title: Ubiquitination of the transcription factor c-MAF is mediated by multiple lysine residues.
abstract: The transcription factor c-MAF could be polyubiquitinated and subsequently degraded in the proteasomes. Theoretically, any lysine residues in c-MAF could be ubiquitinated. In the present study, we tried to find out the specific lysine residue(s) mediating c-MAF ubiquitination. Through a series of mutational screens from lysine (K) to arginine (R), we found that any single lysine mutation (K to R) failed to prevent c-MAF ubiquitination, and any single lysine residue alone could not mediate c-MAF ubiquitination, which indicated that multiple lysine residues were required for c-MAF ubiquitination. Bioinformatics and computing analyses revealed that K85 and K350 could mediate c-MAF ubiquitination, which was confirmed by the cell-based assays. However, this duo was not the only pair because the K85R/K350R mutant could also be ubiquitinated. Functionally, both M12 (K85/K350) and W12 (K85R/K350R) mutants increased cyclin D2 promoter-driven luciferase activity, but they were less potent than the lysine-free counterpart (M14). In addition, M14 induced a higher level of expression of cyclin D2 at both mRNA and protein levels. Therefore, we demonstrated that c-MAF ubiquitination is mediated by multiple lysine residues, of which K85 and K350 were sufficient but not the only residues in mediating c-MAF ubiquitination. Moreover, c-MAF was found to be degraded by lysosomes. This study added a novel insight for c-MAF ubiquitination and degradation, suggesting that c-MAF stability is strictly regulated.
authors.affiliation: Jiangsu Key Laboratory for Translational Research and Therapeutics of Neuro-Psycho-Diseases, Department of Pharmacology, College of Pharmaceutical Sciences, Soochow University, Suzhou, Jiangsu 215123, PR China; Cyrus Tang Hematology Center, Jiangsu Institute of Hematology, The First Affiliated Hospital, Soochow University, Suzhou, Jiangsu 215123, PR China.
authors.forename: Guodong
authors.initials: G
authors.lastname: Chen
authors.affiliation: Jiangsu Key Laboratory for Translational Research and Therapeutics of Neuro-Psycho-Diseases, Department of Pharmacology, College of Pharmaceutical Sciences, Soochow University, Suzhou, Jiangsu 215123, PR China; Cyrus Tang Hematology Center, Jiangsu Institute of Hematology, The First Affiliated Hospital, Soochow University, Suzhou, Jiangsu 215123, PR China.
authors.forename: Xin
authors.initials: X
authors.lastname: Xu
authors.affiliation: Program in Molecular Structure and Function, The Hospital for Sick Children, Department of Molecular Genetics, University of Toronto, Toronto M5G 0A4, Canada.
authors.forename: Jiefei
authors.initials: J
authors.lastname: Tong
authors.affiliation: Jiangsu Key Laboratory for Translational Research and Therapeutics of Neuro-Psycho-Diseases, Department of Pharmacology, College of Pharmaceutical Sciences, Soochow University, Suzhou, Jiangsu 215123, PR China; Cyrus Tang Hematology Center, Jiangsu Institute of Hematology, The First Affiliated Hospital, Soochow University, Suzhou, Jiangsu 215123, PR China.
authors.forename: Kunkun
authors.initials: K
authors.lastname: Han
authors.affiliation: Jiangsu Key Laboratory for Translational Research and Therapeutics of Neuro-Psycho-Diseases, Department of Pharmacology, College of Pharmaceutical Sciences, Soochow University, Suzhou, Jiangsu 215123, PR China; Cyrus Tang Hematology Center, Jiangsu Institute of Hematology, The First Affiliated Hospital, Soochow University, Suzhou, Jiangsu 215123, PR China.
authors.forename: Zubin
authors.initials: Z
authors.lastname: Zhang
authors.affiliation: Jiangsu Key Laboratory for Translational Research and Therapeutics of Neuro-Psycho-Diseases, Department of Pharmacology, College of Pharmaceutical Sciences, Soochow University, Suzhou, Jiangsu 215123, PR China; Cyrus Tang Hematology Center, Jiangsu Institute of Hematology, The First Affiliated Hospital, Soochow University, Suzhou, Jiangsu 215123, PR China.
authors.forename: Juan
authors.initials: J
authors.lastname: Tang
authors.affiliation: Jiangsu Key Laboratory for Translational Research and Therapeutics of Neuro-Psycho-Diseases, Department of Pharmacology, College of Pharmaceutical Sciences, Soochow University, Suzhou, Jiangsu 215123, PR China; Cyrus Tang Hematology Center, Jiangsu Institute of Hematology, The First Affiliated Hospital, Soochow University, Suzhou, Jiangsu 215123, PR China.
authors.forename: Siyue
authors.initials: S
authors.lastname: Li
authors.affiliation: Jiangsu Key Laboratory for Translational Research and Therapeutics of Neuro-Psycho-Diseases, Department of Pharmacology, College of Pharmaceutical Sciences, Soochow University, Suzhou, Jiangsu 215123, PR China; Cyrus Tang Hematology Center, Jiangsu Institute of Hematology, The First Affiliated Hospital, Soochow University, Suzhou, Jiangsu 215123, PR China.
authors.forename: Chuanqi
authors.initials: C
authors.lastname: Yang
authors.affiliation: Jiangsu Key Laboratory for Translational Research and Therapeutics of Neuro-Psycho-Diseases, Department of Pharmacology, College of Pharmaceutical Sciences, Soochow University, Suzhou, Jiangsu 215123, PR China; Cyrus Tang Hematology Center, Jiangsu Institute of Hematology, The First Affiliated Hospital, Soochow University, Suzhou, Jiangsu 215123, PR China.
authors.forename: Jie
authors.initials: J
authors.lastname: Li
authors.affiliation: Jiangsu Key Laboratory for Translational Research and Therapeutics of Neuro-Psycho-Diseases, Department of Pharmacology, College of Pharmaceutical Sciences, Soochow University, Suzhou, Jiangsu 215123, PR China; Cyrus Tang Hematology Center, Jiangsu Institute of Hematology, The First Affiliated Hospital, Soochow University, Suzhou, Jiangsu 215123, PR China.
authors.forename: Biyin
authors.initials: B
authors.lastname: Cao
authors.affiliation: Cyrus Tang Hematology Center, Jiangsu Institute of Hematology, The First Affiliated Hospital, Soochow University, Suzhou, Jiangsu 215123, PR China.
authors.forename: Haixia
authors.initials: H
authors.lastname: Zhou
authors.affiliation: Cyrus Tang Hematology Center, Jiangsu Institute of Hematology, The First Affiliated Hospital, Soochow University, Suzhou, Jiangsu 215123, PR China.
authors.forename: Depei
authors.initials: D
authors.lastname: Wu
authors.affiliation: Program in Molecular Structure and Function, The Hospital for Sick Children, Department of Molecular Genetics, University of Toronto, Toronto M5G 0A4, Canada.
authors.forename: Michael F
authors.initials: MF
authors.lastname: Moran
authors.affiliation: Jiangsu Key Laboratory for Translational Research and Therapeutics of Neuro-Psycho-Diseases, Department of Pharmacology, College of Pharmaceutical Sciences, Soochow University, Suzhou, Jiangsu 215123, PR China; Cyrus Tang Hematology Center, Jiangsu Institute of Hematology, The First Affiliated Hospital, Soochow University, Suzhou, Jiangsu 215123, PR China. Electronic address: xinliangmao@suda.edu.cn.
authors.forename: Xinliang
authors.initials: X
authors.lastname: Mao
mesh_terms: D000595:Amino Acid Sequence; D045744:Cell Line, Tumor; D057809:HEK293 Cells; D006367:HeLa Cells; D006801:Humans; D008239:Lysine / Q000235:genetics / Q000378:metabolism*; D008247:Lysosomes / Q000378:metabolism; D008969:Molecular Sequence Data; D009101:Multiple Myeloma / Q000235:genetics / Q000378:metabolism*; D009154:Mutation; D046988:Proteasome Endopeptidase Complex / Q000378:metabolism; D051257:Proto-Oncogene Proteins c-maf / Q000235:genetics / Q000378:metabolism*; D014162:Transfection; D025801:Ubiquitin / Q000378:metabolism; D054875:Ubiquitination
chemical_list: C495607:MAF protein, human; D051257:Proto-Oncogene Proteins c-maf; D025801:Ubiquitin; D046988:Proteasome Endopeptidase Complex; D008239:Lysine
keywords: Lysosome; Multiple myeloma; Proteasome; Ubiquitination; c-MAF