Shear stress stimulates phosphorylation of protein kinase A substrate proteins including endothelial nitric oxide synthase in endothelial cells.
- Author:
Yong Chool BOO
1
Author Information
1. Department of Molecular Medicine, Kyungpook National University School of Medicine, Daegu 700-422, Korea. ycboo@knu.ac.kr
- Publication Type:Retracted Publication ; Original Article ; Comparative Study ; Research Support, Non-U.S. Gov't
- Keywords:
cyclic AMP responsive element-binding protein;
endothelial cells;
nitric oxide synthase type III;
protein kinase A
- MeSH:
Animals;
Aorta, Thoracic/cytology;
Blotting, Western;
Cattle;
Cell Culture Techniques;
Cell Extracts;
Cells, Cultured;
Comparative Study;
Cyclic AMP-Dependent Protein Kinases/analysis/*metabolism;
Endothelium, Vascular/cytology/*enzymology/*metabolism;
Nitric Oxide Synthase Type III/analysis/*metabolism;
Phosphorylation;
Precipitin Tests;
Research Support, Non-U.S. Gov't;
Stress, Mechanical;
Time Factors
- From:Experimental & Molecular Medicine
2006;38(1):63-71
- CountryRepublic of Korea
- Language:English
-
Abstract:
Fluid shear stress plays a critical role in vascular health and disease. While protein kinase A (PKA) has been implicated in shear-stimulated signaling events in endothelial cells, it remains unclear whether and how PKA is stimulated in response to shear stress. This issue was addressed in the present study by monitoring the phosphorylation of endogenous substrates of PKA. Shear stress stimulated the phosphorylation of cAMP responsive element binding protein (CREB) in a PKA-dependent manner. Western blot analysis using the antibody reactive against the consensus motif of PKA substrates detected two proteins, P135 and P50, whose phosphorylation was increased by shear stress. The phosphorylation of P135 was blocked by a PKA inhibitor, H89, but not by a phosphoinositide 3-kinase inhibitor, wortmannin. Expression of a constitutively active PKA subunit stimulated P135 phosphorylation, supporting the potential of P135 as a PKA substrate. P135 was identified as endothelial nitric oxide synthase (eNOS) by immunoprecipitation study. PKA appeared to mediate shear stress-stimulated eNOS activation. Shear stress stimulated intracellular translocation of PKA activity from 'soluble' to 'particulate' fractions without involving cellular cAMP increase. Taken together, this study suggests that shear stress stimulates PKA-dependent phosphorylation of target proteins including eNOS, probably by enhancing intracellular site-specific interactions between protein kinase and substrates.
