RNA结合蛋白HuR通过其RNA识别模体调节hsa-let-7c表达
宋峣, 冯伟, 施国敏, 陈超, 张幼怡^*
北京大学第三医院心内科血管医学研究所，卫生部心血管分子生物学与调节肽重点实验室，教育部分子心血管学重点实验室，心血管受体研究北京市重点实验室，北京 100191
摘要
微小RNA (microRNAs, miRNA)是一种短链的非编码RNA，它通过抑制RNA的翻译或促进RNA的降解调控多种细胞活动和机体的发育。机体主要通过转录和转录后两个层面对miRNA的表达进行调控，其中对miRNA转录水平的调控决定了miRNA表达的特异性，而目前我们对其转录后调控的机制还知之甚少。本研究旨在证实RNA结合蛋白HuR是否通过与pri-miRNA中富含AU的序列相结合调节miRNA的表达。利用生物信息学方法对pri-miRNA中的AUUUA模体进行筛查，发现在hsa-let-7c下游富含AUUUA模体，而hsa-miR-21则不具备这一模体。通过转染HuR质粒到HEK293T细胞构建过表达模型，然后用Western blot和real-time PCR分别检测HuR蛋白和miRNAs表达水平。结果显示，过表达HuR能够促进成熟hsa-let-7c而非hsa-miR-21表达。而过表达缺失RNA识别模体3 (RNA recognition motif, RRM3)的突变体HuR则不能促进hsa-let-7c的表达。以上结果提示RRM3是HuR介导成熟hsa-let-7c表达的关键序列，而HuR在调控miRNA生物合成中可能扮演了一种新的角色，即在转录后水平调节miRNA的表达。

关键词： 微小RNA; HuR ; let-7c ; 转录后调节
分类号：Q522

RNA-binding protein HuR regulates hsa-let-7c expression by its RNA recognition motif
Song Yao, FENG Wei, SHI Guo-Min, CHEN Chao, ZHANG YOU-YI ^*
Department of Cardiology and Institute of Vascular Medicine, Peking University Third Hospital; Key Laboratory of Cardiovascular Molecular Biology and Regulatory Peptides, Ministry of Health; Key Laboratory of Molecular Cardiovascular Science, Ministry of Education; Beijing Key Laboratory of Cardiovascular Receptors Research, Beijing 100191, China
Abstract
MicroRNAs (miRNAs) are small noncoding RNAs that control diverse cellular and developmental events through repression of large sets of target mRNAs. miRNAs expressions were mainly regulated at two levels: transcriptional and post-transcriptional. Transcriptional regulation of miRNA-encoding genes produce specific expression patterns of individual miRNA. However, the mechanism of post-transcriptional regulation of miRNAs remains largely unknown. The present study was aimed to clarify whether HuR, an evolutionary conserved AU-rich binding protein, could regulate miRNAs expressions. By means of a computational screen for AUUUA motifs within pri-miRNAs, we found that the downstream of hsa-let-7c but not hsa-miR-21 was enriched of AUUUA motifs. Then we transfected HuR and mutant HuR lacking RNA recognition motif 3 (RRM3) respectively into HEK293T cells. And HuR protein and miRNAs expressions were detected by Western blot and real-time PCR, respectively. The results showed that the overexpression of HuR promoted mature hsa-let-7c expression but not hsa-miR-21 expression. Furthermore, overexpression of HuR deletion mutant lacking RRM3 did not promote hsa-let-7c expression. These results suggest that RRM3 is crucial for HuR mediating mature hsa-let-7c expression. Collectively, these findings proposed a novel role of HuR in biogenesis of miRNAs, possibly by way of post-transcriptional regulation of miRNAs.

Key words: microRNA; HuR ; let-7c ; post-transcriptional regulation

收稿日期：2017-03-11　　录用日期：2018-01-24
通讯作者：张幼怡　　E-mail: zhangyy@bjmu.edu.cn
DOI: 10.13294/j.aps.2018.0008
引用本文：
宋峣, 冯伟, 施国敏, 陈超, 张幼怡. RNA结合蛋白HuR通过其RNA识别模体调节hsa-let-7c表达[J]. 生理学报 2018; 70 (1): 1-8.
Song Yao, FENG Wei, SHI Guo-Min, CHEN Chao, ZHANG YOU-YI . RNA-binding protein HuR regulates hsa-let-7c expression by its RNA recognition motif. Acta Physiol Sin 2018; 70 (1): 1-8



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