title: Mixed Lineage Leukemia 5 (MLL5) Protein Stability Is Cooperatively Regulated by O-GlcNac Transferase (OGT) and Ubiquitin Specific Protease 7 (USP7).
abstract: Mixed lineage leukemia 5 (MLL5) protein is a trithorax family histone 3 lysine 4 (H3K4) methyltransferase that regulates diverse biological processes, including cell cycle progression, hematopoiesis and cancer. The mechanisms by which MLL5 protein stability is regulated have remained unclear to date. Here, we showed that MLL5 protein stability is cooperatively regulated by O-GlcNAc transferase (OGT) and ubiquitin-specific protease 7 (USP7). Depletion of OGT in cells led to a decrease in the MLL5 protein level through ubiquitin/proteasome-dependent proteolytic degradation, whereas ectopic expression of OGT protein suppressed MLL5 ubiquitylation. We further identified deubiquitinase USP7 as a novel MLL5-associated protein using mass spectrometry. USP7 stabilized the MLL5 protein through direct binding and deubiquitylation. Loss of USP7 induced degradation of MLL5 protein. Conversely, overexpression of USP7, but not a catalytically inactive USP7 mutant, led to decreased ubiquitylation and increased MLL5 stability. Co-immunoprecipitation and co-immunostaining assays revealed that MLL5, OGT and USP7 interact with each other to form a stable ternary complex that is predominantly located in the nucleus. In addition, upregulation of MLL5 expression was correlated with increased expression of OGT and USP7 in human primary cervical adenocarcinomas. Our results collectively reveal a novel molecular mechanism underlying regulation of MLL5 protein stability and provide new insights into the functional interplay among O-GlcNAc transferase, deubiquitinase and histone methyltransferase.
authors.affiliation: Department of Immunology, Nanjing Medical University, Jiangsu, China.|Key Laboratory of Molecular Virology and Immunology, Institut Pasteur of Shanghai, Chinese Academy of Sciences, Shanghai, China.
authors.forename: Xiaodan
authors.initials: X
authors.lastname: Ding
authors.affiliation: Shanghai Red House Obstetrics and Gynecology Hospital, Fudan University, Shanghai, China.
authors.forename: Wei
authors.initials: W
authors.lastname: Jiang
authors.affiliation: Key Laboratory of Molecular Virology and Immunology, Institut Pasteur of Shanghai, Chinese Academy of Sciences, Shanghai, China.
authors.forename: Peipei
authors.initials: P
authors.lastname: Zhou
authors.affiliation: Key Laboratory of Molecular Virology and Immunology, Institut Pasteur of Shanghai, Chinese Academy of Sciences, Shanghai, China.|Institute of Biology and Medical Sciences, Soochow University, Jiangsu, China.
authors.forename: Lulu
authors.initials: L
authors.lastname: Liu
authors.affiliation: Key Laboratory of Molecular Virology and Immunology, Institut Pasteur of Shanghai, Chinese Academy of Sciences, Shanghai, China.
authors.forename: Xiaoling
authors.initials: X
authors.lastname: Wan
authors.affiliation: Key Laboratory of Molecular Virology and Immunology, Institut Pasteur of Shanghai, Chinese Academy of Sciences, Shanghai, China.
authors.forename: Xiujie
authors.initials: X
authors.lastname: Yuan
authors.affiliation: College of life science, Sun Yet-Sen University, Guangzhou, China.
authors.forename: Xizi
authors.initials: X
authors.lastname: Wang
authors.affiliation: Key Laboratory of Molecular Virology and Immunology, Institut Pasteur of Shanghai, Chinese Academy of Sciences, Shanghai, China.|College of Life Science, Shanghai Normal University, Shanghai, China.
authors.forename: Miao
authors.initials: M
authors.lastname: Chen
authors.affiliation: College of Life Science, Shanghai Normal University, Shanghai, China.
authors.forename: Jun
authors.initials: J
authors.lastname: Chen
authors.affiliation: Key Laboratory of Molecular Virology and Immunology, Institut Pasteur of Shanghai, Chinese Academy of Sciences, Shanghai, China.
authors.forename: Jing
authors.initials: J
authors.lastname: Yang
authors.affiliation: Key Laboratory of Molecular Virology and Immunology, Institut Pasteur of Shanghai, Chinese Academy of Sciences, Shanghai, China.
authors.forename: Chao
authors.initials: C
authors.lastname: Kong
authors.affiliation: Key Laboratory of Molecular Virology and Immunology, Institut Pasteur of Shanghai, Chinese Academy of Sciences, Shanghai, China.
authors.forename: Bin
authors.initials: B
authors.lastname: Li
authors.affiliation: National Center for Protein Science Shanghai, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China.
authors.forename: Chao
authors.initials: C
authors.lastname: Peng
authors.affiliation: National Center for Protein Science Shanghai, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China.
authors.forename: Catherine C L
authors.initials: CC
authors.lastname: Wong
authors.affiliation: National Center for Protein Science Shanghai, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China.
authors.forename: Fajian
authors.initials: F
authors.lastname: Hou
authors.affiliation: Key Laboratory of Molecular Virology and Immunology, Institut Pasteur of Shanghai, Chinese Academy of Sciences, Shanghai, China.
authors.forename: Yan
authors.initials: Y
authors.lastname: Zhang
mesh_terms: D000230:Adenocarcinoma / Q000378:metabolism*; D000595:Amino Acid Sequence; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D005260:Female; D057809:HEK293 Cells; D006367:HeLa Cells; D006801:Humans; D008969:Molecular Sequence Data; D017351:N-Acetylglucosaminyltransferases / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding; D055550:Protein Stability; D043222:Ubiquitin Thiolesterase / Q000235:genetics / Q000378:metabolism*; D000076084:Ubiquitin-Specific Peptidase 7; D054875:Ubiquitination; D015854:Up-Regulation; D002583:Uterine Cervical Neoplasms / Q000378:metabolism*
chemical_list: D004268:DNA-Binding Proteins; C460660:KMT2E protein, human; D017351:N-Acetylglucosaminyltransferases; C449880:O-GlcNAc transferase; C464569:USP7 protein, human; D043222:Ubiquitin Thiolesterase; D000076084:Ubiquitin-Specific Peptidase 7