Yi-Rong Zeng
Meng-Li Zhang
Peng Liu
Fang Liu
Hao Zhang
Chen-Xi He
Yi-Ping Sun
Jin-Ye Zhang
Cheng Zhang
Lei Song
Chen Ding
Yu-Jie Tang
Zhen Yang
Chen Yang
Pu Wang
Kun-Liang Guan
Yue Xiong
Dan Ye
1 Huashan Hospital, Fudan University, and Molecular and Cell Biology Lab, Institutes of Biomedical Sciences, and the Shanghai Key Laboratory of Medical Epigenetics, and the Key Laboratory of Metabolism and Molecular, Ministry of Education, Shanghai 200032, China;
2 The International Co-Laboratory of Medical Epigenetics and Metabolism, Ministry of Science and Technology, Shanghai 200032, China;
3 Department of Neurosurgery, Huashan Hospital, Fudan University, Shanghai 200032, China;
4 Key Laboratory of Cell Differentiation and Apoptosis of National Ministry of Education, Department of Pathophysiology, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China;
5 Key Laboratory of Synthetic Biology, Institute of Plant Physiology and Ecology, Shanghai 200032, China;
6 Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200032, China;
7 State Key Laboratory of Proteomics, Beijing Proteome Research Center, Beijing Institute of Radiation Medicine, Beijing 102206, China;
8 National Center for Protein Sciences(The PHOENIX Center, Beijing), Beijing 102206, China;
9 State Key Laboratory of Genetic Engineering and Collaborative Innovation Center for Genetics and Development, School of Life Sciences, Institutes of Biomedical Sciences, Fudan University, Shanghai 200032, China 10 Department of Pharmacology and Moores Cancer Center, University of California San Diego, La Jolla, CA, USA 11 Lineberger Comprehensive Cancer Center, Department of Biochemistry and Biophysics, University of North Carolina, Chapel Hill, NC, USA 12 Department of General Surgery, Huashan Hospital, Fudan University, Shanghai 200032, China
Funds: We thank members of the Fudan MCB Laboratory for discussions and support throughout this study. We are grateful for the kind offer of human ASXL1 cDNA from Dr. Xudong Wu (Tianjin Medical University), and Kasumi-1 cells from Ruijin Hospital, Shanghai Institute of Hematology, Shanghai Jiao Tong University School of Medicine. This work was supported by the National Key R&D Program of China (No. 2016YFA0501800 to D.Y.
81572761, 81772655 and 81972646 to Y.T.), the Innovative Research Team of High-Level Local Universities in Shanghai (to D. Y.), the Recruitment Program of Global Experts of China (Y.T.), the Program for Professor of Special Appointment (Eastern Scholar) at Shanghai Institutions of Higher Learning (Y.T.), and Shanghai Rising-Star Program (Y.T.).
2016YFC1303303 to C. Y.), the NSFC Grant (No. 31871431 and No. 31821002 to D.Y.
Received Date: 2020-04-12
Rev Recd Date:2020-06-17
Publish Date:2021-07-08
Abstract
Abstract
Additional sex combs-like 1 (ASXL1) interacts with BRCA1-associated protein 1 (BAP1) deubiquitinase to oppose the polycomb repressive complex 1 (PRC1)- mediated histone H2A ubiquitylation. Germline BAP1 mutations are found in a spectrum of human malignancies, while ASXL1 mutations recurrently occur in myeloid neoplasm and are associated with poor prognosis. Nearly all ASXL1 mutations are heterozygous frameshift or nonsense mutations in the middle or to a less extent the C-terminal region, resulting in the production of C-terminally truncated mutant ASXL1 proteins. How ASXL1 regulates specific target genes and how the C-terminal truncation of ASXL1 promotes leukemogenesis are unclear. Here, we report that ASXL1 interacts with forkhead transcription factors FOXK1 and FOXK2 to regulate a subset of FOXK1/K2 target genes. We show that the C-terminally truncated mutant ASXL1 proteins are expressed at much higher levels than the wild-type protein in ASXL1 heterozygous leukemia cells, and lose the ability to interact with FOXK1/K2. Specific deletion of the mutant allele eliminates the expression of C-terminally truncated ASXL1 and increases the association of wild-type ASXL1 with BAP1, thereby restoring the expression of BAP1-ASXL1-FOXK1/K2 target genes, particularly those involved in glucose metabolism, oxygen sensing, and JAK-STAT3 signaling pathways. In addition to FOXK1/K2, we also identify other DNA-binding transcription regulators including transcription factors (TFs) which interact with wild-type ASXL1, but not C-terminally truncated mutant. Our results suggest that ASXL1 mutations result in neomorphic alleles that contribute to leukemogenesis at least in part through dominantly inhibiting the wild-type ASXL1 from interacting with BAP1 and thereby impairing the function of ASXL1- BAP1-TF in regulating target genes and leukemia cell growth.Keywords: ASXL1,
BAP1,
FOXK1/K2,
leukemia,
epigenetics
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