CHARACTERIZATION OF THE 5'-FLANKING REGION OF THE GENE FOR THE CAMP-INDUCIBLE PROTEIN-KINASE-A SUBUNIT, RII-BETA, IN SERTOLI-CELLS

Activation of cyclic AMP-dependent protein kinases (protein kinase A, PKA) by gonadotropins and cyclic AMP (cAMP) plays an important role in the regulation of testicular functions. A regulatory subunit, RII bet a, of PKA is transcriptionally induced in rat Sertoli cells in respons e to treatment with cAMP. The present study addresses regulatory mecha nisms leading to increased transcription of the rat RII beta gene. We have localized a footprint which overlaps one of the major transcripti on initiation sites in the basal promoter (-293 to -123). One of the p roteins binding this sequence belongs to the NF-1 family of transcript ion factors. We also observed binding to a basic helix-loop-helix (bHL H) response element. Furthermore, transfection studies of various 5'-d eletions of the rat RII beta gene in primary cultures of rat Sertoli c ells and in peritubular cells revealed the presence of an upstream reg ion (-723 to -395, cAMP-responsive region) inhibiting basal expression from the rat RII beta gene only in Sertoli cells. This region was fou nd to enhance cAMP responsiveness in Sertoli cells but not in peritubu lar cells. Interactions with downstream elements seemed to be importan t for the function of the cAMP-responsive region. Although some short stretches reveal homology to the cAMP-responsive regions of other slow ly cAMP-responding genes, and an AP-1-like element is present, no stro ng resemblance to any known regulatory element responsive to cAMP is f ound. (C) 1997 Elsevier Science Ireland Ltd.