Differential activation of mitogen-activated protein kinase cascades and apoptosis by protein kinase C epsilon and delta in neonatal rat ventricular myocytes.
Protein kinase C (PKC) epsilon and PKCdelta translocation in neonatal rat ventricular myocytes (NRVMs) is accompanied by subsequent activation of the ERK, JNK, and p38(MAPK) cascades; however, it is not known if either or both novel PKCs are necessary for their downstream activation. Use of PKC inhibitors to answer this question is complicated by a lack of isoenzyme specificity, and the fact that many PKC inhibitors stimulate JNK and p38(MAPK) activity. Therefore, replication-defective adenoviruses (Advs) encoding constitutively active (ca) mutants of PKCepsilon and PKCdelta were used to test if either or both of these PKCs are sufficient to activate ERKs, JNKs, and/or p38(MAPK) in NRVMs. Adv-caPKCepsilon infection (1 to 25 multiplicities of viral infection (MOI); 4 to 48 hours) increased total PKCepsilon levels in a time- and dose-dependent manner, with maximal expression observed 8 hours after Adv infection. Adv-caPKCepsilon induced a time- and dose-dependent increase in phosphorylated p42 and p44 ERKs, as compared with a control Adv encoding beta-galactosidase (Adv-nebetagal). Maximal ERK phosphorylation occurred 8 hours after Adv infection. In contrast, JNK was only minimally activated, and p38(MAPK) was relatively unaffected. Adv-caPKCdelta infection (1 to 25 MOI, 4 to 48 hours) increased total PKCdelta levels in a similar fashion. Adv-caPKCdelta (5 MOI) induced a 29-fold increase in phosphorylated p54 JNK, and a 15-fold increase in phosphorylated p38(MAPK) 24 hours after Adv infection. In contrast, p42 and p44 ERK were only minimally activated. Whereas neither Adv induced NRVM hypertrophy, Adv-caPKCdelta, but not Adv-caPKCepsilon, induced NRVM apoptosis. We conclude that the novel PKCs differentially regulate MAPK cascades and apoptosis in an isoenzyme-specific and time-dependent manner.
Heidkamp
M C
MC
Cardiovascular Institute, Loyola University Chicago, Maywood, Illinois, USA. mheidka@lumc.edu
Bayer
A L
AL
Martin
J L
JL
Samarel
A M
AM
D000256:Adenoviridae / Q000235:genetics; D000818:Animals; D000831:Animals, Newborn; D017209:Apoptosis / Q000502:physiology*; D048429:Cell Size / Q000187:drug effects; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D004789:Enzyme Activation / Q000187:drug effects / Q000235:genetics; D004791:Enzyme Inhibitors / Q000494:pharmacology; D015870:Gene Expression; D005822:Genetic Vectors / Q000008:administration & dosage / Q000235:genetics; D006352:Heart Ventricles / Q000166:cytology / Q000187:drug effects / Q000201:enzymology; D020287:In Situ Nick-End Labeling; D007527:Isoenzymes / Q000008:administration & dosage / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D048031:JNK Mitogen-Activated Protein Kinases; D020935:MAP Kinase Signaling System / Q000502:physiology*; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D009206:Myocardium / Q000201:enzymology*; D010766:Phosphorylation / Q000187:drug effects; D011493:Protein Kinase C / Q000008:administration & dosage / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D051745:Protein Kinase C-delta; D051744:Protein Kinase C-epsilon; D051381:Rats; D048051:p38 Mitogen-Activated Protein Kinases
D004791:Enzyme Inhibitors; D007527:Isoenzymes; C497260:Prkcd protein, rat; C497257:Prkce protein, rat; D011493:Protein Kinase C; D051745:Protein Kinase C-delta; D051744:Protein Kinase C-epsilon; D048031:JNK Mitogen-Activated Protein Kinases; D020928:Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases