Transcriptional regulation of human Rev-erbalpha gene expression by the orphan nuclear receptor retinoic acid-related orphan receptor alpha

Raspè, E.; Mautino, G.èl.; Duval, C.; Fontaine, C.; Duez, H.él.èn.; Barbier, O.; Monte, D.; Fruchart, J.; Fruchart, J.-C.; Staels, B.

Journal of Biological Chemistry 277(51): 49275-49281

2002


ISSN/ISBN: 0021-9258
PMID: 12377782
DOI: 10.1074/jbc.m206215200
Accession: 011582887

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Abstract
The Rev-erb and retinoic acid-related orphan receptors (ROR) are two related families of orphan nuclear receptors that recognize similar response elements but have opposite effects on transcription. Recently, the Rev-erbalpha gene promoter has been characterized and shown to harbor a functional Rev-erbalpha-binding site known as Rev-DR2, responsible for negative feedback down-regulation of promoter activity by Rev-erbalpha itself. The present study aimed to investigate whether Rev-erbalpha gene expression is regulated by RORalpha. Gel shift analysis demonstrated that in vitro translated hRORalpha1 protein binds to the Rev-DR2 site, both as monomer and dimer. Chromatin immunoprecipitation assays demonstrated that binding of RORalpha to this site also occurred in vivo in human hepatoma HepG2 cells. The Rev-DR2 site was further shown to be functional as it conferred hRORalpha1 responsiveness to a heterologous promoter and to the natural human Rev-erbalpha gene promoter in these cells. Mutation of this site in the context of the natural Rev-erbalpha gene promoter abolished its activation by RORalpha, indicating that this site plays a key role in hRORalpha1 action. Finally, adenoviral overexpression of hRORalpha1 in HepG2 cells led to enhanced hRev-erbalpha mRNA accumulation, further confirming the physiological importance of RORalpha1 in the regulation of Rev-erbalpha expression.