PKCdelta is required for mitochondrial-dependent apoptosis in salivary epithelial cells.
We report here that the novel protein kinase C isoform, PKCdelta, is required at or prior to the level of the mitochondria for apoptosis induced by a diverse group of cell toxins. We have used adenoviral expression of a kinase-dead (KD) mutant of PKCdelta to explore the requirement for PKCdelta in the mitochondrial-dependent apoptotic pathway. Expression of PKCdeltaKD, but not PKCalphaKD, in salivary epithelial cells resulted in a dose-dependent inhibition of apoptosis induced by etoposide, UV-irradiation, brefeldin A, and paclitaxel. DNA fragmentation was blocked up to 71% in parotid C5 cells infected with the PKCdeltaKD adenovirus, whereas caspase-3 activity was inhibited up to 65%. The activation of caspase-9-like proteases by all agents was also inhibited in parotid C5 cells expressing PKCdeltaKD. The ability of PKCdeltaKD to block the loss of mitochondrial membrane potential was similarly determined. Expression of PKCdeltaKD blocked the decrease in mitochondrial membrane potential observed in cells treated with etoposide, UV, brefeldin A, or paclitaxel in a dose-dependent manner. In contrast to the protective function of PKCdeltaKD, expression of PKCdeltaWT resulted in a potent induction of apoptosis, which could be inhibited by co-infection with PKCdeltaKD. These results suggest that PKCdelta is a common intermediate in mitochondrial-dependent apoptosis in salivary epithelial cells.
Matassa
A A
AA
Departments of Basic Science and Oral Research, School of Dentistry and Cell and Structural Biology, School of Medicine, University of Colorado Health Sciences Center, Denver, Colorado 80262, USA.
Carpenter
L
L
Biden
T J
TJ
Humphries
M J
MJ
Reyland
M E
ME
D000256:Adenoviridae / Q000235:genetics; D000818:Animals; D017209:Apoptosis; D015153:Blotting, Western; D020126:Brefeldin A / Q000494:pharmacology; D053148:Caspase 3; D053453:Caspase 9; D020169:Caspases / Q000378:metabolism; D002460:Cell Line; D002469:Cell Separation; D053938:DNA Fragmentation; D004305:Dose-Response Relationship, Drug; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004847:Epithelial Cells / Q000378:metabolism*; D005047:Etoposide / Q000494:pharmacology; D005434:Flow Cytometry; D005799:Genes, Dominant; D007527:Isoenzymes / Q000737:chemistry* / Q000502:physiology*; D007763:Lac Operon; D008928:Mitochondria / Q000378:metabolism*; D009154:Mutation; D019384:Nucleic Acid Synthesis Inhibitors / Q000494:pharmacology; D017239:Paclitaxel / Q000494:pharmacology; D020033:Protein Isoforms; D011493:Protein Kinase C / Q000737:chemistry* / Q000502:physiology*; D051745:Protein Kinase C-delta; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology; D011838:Radiation-Sensitizing Agents / Q000494:pharmacology; D051381:Rats; D012469:Salivary Glands / Q000378:metabolism*; D013997:Time Factors; D014466:Ultraviolet Rays
D004791:Enzyme Inhibitors; D007527:Isoenzymes; D019384:Nucleic Acid Synthesis Inhibitors; D020033:Protein Isoforms; D011500:Protein Synthesis Inhibitors; D011838:Radiation-Sensitizing Agents; D020126:Brefeldin A; D005047:Etoposide; C497260:Prkcd protein, rat; D011493:Protein Kinase C; D051745:Protein Kinase C-delta; C505410:Casp3 protein, rat; C506435:Casp9 protein, rat; D053148:Caspase 3; D053453:Caspase 9; D020169:Caspases; D017239:Paclitaxel