Meissner JD, Chang KC, Kubis HP, Nebreda AR, Gros G, Scheibe RJ. The p38α/β Mitogen-activated Protein Kinases Mediate Recruitment of CREB-binding Protein to Preserve Fast Myosin Heavy Chain IId/x Gene Activity in Myotubes.
J Biol Chem 2007;
282:7265-75. [PMID:
17210568 DOI:
10.1074/jbc.m609076200]
[Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
In skeletal muscle, the transformation of fast into slow fiber type is accompanied by shifts in fiber type-specific gene expression that includes down-regulation of the adult fast fiber myosin heavy chain IId/x (MyHCIId/x) gene. Here, we report that the mitogen-activated protein kinases (MAPKs) p38alpha/beta regulate MyHCIId/x gene expression. Electrical stimulation of rabbit skeletal muscle cells with a slow fiber type activity pattern and treatment of C2C12 myotubes with Ca(2+)-ionophore inhibited p38alpha/beta MAPKs and reduced fast fiber type MyHC protein expression and promoter activity. Pharmacological inhibition of p38alpha/beta also down-regulated MyHCII gene expression. In controls, binding of the myocyte enhancer factor-2 (MEF-2) isoforms C and D as a heterodimer to a proximal consensus site within the MyHCIId/x promoter and recruitment of a transcriptional coactivator, the CREB-binding protein CBP, were observed. Overexpression of wild type MEF-2C but not of a MEF-2C mutant that cannot be phosphorylated by p38 induced promoter activity. Mutation of the MEF-2-binding site decreased the inducing effect of overexpressed CBP. Inhibition of p38alpha/beta MAPKs abolished CBP binding, whereas enforced induction of p38 by activated MAPK kinase 6 (MKK6EE) enhanced binding of CBP and increased promoter activity. Furthermore, knockdown of endogenous CBP by RNA interference eliminated promoter activation by MEF-2C or MKK6EE. In electrical stimulated and Ca(2+)-ionophore-treated myotubes, CBP was absent in complex formation at that site. Taken together, the data indicate that p38alpha/beta MAPKs-mediated coactivator recruitment at a proximal MEF-2 site is important for MyHCIId/x gene regulation in skeletal muscle.
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