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Title: Phenylephrine promotes phosphorylation of bad in cardiac myocytes through the extracellular signal-regulated kinases 1/2 and protein kinase A
Authors: Valks D.M.
Cook S.A. 
Pham F.H.
Morrison P.R.
Clerk A.
Sugden P.H.
Keywords: Adrenoceptors
Bcl-2 proteins
Cardiac myocytes
Mitogen-activated protein kinases
Issue Date: 2002
Publisher: Academic Press
Citation: Valks D.M., Cook S.A., Pham F.H., Morrison P.R., Clerk A., Sugden P.H. (2002). Phenylephrine promotes phosphorylation of bad in cardiac myocytes through the extracellular signal-regulated kinases 1/2 and protein kinase A. Journal of Molecular and Cellular Cardiology 34 (7) : 749-763. ScholarBank@NUS Repository.
Abstract: Studies in non-cardiomyocytic cells have shown that phosphorylation of the Bcl-2 family protein Bad on Ser-112. Ser-136 and Ser-155 decreases its pro-apoptotic activity. Both phenylephrine (100 �M) and the cell membrane-permeating cAMP analog, 8-(4-chlorophenylthio)-cAMP (100 �M), protected against 2-deoxy-D-glucose-induced apoptosis in neonatal rat cardiac myocytes as assessed by terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL). In cardiac myocytes, phenylephrine primarily stimulates the ?-adrenoceptor, but, at high concentrations (100 �M), it also increases the activity of the cAMP-dependent protein kinase, protein kinase A (PKA) through the ?-adrenoceptor. Phenylephrine (100 �M) promoted rapid phosphorylation of Bad(Ser-112) and Bad(Ser-155), though we were unable to detect phosphorylation of Bad(Ser-136). Phosphorylation of Bad(Ser-112) was antagonized by either prazosin or propranolol, indicating that this phosphorylation required stimulation of both ?1- and ?-adrenoceptors. Phosphorylation of Bad(Ser-155) was antagonized only by propranolol and was thus mediated through the ?-adrenoceptor. Inhibitor studies and partial purification of candidate kinases by fast protein liquid chromatography showed that the p90 ribosomal S6 kinases, p90RSK2/3 [which are activated by the extracellular signal-regulated kinases 1 and 2 (ERK1/2)] directly phosphorylated Bad(Ser-112), whereas the PKA catalytic subunit directly phosphorylated Bad(Ser-155). However, efficient phosphorylation of Bad(Ser-112) also required PKA activity. These data suggest that, although p90RSK2/3 phosphorylate Bad(Ser-112) directly, phosphorylation of this site is enhanced by phosphorylation of Bad(Ser-155). These phosphorylations potentially diminish the pro-apoptotic activity of Bad and contribute to the cytoprotective effects of phenylephrine and 8-(4-chlorophenylthio)-cAMP. � 2002 Elsevier Science Ltd. All rights reserved.
Source Title: Journal of Molecular and Cellular Cardiology
ISSN: 222828
DOI: 10.1006/jmcc.2002.2014
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