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PECAM-1 interacts with nitric oxide synthase in human endothelial cells: implication for flow-induced nitric oxide
N Dusserre1, N L'Heureux, K S Bell
1Department of Bioengineering, University of California San Diego, La Jolla, Calif, USA.
Arteriosclerosis, Thrombosis, and Vascular Biology
|July 31, 2004
Summary
Fluid shear stress (FSS) temporal gradients, not steady FSS, activate endothelial nitric oxide synthase (eNOS) by disrupting its complex with PECAM-1 at cell junctions, modulating eNOS activity.
Area of Science:
- Endothelial cell biology
- Mechanotransduction
- Cardiovascular physiology
Background:
- Endothelial nitric oxide synthase (eNOS) activity is regulated by fluid shear stress (FSS).
- Mechanotransduction pathways distinguish between rapid FSS changes and sustained FSS.
- eNOS localization at cell-cell junctions may influence its response to FSS.
Purpose of the Study:
- To investigate the role of eNOS sublocalization at cell-cell junctions in its response to FSS.
- To test the hypothesis that eNOS is activated by temporal gradients of FSS at the cell junction.
Main Methods:
- Immunofluorescence staining for eNOS and PECAM-1 in HUVECs and mouse aorta.
- Co-immunoprecipitation to confirm eNOS/PECAM-1 association.
- Application of impulse and ramped FSS to HUVECs to measure eNOS activity (cGMP production).
Main Results:
- eNOS localizes at cell-cell junctions with PECAM-1 in HUVECs and wild-type mouse aorta.
- Loss of junctional eNOS in PECAM-1 knockout mice and near arterial branches.
- Impulse FSS transiently disrupted the eNOS/PECAM-1 complex, increasing eNOS activity and cGMP production.
- Ramped FSS did not affect the complex or eNOS activity.
- PECAM-1 directly inhibits eNOS activity in a cell-free system.
Conclusions:
- eNOS forms a complex with PECAM-1 at endothelial cell-cell junctions.
- This complex is sensitive to temporal gradients in FSS, leading to eNOS activation.
- FSS temporal gradients, not steady FSS, modulate eNOS activity via junctional complex dynamics.