Regulation of CCK-induced amylase release by PKC- in rat pancreatic acinar cells

Li, Chenwei, Xuequn Chen, and John A. Williams. Regulation of CCK-induced amylase release by PKCin rat pancreatic acinar cells. Am J Physiol Gastrointest Liver Physiol 287: G764–G771, 2004. First published June 24, 2004; 10.1152/ajpgi.00111.2004.— PKC is known to be activated by pancreatic secretagogues such as CCK and carbachol and to participate along with calcium in amylase release. Four PKC isoforms, , , , and , have been identified in acinar cells, but which isoforms participate in amylase release are unknown. To identify the responsible isoforms, we used translocation assays, chemical inhibitors, and overexpression of individual isoforms and their dominant-negative variants by means of adenoviral vectors. CCK stimulation caused translocation of PKC, , and , but not from soluble to membrane fraction. CCK-induced amylase release was inhibited 30% by GF109203X, a broad spectrum PKC inhibitor, and by rottlerin, a PKCinhibitor, but not by Gö6976, a PKCinhibitor, at concentrations from 1 to 5 M. Neither overexpression of wild-type or dominant-negative PKCaffected CCK-induced amylase release. Overexpression of PKCand enhanced amylase release, whereas only dominant-negative PKCinhibited amylase release by 25%. PKCoverexpression increased amylase release at all concentrations of CCK, but dominant-negative PKConly inhibited the maximal concentration; both similarly affected carbachol and JMV-180-induced amylase release. Overexpression of both PKCand its dominant-negative variant affected the late but not the early phase of amylase release. GF109203X totally blocked the enhancement of amylase release by PKCbut had no further effect in the presence of dominant-negative PKC. These results indicate that PKCis the PKC isoform involved with amylase secretion.