ROLE OF E-BOX AND INITIATOR REGION IN THE EXPRESSION OF THE RAT FOLLICLE-STIMULATING-HORMONE RECEPTOR

The promoter for the rat follicle-stimulating hormone receptor (FSHR) gene contains a conserved consensus E box sequence and an initiator-li ke region (InR) sequence. Deletion analysis and transient transfection s showed that a 114-base pair region (-143 to -30) that encompasses th e E box and the InR was sufficient for greater than 75% of promoter fu nction. DNase I footprint analysis showed that the E box and InR were protected by nuclear proteins from rat Sertoli cells, and the E box re gion was shown by electrophoretic mobility shift assays (EMSA) to be a site of Sertoli protein interactions. Mutations in the E box disrupte d these interactions and reduced FSHR promoter activity. Co-transfecti on of the inhibitor of DNA binding (Id) with an FSHR/luciferase constr uct into mouse Sertoli 1 cells reduced FSHR promoter activity. Using E MSA, the upstream stimulatory factor was shown to be a component of th e complexes that interacted with the E box in the FSHR promoter. Bindi ng of proteins from rat Sertoli cells to the InR was demonstrated usin g EMSA. Also, an oligonucleotide that represented the sequence of the terminal deoxynucleotidyltransferase InR displaced the complexes at th e FSHR InR. Mutations in the InR resulted in a significant reduction o f FSHR promoter activity.