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Mol Cell. 2012 Apr 27;46(2):187-99. doi: 10.1016/j.molcel.2012.02.007. Epub 2012 Mar 15.

The Sam68 STAR RNA-binding protein regulates mTOR alternative splicing during adipogenesis.

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  • 1Terry Fox Molecular Oncology Group and Bloomfield Center for Research on Aging, Lady Davis Institute for Medical Research, McGill University, Montreal, QC H3T 1E2, Canada.

Abstract

We report that mice ablated for the Sam68 RNA-binding protein exhibit a lean phenotype as a result of increased energy expenditure, decreased commitment to early adipocyte progenitors, and defects in adipogenic differentiation. The Sam68(-/-) mice were protected from obesity, insulin resistance, and glucose intolerance induced with a high-fat diet. To identify the alternative splice events regulated by Sam68, genome-wide exon usage profiling in white adipose tissue was performed. Adipocytes from Sam68(-/-) mice retained intron 5 within the mTOR transcript introducing a premature termination codon, leading to an unstable mRNA. Consequently, Sam68-depleted cells had reduced mTOR levels resulting in lower levels of insulin-stimulated S6 and Akt phosphorylation leading to defects in adipogenesis, and this defect was rescued by the exogenous expression of full-length mTOR. Sam68 bound intronic splice elements within mTOR intron 5 required for the usage of the 5' splice site. We propose that Sam68 regulates alternative splicing during adipogenesis.

PMID:
22424772
DOI:
10.1016/j.molcel.2012.02.007
[PubMed - indexed for MEDLINE]
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