Differential regulation of protein kinase C isoforms in isolated neonatal and adult rat cardiomyocytes
| Autor: | M, Pucéat, R, Hilal-Dandan, B, Strulovici, L L, Brunton, J H, Brown |
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| Rok vydání: | 1994 |
| Předmět: |
Aging
Myocardium Blotting Western Cell Membrane Genes fos Heart Phosphoproteins Propranolol Gene Expression Regulation Enzymologic Rats Isoenzymes Kinetics Cytosol Animals Newborn Animals Tetradecanoylphorbol Acetate Carbachol Phosphorylation Egtazic Acid Proto-Oncogene Proteins c-fos Cells Cultured Protein Kinase C |
| Zdroj: | The Journal of biological chemistry. 269(24) |
| ISSN: | 0021-9258 |
| Popis: | We have immunologically identified the isoforms of protein kinase C (PKC) present in neonatal and adult rat cardiomyocytes and examined their regulation by hormones and phorbol ester. Both cell types express the Ca(2+)-dependent alpha-PKC and the Ca(2+)-independent epsilon- and delta-PKC isoforms. The atypical zeta-PKC isoform is also expressed in neonatal, but only weakly in adult cells. Stimulation of the alpha 1-adrenergic or purinergic receptor with phenylephrine or ATP, respectively, increases membrane-associated immunoreactivity of both epsilon- and delta-PKC in neonatal and adult cells; endothelin and carbachol are also effective in adult cells. In contrast, none of the agonists leads to increases in membrane-associated alpha-PKC in cardiomyocytes. PKC zeta is also unaffected by receptor stimulation. The phorbol ester phorbol 12-myristate 13-acetate causes redistribution and subsequently down-regulation of alpha-, epsilon-, and delta- but not zeta-PKC. The three isoforms are down-regulated at distinctively different rates, with alpha-PKC being the most rapid and epsilon-PKC the slowest. We used selective down-regulation of alpha-, epsilon-, and delta-PKC to investigate the role of these isoforms in PKC phosphorylation-dependent events in neonatal myocytes. Our findings suggest that epsilon-PKC is responsible for the phenylephrine-induced phosphorylation of MARCKS, an endogenous PKC-specific substrate. In contrast, agonist-induced c-fos expression is unlikely to be mediated by epsilon-PKC since the response is rapidly down-regulated and apparently Ca(2+)-dependent. Our finding that the PKC isoforms are differentially responsive to neurohormones suggests that they play distinct and specific roles in cardiac function. |
| Databáze: | OpenAIRE |
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