title: Protein kinase C-zeta modulates thromboxane A(2)-mediated apoptosis in adult ventricular myocytes via Akt.
abstract: 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.
authors.affiliation: 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
authors.forename: Yukitaka
authors.initials: Y
authors.lastname: Shizukuda
authors.forename: Peter M
authors.initials: PM
authors.lastname: Buttrick
mesh_terms: 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
chemical_list: 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