Effect of protein kinase C activation on intracellular Ca2+ signaling and integrity of intestinal epithelial cells.
Protein kinase C (PKC) activation and increases in cytosolic Ca(2+) cause intestinal injury. Since PKC activation can alter Ca(2+) homeostasis and increase Ca(2+) levels, we examined the effects of PKC activation on intestinal cellular integrity and the role of Ca(2+) signaling in this response. The epithelial cell line, IEC-18 was incubated with the PKC activator phorbol myristate acetate (PMA; 0.1-1.0 microM). In some experiments, cells were incubated in Ca(2+)-free medium. PMA treatment produced a concentration-dependent increase in cell injury and PKC activity. This response was attenuated by addition of the pan-specific PKC inhibitor, GF 109203X. Furthermore, cell viability was maintained in cells preincubated with PKC isoform-specific inhibitors to PKCalpha, PKCdelta and PKCepsilon. Cell injury was also reduced if cells were incubated in Ca(2+)-free medium or in the presence of the Ca(2+) channel antagonist, verapamil or the intracellular chelator BAPTA-AM. PMA, but not the inactive phorbol ester, 4alphaPMA, induced a dose-dependent increase in cellular Ca(2+) that was characterized by a rapid, transient spike followed by a tonic plateau phase which approximated control levels. These responses were eliminated by the addition of BAPTA-AM. Furthermore the increase in the Ca(2+) spike was reduced or eliminated by co-incubation with the PKCdelta antagonist, rottlerin. Inhibition of PKCalpha or PKCepsilon was less effective or ineffective in this regard. These data suggest that PKC activation via PMA challenge affects the integrity of rat intestinal epithelial cells. PKCdelta, but not PKCepsilon or PKCalpha activation appears to mediate this effect via an increase in cellular Ca(2+).
Tepperman
Barry L
BL
Department of Physiology and Pharmacology, University of Western Ontario, London Ontario, Canada N6A 5C1. btepperm@med.uwo.ca
Soper
Brian D
BD
Chang
Qing
Q
D000098:Acetophenones / Q000494:pharmacology; D000818:Animals; D001578:Benzopyrans / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism*; D002121:Calcium Channel Blockers / Q000494:pharmacology; D020013:Calcium Signaling / Q000187:drug effects; D002227:Carbazoles / Q000494:pharmacology; D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects; D002614:Chelating Agents / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004533:Egtazic Acid / Q000031:analogs & derivatives / Q000494:pharmacology; D004789:Enzyme Activation / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004847:Epithelial Cells / Q000187:drug effects / Q000378:metabolism*; D007211:Indoles / Q000494:pharmacology; D007413:Intestinal Mucosa / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D042541:Intracellular Space / Q000187:drug effects / Q000378:metabolism; D008301:Maleimides / Q000494:pharmacology; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000378:metabolism*; D051571:Protein Kinase C-alpha; D051745:Protein Kinase C-delta; D051744:Protein Kinase C-epsilon; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D014700:Verapamil / Q000494:pharmacology
D000098:Acetophenones; D001578:Benzopyrans; D002121:Calcium Channel Blockers; D002227:Carbazoles; D002614:Chelating Agents; D004791:Enzyme Inhibitors; D007211:Indoles; D008301:Maleimides; C081021:Go 6976; C070379:1,2-bis(2-aminophenoxy)ethane N,N,N',N'-tetraacetic acid acetoxymethyl ester; D004533:Egtazic Acid; D014700:Verapamil; C085746:rottlerin; D011493:Protein Kinase C; D051571:Protein Kinase C-alpha; D051745:Protein Kinase C-delta; D051744:Protein Kinase C-epsilon; C070515:bisindolylmaleimide I; D013755:Tetradecanoylphorbol Acetate; D002118:Calcium