Promoter and regulatory regions of the rat luteinizing hormone receptor gene.

The region of transcriptional activity in the rat luteinizing hormone receptor gene was localized to the 5'-flanking 173-base pair (bp) sequence in transfected mouse Leydig tumor cells and non-expressing Chinese hamster ovarian (CHO) and HeLa cells. Repression of activity in all cell types was induced by at least two domains located between -174 and -990 bp. An additional inhibitory region between -1237 and -2056 bp observed only in CHO and HeLa cells may contribute to the absence of receptor expression in these cells. Analysis of the 173-bp region revealed a promoter domain between -1 and -137 bp containing no TATA or CAAT boxes, but with three SP1 sites and three initiator elements located at transcriptional start sites -14, -19, and -33. Gel retardation studies showed a protein-binding DNA domain about 30 bp upstream of the transcriptional start sites and an adjacent domain containing an SP1 element that are required for maximal activity in all cell types and may play a role in basal transcription. A second promoter domain (-120 to -173 bp) with a protein-binding SP1 element had minor activity in Leydig cells but was prominent in CHO and HeLa cells. Leydig cell-specific DNA-binding protein(s) for each of the promoter domains were detected and may be of importance in transcriptional regulation. The control of gene transcription by differential activation of these promoter domains could be involved in hormone-induced regulation of luteinizing hormone receptor expression in the gonads.