Deubiquitinating Enzyme USP29 Regulates the Protein Stability of CBX6
CHEN Mao-He1), CHEN Xiao-Xia2), HUANG Wen-Yang3), CHEN Rui1), LIN Han-Bin3)*
1)Cardiovascular Department, First Affiliated Hospital of Fujian Medical University, Fuzhou 350005, China; 2)General Practice Department, Affiliated Fuzhou First Hospital of Fujian Medical University, Fuzhou 350005, China; 3)Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Fujian Medical University, Fuzhou 350122, China
Abstract：Polycomb group (PcG) proteins are transcriptional repressors that control cell fate and the development of embryo, and they elicit function mainly in the form of polycomb repressive complex (PRC). Chromobox protein homolog 6 (CBX6) is one of the core protein subunits of PRC1, which plays an important role in gene expression regulation, cell renewal and differentiation, tumorigenesis and development, and stem cell maintenance. In this study, CBX6 was found to be degraded through a ubiquitin-proteasome dependent pathway. Then the gene expression library containing 92 deubiquitinating enzymes (DUB) was used to screen DUB targeting CBX6 and results found that ubiquitin-specific protease 29 (USP29) could obviously stabilize CBX6 protein level and extend its half-life (P<0.05). Immunoprecipitation experiments found that CBX6 interacted with USP29 through its C-terminal domains; Further studies found that USP29 regulated the protein stability of CBX6 by deubiquitination in an enzymatic-activity dependent manner. Cell proliferation assay also found that USP29 inhibited the proliferation of MCF7 cells (P<0.0001). Taken together, through screening, this study found that USP29 could stabilize CBX6 protein level through deubiquitinating CBX6 and inhibit the cell proliferation of MCF7.
[1] Lewis E B. A gene complex controlling segmentation in Drosophila[J]. Nature, 1978, 276(5688): 565-570
[2] Bracken A P, Dietrich N, Pasini D, et al. Genome-wide mapping of Polycomb target genes unravels their roles in cell fate transitions[J]. Genes Dev, 2006, 20(9): 1123-1136
[3] Chan H L, Morey L. Emerging roles for polycomb-group proteins in stem cells and cancer[J]. Trends Biochem Sci, 2019, 44(8): 688-700
[4] Jaenisch R, Young R. Stem cells, the molecular circuitry of pluripotency and nuclear reprogramming[J]. Cell, 2008, 132(4): 567-582
[5] Geng Z, Gao Z. Mammalian PRC1 complexes: compositional complexity and diverse molecular mechanisms[J]. Int J Mol Sci, 2020, 21(22): 8594
[6] Margueron R, Reinberg D. The polycomb complex PRC2 and its mark in life[J]. Nature, 2011, 469(7330): 343-349
[7] Connelly K E, Dykhuizen E C. Compositional and functional diversity of canonical PRC1 complexes in mammals[J]. Biochim Biophys Acta Gene Regul Mech, 2017, 1860(2): 233-245
[8] Senthilkumar R, Mishra R K. Novel motifs distinguish multiple homologues of Polycomb in vertebrates: expansion and diversification of the epigenetic toolkit[J]. BMC Genomics, 2009, 10: 549
[9] Morey L, Pascual G, Cozzuto L, et al. Nonoverlapping functions of the Polycomb group Cbx family of proteins in embryonic stem cells[J]. Cell Stem Cell, 2012, 10(1): 47-62
[10] Deng H, Guan X, Gong L, et al. CBX6 is negatively regulated by EZH2 and plays a potential tumor suppressor role in breast cancer[J]. Sci Rep, 2019, 9(1): 197
[11] Wang J, He H, Jiang Q, et al. CBX6 promotes HCC metastasis via transcription factors Snail/Zeb1-mediated EMT mechanism[J]. Onco Targets Ther, 2020, 13: 12489-12500
[12] Sakai K, Nishiuchi T, Tange S, et al. Proteasomal degradation of polycomb-group protein CBX6 confers MMP-2 expression essential for mesothelioma invasion[J]. Sci Rep, 2020, 10(1): 16678
[13] Li G, Warden C, Zou Z, et al. Altered expression of polycomb group genes in glioblastoma multiforme[J]. PLoS One, 2013, 8(11): e80970
[14] Yau R G, Doerner K, Castellanos E R, et al. Assembly and function of heterotypic ubiquitin chains in cell-cycle and protein quality control[J]. Cell, 2017, 171(4): 918-933.e20
[15] Hoeller D, Dikic I. Targeting the ubiquitin system in cancer therapy[J]. Nature, 2009, 458(7237): 438-444
[16] Komander D, Clague M J, Urbe S. Breaking the chains: structure and function of the deubiquitinases[J]. Nat Rev Mol Cell Biol, 2009, 10(8): 550-563
[17] Di Croce L, Helin K. Transcriptional regulation by polycomb group proteins[J]. Nat Struct Mol Biol, 2013, 20(10): 1147-1155
[18] Santanach A, Blanco E, Jiang H, et al. The polycomb group protein CBX6 is an essential regulator of embryonic stem cell identity[J]. Nat Commun, 2017, 8(1): 1235
[19] Zheng H, Jiang W H, Tian T, et al. CBX6 overexpression contributes to tumor progression and is predictive of a poor prognosis in hepatocellular carcinoma[J]. Oncotarget, 2017, 8(12): 18872-18884
[20] Vandamme J, Volkel P, Rosnoblet C, et al. Interaction proteomics analysis of polycomb proteins defines distinct PRC1 complexes in mammalian cells[J]. Mol Cell Proteomics, 2011, 10(4): M110.002642
[21] Hou Z, Shi W, Feng J, et al. Self-stabilizing regulation of deubiquitinating enzymes in an enzymatic activity-dependent manner[J]. Int J Biol Macromol, 2021, 181: 1081-1091
[22] Van Wijnen A J, Bagheri L, Badreldin A A, et al. Biological functions of chromobox (CBX) proteins in stem cell self-renewal, lineage-commitment, cancer and development[J]. Bone, 2021, 143: 115659
[23] Park J, Cho J, Song E J. Ubiquitin-proteasome system (UPS) as a target for anticancer treatment[J]. Arch Pharm Res, 2020, 43(11): 1144-1161
[24] Qian W, Li Q, Wu X, et al. Deubiquitinase USP29 promotes gastric cancer cell migration by cooperating with phosphatase SCP1 to stabilize Snail protein[J]. Oncogene, 2020, 39(44): 6802-6815
[25] Zhang Q, Tang Z, An R, et al. USP29 maintains the stability of cGAS and promotes cellular antiviral responses and autoimmunity[J]. Cell Res, 2020, 30(10): 914-927
[26] Huang Z, Khan M, Xu J, et al. The deubiquitinating gene Usp29 is dispensable for fertility in male mice[J]. Sci China Life Sci, 2019, 62(4): 544-552
[27] Martin Y, Cabrera E, Amoedo H, et al. USP29 controls the stability of checkpoint adaptor Claspin by deubiquitination[J]. Oncogene, 2015, 34(8): 1058-1063
