Induction of ornithine decarboxylase in guinea‐pig lymphocytes

Publisher Website
Google Scholar
Abstract
Calmodulin antagonists, N-(6-aminohexyl)-5-chloro-1-naphthalenesulfonamide (W-7), N-(6-aminohexyl)-1-naphthalenesulfonamide (W-5) and trifluoperazine inhibited ornithine decarboxylase induction in lymphocytes activated with phytohemagglutinin or ionophore A23187 [calcimycin]. W-7, a more potent calmodulin antagonist than W-5, suppressed ornithine decarboxylase induction in a higher extent than did W-5. Calmodulin may play an important role in ornithine decarboxylase induction in the activated lymphocytes. The extent of ornithine decarboxylase induction was greater in cells pretreated with Clostridium phospholipase C and then incubated with ionophore A23187 than in cells incubated with ionophore A23187 without the pretreatment. Combined treatment of cells with ionophore A23187 and tumor promotor, phorbol 12-myristate 13-acetate, caused synergistic induction of ornithine decarboxylase activity. Apparently, both activations of Ca2+-activated phospholipid-dependent protein kinase by diacylglycerol and of calmodulin-dependent function resulted from an elevation of cytosolic Ca2+ concentration may operate in the induction of ornithine decarboxylase in the activated lymphocytes.