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Nucleic Acids Res. 2016 Mar 18;44(5):2393-408. doi: 10.1093/nar/gkw023. Epub 2016 Jan 26.

Novel RNA-binding activity of MYF5 enhances Ccnd1/Cyclin D1 mRNA translation during myogenesis.

Author information

1
Laboratory of Genetics, National Institute on Aging, NIH, Baltimore, MD21224, USA amaresh.panda@nih.gov.
2
Laboratory of Genetics, National Institute on Aging, NIH, Baltimore, MD21224, USA.
3
Translational Gerontology Branch, National Institute on Aging, NIH, Baltimore, MD 21224, USA Faculty of Veterinary Medicine, University of Teramo, Teramo, Italy.
4
Department of Biochemistry and Molecular Biology and Marlene and Stewart Greenebaum Cancer Center, University of Maryland School of Medicine, Baltimore, MD 21201, USA.
5
Translational Gerontology Branch, National Institute on Aging, NIH, Baltimore, MD 21224, USA.

Abstract

Skeletal muscle contains long multinucleated and contractile structures known as muscle fibers, which arise from the fusion of myoblasts into multinucleated myotubes during myogenesis. The myogenic regulatory factor (MRF) MYF5 is the earliest to be expressed during myogenesis and functions as a transcription factor in muscle progenitor cells (satellite cells) and myocytes. In mouse C2C12 myocytes, MYF5 is implicated in the initial steps of myoblast differentiation into myotubes. Here, using ribonucleoprotein immunoprecipitation (RIP) analysis, we discovered a novel function for MYF5 as an RNA-binding protein which associated with a subset of myoblast mRNAs. One prominent MYF5 target was Ccnd1 mRNA, which encodes the key cell cycle regulator CCND1 (Cyclin D1). Biotin-RNA pulldown, UV-crosslinking and gel shift experiments indicated that MYF5 was capable of binding the 3' untranslated region (UTR) and the coding region (CR) of Ccnd1 mRNA. Silencing MYF5 expression in proliferating myoblasts revealed that MYF5 promoted CCND1 translation and modestly increased transcription of Ccnd1 mRNA. Accordingly, overexpressing MYF5 in C2C12 cells upregulated CCND1 expression while silencing MYF5 reduced myoblast proliferation as well as differentiation of myoblasts into myotubes. Moreover, MYF5 silencing reduced myogenesis, while ectopically restoring CCND1 abundance partially rescued the decrease in myogenesis seen after MYF5 silencing. We propose that MYF5 enhances early myogenesis in part by coordinately elevating Ccnd1 transcription and Ccnd1 mRNA translation.

PMID:
26819411
PMCID:
PMC4797292
DOI:
10.1093/nar/gkw023
[Indexed for MEDLINE]
Free PMC Article

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