α1-adrenergic stimulation differentially activates the mitogen-activated protein kinase subfamilies in adult rat cardiac myocytes

2000 ◽  
Vol 28 (5) ◽  
pp. A431-A431
Author(s):  
T. Markou ◽  
A. Lazou
Keyword(s):  
Protein Kinase ◽  
Cardiac Myocytes ◽  
Mitogen Activated Protein Kinase ◽  
Adrenergic Stimulation ◽  
Adult Rat ◽  
Mitogen Activated Protein ◽  
Rat Cardiac Myocytes

scholarly journals Phosphorylation and activation of mitogen- and stress-activated protein kinase-1 in adult rat cardiac myocytes by G-protein-coupled receptor agonists requires both extracellular-signal-regulated kinase and p38 mitogen-activated protein kinase

2002 ◽  
Vol 365 (3) ◽  
pp. 757-763 ◽  
Author(s):  
Thomais MARKOU ◽  
Antigone LAZOU
Keyword(s):  
Protein Kinase ◽  
G Protein ◽  
Cardiac Myocytes ◽  
P38 Mapk ◽  
Mitogen Activated Protein Kinase ◽  
G Protein Coupled Receptor ◽  
Receptor Agonists ◽  
Adult Rat ◽  
G Protein Coupled ◽  
Rat Cardiac Myocytes

G-protein-coupled receptor agonists are powerful stimulators of mitogen-activated protein kinase (MAPK) cascades in cardiac myocytes. However, little is known regarding the physiological activation of enzymes downstream of MAPKs. We examined the activation of mitogen- and stress-activated protein kinase-1 (MSK1), a downstream target of MAPKs, in adult rat cardiac myocytes by phenylephrine and endothelin-1. Both agonists induced the phosphorylation of MSK1 at Thr-581 and Ser-376 but not at Ser-360. Maximal phosphorylation was observed at 10–15min after stimulation and it correlated with increased activity. Maximal activation of MSK1 in adult cardiomyocytes temporally coincided with maximal p38 MAPK activation while activation of the extracellular-signal-regulated kinase (ERK) cascade was more rapid. Phosphorylation and activation of MSK1 was completely inhibited by either PD98059 (ERK1/2 pathway inhibitor) or SB203580 (p38 MAPK inhibitor) alone. These data demonstrate that MSK1 activation in adult rat cardiac myocytes by G-protein-coupled receptor agonists requires the simultaneous activation of both the ERK and p38 MAPK pathways. However, the lack of phosphorylation at Ser-360, an identified phosphorylation site targeted by MAPKs, may indicate that MSK1 is not a direct substrate of ERK1/2 and p38 MAPK in adult rat cardiomyocytes.

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