Mol. Cell. Biol. doi:10.1128/MCB.01608-07
Copyright (c) 2008, American Society for Microbiology and/or the Listed Authors/Institutions. All Rights Reserved.
Bifunctional Role of Rev-erb
in Adipocyte Differentiation
Jing Wang
and
Mitchell A. Lazar*
Division of Endocrinology, Diabetes, and Metabolism, Department of Medicine and Department of Genetics, and The Institute for Diabetes, Obesity, and Metabolism, University of Pennsylvania School of Medicine, Philadelphia, PA 19104
* To whom correspondence should be addressed. Email:
lazar{at}mail.med.upenn.edu.
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Abstract |
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The nuclear receptor Rev-erb
is a potent transcriptional repressor that regulates circadian rhythm and metabolism. Here we demonstrate a dissociation between Rev-erb
mRNA and protein levels that profoundly influences adipocyte differentiation. During adipogenesis, Rev-erb
gene expression initially declines and subsequently increases. Remarkably, Rev-erb
protein levels are nearly opposite, increasing early in adipogenesis and then markedly decreasing in adipocytes. The Rev-erb
protein is necessary for the early mitotic events that are required for adipogenesis. The subsequent reduction in Rev-erb
protein, due to increased degradation via the 26S proteasome, is also required for adipocyte differentiation because Rev-erb
represses expression of PPAR
2, the master transcriptional regulator of adipogenesis. Thus, opposite to what might be predicted from Rev-erb
gene expression, Rev-erb
protein levels must rise and then fall for adipocyte differentiation to occur.