靶基因的失控,进而导致疾病的发生[1]。目前的研究表明,miRNA的表达受到多个层面的调控：(1)转录水平的调控。位于基因间的miRNA由其独立的启动子启动转录,而位于内含子区的miRNA则可跟随宿主基因一起转录或独立转录。miRNA的启动子也受到转录因子、增强子、沉默元件和染色质修饰等调控[7]。目前,已报道参与 miRNA转录调控的转录因子约有75种,较常见的转录因子有NK-κB、c-Myc、p53和C/EBPα等。
(2)转录后水平的调控。miRNA基因转录后,从 pri-miRNA直到最后加工成熟并组装成RISC的全过程均受到机体精细的调控,其机制主要有RNA 编辑、miRNA微加工复合物的调控和RNA结合蛋白对特异miRNA的调控[2]。miRNA加工成熟过程中的关键分子Drosha和Dicer均需与相应的辅助分子组成复合体以发挥作用,以上分子的表达水平和活性也均受到精细的调控[2,7]。
(3)降解的调控。目前的研究表明,miRNA降解的调控主要包括腺苷或尿嘧啶残基的修饰、形成RNA-蛋白质复合体以及核酸酶的降解等[5]。此外,最近研究发现了一种新兴的miRNA的降解途径：TDMD (target RNA-directed microRNA degradation),即特异性靶RNA与具有广泛互补性的miRNA的结合,可触发结合的miRNA的降解[8]。
(4)表观遗传调控。据估计,约50% miRNA基因与CpG岛相关联,许多miRNA的表达受到DNA甲基化的影响[9]。也有研究表明,许多miRNA可同时接受甲基化和乙酰化的表观遗传学调控。近年研究显示,有些miRNA也可以反馈调节表观遗传机制,体现了miRNA调控网络的复杂性,也增加了基因调控系统的稳固性[9]。
2 miRNA与肾脏发育
2.1 肾脏发育的主要阶段
哺乳动物的肾脏起源于中胚层体节外侧的细胞索,即生肾索。在人类胚胎的第18天(embryonic day 18, E18)/小鼠(Mus musculus) E8.5时,肾脏开始出现。按时间顺序,肾脏发育经历前肾、中肾和后肾3个阶段。前肾和中肾是暂时性器官,在胚胎发育过程中相继退化,后肾则发育成为永久性肾脏[10]。在人类E22/小鼠E9.5时,生肾索头端的生肾节内开始形成前肾管。继而生肾索尾侧开始逐渐形成中肾管。人类E35/小鼠E10.5时,中肾导管尾端向背侧长出输尿管芽(ureter bud, UB)。输尿管芽顶端侵入间充质时,生肾索分化为后肾间充质(metanephric mesenchyme, MM)。UB和MM组成后肾,二者相互诱导,促使后肾发育成熟。UB逐级分支,最终形成完整的泌尿集合管系统。后肾间充质细胞则经历间充质-上皮转变,一部分分化为非上皮化的基质细胞,最终形成平滑肌、基质和肾的微脉管系统;另一部分分化形成肾单位,包括肾小体、近曲小管、髓袢和远曲小管[10]。
2.2 肾脏发育过程中miRNA的表达
尽管关于肾脏中的miRNA的相关研究日渐丰富,但关于miRNA在肾脏发育中作用的数据有限,其相关功能尚不清晰。近年来的测序研究确定了小鼠胚胎肾脏中miRNA的表达谱,促进了对肾脏发育中miRNA的研究[11,12]。Aguilar等[11]发现,在小鼠E12和E13时,胎肾中的miR-199b、miR-25、miR-27b和miR-200b表达非常丰富,而在成年肾脏组织中表达较少,这表明在肾脏发育过程中miRNA表达具有时间差异性。此外,从E12至E13,并至小鼠成年的过程中,肾脏中下调的miRNA还有miR-17、196a、15b、23b、20a、200c、93、26b、16、218和151-5p等;上调的miRNA有miR-320、351、652、107、103、322、106b、210、125b-5p、199a-5p和433等;而未发生变化的有miR-134、152、669b、15a、125-5p、126-5p、99b和let-7c等[11]。这些miRNA在发育过程中的时间差异性值得人们进一步探索。2.3 miRNA对肾脏发育的影响
大量研究提示miRNA在胚胎发育和分化中执行调节发育时机功能[13,14]。最近的一项研究发现,肾脏发育过程中具有时间差异表达的Lin28b/let-7轴可通过上调生长促进基因重组人胰岛素样生长因子-2 (insulin like growth factor-2, Igf2)来调节肾生成的停止,从而控制小鼠肾脏发育的持续时间[15]。这暗示了上述时间差异表达的miRNA在肾脏发育不同阶段起相应调控作用的潜能。另外一些研究通过特异性敲除肾脏组织/细胞中的miRNA或miRNA生物合成中的关键组件如Drosha和Dicer等,进而研究miRNA在肾脏发育中所起的作用[16,17]。这些胚胎发展出一系列肾脏缺陷,包括水肿形成、肾上皮分化延迟及肾小球数目减少等,直接或/和间接地说明了肾脏发育过程中miRNA基因调控的重要性(表1)。
Table 1
Table 1miRNA-knockout animal models related to kidney development
| 种属 | 组织/细胞特异性 | 敲除靶标 | 现象 | 参考文献 |
|---|---|---|---|---|
| 非洲爪蟾 (Xenopus laevis) | 非肾脏特异性 | Dicer、 Dgcr8 | 肾脏水肿,前肾导管中肾上皮细胞分化延迟,肾形态异常 | [16] |
| 小鼠 | 产生肾素的细胞 | Dicer | 成年肾脏中近球细胞数量严重减少,出现肾血管疾病和条纹状纤维化 | [18] |
| 小鼠 | 肾单位祖细胞 | Dicer | 肾单位祖细胞过早耗竭 | [19] |
| 小鼠 | 肾单位和UB来源的集合管系统 | Dicer | 肾单位祖细胞过早凋亡,UB分支缺陷 | [20] |
| 小鼠 | 肾小管和输尿管芽 | Dicer | 肾小管分支减少,肾单位减少,双侧肾积水 | [21] |
| 小鼠 | 前肾间充质 | Dicer | 输尿管芽分支和肾单位祖细胞分化失败 | [22] |
| 小鼠 | 肾祖细胞及其衍生物 | miR-17~ 92 | 肾单位数量减少,出生后发展为肾小球功能障碍和蛋白尿性肾脏疾病。 | [23] |
| 小鼠 | 泌尿生殖道和肾小管系统 | Dgcr8 | 出生后两个月内出现严重肾积水,肾囊肿,进行性肾衰竭 | [24] |
| 小鼠 | 肾脏基质细胞 | Dicer1 | 肾脏发育不良,肾小管和脉管系统异常分化 | [25] |
新窗口打开|下载CSV
2.3.1 miRNA与肾脏发育过程中的关键转录因子
研究表明,miRNA可能通过影响关键转录因子参与早期肾脏发育过程。肾单位祖细胞表达的几种转录因子,包括Six2、Sall1、Pax2和WT1等,对其增殖和存活以及随后的分化是必不可少的[26,27,28]。一项研究发现,在前肾间充质中消除了Dicer功能后,肾单位祖细胞中的Six2、Sall1、WT1、Pax2和Cited1等明显减少,且后肾间充质中促凋亡蛋白Bim明显增加,最终导致严重的肾发育不良[22]。有研究提出在胚胎干细胞中沉默let-7e时,WT1、Pax2和Wnt4被下调[29]。此外,有研究发现,miR-743a在体外可通过靶向WT1抑制后肾间充质干细胞细胞的增殖,因此其可能在肾脏发育和肾脏相关疾病中发挥重要功能[30]。这些研究提示了miRNA在早期肾脏器官发生期间对调节这些细胞谱系的存活起关键作用。
LIM级联的同源因子(LIM-class homeobox factor, Xlim1/Lhx1)是早期肾管形成和肾单位分化所必需的重要转录因子。它在肾脏发育过程中表现为需要严格控制的动态表达模式[31]。一项对非洲爪蟾前肾发育的研究表明,敲除肾脏中的miR-30a-5p可导致分化延迟,肾单位减小和增殖减少[16]。研究进一步发现,miR-30a-5p可靶向抑制Xlim1/Lhx1。在没有miR-30a-5p的情况下,Xlim1/Lhx1维持在高水平,从而导致肾上皮细胞的终末分化延迟[16]。此外,Lhx1也可与转录共激活因子Fryl协同作用,通过调控miR-199a/214和miR-23b/27b/24a簇的表达来调节早期肾脏发育[32]。这些研究表明,miRNA在调节前肾发育的过程中是不可或缺的。
2.3.2 miRNA与肾脏发育过程中的GDNF/Ret信号通路
在后肾发育过程中,输尿管芽的出芽和分支是关键步骤。胶质源性神经营养因子(glial-cell-line- derived neurotrophic factor, GDNF)/c-Ret酪氨酸激酶受体(c-Ret tyrosine kinase receptor, c-Ret)信号通路是输尿管芽分支的主要诱导者[33]。研究发现,在肾单位谱系和输尿管芽来源的集合管系统细胞内特异性敲除Dicer的小鼠中分支形态发生破坏,其表型与输尿管尖端的Wnt11和c-Ret表达的下调相关。因此,可推断Dicer通过影响Dicer依赖性miRNA活性,进而影响GDNF/c-Ret信号通路,在发育中的小鼠肾内起调节作用[34]。先前一些神经系统发育和疾病相关的研究显示,miR-9、miR-96、miR-133b和miR-146a通过与GDNF的3'UTR 相互作用抑制了GDNF的表达,并且在体内替换了对GDNF 的3'UTR序列反应较不敏感的miRNA和RNA结合蛋白可导致内源性GDNF表达增加(Gdnf hyper)[35]。最近一项研究发现,这种Gdnf hyper / hyper小鼠的肾脏体积较小且出现畸形[36]。证明了肾脏发育中GDNF的水平和功能受其3'UTR影响。这些研究提示在miRNA可通过影响GDNF/c-Ret信号通路而参与肾脏发育。
2.3.3 miRNA与肾脏发育过程中的TGF-β/BMP信号通路
骨形态发生蛋白(bone morphogenic proteins, BMPs)是转化生长因子-β (transforming growth factor-β, TGF-β)超家族生长因子的成员。肾脏发育过程中正常的输尿管芽和肾单位的发生需要BMP信号诱导,且BMP4基因突变可导致肾脏发育不良。最近的许多研究提供了miRNA与TGF-β/BMP信号通路关键基因相互影响的证据。
TGF-β/BMP信号通路调控miRNA水平的一种机制是其下游效应蛋白Smad与Drosha相互作用[37]。在血管平滑肌细胞中,Smad-Drosha相互作用可促进miR-21初级转录物加工成成熟的miR-21[37]。而miR-21在肾脏中也起着重要作用。有文章报道,miR-21因其促增殖和抗凋亡而在鱼的肾脏再生中起作用[38]。这些线索提示miR-21很可能参与肾脏发育,当然这可能也涉及除了TGF-β/BMP信号通路以外的机制。
许多研究表明,miRNA可通过TGF-β受体2 (TGF-beta receptor type-2, TGFβR2)参与上皮-间质转化(epithelial-mesenchymal transition, EMT)过程的调节。EMT涉及生理过程和各种病理事件的许多方面,不仅在和肾纤维化中起关键作用,也参与胚胎发育。研究证实TGFβR2是miR-302靶标。在肾小球系膜细胞中,miR-302d表达增加可导致TGFβR2表达降低[39]。miR-590也是靶向TGFβR2的EMT抑制性miRNA。miR-590的过表达可通过上调上皮细胞标志物E-钙粘蛋白来抑制EMT,并且在人肾2 (HK2)细胞系中下调间充质标记物laminin和α-SMA等[40]。另有研究发现miR-200a通过直接靶向近端小管上皮细胞中的β-catenin来抑制TGF-β1诱导的EMT[41]。miR-200家族也在早期肾脏中高表达[16],这提示高水平的miR-200可能在肾脏发育过程中保护肾脏上皮细胞免于自发的去分化。而miR-21过表达则可以通过抑制靶标Smad7,进而增强TGF-β1诱导的EMT[42]。let-7b/c也被证实可通过导致TGFβR1下调来抑制TGF-β/Smad信号激活[43]。这些研究均提示了miRNA与肾脏发育潜在的联系。
此外,在miRNA对涉及肾纤维化的关键分子的调节的研究中发现,miR-22和BMP-7/6处于调节反馈环路中,不仅miR-22抑制BMP-7/6表达,而且miR-22本身表达可由BMP-7/6诱导,此研究证明了miR-22在BMP信号级联中起关键作用[44]。尽管有大量miRNA与TGF-β/BMP信号传导相互影响的证据,但是在发育中的肾脏中,这些miRNA的功能在很大程度上还不确定,这也为未来miRNA与肾脏发育的研究提供了新的方向。
2.3.4 miRNA与肾脏发育过程中的肾素-血管紧张素系统
肾素-血管紧张素系统(renin-angiotensin system, RAS)是血压和液体/电解质稳态的主要调节器,也在控制正常肾脏发育中起着核心作用[45]。RAS系统主要成分包括：肾素、血管紧张素原、血管紧张素转换酶、血管紧张素I (angiotensin I, Ang I)、Ang Ⅱ、血管紧张素1型受体(angiotensin Ⅱ type 1 receptor, AT1R)和AT2R。RAS的所有组成部分在肾脏发育期间高度表达。Sequeira-Lopez等[18]通过构建在表达肾素的细胞中条件性敲除Dicer的小鼠,从而仅在产生肾素的细胞中选择性抑制miRNA的成熟。Dicer的敲除导致成年肾脏中近球细胞数量严重减少,同时肾素Ren1和Ren2的基因表达下降、血浆肾素浓度下降,并出现肾功能异常和严重的肾血管异常。这表明miRNA对于肾素细胞规格和肾血管正常发育是必需的。此外,一些在成年组织中的研究已证明miRNA可调节RAS中所有环节的蛋白质表达[46]。例如,内皮细胞、血管平滑肌细胞等细胞中的miR-155靶向抑制AT1R的表达,从而显着降低Ang II诱导的信号传导[47,48]。这也提示了miRNA在RAS信号传导调控中的重要地位。然而,对于肾脏发育过程中调控RAS组分的特定miRNA仍鲜有报道。
2.3.5 miRNA与肾脏发育过程中的HDAC
染色质修饰是一种表观遗传机制,可影响基因的转录活性。其中组蛋白脱乙酰酶(histone deacetylase, HDAC)在许多细胞过程中起重要作用,包括细胞周期、增殖、分化和细胞死亡[49]。一些对斑马鱼和小鼠的研究均表明了HDAC与前肾和后肾的发育有关。使用HDAC抑制剂处理斑马鱼胚胎中肾祖细胞数量增加,最终因肾祖细胞增生而导致肾功能受损[50]。将E13.5的小鼠肾脏用Scriptaid (I类和II类HDAC的抑制剂)培养后,后肾发育所必需的转录因子表达受到抑制,细胞正常的增殖和凋亡受到影响,最终导致肾脏发育不良[51]。这些研究提示HDAC对调节肾脏发育至关重要。有研究表明,高血糖可通过抑制miR-29a信号转导从而加剧HDAC4的作用,导致足细胞中蛋白质脱乙酰基及蛋白质降解,最终导致肾功能障碍[52]。也有研究发现,HDAC抑制剂治疗可通过刺激小鼠肾脏miR-9和miR-374基因的转录来抑制钙转运相关基因Claudin-14的表达,从而减少小鼠尿钙排泄[53]。这提示miRNA与HDAC的相互影响及其对下游靶基因的影响可能在肾脏稳态中起重要作用。虽然很少有报道具体研究它们在肾脏发育中的作用机制,但这些证据提供了miRNA和HDAC之间的互作与肾脏发育的联系,这也是值得我们未来深入研究的一个方向。
3 肾脏miRNA表达改变与肾脏发育异常
如前所述,一些研究通过敲除肾脏局部特定细胞谱系中miRNA生物合成关键酶的方法,探究了miRNA介导的基因调节在肾脏发育中的作用。结果发现,缺乏miRNA动物的肾脏表型出现各种先天性肾脏和泌尿道异常(congenital anomalies of kidney and urinary tract, CAKUT)[21]。那么,miRNA是否在胎儿肾脏发育异常的机制中发挥重要作用?这个问题在近年来引起了越来越多研究者的关注。3.1 引起肾脏发育异常的因素
近几十年的科学研究使人们对肾脏发育异常的认知越来越透彻。研究表明,遗传变异和胎儿环境的改变是导致胎儿肾脏异常发育的主要因素[54]。3.1.1 遗传变异
染色体异常、拷贝数变异和单基因遗传异常是导致CAKUT的最常见因素。目前,相关的人群研究和动物研究已证实了多个与CAKUT发病相关的基因,如Hnf1β、Pax2、Eya1、Six5、Ret、Sall1和WT1等[55]。其中常染色体Hnf1β显性突变是CAKUT 最常见的单基因病因,常与肾脏发育不全及无功能的多囊性发育不良肾脏有关[56]。另外,Ret的双等位基因失活基因突变与最严重的CAKUT表现即双侧肾发育不全有关[57]。此外,Pax2突变或表达异常多见于肾脏发育缺损或发育不良[58];Eya1/Six1的突变多与腮-耳-肾综合征有关[58]。
3.1.2 胎儿环境改变
胎儿环境改变是诱发CAKUT和肾脏发育迟缓的另一个重要因素[59]。大量研究表明,孕期暴露于不良环境可影响肾脏发育,导致肾单位数量降低,肾功能下降,并存在成年高血压和慢性肾脏病编程[60]。这些因素包括孕妇营养不良[61]、胎盘供血不足[62]、孕妇糖尿病[63]、糖皮质激素[64]、尼古丁[65]、酒精[66]、维生素A缺乏症[67]以及孕妇用药暴露(例如血管紧张素转换酶抑制剂、抗生素、霉酚酸酯、抗癫痫药物和环磷酰胺)等[60,63,68,69],其影响机制也得到了较为充分研究。
研究表明,母鼠孕期低蛋白饮食(low protein diet, LP)可致子代宫内发育迟缓(intrauterine growth retardation, IUGR),并表现有肾脏发育不良,可能与RAS抑制及Na+-ATP酶活性升高等有关[61]。本实验的系列动物研究也证实,孕期咖啡因、乙醇、尼古丁、地塞米松等外源物暴露均可影响胎儿肾脏RAS相关基因表达,导致子代肾脏发育不良[64,70~72]。此外,我们发现孕期咖啡因暴露也可通过KLF4低表达编程引发子代足细胞发育毒性,进而导致成年肾脏疾病易感[73]。而在孕期乙醇暴露的IUGR动物模型中,“GC-IGF1”轴编程改变也对肾脏发育不良及成年后肾小球硬化易感起到了至关重要的作用[70]。另外也有研究也提出,母亲吸烟可引起肾脏氧化应激、线粒体变化,对后代成年肾结构、血压、尿钠排泄造成影响[63]。此外,孕期地塞米松暴露也可通过影响Wnt4表达,进而影响TGF-β表达,导致细胞凋亡增加、促凋亡基因Bax增加及抗凋亡基因Bcl-2降低,进而造成肾单位数减少[74]。
3.2 miRNA表达的改变可能与参与肾脏发育异常
近年来,大量研究已表明miRNA表达失调与各种生物体和器官系统的发育缺陷表型有关。一些研究也提供了miRNA参与肾脏异常发育发病机制的证据。3.2.1 遗传变异所致肾脏异常发育中的miRNA
基因测序技术为基因组学的研究提供了便利,推动了miRNA在疾病中的相关研究。目前,只有少数研究在miRNA与特定的遗传变异的肾脏疾病之间建立了明确的联系。Jovanovic等[75]通过对19名CAKUT患者和9名对照的输尿管组织样本中收集的全基因组表达数据进行分析,鉴定出了7种可能在CAKUT中发挥潜在作用的miRNA：hsa-miR-144、hsa-miR-101、hsa-miR-375、hsa-miR-200a、hsa-miR- 183、hsa-miR-495和hsa-miR-222。其中hsa-miR-144被验证在CAKUT患者组织中表达显著增加,且可能与对肾脏和尿道正常发育至关重要的生物学过程有关[75]。但仍需进行进一步的功能分析以揭示这些特定miRNA在肾脏异常发育中的作用。研究发现,miR-17~92簇在胚胎的正常发育中似乎是必不可少的,其缺失可导致人类发育障碍的Feingold综合征,其特征包括肾脏发育缺陷[76]。此外多项研究表明,在多种多囊肾病小鼠模型中miR-17~92簇被上调,而miR-17~92簇的失活减慢了囊肿的增殖[77]。这主要是因为miR-17~92簇靶向抑制囊性肾脏疾病基因,包括Pkd1、Pkd2和Hnf1β。另一个被认为与常染色体显性遗传性多囊肾病有关的miRNA是miR-21,其在患有多囊肾病(polycystic kidney disease, PKD)的人和鼠的囊肿中表达增加。miR-21加剧囊肿生长的潜在机制可能涉及直接抑制促凋亡的肿瘤抑制因子PDCD4[78]。这些研究表明,miRNA是肾脏发育相关疾病发病机制的关键调节剂之一。
3.2.2 环境因素所致肾脏异常发育中的miRNA
在环境因素引起的肾脏异常发育中,miRNA的调控作用也可能起着关键作用。最近一项研究发现,怀孕的母鼠给予miRNA抑制剂后,在子代肾脏等脏器中可检测到miRNA水平持续显着降低。这表明孕期服用的一些可诱导miRNA表达的药物(如基于多西环素的四环素控制的反式激活剂和基于他莫昔芬的雌激素受体系统)可凭借母体-胎盘-胎儿传递,进而影响子代肾脏中miRNA表达[79]。此外,一项关于母体蛋白摄食限制的动物研究发现,LP后代大鼠(Rattus norvegicus)肾小球中一些miRNA显著下调,如miR-141 (71%)、miR-200a (50%)、miR-200b (60%)和miR-429 (59%)[80]。虽然这些研究未探究miRNA表达失调与子代肾脏发育异常的直接关系,但其表明了miRNA与环境因素所致肾脏异常发育的关联。更多miRNA的具体作用仍需得到更多的关注。
4 结语与展望
近些年来,miRNA作为肾脏发育和疾病中的重要调控分子备受研究者关注。随着研究的不断深入,越来越多的miRNA被发现在肾脏发育中差异表达,它们可通过影响关键生长因子或相关信号通路来参与肾脏发育过程。Drosha或Dicer等敲除的研究及肾脏发育相关疾病中的研究也提示了miRNA在肾脏发育中是必不可少的。但是,仍然存在许多问题需要解决：Drosha或Dicer的敲除可影响全部miRNA表达的改变,而单个miRNA或某miRNA簇参与肾脏发育过程的具体作用机制仍不明确;此外,miRNA在肾脏发育异常相关疾病中的确切作用仍然未知。未来的工作应侧重于阐明肾脏发育过程中单个或一系列miRNA的具体功能,了解其调控生理和在病理过程中的作用的精确机制,并充分利用先进的测序技术来探究在肾脏发育异常相关疾病中起关键作用的miRNA。肾脏发育中miRNA相关基因网络的构建将有助于进一步了解其在肾脏发育及相关疾病中的作用,并有望提出更具临床应用价值的肾脏疾病早期预警标志物及治疗靶标。参考文献 原文顺序
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被引期刊影响因子
DOI:10.1002/jcp.27486URLPMID:30471116 [本文引用: 3]
MicroRNAs (miRNAs) are a class of small noncoding RNAs, which function in posttranscriptional regulation of gene expression. They are powerful regulators of various cellular activities including cell growth, differentiation, development, and apoptosis. They have been linked to many diseases, and currently miRNA-mediated clinical trial has shown promising results for treatment of cancer and viral infection. This review provides an overview and update on miRNAs biogenesis, regulation of miRNAs expression, their biological functions, and role of miRNAs in epigenetics and cell-cell communication. In addition, alteration of miRNAs following exercise, their association with diseases, and therapeutic potential will be explained. Finally, miRNA bioinformatics tools and conventional methods for miRNA detection and quantification will be discussed.
DOI:10.1016/j.jaci.2017.08.034URLPMID:29074454 [本文引用: 5]
MicroRNAs (miRNAs) are small endogenous RNAs that regulate gene-expression posttranscriptionally. MiRNA research in allergy is expanding because miRNAs are crucial regulators of gene expression and promising candidates for biomarker development. MiRNA mimics and miRNA inhibitors currently in preclinical development have shown promise as novel therapeutic agents. Multiple technological platforms have been developed for miRNA isolation, miRNA quantitation, miRNA profiling, miRNA target detection, and modulating miRNA levels in vitro and in vivo. Here we will review the major technological platforms with consideration given for the advantages and disadvantages of each platform.
DOI:10.1681/ASN.2011080797URL [本文引用: 2]
MicroRNAs (miRNAs) are a group of small, noncoding RNAs that act as novel regulators of gene expression through the post-transcriptional repression of their target mRNAs. miRNAs have been implicated in diverse biologic processes, and it is estimated that up to half of all transcripts are regulated by miRNAs. Recent studies also demonstrate a critical role for miRNAs in renal development, physiology, and pathophysiology. Understanding the function of miRNAs in the kidney may lead to innovative approaches to renal disease.
[本文引用: 1]
[本文引用: 1]
DOI:10.1042/bse0540079URL [本文引用: 2]
DOI:10.1016/j.cell.2007.01.038URLPMID:17382880 [本文引用: 1]
AU-rich elements (AREs), present in mRNA 3'-UTRs, are potent posttranscriptional regulatory signals that can rapidly effect changes in mRNA stability and translation, thereby dramatically altering gene expression with clinical and developmental consequences. In human cell lines, the TNFalpha ARE enhances translation relative to mRNA levels upon serum starvation, which induces cell-cycle arrest. An in vivo crosslinking-coupled affinity purification method was developed to isolate ARE-associated complexes from activated versus basal translation conditions. We surprisingly found two microRNP-related proteins, fragile-X-mental-retardation-related protein 1 (FXR1) and Argonaute 2 (AGO2), that associate with the ARE exclusively during translation activation. Through tethering and shRNA-knockdown experiments, we provide direct evidence for the translation activation function of both FXR1 and AGO2 and demonstrate their interdependence for upregulation. This novel cell-growth-dependent translation activation role for FXR1 and AGO2 allows new insights into ARE-mediated signaling and connects two important posttranscriptional regulatory systems in an unexpected way.
DOI:10.1038/sj.embor.7401011URLPMID:17599088 [本文引用: 2]
MicroRNAs (miRNAs) mediate translational repression or degradation of their target messenger RNAs by RNA interference (RNAi). The primary transcripts of miRNA genes (pri-miRNAs) are sequentially processed by the nuclear Drosha-DGCR8 complex to approximately 60-70 nucleotide (nt) intermediates (pre-miRNAs) and then by the cytoplasmic Dicer-TRBP complex to approximately 20-22 nt mature miRNAs. Certain pri-miRNAs are subject to RNA editing that converts adenosine to inosine (A --> I RNA editing); however, the fate of edited pri-miRNAs is mostly unknown. Here, we provide evidence that RNA editing of pri-miR-151 results in complete blockage of its cleavage by Dicer and accumulation of edited pre-miR-151 RNAs. Our results indicate that A --> I conversion at two specific positions of the pre-miRNA foldback structure can affect its interaction with the Dicer-TRBP complex, showing a new regulatory role of A --> I RNA editing in miRNA biogenesis.
DOI:10.3389/fgene.2018.00435URLPMID:30333855 [本文引用: 1]
MicroRNAs are extensively studied regulatory non-coding small RNAs that silence animal genes throughout most biological processes, typically doing so by binding to partially complementary sequences within target RNAs. A plethora of studies has described detailed mechanisms for microRNA biogenesis and function, as well as their temporal and spatial regulation during development. By inducing translational repression and/or degradation of their target RNAs, microRNAs can contribute to achieve highly specific cell- or tissue-specific gene expression, while their aberrant expression can lead to disease. Yet an unresolved aspect of microRNA biology is how such small RNA molecules are themselves cleared from the cell, especially under circumstances where fast microRNA turnover or specific degradation of individual microRNAs is required. In recent years, it was unexpectedly found that binding of specific target RNAs to microRNAs with extensive complementarity can reverse the outcome, triggering degradation of the bound microRNAs. This emerging pathway, named TDMD for Target RNA-Directed MicroRNA Degradation, leads to microRNA 3'-end tailing by the addition of A/U non-templated nucleotides, trimming or shortening from the 3' end, and highly specific microRNA loss, providing a new layer of microRNA regulation. Originally described in flies and known to be triggered by viral RNAs, novel endogenous instances of TDMD have been uncovered and are now starting to be understood. Here, we review our current knowledge of this pathway and its potential role in the control and diversification of microRNA expression patterns.
DOI:10.7150/ijbs.19032URLPMID:28539830 [本文引用: 2]
MicroRNA-370 (miR-370) has been observed to act as a tumor suppressor through the targeting of different proteins in a variety of tumors. Our previous study indicated that miR-370 was able to target forkhead box protein M1 (FOXM1) to inhibit cell growth and metastasis in human osteosarcoma cells. In this study, we reported that FOXM1 interacted with beta-catenin in vitro and in vivo. Similar to FOXM1, critical components of the Wnt signaling pathway, including beta-catenin, c-Myc, and Cyclin D1, were also highly expressed in different human osteosarcoma cells lines. Pharmacological inhibition of FOXM1 or beta-catenin but not of c-Myc was associated with the increased expression of miR-370. Ectopic expression of miR-370 inhibited the downstream signaling of beta-catenin. Moreover, osteosarcoma cells treated with 5-AZA-2'-deoxycytidine (AZA), a DNA methylation inhibitor, exhibited increased levels of miR-370 and decreased levels of beta-catenin downstream targets, which resulted in inhibition of cell proliferation and colony formation ability. In conclusion, our results supported a model in which the DNA methylation-mediated down-regulation of miR-370 reduced its inhibitory effect on FOXM1, thereby promoting FOXM1-beta-catenin interaction and activating the Wnt/beta-Catenin signaling pathway in human osteosarcoma cells.
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As in most organs, the emerging theme in kidney development is the importance of cross-talk between several tissues and cell lineages to allow morphogenesis to proceed in a complex but highly regulated way. Over the past few years, knock-out and transgenic analyses in mice and evolutionary comparison with non-mammalian species have been particularly instrumental in identifying molecules with crucial functions for tissue-tissue interactions. The transcription factors Wt1 and Eya1, the signalling molecules Gdnf and LIF and the receptors c-Ret and GdnfRalpha have been demonstrated to fulfil fundamental roles in the first step of metanephric induction, the outgrowth of the ureter. Signalling by members of the Wnt, BMP and FGF families, regulated by transcription factors such as Pax2, mediates nephrogenesis by adjusting the balance between the ureteric bud epithelium, stromal and nephrogenic tissues. The stromal tissue, neglected for many years, has been shown to serve important functions in regulating the growth of nephrons. Finally, we have also begun to gain insight into the molecular events underlying patterning of the nephron into distinct functional units including glomerulus, proximal and distal tubule.
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microRNAs (miRNAs) are small non-coding RNAs with fundamental roles in the regulation of gene expression. miRNAs assemble with Argonaute (Ago) proteins to miRNA-protein complexes (miRNPs), which interact with distinct binding sites on mRNAs and regulate gene expression. Specific miRNAs are key regulators of tissue and organ development and it has been shown in mammals that miRNAs are also involved in the pathogenesis of many diseases including cancer. Here, we have characterized the miRNA expression profile of the developing murine genitourinary system. Using a computational approach, we have identified several miRNAs that are specific for the analyzed tissues or the developmental stage. Our comprehensive miRNA expression atlas of the developing genitourinary system forms an invaluable basis for further functional in vivo studies.
DOI:10.1002/dvdy.24221URLPMID:25369991 [本文引用: 1]
BACKGROUND: Our previous study on mouse mutants with the ureteric bud (UB) epithelium-specific Dicer deletion (Dicer UB mutants) demonstrated the significance of UB epithelium-derived miRNAs in UB development. RESULTS: Our whole-genome transcriptional profiling showed that the Dicer mutant UB epithelium abnormally retained transcriptional features of the early UB epithelium and failed to express many genes associated with collecting duct differentiation. Furthermore, we identified a temporal expression pattern of early UB genes during UB epithelium development in which gene expression was detected at early developmental stages and became undetectable by embryonic day 14.5. In contrast, expression of early UB genes persisted at later stages in the Dicer mutant UB epithelium and increased at early stages. Our bioinformatic analysis of the abnormally persistently expressed early genes in the Dicer mutant UB epithelium showed significant enrichment of the let-7 family miRNA targets. We further identified a temporal expression pattern of let-7 miRNAs in the UB epithelium that is anti-parallel to that of some early UB genes during kidney development. CONCLUSIONS: We propose a model in which the let-7 family miRNAs silence the expression of a subset of early genes in the UB epithelium at later developmental stages to promote collecting duct differentiation. Developmental Dynamics 244:444-456, 2015. (c) 2014 Wiley Periodicals, Inc.
DOI:10.1016/j.gde.2011.04.003URL [本文引用: 1]
MicroRNAs regulate temporal transitions in gene expression associated with cell fate progression and differentiation throughout animal development. Genetic analysis of developmental timing in the nematode Caenorhabditis elegans identified two evolutionarily conserved microRNAs, lin-4/mir-125 and let-7, that regulate cell fate progression and differentiation in C. elegans cell lineages. MicroRNAs perform analogous developmental timing functions in other animals, including mammals. By regulating cell fate choices and transitions between pluripotency and differentiation, microRNAs help to orchestrate developmental events throughout the developing animal, and to play tissue homeostasis roles important for disease, including cancer.
DOI:10.1002/dvdy.20599URLPMID:16247770 [本文引用: 1]
In C. elegans, heterochronic genes control the timing of cell fate determination during development. Two heterochronic genes, let-7 and lin-4, encode microRNAs (miRNAs) that down-regulate a third heterochronic gene lin-41 by binding to complementary sites in its 3'UTR. let-7 and lin-4 are conserved in mammals. Here we report the cloning and sequencing of mammalian lin-41 orthologs. We find that mouse and human lin-41 genes contain predicted conserved complementary sites for let-7 and the lin-4 ortholog, mir-125, in their 3'UTRs. Mouse lin-41 (Mlin-41) is temporally expressed in developing mouse embryos, most dramatically in the limb buds. Mlin-41 is down-regulated during mid-embryogenesis at the time when mouse let-7c and mir-125 RNA levels are up-regulated. Our results suggest that mammalian lin-41 is temporally regulated by miRNAs in order to direct key developmental events such as limb formation.
DOI:10.1038/s41467-018-08127-4URLPMID:30635573 [本文引用: 1]
In humans and in mice the formation of nephrons during embryonic development reaches completion near the end of gestation, after which no new nephrons are formed. The final nephron complement can vary 10-fold, with reduced nephron number predisposing individuals to hypertension, renal, and cardiovascular diseases in later life. While the heterochronic genes lin28 and let-7 are well-established regulators of developmental timing in invertebrates, their role in mammalian organogenesis is not fully understood. Here we report that the Lin28b/let-7 axis controls the duration of kidney development in mice. Suppression of let-7 miRNAs, directly or via the transient overexpression of LIN28B, can prolong nephrogenesis and enhance kidney function potentially via upregulation of the Igf2/H19 locus. In contrast, kidney-specific loss of Lin28b impairs renal development. Our study reveals mechanisms regulating persistence of nephrogenic mesenchyme and provides a rationale for therapies aimed at increasing nephron mass.
DOI:10.1242/dev.037432URLPMID:19906860 [本文引用: 5]
MicroRNAs (miRNAs) are small non-coding RNA molecules that regulate gene expression at the post-transcriptional level. They are involved in diverse biological processes, such as development, differentiation, cell proliferation and apoptosis. To study the role of miRNAs during pronephric kidney development of Xenopus, global miRNA biogenesis was eliminated by knockdown of two key components: Dicer and Dgcr8. These embryos developed a range of kidney defects, including edema formation, delayed renal epithelial differentiation and abnormal patterning. To identify a causative miRNA, mouse and frog kidneys were screened for putative candidates. Among these, the miR-30 family showed the most prominent kidney-restricted expression. Moreover, knockdown of miR-30a-5p phenocopied most of the pronephric defects observed upon global inhibition of miRNA biogenesis. Molecular analyses revealed that miR-30 regulates the LIM-class homeobox factor Xlim1/Lhx1, a major transcriptional regulator of kidney development. miR-30 targeted Xlim1/Lhx1 via two previously unrecognized binding sites in its 3'UTR and thereby restricted its activity. During kidney development, Xlim1/Lhx1 is required in the early stages, but is downregulated subsequently. However, in the absence of miR-30 activity, Xlim1/Lhx1 is maintained at high levels and, therefore, may contribute to the delayed terminal differentiation of the amphibian pronephros.
URLPMID:28446592 [本文引用: 1]
DOI:10.1681/ASN.2009090964URLPMID:20056748 [本文引用: 2]
Juxtaglomerular cells are highly specialized myoepithelioid granulated cells located in the glomerular afferent arterioles. These cells synthesize and release renin, which distinguishes them from other cells. How these cells maintain their identity, restricted localization, and fate is unknown and is fundamental to the control of BP and homeostasis of fluid and electrolytes. Because microRNAs may control cell fate via temporal and spatial gene regulation, we generated mice with a conditional deletion of Dicer, the RNase III endonuclease that produces mature microRNAs in cells of the renin lineage. Deletion of Dicer severely reduced the number of juxtaglomerular cells, decreased expression of the renin genes (Ren1 and Ren2), lowered plasma renin concentration, and decreased BP. As a consequence of the disappearance of renin-producing cells, the kidneys developed striking vascular abnormalities and prominent striped fibrosis. We conclude that microRNAs maintain the renin-producing juxtaglomerular cells and the morphologic integrity and function of the kidney.
DOI:10.1681/ASN.2010080841URL [本文引用: 1]
Understanding the mechanisms that regulate nephron progenitors during kidney development should aid development of therapies for renal failure. MicroRNAs, which modulate gene expression through post-transcriptional repression of specific target mRNAs, contribute to the differentiation of stem cells, but their role in nephrogenesis is incompletely understood. Here, we found that the loss of miRNAs in nephron progenitors results in a premature depletion of this population during kidney development. Increased apoptosis and expression of the pro-apoptotic protein Bim accompanied this depletion. Profiling of miRNA expression during nephrogenesis identified several highly expressed miRNAs (miR-10a, nniR-106b, miR-17-5p) in nephron progenitors that are either known or predicted to target Bim. We propose that modulation of apoptosis by miRNAs may determine congenital nephron endowment. Furthermore, our data implicate the pro-apoptotic protein Bim as a miRNA target in nephron progenitors.
DOI:10.1038/ki.2010.385URL [本文引用: 1]
MicroRNAs (miRNAs) are a large and growing class of small, non-coding, regulatory RNAs that control gene expression predominantly at the post-transcriptional level. The production of most functional miRNAs depends on the enzymatic activity of Dicer, an RNase III class enzyme. To address the potential action of Dicer-dependent miRNAs in mammalian kidney development, we conditionally ablated Dicer function within cells of nephron lineage and the ureteric bud-derived collecting duct system. Six2Cre-mediated removal of Dicer activity from the progenitors of the nephron epithelium led to elevated apoptosis and premature termination of nephrogenesis. Thus, Dicer action is important for maintaining the viability of this critical self-renewing progenitor pool and, consequently, development of a normal nephron complement. HoxB7Cre-mediated removal of Dicer function from the ureteric bud epithelium led to the development of renal cysts. This was preceded by excessive cell proliferation and apoptosis, and accompanied by disrupted ciliogenesis within the ureteric bud epithelium. Dicer removal also disrupted branching morphogenesis with the phenotype correlating with downregulation of Wnt11 and c-Ret expression at ureteric tips. Thus Dicer, and by inference Dicer-dependent miRNA activity, have distinct regulatory roles within different components of the developing mouse kidney. Furthermore, an understanding of miRNA action may provide new insights into the etiology and pathogenesis of renal cyst-based kidney disease. Kidney International (2011) 79, 317-330; doi:10.1038/ki.2010.385; published online 13 October 2010
DOI:10.1007/s00109-013-1000-xURL [本文引用: 2]
DOI:10.1152/ajprenal.00426.2013URLPMID:24500693 [本文引用: 2]
MicroRNAs (miRNAs) are small, noncoding regulatory RNAs that act as posttranscriptional repressors by binding to the 3'-untranslated region (3'-UTR) of target genes. They require processing by Dicer, an RNase III enzyme, to become mature regulatory RNAs. Previous work from our laboratory revealed critical roles for miRNAs in nephron progenitors at midgestation (Ho J, Pandey P, Schatton T, Sims-Lucas S, Khalid M, Frank MH, Hartwig S, Kreidberg JA. J Am Soc Nephrol 22: 1053-1063, 2011). To interrogate roles for miRNAs in the early metanephric mesenchyme, which gives rise to nephron progenitors as well as the renal stroma during kidney development, we conditionally ablated Dicer function in this lineage. Despite normal ureteric bud outgrowth and condensation of the metanephric mesenchyme to form nephron progenitors, early loss of miRNAs in the metanephric mesenchyme resulted in severe renal dysgenesis. Nephron progenitors are initially correctly specified in the mutant kidneys, with normal expression of several transcription factors known to be critical in progenitors, including Six2, Pax2, Sall1, and Wt1. However, there is premature loss of the nephron progenitor marker Cited1, marked apoptosis, and increased expression of the proapoptotic protein Bim shortly after the initial inductive events in early kidney development. Subsequently, there is a failure in ureteric bud branching and nephron progenitor differentiation. Taken together, our data demonstrate a previously undetermined requirement for miRNAs during early kidney organogenesis and indicate a crucial role for miRNAs in regulating the survival of this lineage.
DOI:10.1681/ASN.2013040390URL [本文引用: 1]
Deletion of all microRNAs (miRNAs) in nephron progenitors leads to premature loss of these cells, but the roles of specific miRNAs in progenitors have not been identified. Deletions in the MIR17HG cluster (miR-17 similar to 92 in mice), detected in a subset of patients with Feingold syndrome, represent the first miRNA mutations to be associated with a developmental defect in humans. Although MIR17HG is expressed in the developing kidney, and patients with Feingold syndrome caused by MYCN mutations have renal anomalies, it remains unclear to what extent MIR17HG contributes to renal development and function. To define the role of miR-17 similar to 92, we generated mice with a conditional deletion of miR-17 similar to 92 in nephron progenitors and their derivatives. The nephron progenitor population was preserved in these mice; however, this deletion impaired progenitor cell proliferation and reduced the number of developing nephrons. Postnatally, mutant mice developed signs of renal disease, including albuminuria by 6 weeks and focal podocyte foot process effacement and glomerulosclerosis at 3 months. Taken together, these data support a role for this miRNA cluster in renal development, specifically in the regulation of nephron development, with subsequent consequences for renal function in adult mice.
DOI:10.1186/s12882-015-0053-1URLPMID:25881298 [本文引用: 1]
BACKGROUND: Small non-coding RNA molecules (miRNAs) play a pivotal role in regulating gene expression in development. miRNAs regulate key processes at the cellular level and thereby influence organismal and tissue development including kidney morphogenesis. A miRNA molecule is initially synthesized as a longer hairneedle-shaped RNA transcript and then processed through an enzymatic complex that contains the RNA-processing enzyme Drosha and its essential interactor Dgcr8. Resulting pre-miRNAs are then cleaved by Dicer. Recent data showed that loss of Dicer resulted in severe developmental kidney phenotypes. However, as Dicer has multiple miRNA-independent functions, it was not entirely clear whether the observed renal phenotypes could be exclusively attributed to a lack of miRNA expression. METHODS: We analyzed the role of miRNAs in kidney development by conditional gene deletion of Dgcr8 in the developing kidney using a transgenic mouse line that expresses Cre recombinase in the distal nephron and derivatives of the ureteric bud in kidney development. RESULTS: Animals with a gene deletion of Dgcr8 in these tissues developed severe hydronephrosis, kidney cysts, progressive renal failure and premature death within the first two months after birth, a phenotype strongly resembling Dicer deletion. CONCLUSIONS: Here we show that conditional gene deletion of the essential miRNA-processing enzyme Dgcr8 in the developing renal tubular system results in severe developmental defects and kidney failure. These data confirm earlier findings obtained in Dicer knock-out animals and clearly illustrate the essential role of miRNAs in kidney development. The data suggests that miRNA dysregulation may play an important, yet ill-defined role in the pathogenesis of inborn defects of the genitourinary system and indicate that miRNA defects may be causative in the development of human disease.
DOI:10.1038/ki.2014.406URLPMID:25651362 [本文引用: 1]
MicroRNAs, activated by the enzyme Dicer1, control post-transcriptional gene expression. Dicer1 has important roles in the epithelium during nephrogenesis, but its function in stromal cells during kidney development is unknown. To study this, we inactivated Dicer1 in renal stromal cells. This resulted in hypoplastic kidneys, abnormal differentiation of the nephron tubule and vasculature, and perinatal mortality. In mutant kidneys, genes involved in stromal cell migration and activation were suppressed as were those involved in epithelial and endothelial differentiation and maturation. Consistently, polarity of the proximal tubule was incorrect, distal tubule differentiation was diminished, and elongation of Henle's loop attenuated resulting in lack of inner medulla and papilla in stroma-specific Dicer1 mutants. Glomerular maturation and capillary loop formation were abnormal, whereas peritubular capillaries, with enhanced branching and increased diameter, formed later. In Dicer1-null renal stromal cells, expression of factors associated with migration, proliferation, and morphogenic functions including alpha-smooth muscle actin, integrin-alpha8, -beta1, and the WNT pathway transcriptional regulator LEF1 were reduced. Dicer1 mutation in stroma led to loss of expression of distinct microRNAs. Of these, miR-214, -199a-5p, and -199a-3p regulate stromal cell functions ex vivo, including WNT pathway activation, migration, and proliferation. Thus, Dicer1 activity in the renal stromal compartment regulates critical stromal cell functions that, in turn, regulate differentiation of the nephron and vasculature during nephrogenesis.
DOI:10.1016/0092-8674(93)90515-rURLPMID:8395349 [本文引用: 1]
In humans, germline mutations of the WT-1 tumor suppressor gene are associated with both Wilms' tumors and urogenital malformations. To develop a model system for the molecular analysis of urogenital development, we introduced a mutation into the murine WT-1 tumor suppressor gene by gene targeting in embryonic stem cells. The mutation resulted in embryonic lethality in homozygotes, and examination of mutant embryos revealed a failure of kidney and gonad development. Specifically, at day 11 of gestation, the cells of the metanephric blastema underwent apoptosis, the ureteric bud failed to grow out from the Wolffian duct, and the inductive events that lead to formation of the metanephric kidney did not occur. In addition, the mutation caused abnormal development of the mesothelium, heart, and lungs. Our results establish a crucial role for WT-1 in early urogenital development.
URLPMID:8187639 [本文引用: 1]
The conversion of mesenchyme to epithelium during the embryonic development of the mammalian kidney requires reciprocal inductive interactions between the ureter and the responding metanephric mesenchyme. The Pax-2 gene is activated in the mesenchyme in response to induction and is subsequently down-regulated in more differentiated cells derived from the mesenchyme. Pax-2 belongs to a family of genes, at least three of which encode morphogenetic regulatory transcription factors. In order to determine the role of Pax-2 during kidney development, we have generated a loss-of-function phenotype using antisense oligonucleotides in mouse kidney organ cultures. These oligonucleotides can specifically inhibit Pax-2 protein accumulation in kidney mesenchyme cells, where the intracellular concentrations are maximal. The kidney organ cultures were stained with uvomurulin and laminin antibodies as markers for epithelium formation. With significantly reduced Pax-2 protein levels, kidney mesenchyme cells fail to aggregate and do not undergo the sequential morphological changes characteristic of epithelial cell formation. The data demonstrate that Pax-2 function is required for the earliest phase of mesenchyme-to-epithelium conversion.
DOI:10.1016/j.trsl.2014.04.007URLPMID:24958601 [本文引用: 1]
The study of epigenetics is intimately linked and inseparable from developmental biology. Many of the genes that imprint epigenetic information on chromatin function during the specification of cell lineages in the developing embryo. These include the histone methyltransferases and their cofactors of the Polycomb and Trithorax gene families. How histone methylation is established and what regulates the tissue and locus specificity of histone methylation is an emerging area of research. The embryonic kidney is used as a model to understand how DNA-binding proteins can specify cell lineages and how such proteins interact directly with the histone methylation machinery to generate a unique epigenome for particular tissues and cell types. In adult tissues, histone methylation marks must be maintained for normal gene expression patterns. In chronic and acute renal disease, epigenetic marks are being characterized and correlated with the establishment of metabolic memory, in part to explain the persistence of pathologies even when optimal treatment modalities are used. Thus, the state of the epigenome in adult cells must be considered when attempting to alleviate or alter gene expression patterns in disease.
DOI:10.1371/journal.pone.0060937URLPMID:23593353 [本文引用: 1]
This study indicates that embryonic stem cells [ESCs] cultured with retinoic acid and activin A significantly upregulate the miRNA let-7e. This specific miRNA modulates the Wnt pathway and the expression of early nephrogenic markers under these differentiation conditions. The differentiation markers WT1, Pax2 and Wnt4 were downregulated when miRNA let-7e was silenced, thus indicating the role of miRNA let-7e in the differentiation process. PKCbeta, GSK3beta phosphorylation (GSK3beta(P)) and beta-catenin expression was reduced in differentiated cells and reversed by miRNA let-7e silencing. Addition of a PKCbeta inhibitor to the miRNA let-7e silenced cells abolished let-7e-derived effects in differentiation markers, and reversed the increase in GSK3beta(P) and beta-catenin, thus indicating that miRNA let-7e is involved in differentiation via the modulation of GSK3beta phosphorylation and beta-catenin production.
DOI:10.3892/mmr.2016.5762URLPMID:27667021 [本文引用: 1]
To seek out the potential microRNAs (miRNAs) that target Wilms' tumor suppressor 1 (WT1), a transcription factor required for progenitor proliferation as well as normal development of the kidney, and to clarify the effects of the miRNAs on WT1, the 3'-untranslated region (3'UTR) of WT1 was initially analyzed and miR743a, a seldomreported miRNA, was identified. In the present paper, luciferase reporter assays were performed to confirm that miR743a is able to directly target the 3'UTR of WT1. Subsequently, reverse transcriptionquantitative polymerase chain reaction, combined with western blotting analyses, were performed, and the results revealed a significant inhibition of WT1 at the mRNA and the protein levels. Furthermore, a 5ethynyl2'deoxyuridine (EdU) cell proliferation assay, coupled with a WT1 rescue strategy, demonstrated that miR743a inhibited the proliferation of metanephric mesenchymal (MM) cells, in part by targeting WT1. In conclusion, by targeting WT1, miR743a suppresses the proliferation of MM cells in vitro, and probably possesses vital functions in kidney development and kidneyassociated diseases.
DOI:10.1146/annurev.cellbio.22.010305.104340URLPMID:16822174 [本文引用: 1]
Mammalian kidney development has helped elucidate the general concepts of mesenchymal-epithelial interactions, inductive signaling, epithelial cell polarization, and branching morphogenesis. Through the use of genetically engineered mouse models, the manipulation of Xenopus and chick embryos, and the identification of human renal disease genes, the molecular bases for many of the early events in the developing kidney are becoming increasingly clear. Early patterning of the kidney region depends on interactions between Pax/Eya/Six genes, with essential roles for lim1 and Odd1. Ureteric bud outgrowth and branching morphogenesis are controlled by the Ret/Gdnf pathway, which is subject to positive and negative regulation by a variety of factors. A clear role for Wnt proteins in induction of the kidney mesenchyme is now well established and complements the classic literature nicely. Patterning along the proximal distal axis as the nephron develops is now being investigated and must involve aspects of Notch signaling. The development of a glomerulus requires interactions between epithelial cells and infiltrating endothelial cells to generate a unique basement membrane. The integrity of the glomerular filter depends in large part on the proteins of the nephrin complex, localized to the slit diaphragm. Despite the kidney's architectural complexity, with the advent of genomics and expression arrays, it is becoming one of the best-characterized organ systems in developmental biology.
DOI:10.1038/s41598-018-34038-xURLPMID:30375416 [本文引用: 1]
The molecular events driving specification of the kidney have been well characterized. However, how the initial kidney field size is established, patterned, and proportioned is not well characterized. Lhx1 is a transcription factor expressed in pronephric progenitors and is required for specification of the kidney, but few Lhx1 interacting proteins or downstream targets have been identified. By tandem-affinity purification, we isolated FRY like transcriptional coactivator (Fryl), one of two paralogous genes, fryl and furry (fry), have been described in vertebrates. Both proteins were found to interact with the Ldb1-Lhx1 complex, but our studies focused on Lhx1/Fry functional roles, as they are expressed in overlapping domains. We found that Xenopus embryos depleted of fry exhibit loss of pronephric mesoderm, phenocopying the Lhx1-depleted animals. In addition, we demonstrated a synergism between Fry and Lhx1, identified candidate microRNAs regulated by the pair, and confirmed these microRNA clusters influence specification of the kidney. Therefore, our data shows that a constitutively-active Ldb1-Lhx1 complex interacts with a broadly expressed microRNA repressor, Fry, to establish the kidney field.
DOI:10.1242/dev.00520URLPMID:12783789 [本文引用: 1]
Reciprocal cell-cell interactions between the ureteric epithelium and the metanephric mesenchyme are needed to drive growth and differentiation of the embryonic kidney to completion. Branching morphogenesis of the Wolffian duct derived ureteric bud is integral in the generation of ureteric tips and the elaboration of the collecting duct system. Wnt11, a member of the Wnt superfamily of secreted glycoproteins, which have important regulatory functions during vertebrate embryonic development, is specifically expressed in the tips of the branching ureteric epithelium. In this work, we explore the role of Wnt11 in ureteric branching and use a targeted mutation of the Wnt11 locus as an entrance point into investigating the genetic control of collecting duct morphogenesis. Mutation of the Wnt11 gene results in ureteric branching morphogenesis defects and consequent kidney hypoplasia in newborn mice. Wnt11 functions, in part, by maintaining normal expression levels of the gene encoding glial cell-derived neurotrophic factor (Gdnf). Gdnf encodes a mesenchymally produced ligand for the Ret tyrosine kinase receptor that is crucial for normal ureteric branching. Conversely, Wnt11 expression is reduced in the absence of Ret/Gdnf signaling. Consistent with the idea that reciprocal interaction between Wnt11 and Ret/Gdnf regulates the branching process, Wnt11 and Ret mutations synergistically interact in ureteric branching morphogenesis. Based on these observations, we conclude that Wnt11 and Ret/Gdnf cooperate in a positive autoregulatory feedback loop to coordinate ureteric branching by maintaining an appropriate balance of Wnt11-expressing ureteric epithelium and Gdnf-expressing mesenchyme to ensure continued metanephric development.
DOI:10.1038/tp.2015.11URL [本文引用: 1]
DOI:10.1371/journal.pgen.1005710URLPMID:26681446 [本文引用: 1]
Degeneration of nigrostriatal dopaminergic system is the principal lesion in Parkinson's disease. Because glial cell line-derived neurotrophic factor (GDNF) promotes survival of dopamine neurons in vitro and in vivo, intracranial delivery of GDNF has been attempted for Parkinson's disease treatment but with variable success. For improving GDNF-based therapies, knowledge on physiological role of endogenous GDNF at the sites of its expression is important. However, due to limitations of existing genetic model systems, such knowledge is scarce. Here, we report that prevention of transcription of Gdnf 3'UTR in Gdnf endogenous locus yields GDNF hypermorphic mice with increased, but spatially unchanged GDNF expression, enabling analysis of postnatal GDNF function. We found that increased level of GDNF in the central nervous system increases the number of adult dopamine neurons in the substantia nigra pars compacta and the number of dopaminergic terminals in the dorsal striatum. At the functional level, GDNF levels increased striatal tissue dopamine levels and augmented striatal dopamine release and re-uptake. In a proteasome inhibitor lactacystin-induced model of Parkinson's disease GDNF hypermorphic mice were protected from the reduction in striatal dopamine and failure of dopaminergic system function. Importantly, adverse phenotypic effects associated with spatially unregulated GDNF applications were not observed. Enhanced GDNF levels up-regulated striatal dopamine transporter activity by at least five fold resulting in enhanced susceptibility to 6-OHDA, a toxin transported into dopamine neurons by DAT. Further, we report how GDNF levels regulate kidney development and identify microRNAs miR-9, miR-96, miR-133, and miR-146a as negative regulators of GDNF expression via interaction with Gdnf 3'UTR in vitro. Our results reveal the role of GDNF in nigrostriatal dopamine system postnatal development and adult function, and highlight the importance of correct spatial expression of GDNF. Furthermore, our results suggest that 3'UTR targeting may constitute a useful tool in analyzing gene function.
DOI:10.1038/s41598-019-40457-1URLPMID:30923332 [本文引用: 1]
Mechanisms controlling ureter lenght and the position of the kidney are poorly understood. Glial cell-line derived neurotrophic factor (GDNF) induced RET signaling is critical for ureteric bud outgrowth, but the function of endogenous GDNF in further renal differentiation and urogenital system development remains discursive. Here we analyzed mice where 3' untranslated region (UTR) of GDNF is replaced with sequence less responsive to microRNA-mediated regulation, leading to increased GDNF expression specifically in cells naturally transcribing Gdnf. We demonstrate that increased Gdnf leads to short ureters in kidneys located in an abnormally caudal position thus resembling human pelvic kidneys. High GDNF levels expand collecting ductal progenitors at the expense of ureteric trunk elongation and result in expanded tip and short trunk phenotype due to changes in cell cycle length and progenitor motility. MEK-inhibition rescues these defects suggesting that MAPK-activity mediates GDNF's effects on progenitors. Moreover, Gdnf (hyper) mice are infertile likely due to effects of excess GDNF on distal ureter remodeling. Our findings suggest that dysregulation of GDNF levels, for example via alterations in 3'UTR, may account for a subset of congenital anomalies of the kidney and urinary tract (CAKUT) and/or congenital infertility cases in humans and pave way to future studies.
DOI:10.1038/nature07086URLPMID:18548003 [本文引用: 2]
MicroRNAs (miRNAs) are small non-coding RNAs that participate in the spatiotemporal regulation of messenger RNA and protein synthesis. Aberrant miRNA expression leads to developmental abnormalities and diseases, such as cardiovascular disorders and cancer; however, the stimuli and processes regulating miRNA biogenesis are largely unknown. The transforming growth factor beta (TGF-beta) and bone morphogenetic protein (BMP) family of growth factors orchestrates fundamental biological processes in development and in the homeostasis of adult tissues, including the vasculature. Here we show that induction of a contractile phenotype in human vascular smooth muscle cells by TGF-beta and BMPs is mediated by miR-21. miR-21 downregulates PDCD4 (programmed cell death 4), which in turn acts as a negative regulator of smooth muscle contractile genes. Surprisingly, TGF-beta and BMP signalling promotes a rapid increase in expression of mature miR-21 through a post-transcriptional step, promoting the processing of primary transcripts of miR-21 (pri-miR-21) into precursor miR-21 (pre-miR-21) by the DROSHA (also known as RNASEN) complex. TGF-beta- and BMP-specific SMAD signal transducers are recruited to pri-miR-21 in a complex with the RNA helicase p68 (also known as DDX5), a component of the DROSHA microprocessor complex. The shared cofactor SMAD4 is not required for this process. Thus, regulation of miRNA biogenesis by ligand-specific SMAD proteins is critical for control of the vascular smooth muscle cell phenotype and potentially for SMAD4-independent responses mediated by the TGF-beta and BMP signalling pathways.
DOI:10.1186/s12861-015-0089-2URLPMID:26577279 [本文引用: 1]
BACKGROUND: Acute kidney injury in mammals, which is caused by cardiovascular diseases or the administration of antibiotics with nephrotoxic side-effects is a life-threatening disease, since loss of nephrons is irreversible in mammals. In contrast, fish are able to generate new nephrons even in adulthood and thus provide a good model to study renal tubular regeneration. RESULTS: Here, we investigated the early response after gentamicin-induced renal injury, using the short-lived killifish Nothobranchius furzeri. A set of microRNAs was differentially expressed after renal damage, among them miR-21, which was up-regulated. A locked nucleic acid-modified antimiR-21 efficiently knocked down miR-21 activity and caused a lag in the proliferative response, enhanced apoptosis and an overall delay in regeneration. Transcriptome profiling identified apoptosis as a process that was significantly affected upon antimiR-21 administration. Together with functional data this suggests that miR-21 acts as a pro-proliferative and anti-apoptotic factor in the context of kidney regeneration in fish. Possible downstream candidate genes that mediate its effect on proliferation and apoptosis include igfbp3 and fosl1, among other genes. CONCLUSION: In summary, our findings extend the role of miR-21 in the kidney. For the first time we show its functional involvement in regeneration indicating that fast proliferation and reduced apoptosis are important for efficient renal tubular regeneration.
DOI:10.1242/jcs.105528URLPMID:22976296 [本文引用: 1]
Signalling interplay between transforming growth factor-beta (TGFbeta) and CCN2 [also called connective tissue growth factor (CTGF)] plays a crucial role in the progression of diabetic nephropathy and has been implicated in cellular differentiation. To investigate the potential role of microRNAs (miRNAs) in the mediation of this signalling network, we performed miRNA screening in mesangial cells treated with recombinant human CCN2. Analysis revealed a cohort of 22 miRNAs differentially expressed by twofold or more, including members of the miR-302 family. Target analysis of miRNA to 3'-untranslated regions (3'-UTRs) identified TGFbeta receptor II (TbetaRII) as a potential miR-302 target. In mesangial cells, decreased TbetaRII expression was confirmed in response to CCN2 together with increased expression of miR-302d. TbetaRII was confirmed as an miR-302 target, and inhibition of miR-302d was sufficient to attenuate the effect of CCN2 on TbetaRII. Data from the European Renal cDNA Biopsy Bank revealed decreased TbetaRII in diabetic patients, suggesting pathophysiological significance. In a mouse model of fibrosis (UUO), miR-302d was increased, with decreased TbetaRII expression and aberrant signalling, suggesting relevance in chronic fibrosis. miR-302d decreased TGFbeta-induced epithelial mesenchymal transition (EMT) in renal HKC8 epithelial cells and attenuated TGFbeta-induced mesangial production of fibronectin and thrombospondin. In summary, we demonstrate a new mode of regulation of TGFbeta by CCN2, and conclude that the miR-302 family has a role in regulating growth factor signalling pathways, with implications for nephropathic cell fate transitions.
DOI:10.3892/mmr.2015.4374URLPMID:26459119 [本文引用: 1]
Over the last few decades, the epithelial-to-mesenchymal transition (EMT) has been identified as being involved in a number of aspects of physiological processes and various pathological events, including embryonic development and renal fibrosis. Transforming growth factorbeta receptor 2 (TGFbetaR2) is a widely studied gene, which fulfils a vital role in the TGFbeta signaling pathway and exerts a crucial function in the progression of EMT. Previous studies demonstrated that the dysregulation of microRNAs (miRNAs) is considered to be associated with the EMT process. However, the precise functional involvement of miRNAs in EMT remains to be fully elucidated. In the present study, the level of miR590 was decreased in an EMT model in vitro and in vivo. Furthermore, the overexpression of miR590 inhibited EMT by upregulating the epithelial marker, Ecadherin, and downregulating the mesenchymal markers, laminin, alphasmooth muscle actin (alphaSMA) and collagen, in the human kidney 2 (HK2) cell line. Furthermore, TGFbetaR2 was negatively regulated by miR590. In addition, performing a knockdown of TGFbetaR2 with smallinterfering RNA had an effect similar to miR590 on EMT in the HK2 cell line, whereas the transfection of pCMVtag2BTGFbetaR2 reversed the effect of miR590 on EMT in HK2 cells. Taken together, the present study demonstrated that miR-590 is a novel EMT-suppressive microRNA, which targets TGFbetaR2.
DOI:10.1159/000479168URLPMID:28817830 [本文引用: 1]
BACKGROUND: The epithelial-mesenchymal transition (EMT) is a crucial event in the development of renal interstitial fibrosis (RIF). A growing body of evidence indicates that beta-catenin plays an important role in various types of fibrosis. Although members of the microRNA (miRNA)-200 family have been suggested to suppress EMT in cancer and fibrosis, the function of miRNA-200a in regulating the progression of RIF is unknown. We speculate that miRNA-200a may hinder this progression through the suppression of beta-catenin. METHODS: Transforming growth factor beta1 (TGF beta1) was used to induce EMT of proximal tubule epithelial (HK-2) cells in vitro, quantitative real time polymerase chain reaction (qPCR) and Western Blot analysis measured the miRNA-200a and beta-catenin expression. qPCR, Western Blot analysis, Migration Assay and cell immunofluorescence were applied to detect the influence of up- and downregulated miRNA-200a expression and beta-catenin siRNA on beta-catenin and EMT. Dual luciferase report plasmid (CTNNB1 UTR WT/MT) verifies the target relationship between miRNA-200a and CTNNB1 (beta-catenin gene). RESULTS: miRNA-200a is downregulated and beta-catenin is upregulated during TGF beta1-induced EMT. Upregulation of miRNA-200a inhibits beta-catenin and attenuates TGF beta1-induced EMT and cell migration, while its downregulation increases beta-catenin and induces EMT and HK-2 cell migration. Further, knocking down beta-catenin suppressed the EMT induced by miRNA-200a downregulation. miRNA-200a directly targets for CTNNB1. CONCLUSIONS: miRNA-200a inhibits TGF beta1-induced EMT by directly targeting beta-catenin in proximal tubule epithelial cells.
DOI:10.1016/j.mce.2014.05.018URLPMID:24887517 [本文引用: 1]
Epithelial-to-mesenchymal transition (EMT) plays an important role in renal interstitial fibrosis (RIF) with diabetic nephropathy (DN). Smad7 (a inhibitory smad), a downstream signaling molecules of TGF-beta1, represses the EMT. The physiological function of miR-21 is closely linked to EMT and RIF. However, it remained unclear whether miR-21 over-expression affected TGF-beta1-induced EMT by regulating smad7 in DN. In this study, real-time RT-PCR, cell transfection, luciferase reporter gene assays, western blot and confocal microscope were used, respectively. Here, we found that miR-21 expression was upregulated by TGF-beta1 in time- and concentration -dependent manner. Moreover, miR-21 over-expression enhanced TGF-beta1-induced EMT(upregulation of a-SMA and downregulation of E-cadherin) by directly down-regulating smad7/p-smad7 and indirectly up-regulating smad3/p-smad3, accompanied by the decrease of Ccr and the increase of col-IV, FN, the content of collagen fibers, RTBM, RTIAW and ACR. Meantime, the siRNA experiment showed that smad7 can directly regulate a-SMA and E-cadherin expression. More importantly, miR-21 inhibitor can not only inhibit EMT and fibrosis but also ameliorate renal structure and function. In conclusion, our results demonstrated that miR-21 overexpression can contribute to TGF-beta1-induced EMT by inhibiting target smad7, and that targeting miR-21 may be a better alternative to directly suppress TGF-beta1-mediated fibrosis in DN.
DOI:10.3390/ijms20205084URL [本文引用: 1]
DOI:10.1074/jbc.M113.498634URLPMID:24163368 [本文引用: 1]
Accumulating evidence suggests that microRNAs (miRNAs) contribute to a myriad of kidney diseases. However, the regulatory role of miRNAs on the key molecules implicated in kidney fibrosis remains poorly understood. Bone morphogenetic protein-7 (BMP-7) and its related BMP-6 have recently emerged as key regulators of kidney fibrosis. Using the established unilateral ureteral obstruction (UUO) model of kidney fibrosis as our experimental model, we examined the regulatory role of miRNAs on BMP-7/6 signaling. By analyzing the potential miRNAs that target BMP-7/6 in silica, we identified miR-22 as a potent miRNA targeting BMP-7/6. We found that expression levels of BMP-7/6 were significantly elevated in the kidneys of the miR-22 null mouse. Importantly, mice with targeted deletion of miR-22 exhibited attenuated renal fibrosis in the UUO model. Consistent with these in vivo observations, primary renal fibroblast isolated from miR-22-deficient UUO mice demonstrated a significant increase in BMP-7/6 expression and their downstream targets. This phenotype could be rescued when cells were transfected with miR-22 mimics. Interestingly, we found that miR-22 and BMP-7/6 are in a regulatory feedback circuit, whereby not only miR-22 inhibits BMP-7/6, but miR-22 by itself is induced by BMP-7/6. Finally, we identified two BMP-responsive elements in the proximal region of miR-22 promoter. These findings identify miR-22 as a critical miRNA that contributes to renal fibrosis on the basis of its pivotal role on BMP signaling cascade.
DOI:10.1007/s00467-020-04795-xURLPMID:33151403 [本文引用: 1]
DOI:10.1097/MNH.0000000000000440URLPMID:30074910 [本文引用: 1]
PURPOSE OF REVIEW: The review describes studies investigating the role of microRNAs in the signaling pathway of the mineralocorticoid hormone, aldosterone. RECENT FINDINGS: Emerging evidence indicates that aldosterone alters the expression of microRNAs in target tissues thereby modulating the expression of key regulatory proteins. SUMMARY: The mineralocorticoid hormone aldosterone is released by the adrenal glands in a homeostatic mechanism to regulate blood volume. The long-term renal action of aldosterone is to increase the retrieval of sodium from filtered plasma to restore blood pressure. Emerging evidence indicates aldosterone may alter noncoding RNAs (ncRNAs) to integrate this hormonal response in target tissue. Expression of the best characterized small ncRNAs, microRNAs, is regulated by aldosterone stimulation. MicroRNAs modulate protein expression at all steps in the renin-angiotensin-aldosterone-signaling (RAAS) system. In addition to acting as a rheostat to fine-tune protein levels in aldosterone-responsive cells, there is evidence that microRNAs down-regulate components of the signaling cascade as a feedback mechanism. The role of microRNAs is, therefore, as signal integrator, and damper in aldosterone signaling, which has implications in understating the RAAS system from both a physiological and pathophysiological perspective. Recent evidence for microRNA's role in RAAS signaling will be discussed.
DOI:10.1016/j.atherosclerosis.2016.02.032URLPMID:27016615 [本文引用: 1]
BACKGROUND AND AIMS: The principal biologic effects of the renin-angiotensin system are mediated by activation of the AT1R receptor. The microRNA miR-155 regulates AT1R expression, with both its, and AT1R's activity, linked to atherosclerosis. Target sites for miR-155 lie within the 3' UTR of the human AT1R gene, and include the AT1R A1166C polymorphism. Thus far, only levels of circulating miR-155 have been investigated with respect to A1166C genotypes. We hypothesized that the A1166C polymorphism could correlate with different, ultra-sonographically defined plaque phenotypes, as well as with an altered expression of AT1R mRNA and protein in human carotid plaques (CP), and altered expression of miR-155 in patients with advanced atherosclerosis. METHODS: Our study cohort comprised 411 patients with advanced carotid atherosclerosis (298 hyperechoic; 113 hypoechoic plaques). PCR analyses identified A1166C genotypes; quantitative real-time PCR determined AT1R and miR-155 expression levels, with AT1R protein expression evaluated by western blot. RESULTS: Genotypes containing the C allele bore a significant association with the hypoechoic plaque phenotype (adjusted OR 1.87, 95% CI 1.16-3.00, p = 0.01). The expression of AT1R mRNA and miR-155 were significantly up-regulated in the CPs of CC genotype carriers compared to the AA/AC genotypes (p = 0.032, p = 0.015, respectively). AT1R protein expression was also significantly higher for CC genotypes (p < 0.01). CONCLUSION: Our results indicate that the AT1R A1166C polymorphism impacts an ultrasonographically-defined human plaque phenotype, with intra-plaque AT1R and miR-155 expression altered in advanced carotid atherosclerosis. Validation and replication of these data should contribute to an improved personalized therapy with which to prevent carotid atherosclerosis.
DOI:10.1016/j.bbrc.2010.08.067URLPMID:20735984 [本文引用: 1]
MicroRNAs (miRNAs), which are genomically encoded small RNAs, negatively regulate target gene expression at the post-transcriptional level. Our recent study indicated that microRNA-155 (miR-155) might be negatively correlated with blood pressure, and it has been suggested that miR-155-mediated target genes could be involved in the cardiovascular diseases. Bioinformatic analyses predict that angiotensin II type 1 receptor (AT(1)R) is a miR-155 target gene. The present study investigated the potential role of miR-155 in regulating AT(1)R expression and phenotypic differentiation in rat aortic adventitial fibroblasts (AFs). Luciferase assay demonstrated that miR-155 suppressed AT(1)R 3'-UTR reporter construct activity. miR-155 overexpression in AFs did not reduce target mRNA levels, but significantly reduced target protein expression. In addition, AFs transfected with pSUPER/miR-155 exhibited reduced Ang II-induced ERK1/2 activation. miR-155 overexpression in cells attenuated Ang II-induced alpha-smooth muscle actin (alpha-SMA, produces myofibroblast) expression, but did not transform growth factor beta-1 (TGF-beta1). This study demonstrated that miR-155 could have an important role in regulating adventitial fibroblast differentiation and contribute to suppression of AT(1)R expression.
DOI:10.1101/cshperspect.a018713URLPMID:24691964 [本文引用: 1]
Histone deacetylases (HDACs) are enzymes that catalyze the removal of acetyl functional groups from the lysine residues of both histone and nonhistone proteins. In humans, there are 18 HDAC enzymes that use either zinc- or NAD(+)-dependent mechanisms to deacetylate acetyl lysine substrates. Although removal of histone acetyl epigenetic modification by HDACs regulates chromatin structure and transcription, deacetylation of nonhistones controls diverse cellular processes. HDAC inhibitors are already known potential anticancer agents and show promise for the treatment of many diseases.
DOI:10.1681/ASN.2009080851URLPMID:20378823 [本文引用: 1]
One of the first hallmarks of kidney regeneration is the reactivation of genes normally required during organogenesis. Identification of chemicals with the potential to enhance this reactivation could therapeutically promote kidney regeneration. Here, we found that 4-(phenylthio)butanoic acid (PTBA) expanded the expression domains of molecular markers of kidney organogenesis in zebrafish. PTBA exhibits structural and functional similarity to the histone deacetylase (HDAC) inhibitors 4-phenylbutanoic acid and trichostatin A; treatment with these HDAC inhibitors also expanded the renal progenitor cell population. Analyses in vitro and in vivo confirmed that PTBA functions as an inhibitor of HDAC activity. Furthermore, PTBA-mediated renal progenitor cell expansion required retinoic acid signaling. In summary, these results support a mechanistic link among renal progenitor cells, HDAC, and the retinoid pathway. Whether PTBA holds promise as a therapeutic agent to promote renal regeneration requires further study.
DOI:10.1074/jbc.M111.248278URLPMID:21778236 [本文引用: 1]
Histone deacetylases (HDACs) regulate fundamental biological processes such as cellular proliferation, differentiation, and survival via genomic and nongenomic effects. This study examined the importance of HDAC activity in the regulation of gene expression and differentiation of the developing mouse kidney. Class I HDAC1-3 and class II HDAC4, -7, and -9 genes are developmentally regulated. Moreover, HDAC1-3 are highly expressed in nephron precursors. Short term treatment of cultured mouse embryonic kidneys with HDAC inhibitors (HDACi) induced global histone H3 and H4 hyperacetylation and H3K4 hypermethylation. However, genome-wide profiling revealed that the HDAC-regulated transcriptome is restricted and encompasses regulators of the cell cycle, Wnt/beta-catenin, TGF-beta/Smad, and PI3K-AKT pathways. Further analysis demonstrated that base-line expression of key developmental renal regulators, including Osr1, Eya1, Pax2/8, WT1, Gdnf, Wnt9b, Sfrp1/2, and Emx2, is dependent on intact HDAC activity. Treatment of cultured embryonic kidney cells with HDACi recapitulated these gene expression changes, and chromatin immunoprecipitation assays revealed that HDACi is associated with histone hyperacetylation of Pax2/Pax8, Gdnf, Sfrp1, and p21. Gene knockdown studies demonstrated that HDAC1 and HDAC2 play a redundant role in regulation of Pax2/8 and Sfrp1 but not Gdnf. Long term treatment of embryonic kidneys with HDACi impairs the ureteric bud branching morphogenesis program and provokes growth arrest and apoptosis. We conclude that HDAC activity is critical for normal embryonic kidney homeostasis, and we implicate class I HDACs in the regulation of early nephron gene expression, differentiation, and survival.
DOI:10.1681/ASN.2013050527URL [本文引用: 1]
Podocyte dysfunction is a detrimental feature in diabetic nephropathy, with loss of nephrin integrity contributing to diabetic podocytopathy. MicroRNAs (miRs) reportedly modulate the hyperglycemia-induced perturbation of renal tissue homeostasis. This study investigated whether regulation of histone deacetylase (HDAC) actions and nephrin acetylation by miR-29 contributes to podocyte homeostasis and renal function in diabetic kidneys. Hyperglycemia accelerated podocyte injury and reduced nephrin, acetylated nephrin, and miR-29a levels in primary renal glomeruli from streptozotocin-induced diabetic mice. Diabetic miR-29a transgenic mice had better nephrin levels, podocyte viability, and renal function and less glomerular fibrosis and inflammation reaction compared with diabetic wild-type mice. Overexpression of miR-29a attenuated the promotion of HDAC4 signaling, nephrin ubiquitination, and urinary nephrin excretion associated with diabetes and restored nephrin acetylation. Knockdown of miR-29a by antisense oligonucleotides promoted HDAC4 action, nephrin loss, podocyte apoptosis, and proteinuria in nondiabetic mice. In vitro, interruption of HDAC4 signaling alleviated the high glucose induced apoptosis and inhibition of nephrin acetylation in podocyte cultures. Furthermore, HDAC4 interference increased the acetylation status of histone H3 at lysine 9 (H3K9Ac), the enrichment of H3K9Ac in miR-29a proximal promoter, and miR-29a transcription in high glucose stressed podocytes. In conclusion, hyperglycemia impairs miR-29a signaling to intensify HDAC4 actions that contribute to podocyte protein deacetylation and degradation as well as renal dysfunction. HDAC4, via epigenetic H3K9 hypoacetylation, reduces miR-29a transcription. The renoprotective effects of miR-29a in diabetes-induced loss of podocyte integrity and renal homeostasis highlights the importance of post-translational acetylation reactions in podocyte microenvironments. Increasing miR-29a action may protect against diabetic podocytopathy.
DOI:10.1681/ASN.2014020129URLPMID:25071082 [本文引用: 1]
The kidney has a major role in extracellular calcium homeostasis. Multiple genetic linkage and association studies identified three tight junction genes from the kidney--claudin-14, -16, and -19--as critical for calcium imbalance diseases. Despite the compelling biologic evidence that the claudin-14/16/19 proteins form a regulated paracellular pathway for calcium reabsorption, approaches to regulate this transport pathway are largely unavailable, hindering the development of therapies to correct calcium transport abnormalities. Here, we report that treatment with histone deacetylase (HDAC) inhibitors downregulates renal CLDN14 mRNA and dramatically reduces urinary calcium excretion in mice. Furthermore, treatment of mice with HDAC inhibitors stimulated the transcription of renal microRNA-9 (miR-9) and miR-374 genes, which have been shown to repress the expression of claudin-14, the negative regulator of the paracellular pathway. With renal clearance and tubule perfusion techniques, we showed that HDAC inhibitors transiently increase the paracellular cation conductance in the thick ascending limb. Genetic ablation of claudin-14 or the use of a loop diuretic in mice abrogated HDAC inhibitor-induced hypocalciuria. The genetic mutations in the calcium-sensing receptor from patients with autosomal dominant hypocalcemia (ADH) repressed the transcription of miR-9 and miR-374 genes, and treatment with an HDAC inhibitor rescued the phenotypes of cell and animal models of ADH. Furthermore, systemic treatment of mice with antagomiRs against these miRs relieved claudin-14 gene silencing and caused an ADH-like phenotype. Together, our findings provide proof of concept for a novel therapeutic principle on the basis of epigenetic regulation of renal miRs to treat hypercalciuric diseases.
DOI:10.1038/nrneph.2015.140URLPMID:26281895 [本文引用: 1]
Congenital anomalies of the kidney and urinary tract (CAKUT) refer to a spectrum of structural renal malformations and are the leading cause of end-stage renal disease in children. The genetic diagnosis of CAKUT has proven to be challenging due to genetic and phenotypic heterogeneity and incomplete genetic penetrance. Monogenic causes of CAKUT have been identified using different approaches, including single gene screening, and gene panel and whole exome sequencing. The majority of the identified mutations, however, lack substantial evidence to support a pathogenic role in CAKUT. Copy number variants or single nucleotide variants that are associated with CAKUT have also been identified. Numerous studies support the influence of epigenetic and environmental factors on kidney development and the natural history of CAKUT, suggesting that the pathogenesis of this syndrome is multifactorial. In this Review we describe the current knowledge regarding the genetic susceptibility underlying CAKUT and the approaches used to investigate the genetic basis of CAKUT. We outline the associated environmental risk factors and epigenetic influences on CAKUT and discuss the challenges and strategies used to fully address the involvement and interplay of these factors in the pathogenesis of the disease.
DOI:10.1038/nrneph.2015.219URLPMID:26831913 [本文引用: 1]
To mark World Kidney Day 2016, Nature Reviews Nephrology invited six leading researchers to highlight the key advances and challenges within their specialist field of paediatric nephrology. Here, advances and remaining challenges in the fields of prenatal patterning, acute kidney injury, renal transplantation, genetics, cardiovascular health, and growth and nutrition, are all discussed within the context of paediatric and neonatal patients with kidney disease. Our global panel of researchers describe areas in which further studies and clinical advances are needed, and suggest ways in which research in these areas should progress to optimize renal care and long-term outcomes for affected patients.
DOI:10.1007/s00330-014-3550-xURLPMID:25638216 [本文引用: 1]
OBJECTIVES: The aim was to report ultrasound (US) patterns of hepatocyte nuclear factor (HNF1beta) mutation throughout childhood and determine whether ultrasound could be predictive of renal failure. METHODS: The sonographic examinations in 34 children with HNF1beta mutation were reviewed. Their sonographic characteristics were compared with renal function. RESULTS: At first postnatal examination renal length was normal in 44 % of the patients, decreased in 24 %, increased in 12 % and asymmetrical in 20 %. Renal cortex was hyperechoic in 97 %. Corticomedullary differentiation was abnormal in 59 %. Cysts were present in 77 % of patients. Cysts were mostly subcapsular (64 %). Twenty-eight patients had follow-up examinations. A modification of the sonographic appearance was observed in 91 % of patients. Eight patients (23 %) had renal failure; no specific US pattern could be demonstrated. CONCLUSIONS: At birth, HNF1beta mutation was typically associated on US with the combination of hyperechoic, normal-sized kidneys with abnormal corticomedullary differentiation (CMD) and multiple cortical cysts. In older children, the appearances can be variable: kidneys may have decreased (32 %) or normal size (33 %); they are usually hyperechoic (50 %) with abnormal CMD (78 %) and (sub)cortical cysts (71 %). No pattern appears to be associated with renal failure. KEY POINTS: * HNF1beta mutations determine significant anomalies of sonographic appearances of kidneys in children. * Kidneys appear mainly hyperechoic, with or without CMD and with subcapsular cysts. * The US pattern may evolve throughout childhood in the same patient. * No correlation was found between any sonographic pattern and renal failure.
DOI:10.1016/j.ajhg.2007.10.008URL [本文引用: 1]
In animal models, kidney formation is known to be controlled by the proteins RET, GDNF, and GFRA1; however, no human studies to date have shown an association between abnormal kidney development and mutation of these genes. We hypothesized that stillborn fetuses with congenital renal agenesis or severe dysplasia would possess mutations in RET, GDNF, or GFRA1. We assayed for mutations in these genes in 33 stillborn fetuses that had bilateral or unilateral renal agenesis (29 subjects) or severe congenital renal dysplasia (4 subjects). Mutations in RET were found in 7 of 19 fetuses with bilateral renal agenesis (37%) and 2 of 10 fetuses (20%) with unilateral agenesis. In two fetuses, there were two different RET mutations found, and a total of ten different sequence variations were identified. We also investigated whether these mutations affected RET activation; in each case, RET phosphorylation was either absent or constitutively activated. A GNDF mutation was identified in only one fetus with unilateral agenesis; this subject also had two RET mutations. No GFRA1 mutations were seen in any fetuses. These data suggest that in humans, mutations in RET and GDNF may contribute significantly to abnormal kidney development.
DOI:10.1681/ASN.2006030277URLPMID:16971658 [本文引用: 2]
Renal hypodysplasia (RHD) is characterized by a reduced nephron number, small kidney size, and disorganized renal tissue. A hereditary basis has been established for a subset of affected patients, suggesting a major role of developmental genes that are involved in early kidney organogenesis. Gene mutations that have dominant inheritance and cause RHD, urinary tract anomalies, and defined extrarenal symptoms have been identified in TCF2 (renal cysts and diabetes syndrome), PAX2 (renal-coloboma syndrome), EYA1 and SIX1 (branchio-oto-renal syndrome), and SALL1 (Townes-Brocks syndrome). For estimation of the prevalence of these events, an unselected cohort of 99 unrelated patients with RHD that was associated with chronic renal insufficiency were screened for mutations in TCF2, PAX2, EYA1, SIX1, and SALL1. Mutations or variants in the genes of interest were detected in 17 (17%) unrelated families: One mutation, two variants, and four deletions of TCF2 in eight unrelated patients; four different PAX2 mutations in six families; one EYA1 mutation and one deletion in two patients with branchio-oto-renal syndrome; and one SALL1 mutation in a patient with isolated RHD. Of a total of 27 patients with renal cysts, six (22%) carried a mutation in TCF2. It is interesting that a SIX1 sequence variant was identified in two siblings with renal-coloboma syndrome as a result of a PAX2 mutation, suggesting an oligogenic inheritance. Careful clinical reevaluation that focused on discrete extrarenal symptoms and thorough family analysis revealed syndrome-specific features in nine of the 17 patients. In conclusion, 15% of patients with RHD show mutations in TCF2 or PAX2, whereas abnormalities in EYA1, SALL1, and SIX1 are less frequent.
DOI:10.1017/S2040174418000454URLPMID:30078383 [本文引用: 1]
Intrauterine growth restriction (IUGR) has been identified as a risk factor for adult chronic kidney disease (CKD), including hypertension (HTN). Accelerated postnatal catch-up growth superimposed to IUGR has been shown to further increase the risk of CKD and HTN. Although the impact of excessive postnatal growth without previous IUGR is less clear, excessive postnatal overfeeding in experimental animals shows a strong impact on the risk of CKD and HTN in adulthood. On the other hand, food restriction in the postnatal period seems to have a protective effect on CKD programming. All these effects are mediated at least partially by the activation of the renin-angiotensin system, leptin and neuropeptide Y (NPY) signaling and profibrotic pathways. Early nutrition, especially in the postnatal period has a significant impact on the risk of CKD and HTN at adulthood and should receive specific attention in the prevention of CKD and HTN.
DOI:10.1016/j.siny.2017.01.004URLPMID:28347404 [本文引用: 2]
The impact of adverse maternal and early gestational issues, ranging from maternal-fetal interactions all the way through to premature birth, are recognized as having influence on the subsequent development of chronic diseases later in life. The development of chronic kidney disease (CKD) as a direct result of early life renal injury or a sequela of diseases such as hypertension or diabetes is a good model example of the potential impact that early life events may have on renal development and lifelong function. The global monetary and human resource cost of CKD is exorbitant. Socio-economic factors, along with other factors (genetic and environmental) may significantly influence the timing and display of phenotypic expression in fetuses and neonates at risk for developing CKD, yet very few of these factors are studied or well understood. In general our focus has been directed at treatment once CKD is established. This strategy has been and remains short-sighted and costly. Earlier understanding of the intrauterine determinants of renal mass development (i.e. environmental
DOI:10.1097/MOP.0000000000000312URLPMID:26963856 [本文引用: 2]
PURPOSE OF REVIEW: Perinatal programming of renal function reflects the epigenetic alteration of genetically determined development by environmental factors. These include intrauterine malnutrition, pre and postnatal overnutrition, glucocorticoids, and certain toxins such as smoking. This review aims to summarize the most important findings. RECENT FINDINGS: Human studies may show an increased susceptibility toward the general prevalence of renal failure in already small for gestational age children and adolescents. In particular, glomerular diseases present with a more severe clinical course. Partially related, partially independently, arterial hypertension is found in this at-risk group. The findings can mostly be confirmed in animal models. Both intrauterine nutrient deprived and overfed rodents show a tendency toward developing glomerulosclerosis and other renal disorders. Animal studies attempt to imitate clinical conditions, however, there are difficulties in transferring the findings to the human setting. The reduction of nephron number, especially in intrauterine growth-restricted humans and animals, is one mechanism of perinatal programming in the kidneys. In addition, vascular and endocrine alterations are prevalent. The molecular changes behind these mechanisms include epigenetic changes such as DNA-methylation, microRNAs, and histone modifications. SUMMARY: Future research will have to establish clinical studies with clear and well defined inclusion criteria which also reflect prenatal life. The use of transgenic animal models might help to obtain a deeper insight into the underlying mechanisms.
DOI:10.1016/j.reprotox.2005.04.007URLPMID:15982850 [本文引用: 1]
Embryonic and fetal growth depend on genetic and environmental factors, and the process is the result of the interaction between these factors. About 7-9% of live-born infants have a birth weight below normal (below the 10th percentile). The rate and extent of intrauterine growth restriction (IUGR) varies by ethnicity and socio-economic status. Some of the suspected causes of IUGR are as follows. (1) Maternal factors such as inadequate or severe malnutrition, chronic maternal diseases, birth order, multiple births, and parental genetic factors. (2) Placental pathology, mainly placental vascular damage that may lead to placental insufficiency. This is often found in maternal diseases such as pre-eclampsia, and Thrombophilia. (3) Intrauterine infections and specific fetal syndromes, including chromosomal aberrations. (4) Non-classified causes such as adolescent's pregnancy, maternal smoking and alcohol drinking, living at high altitudes. Several existing animal models for IUGR, including uterine artery ligation or gene knock out models, although insightful of potential mechanism(s) underlying intrauterine growth restriction, are limited in that they do not reflect human causality. As the ultimate goal is prevention, we seem still to be distant from achieving this goal.
DOI:10.1038/pr.2014.205URLPMID:25521920 [本文引用: 3]
BACKGROUND: Diseases of adulthood, such as diabetes and hypertension, may be related to changes during pregnancy, particularly in kidney. We hypothesized that acute kidney injury progresses more rapidly in cases of fetal programming. METHODS: Diabetic dams' offspring were divided into: CC (controls, receiving vehicle); DC (diabetics, receiving vehicle); CA (controls receiving folic Acid solution, 250 mg/kg); and DA (diabetics receiving folic acid solution). Renal function tests, morphometry, gene, and protein expression of epithelial-mesenchymal transition (EMT) markers were analyzed by qPCR and immunohistochemistry, respectively. RESULTS: Creatinine, urea, Bowman's space, and EMT markers were increased in CA and DA groups. TGF-beta3, actin, and fibronectin expression was higher in CA and DA, with significant increase in DA compared to CA 2-mo offspring. There was higher expression level of TGF-beta1, TGF-beta3, fibronectin, and vimentin in the offspring of diabetic dams at 5 mo. Increases in TGF-beta1 and TGF-beta3 were more evident in the offspring of diabetic dams. CONCLUSION: Fetal programming promotes remarkable changes in kidney morphology, and function in offspring and renal failure progression may be faster in younger offspring of diabetic dams subjected to an additional injury.
DOI:10.1016/j.tox.2018.10.013URLPMID:30359671 [本文引用: 2]
This study aimed to demonstrate that prenatal dexamethasone exposure (PDE) can induce kidney dysplasia in utero and adult glomerulosclerosis in male offspring, and to explore the underlying intrauterine programming mechanisms. Pregnant rats were subcutaneously administered dexamethasone 0.2 mg/kg.d from gestational day (GD) 9 to GD20. The male fetus on GD20 and the adult offspring at age of postnatal week 28 were analyzed. The adult offspring kidneys in the PDE group displayed glomerulosclerosis, elevated levels of serum creatinine and urine protein, ultrastructural damage of podocytes, the reduced expression levels of podocyte marker genes, nephrin and podocin. The histone 3 lysine 9 acetylation (H3K9ac) level in the promoter of renal angiotensin II receptor type 2 (AT2R) and its expression were reduced, whereas the angiotensin II receptor type 1a (AT1aR)/AT2R expression ratio was increased. The fetal kidneys in the PDE group displayed an enlarged Bowman's space and a shrunken glomerular tuft, a reduced cortex width and an increase in the nephrogenic zone/cortical zone ratio, reduced the expression level of glial-cell-line derived neurotrophic factor/c-Ret tyrosine kinase receptor (GDNF/c-Ret) signal pathway and podocyte marker genes. Moreover, the H3K9ac and H3K27ac levels of AT2R as well as the gene and protein expression levels of AT2R in fetal kidneys were inhibited by PDE. In vitro, primary metanephric mesenchyme stem cells (MMSCs) were treated with dexamethasone. Overexpression of AT2R reversed the inhibited expression of GDNF/c-Ret and podocin/nephrin induced by dexamethasone, and glucocorticoids receptor antagonist abolished the decreased H3K9ac level and gene expression of AT2R. In conclusion, PDE induced the offspring's kidney dysplasia as well as adult glomerulosclerosis, which was mediated by a sustained decrease in renal AT2R expression via decreasing the H3 K9ac level.
DOI:10.1016/j.biocel.2015.03.017URLPMID:25849459 [本文引用: 1]
An adverse in-utero environment is increasingly recognized to predispose to chronic disease in adulthood. Maternal smoking remains the most common modifiable adverse in-utero exposure leading to low birth weight, which is strongly associated with chronic kidney disease (CKD) in later life. In order to investigate underlying mechanisms for such susceptibility, female Balb/c mice were sham or cigarette smoke-exposed (SE) for 6 weeks before mating, throughout gestation and lactation. Offspring kidneys were examined for oxidative stress, expression of mitochondrial proteins, mitochondrial structure as well as renal functional parameters on postnatal day 1, day 20 (weaning) and week 13 (adult age). From birth throughout adulthood, SE offspring had increased renal levels of mitochondrial-derived reactive oxygen species (ROS), which left a footprint on DNA with increased 8-hydroxydeoxyguanosin (8-OHdG) in kidney tubular cells. Mitochondrial structural abnormalities were seen in SE kidneys at day 1 and week 13 along with a reduction in oxidative phosphorylation (OXPHOS) proteins and activity of mitochondrial antioxidant Manganese superoxide dismutase (MnSOD). Smoke exposure also resulted in increased mitochondrial DNA copy number (day 1-week 13) and lysosome density (day 1 and week 13). The appearance of mitochondrial defects preceded the onset of albuminuria at week 13. Thus, mitochondrial damage caused by maternal smoking may play an important role in development of CKD at adult life.
DOI:10.1681/ASN.2010040368URLPMID:20829403 [本文引用: 1]
Prenatal ethanol exposure is teratogenic, but the effects of ethanol on kidney development and the health of offspring are incompletely understood. Our objective was to investigate the effects of acute ethanol exposure during pregnancy on nephron endowment, mean arterial pressure, and renal function in offspring. We administered ethanol or saline by gavage to pregnant Sprague-Dawley rats on embryonic days 13.5 and 14.5. At 1 month of age, the nephron number was 15% lower and 10% lower in ethanol-exposed males and females, respectively, compared with controls. Mean arterial pressure, measured in conscious animals via indwelling tail-artery catheter, was 10% higher in both ethanol-exposed males and females compared with controls. GFR was 20% higher in ethanol-exposed males but 15% lower in ethanol-exposed females; moreover, males had increased proteinuria compared with controls. Furthermore, embryonic kidneys cultured in the presence of ethanol for 48 hours had 15% fewer ureteric branch points and tips than kidneys cultured in control media. Taken together, these data demonstrate that acute prenatal ethanol exposure reduces the number of nephrons, possibly as a result of inhibited ureteric branching morphogenesis, and that these changes affect adult cardiovascular and renal function.
DOI:10.1007/s00467-006-0213-4URLPMID:17093988 [本文引用: 1]
Nephron endowment ranges widely in normal human populations. Recent autopsy studies have drawn attention to the possibility that subtle congenital nephron deficits may be associated with increased risk of developing hypertension later in life. Since modest maternal vitamin A deficiency reduces nephron number in rats, we designed a pilot study to determine the prevalence of maternal vitamin A deficiency in Montreal (Canada) and Bangalore (India) and the usefulness of newborn renal volume as a surrogate for nephron endowment. Among 48 pregnant Montreal women, two (4%) had one isolated mid-gestation retinol level slightly below the accepted limit of normal (0.9 mumol/L), whereas 25 (55%) of 46 pregnant women in Bangalore had at least one sample below this limit. Average estimated retinoid intake was correlated with mean serum retinol in pregnant women from Bangalore. In Montreal where maternal vitamin A deficiency was negligible, we found that newborn renal volume (estimated by renal ultrasonography at 2-6 weeks of age) was correlated with surface area at birth and was inversely correlated with serum creatinine at 1 month. Interestingly, renal volume adjusted for body surface area in Montreal (184+/-44 ml/m(2)) was significantly greater than in Bangalore (114+/-33 ml/m(2)) (p<0.01). Definitive studies are needed to establish whether maternal vitamin A deficiency accounts for subtle renal hypoplasia in Indian newborns. If so, there may be important public health implications for regions of the world where maternal vitamin A deficiency is prevalent.
DOI:10.1016/j.siny.2017.01.001URLPMID:28161315 [本文引用: 1]
Congenital abnormalities of the kidney and urinary tract (CAKUT) are one of the leading congenital defects to be identified on prenatal ultrasound. CAKUT represent a broad spectrum of abnormalities, from transient hydronephrosis to severe bilateral renal agenesis. CAKUT are a major contributor to chronic and end stage kidney disease (CKD/ESKD) in children. Prenatal imaging is useful to identify CAKUT, but will not detect all defects. Both genetic abnormalities and the fetal environment contribute to CAKUT. Monogenic gene mutations identified in human CAKUT have advanced our understanding of molecular mechanisms of renal development. Low nephron number and solitary kidneys are associated with increased risk of adult onset CKD and ESKD. Premature and low birth weight infants represent a high risk population for low nephron number. Additional research is needed to identify biomarkers and appropriate follow-up of premature and low birth weight infants into adulthood.
DOI:10.1038/nrneph.2014.251URLPMID:25599618 [本文引用: 1]
An adverse intrauterine environment is associated with an increased risk of elevated blood pressure and kidney disease in later life. Many studies have focused on low birth weight, prematurity and growth restriction as surrogate markers of an adverse intrauterine environment; however, high birth weight, exposure to maternal diabetes and rapid growth during early childhood are also emerging as developmental risk factors for chronic diseases. Altered programming of nephron number is an important link between exposure to developmental stressors and subsequent risk of hypertension and kidney disease. Maternal, fetal, and childhood nutrition are crucial contributors to these programming effects. Resource-poor countries experience the sequential burdens of fetal and childhood undernutrition and subsequent overnutrition, which synergistically act to augment the effects of developmental programming; this observation might explain in part the disproportionate burden of chronic disease in these regions. Numerous nutritional interventions have been effective in reducing the short-term risk of low birth weight and prematurity. Understanding the potential long-term benefits of such interventions is crucial to inform policy decisions to interrupt the developmental programming cycle and stem the growing epidemics of hypertension and kidney disease worldwide.
DOI:10.1016/j.toxlet.2019.11.026URLPMID:31811911 [本文引用: 2]
This study was aimed to investigate the effect of prenatal ethanol exposure (PEE) on the susceptibility of offspring rats to glomerulosclerosis and to explore the mechanism. Pregnant Wistar rats were intragastrically administered ethanol (4g/kg.d) from gestational day (GD) 9 to GD 20, and the control group was given equal volume of normal saline. The offspring rats were all fed with high-fat diet after weaning, and were sacrificed at postnatal week 24 (PW24). The results revealed that the adult offspring kidneys in the male and female PEE groups exhibited higher glomerulosclerosis index and interstitial fibrosis index compared with the high-fat diet control groups, accompanied by elevated serum creatinine level. The protein expression of Nephrin and WT1, which were the marker genes of podocytes, was significantly decreased, whereas the protein expression of desmin and alpha-SMA, the marker genes of mesenchymal cells, was remarked enhanced in the male and female PEE groups. Compared with the high-fat diet control groups, the mRNA and protein expressions of renal angiotensin II receptor type 2 (AT2R) were decreased in the male PEE group, but increased in the female PEE group. PEE increased the mRNA and protein expressions of glucocorticoid (GC) activation system and inhibited the expression of insulin-like growth factor 1 (IGF1) signaling pathway in male offspring kidney; on the contrary, in female offspring kidney, PEE inhibited the mRNA and protein expression of glucocorticoid activation system and increased the expression of IGF1 signaling pathway. Taken together, PEE increased the susceptibility of the adult offspring to glomerulosclerosis, and the programming of renal AT2R or GC-IGF1 is respectively involved in the toxicity of PEE to the male or female offspring.
DOI:10.1016/j.taap.2015.05.007URLPMID:25986755
Our previous study has indicated that prenatal caffeine exposure (PCE) could induce intrauterine growth retardation (IUGR) of offspring. Recent research suggested that IUGR is a risk factor for glomerulosclerosis. However, whether PCE could induce glomerulosclerosis and its underlying mechanisms remain unknown. This study aimed to demonstrate the induction to glomerulosclerosis in adult offspring by PCE and its intrauterine programming mechanisms. A rat model of IUGR was established by PCE, male fetuses and adult offspring at the age of postnatal week 24 were euthanized. The results revealed that the adult offspring kidneys in the PCE group exhibited glomerulosclerosis as well as interstitial fibrosis, accompanied by elevated levels of serum creatinine and urine protein. Renal angiotensin II receptor type 2 (AT2R) gene expression in adult offspring was reduced by PCE, whereas the renal angiotensin II receptor type 1a (AT1aR)/AT2R expression ratio was increased. The fetal kidneys in the PCE group displayed an enlarged Bowman's space and a shrunken glomerular tuft, accompanied by a reduced cortex width and an increase in the nephrogenic zone/cortical zone ratio. Observation by electronic microscope revealed structural damage of podocytes; the reduced expression level of podocyte marker genes, nephrin and podocin, was also detected by q-PCR. Moreover, AT2R gene and protein expressions in fetal kidneys were inhibited by PCE, associated with the repression of the gene expression of glial-cell-line-derived neurotrophic factor (GDNF)/tyrosine kinase receptor (c-Ret) signaling pathway. These results demonstrated that PCE could induce dysplasia of fetal kidneys as well as glomerulosclerosis of adult offspring, and the low functional programming of renal AT2R might mediate the developmental origin of adult glomerulosclerosis.
DOI:10.1039/C5TX00040HURL [本文引用: 1]
DOI:10.1016/j.toxlet.2019.07.011URLPMID:31306741 [本文引用: 1]
This study aimed to verify the toxic effects of prenatal caffeine exposure (PCE) on the podocyte development in male offspring, and to explore the underlying intrauterine programming mechanisms. The pregnant rats were administered with caffeine (30 to 120 mg/kgd) during gestational day (GD) 9 to 20. The male fetus on GD20 and the offspring at postnatal week (PW) 6 and PW28 were sacrificed. The results indicated that PCE caused ultrastructural abnormalities on podocyte, and inhibited the expression of podocyte marker genes such as Nephrin, Wilms tumor 1 (WT1), the histone 3 lysine 9 acetylation (H3K9ac) level in the Kruppel-like factor 4 (KLF4) promoter and its expression in the male offspring from GD20 to PW28. Meanwhile, the expression of glucocorticoid receptor (GR) and histone deacetylase 7 (HDAC7) in the fetus were increased by PCE. In vitro, corticosterone increased GR and HDAC7 whereas reduced the H3K9ac level of KLF4 and KLF4/Nephrin expression. KLF4 over-expression reversed the reduction of Nephrin expression, knockdown of HDAC7 and GR antagonist RU486 partially reversed the inhibitory effects of corticosterone on H3K9ac level and KLF4 expression. In conclusion, PCE caused podocyte developmental toxicity in male offspring, which was associated with corticosterone-induced low-functional programming of KLF4 through GR/HDAC7/H3K9ac pathway.
DOI:10.1016/j.lfs.2015.04.005URLPMID:25921765 [本文引用: 1]
AIMS: Antenatal glucocorticoids can induce long-term effects on offspring health, including hypertension. Programmed hypertension has been observed in a prenatal dexamethasone (DEX) exposure model. However, how renal programming responds to prenatal DEX at different stages of development and the impact of DEX on programmed hypertension remain unclear. Therefore, we utilized RNA next-generation sequencing (NGS) to analyze the renal transcriptome in the offspring to examine whether key genes and pathways are responsible for DEX-induced renal programming and hypertension. MAIN METHODS: Pregnant rats received intraperitoneal dexamethasone from gestational day 16 to 22. Prenatal DEX-induced programmed hypertension was examined in male offspring at 16 weeks of age. KEY FINDINGS: Prenatal DEX modified 431 renal transcripts from the nephrogenesis stage to adulthood in a constant manner. At the pre-hypertensive and established hypertension stages, we identified 11 and 13 differentially expressed genes related to blood pressure regulation, respectively. Among these genes, Npr3, Ptgs2, Agt, Edn3, Ephx2, Agtr1b, and Gucy1a3 are associated with endothelium-derived hyperpolarizing and contractile factors (EDHF and EDCF). Genes in the arachidonic acid metabolism pathway may potentially be key genes contributing to programmed hypertension. In addition, DEX induced soluble epoxide hydrolase expression (Ephx2 gene encoding protein). SIGNIFICANCE: Prenatal DEX elicits an imbalance between EDHFs and EDCFs that might lead to renal programming and hypertension. The arachidonic acid metabolism pathway is a common pathway contributing to programmed hypertension. Our results highlight candidate genes and pathways involved in renal programming as targets for therapeutic approaches to prevent programmed hypertension in children exposed to antenatal corticosteroids.
DOI:10.1186/s12967-016-0955-0URLPMID:27364533 [本文引用: 2]
BACKGROUND: The genetic cause of most congenital anomalies of the kidney and urinary tract (CAKUT) cases remains unknown, therefore the novel approaches in searching for the common disease denominators are required. miRs regulate gene expression in humans and therefore have potentially therapeutic and biomarker properties. No studies thus far have attempted to explore the miRs in human CAKUT. We applied a new strategy to identify most specific miRs associated with CAKUT, in pediatric patients. METHODS: Data from the whole genome expression, gathered from ureter tissue samples of 19 patients and 7 controls, were used for the bioinformatic prediction of miRs activity in CAKUT. We integrated microarray gene expression data and miR target predictions from multiple prediction algorithms using Co-inertia analysis (CIA) in conjunction with correspondence analysis and between group analysis, to produce a ranked list of miRs associated with CAKUT. The CIA included five different sequence based miR target prediction algorithms and the Co-expression Meta-analysis of miR Targets. For the experimental validation of expression of miRs identified by the CIA we used tissue from 36 CAKUT patients and 9 controls. The results of gene ontology (GO) analysis on co-expressed targets of miRs associated with CAKUT were used for the selection of putative biological processes relevant to CAKUT. RESULTS: We identified 7 miRs with a potential role in CAKUT. The top ranked miRs from miRCos communities 4, 1 and 7 were chosen for experimental validation of expression in CAKUT tissue. The 5.7 fold increase of hsa-miR-144 expression in human tissue from CAKUT patients compared to controls (p = 0.005) was observed. From the GO we selected 7 biological processes that could contribute to CAKUT, which genes are potentially influenced by hsa-miR-144. The hsa-miR-200a, hsa-miR-183 and hsa-miR-375 weren't differentially expressed in CAKUT. CONCLUSIONS: This study shows that integrative approach applied here was useful in identification of the miRs associated with CAKUT. The hsa-miR-144, first time identified in CAKUT, could be connected with biological processes crucial for normal development of kidney and urinary tract. Further functional analysis must follow to reveal the impact of hsa-miR-144 on CAKUT occurrence.
URLPMID:21892160 [本文引用: 1]
DOI:10.1073/pnas.1301693110URLPMID:23759744 [本文引用: 1]
Polycystic kidney disease (PKD), the most common genetic cause of chronic kidney failure, is characterized by the presence of numerous, progressively enlarging fluid-filled cysts in the renal parenchyma. The cysts arise from renal tubules and are lined by abnormally functioning and hyperproliferative epithelial cells. Despite recent progress, no Food and Drug Administration-approved therapy is available to retard cyst growth. MicroRNAs (miRNAs) are short noncoding RNAs that inhibit posttranscriptional gene expression. Dysregulated miRNA expression is observed in PKD, but whether miRNAs are directly involved in kidney cyst formation and growth is not known. Here, we show that miR-17 approximately 92, an oncogenic miRNA cluster, is up-regulated in mouse models of PKD. Kidney-specific transgenic overexpression of miR-17 approximately 92 produces kidney cysts in mice. Conversely, kidney-specific inactivation of miR-17 approximately 92 in a mouse model of PKD retards kidney cyst growth, improves renal function, and prolongs survival. miR-17 approximately 92 may mediate these effects by promoting proliferation and through posttranscriptional repression of PKD genes Pkd1, Pkd2, and hepatocyte nuclear factor-1beta. These studies demonstrate a pathogenic role of miRNAs in mouse models of PKD and identify miR-17 approximately 92 as a therapeutic target in PKD. Our results also provide a unique hypothesis for disease progression in PKD involving miRNAs and regulation of PKD gene dosage.
DOI:10.1681/ASN.2015060634URLPMID:26677864 [本文引用: 1]
Autosomal dominant polycystic kidney disease (ADPKD), one of the most common monogenetic disorders, is characterized by kidney failure caused by bilateral renal cyst growth. MicroRNAs (miRs) have been implicated in numerous diseases, but the role of these noncoding RNAs in ADPKD pathogenesis is still poorly defined. Here, we investigated the role of miR-21, an oncogenic miR, in kidney cyst growth. We found that transcriptional activation of miR-21 is a common feature of murine PKD. Furthermore, compared with renal tubules from kidney samples of normal controls, cysts in kidney samples from patients with ADPKD had increased levels of miR-21. cAMP signaling, a key pathogenic pathway in PKD, transactivated miR-21 promoter in kidney cells and promoted miR-21 expression in cystic kidneys of mice. Genetic deletion of miR-21 attenuated cyst burden, reduced kidney injury, and improved survival of an orthologous model of ADPKD. RNA sequencing analysis and additional in vivo assays showed that miR-21 inhibits apoptosis of cyst epithelial cells, likely through direct repression of its target gene programmed cell death 4 Thus, miR-21 functions downstream of the cAMP pathway and promotes disease progression in experimental PKD. Our results suggest that inhibiting miR-21 is a potential new therapeutic approach to slow cyst growth in PKD.
DOI:10.1261/rna.063206.117URLPMID:29540511 [本文引用: 1]
The emergence of microRNA as regulators of organogenesis and tissue differentiation has stimulated interest in the ablation of microRNA expression and function during discrete periods of development. To this end, inducible, conditional modulation of microRNA expression with doxycycline-based tetracycline-controlled transactivator and tamoxifen-based estrogen receptor systems has found widespread use. However, the induction agents and components of genome recombination systems negatively impact pregnancy, parturition, and postnatal development; thereby limiting the use of these technologies between late gestation and the early postnatal period. MicroRNA inhibitor (antimiR) administration also represents a means of neutralizing microRNA function in vitro and in vivo. To date, these studies have used direct (parenteral) administration of antimiRs to experimental animals. As an extension of this approach, an alternative means of regulating microRNA expression and function is described here: the maternal-placental-fetal transmission of antimiRs. When administered to pregnant dams, antimiRs were detected in offspring and resulted in a pronounced and persistent reduction in detectable steady-state free microRNA levels in the heart, kidney, liver, lungs, and brain. This effect was comparable to direct injection of newborn mouse pups with antimiRs, although maternal delivery resulted in fewer off-target effects. Furthermore, depletion of steady-state microRNA levels via the maternal route resulted in concomitant increases in steady-state levels of selected microRNA targets. This novel methodology permits the temporal regulation of microRNA function during late gestation and in neonates, without recourse to conventional approaches that rely on doxycycline and tamoxifen, which may confound studies on developmental processes.
DOI:10.1371/journal.pone.0071310URLPMID:23977013 [本文引用: 1]
Prior study shows that maternal protein-restricted (LP) 16-wk-old offspring have pronounced reduction of nephron number and arterial hypertension associated with unchanged glomerular filtration rate, besides enhanced glomerular area, which may be related to glomerular hyperfiltration/overflow and which accounts for the glomerular filtration barrier breakdown and early glomerulosclerosis. In the current study, LP rats showed heavy proteinuria associated with podocyte simplification and foot process effacement. TGF-beta1 glomerular expression was significantly enhanced in LP. Isolated LP glomeruli show a reduced level of miR-200a, miR-141, miR-429 and ZEB2 mRNA and upregulated collagen 1alpha1/2 mRNA expression. By western blot analyzes of whole kidney tissue, we found significant reduction of both podocin and nephrin and enhanced expression of mesenchymal protein markers such as desmin, collagen type I and fibronectin. From our present knowledge, these are the first data showing renal miRNA modulation in the protein restriction model of fetal programming. The fetal-programmed adult offspring showed pronounced structural glomerular disorders with an accentuated and advanced stage of fibrosis, which led us to state that the glomerular miR-200 family would be downregulated by TGF-beta1 action inducing ZEB 2 expression that may subsequently cause glomeruli epithelial-to-mesenchymal transition.
