FOLLICLE-STIMULATING-HORMONE REGULATION OF A-KINASE ANCHORING PROTEINS IN GRANULOSA-CELLS

It has been well established that the biochemical and morphological ch anges during maturation of granulosa cells that are induced by follicl e-stimulating hormone (FSH) occur through the elevation of intracellul ar cAMP and consequent activation of the cAMP-dependent protein kinase (PKA). In this report we show that FSH action alters the expression o f A-Kinase Anchoring Proteins (AKAPs), which function to target the su bcellular distribution of the type II PKA. Exposure of granulosa cells grown in primary culture with FSH and estradiol for 72 h resulted in the up-regulation of an 80-kDa AKAP and the RIIbeta subunit of PKA, wh ereas cells grown in control medium containing only estradiol produced a time-dependent increase of a 140-kDa AKAP. RII overlays performed w ith [P-32]RIIalpha preferentially detected RII-binding bands of 80 and 95 kDa compared to blots probed with [P-32]RIIbeta, suggesting that F SH may alter the subcellular location of PKA in an isoform-specific ma nner. FSH treatment causes a translocation of RIIalpha from the partic ulate to the cytosolic fraction coincident with the induction of the 8 0-kDa AKAP, which is also predominately cytosolic. These data suggest that FSH promotes a redistribution of the type II PKA holoenzyme throu gh the selective induction of an RII isoform-specific AKAP.