Ubiquitin-specific protease 4 (USP4) suppresses myoblast differentiation by down regulating MyoD activity in a catalytic-independent manner.
For myotube formation, proliferation and differentiation of myoblasts must be tightly regulated by various myogenic regulatory factors (MRFs) such as MyoD, myogenic factor 5 (Myf5), myogenin, and muscle-specific regulatory factor 4 (MRF4). However, it is not clear how the expression or activity of these MRFs is controlled during myogenesis. In this study, we identified ubiquitin-specific protease 4 (USP4), one of deubiquitinating enzymes, as a suppressor of MRFs by demonstrating that a knockdown of USP4 enhances myogenesis by controlling MyoD and the level of myogenesis marker proteins in C2C12 cells. However, it was revealed that the effect of USP4 on myogenesis is independent of its deubiquitinase activity because the catalytic-site mutant has the same inhibitory effects as the wild-type USP4 on myogenesis. We observed that the activity and protein levels of both HDAC1 and HDAC4 are decreased when myoblast differentiation is promoted by the USP4 knockdown. We also found that the role of USP4 in muscle differentiation is correlated with two major signaling pathways in myogenesis, AKT and the p38 mitogen-activated protein kinase pathways. According to these results, we propose that USP4 is a key player in myogenic differentiation; it controls myogenic regulatory factors in a catalytic-independent manner.
Department of Molecular Cell Biology, Sungkyunkwan University School of Medicine, Suwon 16419, Republic of Korea.
Sun-Il
SI
Yun
Department of Molecular Cell Biology, Sungkyunkwan University School of Medicine, Suwon 16419, Republic of Korea. Electronic address: kyeongkyu@skku.edu.
Kyeong Kyu
KK
Kim
D000818:Animals; D002454:Cell Differentiation / Q000235:genetics; D002460:Cell Line; D049109:Cell Proliferation / Q000235:genetics; D018507:Gene Expression Regulation, Developmental / Q000235:genetics; D056284:Histone Deacetylase 1 / Q000235:genetics; D006655:Histone Deacetylases / Q000235:genetics; D051379:Mice; D024510:Muscle Development / Q000235:genetics*; D018485:Muscle Fibers, Skeletal / Q000378:metabolism; D017570:MyoD Protein / Q000235:genetics*; D032446:Myoblasts / Q000378:metabolism*; D051787:Myogenic Regulatory Factor 5 / Q000235:genetics; D018008:Myogenin / Q000235:genetics; D064570:Ubiquitin-Specific Proteases / Q000235:genetics*
C497418:Myf5 protein, mouse; D017570:MyoD Protein; D051787:Myogenic Regulatory Factor 5; D018008:Myogenin; C082325:Usp4 protein, mouse; D064570:Ubiquitin-Specific Proteases; C484389:Hdac1 protein, mouse; C498618:Hdac5 protein, mouse; D056284:Histone Deacetylase 1; D006655:Histone Deacetylases
Histone deacetylases 1, HDAC1; Histone deacetylases 4, HDAC4; MyoD; Myoblast differentiation; Ubiquitin-specific protease 4, USP4