PKC-[delta] and -[epsilon] regulate NF-[kappa]B activation induced by cholecystokinin and TNF-[alpha] in pancreatic acinar cells

Although NF-[kappa]B plays an important role in pancreatitis, mechanisms underlying its activation remain unclear. We investigated the signaling pathways mediating NF-[kappa]B activation in pancreatic acinar cells induced by high-dose cholecystokinin-8 (CCK-8), which causes pancreatitis in rodent models, and TNF-[alpha], which contributes to inflammatory responses of pancreatitis, especially the role of PKC isoforms. We determined subcellular distribution and kinase activities of PKC isoforms and NF-[kappa]B activation in dispersed rat pancreatic acini. We applied isoform-specific, cell-permeable peptide inhibitors to assess the role of individual PKC isoforms in NF-[kappa]B activation. Both CCK-8 and TNF-[alpha] activated the novel isoforms PKC-[delta] and -[epsilon] and the atypical isoform PKC-[zeta] but not the conventional isoform PKC-[alpha]. Inhibition of the novel PKC isoforms but not the conventional or the atypical isoform resulted in the prevention of NF-[kappa]B activation induced by CCK-8 and TNF-[alpha]. NF-[kappa]B activation by CCK-8 and TNF-[alpha] required translocation but not tyrosine phosphorylation of PKC-[delta]. Activation of PKC-[delta], PKC-[epsilon], and NF-[kappa]B with CCK-8 involved both phosphatidylinositol-specific PLC and phosphatidylcholine (PC)-specific PLC, whereas with TNF-[alpha] they only required PC-specific PLC for activation. Results indicate that CCK-8 and TNF-[alpha] initiate NF-[kappa]B activation by different PLC pathways that converge at the novel PKCs ([delta] and [epsilon]) to mediate NF-[kappa]B activation in pancreatic acinar cells. These findings suggest a key role for the novel PKCs in pancreatitis. phosphatidylcholine-specific phospholipase C; phosphatidylinositol-specific phospholipase C: Src kinases; translocation; tyrosine phosphorylation