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

It has been well established that the biochemical and morphological changes during maturation of granulosa cells that are induced by follicle-stimulating hormone (FSH) occur through the elevation of intracellular cAMP and consequent activation of the cAMP-dependent protein kinase (PKA). In this report we show that FSH action alters the expression of A-Kinase Anchoring Proteins (AKAPs), which function to target the subcellular 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, whereas cells grown in control medium containing only estradiol produced a time-dependent increase of a 140-kDa AKAP. RII overlays performed with [P-32]RIIalpha preferentially detected RII-binding bands of 80 and 95 kDa compared to blots probed with [P-32]RIIbeta, suggesting that FSH may alter the subcellular location of PKA in an isoform-specific manner. FSH treatment causes a translocation of RIIalpha from the particulate to the cytosolic fraction coincident with the induction of the 80-kDa AKAP, which is also predominately cytosolic. These data suggest that FSH promotes a redistribution of the type II PKA holoenzyme through the selective induction of an RII isoform-specific AKAP.