Selective degradation of the PKC-epsilon isoform during cell death in AKR-2B fibroblasts.
The protein kinase C (PKC) family of serine/threonine protein kinases is involved in intracellular signals that regulate growth, differentiation, and apoptosis. AKR-2B cells express the PKC isoforms alpha, gamma, epsilon, lambda, mu, und zeta (J. Hoppe, R. Schäfer, V. Hoppe, and A. Sachinidis, Cell Death Differ. 6, 546-556). Here we show that during serum starvation only PKC-epsilon was cleaved. An N-terminal fragment of 42 kDa remained associated with subcellular components, presumably the Golgi apparatus. The C-terminal part (catalytic domain) was further degraded and was no longer detectable in vivo. As published before, the activation of the DEVDase in AKR-2B cells is prevented by numerous agents like PDGF, TPA, and DEVD.cmk (R. Schäfer, D. Karbach, and J. Hoppe, Exp. Cell Res. 240, 28--39). All these agents completely prevented PKC-epsilon cleavage, indicating a tight correlation between DEVDase activity and PKC-epsilon cleavage. By using recombinant caspase-3 or highly purified DEVDase from cytosolic extracts we localized by Edman degradation the cleavage site in recombinant PKC-epsilon to asp383 in the hinge region between regulatory and catalytic domains. The corresponding tetrapeptide sequences SSPD and SATD for human and mouse PKC-epsilon, respectively, are unusual for caspase-3. Expression of the catalytic domain or of the cleavage-resistant mutant D383A had no effect on cell death in AKR-2B cells.
Hoppe
J
J
Biozentrum, Department ot Physiological Chemistry, University of Würzburg, Am Hubland, 97074 Würzburg, Germany. hoppe@biozentrum.uni-wuerzburg.de
Hoppe
V
V
Schäfer
R
R
D000818:Animals; D017209:Apoptosis / Q000187:drug effects / Q000502:physiology*; D053148:Caspase 3; D020169:Caspases / Q000378:metabolism; D020134:Catalytic Domain / Q000235:genetics; D002478:Cells, Cultured / Q000166:cytology / Q000201:enzymology*; D016895:Culture Media, Serum-Free / Q000494:pharmacology; D005347:Fibroblasts / Q000166:cytology / Q000201:enzymology*; D006056:Golgi Apparatus / Q000201:enzymology / Q000648:ultrastructure; D007527:Isoenzymes / Q000187:drug effects / Q000378:metabolism*; D051379:Mice; D008806:Mice, Inbred AKR; D009154:Mutation / Q000187:drug effects / Q000502:physiology; D010447:Peptide Hydrolases / Q000494:pharmacology; D011493:Protein Kinase C / Q000187:drug effects / Q000378:metabolism*; D051744:Protein Kinase C-epsilon; D017434:Protein Structure, Tertiary / Q000502:physiology; D013217:Starvation / Q000201:enzymology
D016895:Culture Media, Serum-Free; D007527:Isoenzymes; C497256:Prkce protein, mouse; D011493:Protein Kinase C; D051744:Protein Kinase C-epsilon; D010447:Peptide Hydrolases; C505407:CASP3 protein, human; C505409:Casp3 protein, mouse; D053148:Caspase 3; D020169:Caspases; C108711:DEVDase