Role of protein kinase C alpha in signaling from the histamine H-1 receptor to the nucleus

Stimulation of histamine H-1 receptors produced a marked activation of inos itol phospholipid hydrolysis, intracellular calcium mobilization, and stimu lation of the c-fos promoter in CHO-H1 cells expressing the H-1 receptor at a level of 3 pmol/mg protein. The latter response was determined using a l uciferase-based reporter gene (pGL3). This response to histamine was not se nsitive to inhibition by pertussis toxin but could be completely attenuated by the protein kinase C (PKC) inhibitor Ro-31-8220, or by 24-h pretreatmen t with the phorbol esters phorbol 12,13-dibutyrate or phorbol-12-myristate- 13-acetate. Several isoforms of PKC can be detected in CHO-H1 cells (alpha, delta, epsilon, mu, iota, zeta) but only PKC alpha and PKC delta were down -regulated by prolonged treatment with phorbol esters. Of the two isoforms that were down-regulated, only protein kinase C alpha was translocated to C HO-H1 cell membranes after stimulation with either histamine or phorbol est ers. The PKC inhibitor Go 6976, which inhibits PKC alpha but not PKC delta, was also able to significantly attenuate the c-fos-luciferase response to histamine. The mitogen-activated protein kinase kinase inhibitor PD 98059 m arkedly inhibited the response to histamine, suggesting that the likely maj or target for PKC alpha was the mitogen-activated protein kinase pathway. T hese data suggest that the histamine H-1 receptor can signal to the nucleus via PKC alpha after activation of phospholipase C beta.