Identification of a nuclear orphan receptor ( XXXX ) as a negative regulator of renin gene transcription.

@entity4878 @entity19 @entity554 @entity39768 @entity134 @entity375 @entity526
A potent transcriptional enhancer was previously identified upstream of the @entity19 renin gene. Within the enhancer is a TGACCT direct-repeat motif, required for enhancer activity, that is the consensus sequence recognized by members of the thyroid hormone subfamily of @entity134 hormone receptors. We previously reported that RAR/RXR bind to this sequence and mediate the induction of renin promoter activity by @entity4878 . However, gel mobility shift assays clearly show that other as yet unidentified factors also bind to this motif. In order to identify some of these TGACCT binding factors, we screened a @entity375 one-hybrid cDNA library derived from @entity19 @entity19 cells. One of these encoded the orphan nuclear receptor @entity39768 . Recombinant @entity39768 was purified from @entity526 and an antipeptide antisera was generated. EMSA showed that purified recombinant @entity39768 specifically binds the TGACCT direct-repeat motif. Transfection assays showed that @entity39768 potently decreases both baseline and @entity554 -induced @entity19 renin promoter activity in a dose-dependent, enhancer-dependent, and sequence-specific manner. Mutations in @entity39768 , which abolish its binding to the TGACCT motif, also abolish transcriptional repression. @entity39768 was identified as a nuclear protein in @entity19 cells, is one of the proteins binding to the TGACCT repeat motif, and its overexpression can repress transcription of the endogenous renin gene in @entity19 cells. These data suggest that @entity39768 is a negative modulator of renin gene transcription in @entity19 cells, and that the renin enhancer may actually encode a complex positive and negative regulator of transcription.
