Protein kinase C-zeta modulates thromboxane A(2)-mediated apoptosis in adult ventricular myocytes via Akt.
We hypothesized that thromboxane A(2) (TxA(2)) receptor stimulation directly induces apoptosis in adult cardiac myocytes. To investigate this, we exposed cultured adult rat ventricular myocytes (ARVM) to a TxA(2) mimetic [1S-[1alpha,2alpha(Z),3beta(1E,3S*),4alpha]]-7-[3-[3-hydroxy-4-(4-iodophenoxy)-1-butenyl]-7-oxabicyclo[2.2.1]hept-2-yl]-5-heptenoic acid (I-BOP) for 24 h. Stimulation with I-BOP induced apoptosis in a dose-dependent manner and was completely prevented by a TxA(2) receptor antagonist, SQ-29548. We further investigated the role of protein kinase C (PKC) in this process. TxA(2) stimulation resulted in membrane translocation of PKC-zeta but not PKC-alpha, -betaII, -delta, and -epsilon at 3 min and 1 h. The activation of PKC-zeta by I-BOP was confirmed using an immune complex kinase assay. Treatment of ARVM with a cell-permeable PKC-zeta pseudosubstrate peptide (zeta-PS) significantly attenuated apoptosis by I-BOP. In addition, I-BOP treatment decreased baseline Akt activity and its decrease was reversed by treatment with zeta-PS. The inhibition of phosphatidylinositol 3-kinase upstream of Akt by wortmannin or LY-294002 abolished the antiapoptotic effect of zeta-PS. Therefore, our results suggest that the activation of PKC-zeta modulates TxA(2) receptor-mediated apoptosis at least, in part, through Akt activity in adult cardiac myocytes.
Shizukuda
Yukitaka
Y
Program in Cardiovascular Sciences, Section of Cardiology, Department of Medicine, University of Illinois at Chicago, M/C 787, 840 S. Wood St., Chicago, IL 60612, USA. shizukud@uic.edu
Buttrick
Peter M
PM
D000595:Amino Acid Sequence; D000730:Androstadienes / Q000494:pharmacology; D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D019086:Bridged Bicyclo Compounds, Heterocyclic / Q000494:pharmacology*; D002478:Cells, Cultured; D002867:Chromones / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005231:Fatty Acids, Unsaturated / Q000494:pharmacology*; D006321:Heart / Q000187:drug effects; D006352:Heart Ventricles; D006801:Humans; D020287:In Situ Nick-End Labeling; D007527:Isoenzymes / Q000378:metabolism; D008297:Male; D008969:Molecular Sequence Data; D009025:Morpholines / Q000494:pharmacology; D009206:Myocardium / Q000378:metabolism*; D010446:Peptide Fragments / Q000737:chemistry; D011493:Protein Kinase C / Q000737:chemistry / Q000378:metabolism*; D017346:Protein Serine-Threonine Kinases; D011505:Protein-Tyrosine Kinases / Q000378:metabolism; D011518:Proto-Oncogene Proteins / Q000378:metabolism*; D051057:Proto-Oncogene Proteins c-akt; D051381:Rats; D017208:Rats, Wistar; D013379:Substrate Specificity; D013928:Thromboxane A2 / Q000494:pharmacology*; D000077191:Wortmannin; D000099221:Protein Kinase C zeta
D000730:Androstadienes; D019086:Bridged Bicyclo Compounds, Heterocyclic; D002867:Chromones; D004791:Enzyme Inhibitors; D005231:Fatty Acids, Unsaturated; D007527:Isoenzymes; D009025:Morpholines; D010446:Peptide Fragments; D011493:Protein Kinase C; D017346:Protein Serine-Threonine Kinases; D011505:Protein-Tyrosine Kinases; D011518:Proto-Oncogene Proteins; D051057:Proto-Oncogene Proteins c-akt; D013928:Thromboxane A2; D000077191:Wortmannin; D000099221:Protein Kinase C zeta; C061750:7-(3-(3-hydroxy-4-(4'-iodophenoxy)-1-butenyl)-7-oxabicyclo(2.2.1)heptan-2-yl)-5-heptenoic acid; C085911:2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one; C494918:AKT1 protein, human; C494920:Akt1 protein, rat