CHARACTERIZATION OF THE FUNCTIONAL-PROPERTIES AND NUCLEAR-BINDING PROTEINS OF THE RAT LUTEINIZING-HORMONE CHORIONIC-GONADOTROPIN RECEPTOR PROMOTER IN LEYDIG-CELLS

The experiments presented herein were designed to study the molecular basis of the restricted cellular localization and transcriptional regu lation of the LH/CG receptor in Leydig cells. Using luciferase fusion constructs transfected into Leydig and Sertoli cell lines, we show tha t the proximal 186 basepairs (relative to the translation start site) of the 5'-flanking region of the rat LH/CG receptor represent a basal promoter that accounts for the Leydig cell-specific expression of this receptor. A region that confers negative transcriptional regulation b y cAMP maps to nucleotides -40 to -70 of this basal promoter. Using mo bility shift and deoxyribonuclease footprinting assays, we also report the detection of Leydig cell-specific protein(s) that bind to the bas al LH/CG receptor promoter. The binding of this protein(s) to the prom oter involves an AP-2 consensus sequence beginning at nucleotide -59 a s well as additional sequences that remain to be identified. In spite of the fact that the AP-2 site is involved, the protein-DNA complexes detected in Leydig cells are not recognized by an antibody to AP-2.