Differential activation of protein kinase C isoforms by endothelin-1 and phenylephrine and subsequent stimulation of p42 and p44 mitogen-activated protein kinases in ventricular myocytes cultured from neonatal rat hearts.
The translocation of protein kinase C (PKC) isoforms PKC-alpha, PKC-delta, PKC-epsilon, and PKC-zeta from soluble to particulate fractions was studied in ventricular cardiomyocytes cultured from neonatal rats. Endothelin-1 (ET-1) caused a rapid ETA receptor-mediated translocation of PKC-delta and PKC-epsilon (complete in 0.5-1 min). By 3-5 min, both isoforms were returning to the soluble fraction, but a greater proportion of PKC-epsilon remained associated with the particulate fraction. The EC50 of translocation for PKC-delta was 11-15 nM ET-1 whereas that for PKC-epsilon was 1.4-1.7 nM. Phenylephrine caused a rapid translocation of PKC-epsilon (EC50 = 0.9 microM) but the proportion lost from the soluble fraction was less than with ET-1. Translocation of PKC-delta was barely detectable with phenylephrine. Neither agonist caused any consistent translocation of PKC-alpha or PKC-zeta. Activation of p42 and p44 mitogen-activated protein kinase (MAPK) by ET-1 or phenylephrine followed more slowly (complete in 3-5 min). Phosphorylation of p42-MAPK occurred simultaneously with its activation. The proportion of the total p42-MAPK pool phosphorylated in response to ET-1 (50%) was greater than with phenylephrine (20%). In addition to activation of MAPK, an unidentified p85 protein kinase was activated by ET-1 in the soluble fraction whereas an unidentified p58 protein kinase was activated in the particulate fraction.
Clerk
A
A
Department of Cardiac Medicine, University of London, United Kingdom.
Bogoyevitch
M A
MA
Anderson
M B
MB
Sugden
P H
PH
D000595:Amino Acid Sequence; D000818:Animals; D000831:Animals, Newborn; D001692:Biological Transport; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000378:metabolism*; D002478:Cells, Cultured; D065128:Endothelin Receptor Antagonists; D016232:Endothelins / Q000494:pharmacology*; D004789:Enzyme Activation; D006352:Heart Ventricles / Q000166:cytology / Q000187:drug effects* / Q000201:enzymology; D007527:Isoenzymes / Q000378:metabolism*; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases; D008969:Molecular Sequence Data; D010456:Peptides, Cyclic / Q000494:pharmacology; D010656:Phenylephrine / Q000494:pharmacology*; D010716:Phosphatidylinositols / Q000378:metabolism; D010766:Phosphorylation; D011493:Protein Kinase C / Q000378:metabolism*; D011505:Protein-Tyrosine Kinases / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley
D065128:Endothelin Receptor Antagonists; D016232:Endothelins; D007527:Isoenzymes; D010456:Peptides, Cyclic; D010716:Phosphatidylinositols; D010656:Phenylephrine; D011505:Protein-Tyrosine Kinases; D011493:Protein Kinase C; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases; C072247:cyclo(Trp-Asp-Pro-Val-Leu)