Calcium-independent activation of extracellular signal-regulated kinases 1 and 2 by cyclic strain.
We have previously demonstrated that cyclic strain induces extracellular signal-regulated kinases 1 and 2 (ERK1/2) activation in endothelial cells (EC). The aim of this study was to investigate the effect of Ca2+ on the activation of ERK1/2. Bovine aortic EC were pretreated with a chelator of extracellular Ca2+, ethylaneglycol-bis(aminoethylether)-tetra-acetate (EGTA), a depleter of Ca2+ pools, 2,5-Di-(tert-butyl)-1,4-benzohydroquinone (BHQ), or a Ca2+ channel blocker, GdCl3, and subjected to an average 10 % strain at a rate of 60 cycles/min for 10 min. BHQ and GdCl3 did not inhibit the strain-induced ERK1/2 activation. Chelation of normal extracellular Ca2+ (1.8 mM) medium with EGTA (3 mM) acutely stimulated baseline phosphorylation and activation of ERK1/2, thereby obscuring any strain-induced activation of ERK1/2. However, in EC preincubated for 24 hours in Ca2+-free medium, elevated baseline phosphorylation was minimally activated by EGTA (200 microM) such that cyclic strain stimulated ERK1/2 in the presence or absence of BHQ. These results suggest a Ca2+ independence of the ERK1/2 signaling pathway by cyclic strain.
Ikeda
M
M
Department of Surgery, Yale University School of Medicine, New Haven, Connecticut, 06510, USA.
Takei
T
T
Mills
I
I
Sumpio
B E
BE
D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002121:Calcium Channel Blockers / Q000494:pharmacology; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000378:metabolism*; D002417:Cattle; D002478:Cells, Cultured; D002614:Chelating Agents / Q000494:pharmacology; D004533:Egtazic Acid / Q000494:pharmacology; D004730:Endothelium, Vascular / Q000166:cytology / Q000201:enzymology* / Q000502:physiology*; D004789:Enzyme Activation; D005110:Extracellular Space / Q000378:metabolism; D005682:Gadolinium / Q000494:pharmacology; D006873:Hydroquinones / Q000494:pharmacology; D007424:Intracellular Fluid / Q000378:metabolism; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases; D010766:Phosphorylation; D013314:Stress, Mechanical
D002121:Calcium Channel Blockers; D002614:Chelating Agents; D006873:Hydroquinones; C019359:2,5-di-tert-butylhydroquinone; D004533:Egtazic Acid; D005682:Gadolinium; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases; C038958:gadolinium chloride; D002118:Calcium