Stimulation of the p38 mitogen-activated protein kinase pathway in neonatal rat ventricular myocytes by the G protein-coupled receptor agonists, endothelin-1 and phenylephrine: a role in cardiac myocyte hypertrophy?
We examined the activation of the p38 mitogen-activated protein kinase (p38-MAPK) pathway by the G protein-coupled receptor agonists, endothelin-1 and phenylephrine in primary cultures of cardiac myocytes from neonatal rat hearts. Both agonists increased the phosphorylation (activation) of p38-MAPK by approximately 12-fold. A p38-MAPK substrate, MAPK-activated protein kinase 2 (MAPKAPK2), was activated approximately fourfold and 10 microM SB203580, a p38-MAPK inhibitor, abolished this activation. Phosphorylation of the MAPKAPK2 substrate, heat shock protein 25/27, was also increased. Using selective inhibitors, activation of the p38-MAPK pathway by endothelin-1 was shown to involve protein kinase C but not Gi/Go nor the extracellularly responsive kinase (ERK) pathway. SB203580 failed to inhibit the morphological changes associated with cardiac myocyte hypertrophy induced by endothelin-1 or phenylephrine between 4 and 24 h. However, it decreased the myofibrillar organization and cell profile at 48 h. In contrast, inhibition of the ERK cascade with PD98059 prevented the increase in myofibrillar organization but not cell profile. These data are not consistent with a role for the p38-MAPK pathway in the immediate induction of the morphological changes of hypertrophy but suggest that it may be necessary over a longer period to maintain the response.
Division of Biomedical Sciences, Imperial College School of Medicine, Charing Cross Campus, London W6 8RF, United Kingdom. aclerk@clara.net
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Sugden
D000818:Animals; D000831:Animals, Newborn; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000378:metabolism*; D006332:Cardiomegaly / Q000201:enzymology / Q000209:etiology; D048429:Cell Size / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D019332:Endothelin-1 / Q000494:pharmacology; D004789:Enzyme Activation / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000494:pharmacology; D019204:GTP-Binding Proteins / Q000378:metabolism; D006352:Heart Ventricles / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D006984:Hypertrophy; D047908:Intracellular Signaling Peptides and Proteins; D020928:Mitogen-Activated Protein Kinases; D009206:Myocardium / Q000201:enzymology* / Q000378:metabolism / Q000473:pathology; D010656:Phenylephrine / Q000494:pharmacology; D010766:Phosphorylation; D011493:Protein Kinase C / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D051381:Rats; D011956:Receptors, Cell Surface / Q000187:drug effects / Q000378:metabolism; D010566:Virulence Factors, Bordetella / Q000494:pharmacology; D048051:p38 Mitogen-Activated Protein Kinases; D000099190:MAP-Kinase-Activated Kinase 2
D017871:Calcium-Calmodulin-Dependent Protein Kinases; D019332:Endothelin-1; D004791:Enzyme Inhibitors; D019204:GTP-Binding Proteins; D047908:Intracellular Signaling Peptides and Proteins; D020928:Mitogen-Activated Protein Kinases; D010656:Phenylephrine; D011493:Protein Kinase C; D017346:Protein Serine-Threonine Kinases; D011956:Receptors, Cell Surface; D010566:Virulence Factors, Bordetella; D048051:p38 Mitogen-Activated Protein Kinases; D000099190:MAP-Kinase-Activated Kinase 2