title: Synergistic up-regulation of muscle LIM protein expression in C2C12 and NIH3T3 cells by myogenin and MEF2C.
abstract: Although the role of muscle LIM protein (MLP, also known as CRP3), a LIM-only protein of LIM domain-containing protein family, is well-characterized, the mechanism by which the MLP gene expresses remains unclear. Herein, we demonstrate that myogenin and myocyte enhancer factor 2C (MEF2C) cooperate in activating the MLP gene in myogenesis. RT-PCR, real-time PCR and Western blotting showed that overexpression of myogenin or myogenin plus MEF2C led to induction of the MLP gene in differentiating C2C12 and NIH3T3 fibroblasts. By contrary, knocking-down of myogenin by RNA interference (RNAi) suppressed MLP expression in differentiating C2C12. Deletion and reporter enzyme assay revealed that the promoter activity was determined largely by the region extending from -260 to -173, which containing three E-box (CANNTG motif) candidates. Site-directed mutagenesis demonstrated that the E-box at position -186 to -180 was crucial for activating the promoter by myogenin. Furthermore, MEF2C could enhance myogenin-mediated activation of the promoter. In addition, chromatin immunoprecipitation (ChIP) and re-ChIP showed that myogenin and MEF2C were associated with the activated MLP promoter. Together, these results suggest that myogenin and MEF2C cooperate in the MLP gene activation. The linking of the MLP gene activation with myogenin and MEF2C may facilitate myogenin-mediated differentiation of striated muscle.
authors.affiliation: Department of Biochemistry and Molecular Biology, Peking University Health Science Center, Xue Yuan Road 38, 100083, Beijing, People's Republic of China.
authors.forename: Zhen-Xing
authors.initials: ZX
authors.lastname: Ji
authors.forename: Chao
authors.initials: C
authors.lastname: Du
authors.forename: Guo-Sheng
authors.initials: GS
authors.lastname: Wu
authors.forename: Shu-Yan
authors.initials: SY
authors.lastname: Li
authors.forename: Guo-Shun
authors.initials: GS
authors.lastname: An
authors.forename: Yu-Xi
authors.initials: YX
authors.lastname: Yang
authors.forename: Ru
authors.initials: R
authors.lastname: Jia
authors.forename: Hong-Ti
authors.initials: HT
authors.lastname: Jia
authors.forename: Ju-Hua
authors.initials: JH
authors.lastname: Ni
mesh_terms: D000818:Animals; D001483:Base Sequence; D002454:Cell Differentiation; D017931:DNA Primers / Q000235:genetics; D060588:LIM Domain Proteins; D064326:MEF2 Transcription Factors; D051379:Mice; D024510:Muscle Development / Q000235:genetics; D009124:Muscle Proteins / Q000235:genetics* / Q000378:metabolism; D032446:Myoblasts / Q000166:cytology / Q000378:metabolism; D018006:Myogenic Regulatory Factors / Q000235:genetics* / Q000378:metabolism; D018008:Myogenin / Q000037:antagonists & inhibitors / Q000235:genetics* / Q000378:metabolism; D041681:NIH 3T3 Cells; D011401:Promoter Regions, Genetic; D034622:RNA Interference; D014162:Transfection; D015854:Up-Regulation
chemical_list: D017931:DNA Primers; D060588:LIM Domain Proteins; D064326:MEF2 Transcription Factors; C578041:Mef2c protein, mouse; D009124:Muscle Proteins; C503801:Myog protein, mouse; D018006:Myogenic Regulatory Factors; D018008:Myogenin; C090114:cysteine and glycine-rich protein 3