MULTIPLE PROTEIN-KINASES ARE REQUIRED FOR BASAL KV1.5 K-EXPRESSION INGH(3) CLONAL PITUITARY-CELLS( CHANNEL GENE)

The role of protein kinases in maintaining basal expression of voltage -gated K+ channel mRNA was examined in GH(3) clonal pituitary cells. N onspecific inhibition of protein kinases with H7 or staurosporine mark edly decreases Kv1.5 Kf channel gene transcription and mRNA without pr oducing a substantial change in Kv1.4 mRNA. Selective inhibitors for p rotein kinase C, Ca2+-calmodulin kinases, and tyrosine kinases do not affect Ky 1.5 mRNA expression. In contrast, the Rp-diastereomer of ade nosine 3',5'-cyclic monophosphorothioate, a specific inhibitor of prot ein kinase A, partially inhibits Kv1.5 mRNA expression (similar to 40% ), and this effect was antagonized by 8-bromo-adenosine 3',5'-cyclic m onophosphate. Thus, protein kinase A and at least one other kinase are required for basal Kv1.5 mRNA expression in pituitary cells.