C-reactive protein adversely alters the protein-protein interaction of the endothelial isoform of nitric oxide synthase.
BACKGROUND
C-reactive protein (CRP) inhibits the activity of the endothelial isoform of nitric oxide synthase (eNOS) via uncoupling of the enzyme both in vitro and in vivo. eNOS activity appears to be related in part to its interaction with other cellular proteins, including heat shock protein 90 (Hsp90), caveolin-1, and porin. In this study, we examined the effect of CRP treatment of human aortic endothelial cells (HAECs) on eNOS interaction with caveolin-1, Hsp90, and porin.


METHODS
We incubated HAECs with CRP (0, 12.5, and 25 mg/L) for 1, 6, or 24 h and assessed the interaction of these proteins with eNOS by immunoprecipitation and western blotting.


RESULTS
CRP treatment (12.5 and 25 mg/L) of HAECs for 24 h significantly increased eNOS binding to caveolin-1 (40% and 54% increase, respectively; P < 0.05) and decreased binding to Hsp90 (33% and 66% decrease, respectively; P < 0.05). CRP (25 mg/L) also significantly decreased the binding of porin to eNOS (11% decrease, P < 0.05). Similar results were seen when HAECs were treated with CRP for 6 h.


CONCLUSIONS
These negative protein-protein interactions of eNOS were able to partly explain the CRP-induced decreases in the activity of this critical enzyme, which caused endothelial dysfunction.
Valleggi
Simona
S
Laboratory for Atherosclerosis and Metabolic Research, Department of Medical Pathology and Laboratory Medicine, UC Davis Medical Center, Sacramento, CA 95817, USA.
Devaraj
Sridevi
S
Dasu
Mohan R
MR
Jialal
Ishwarlal
I
D002097:C-Reactive Protein / Q000494:pharmacology / Q000502:physiology*; D051242:Caveolin 1 / Q000378:metabolism; D002478:Cells, Cultured; D042783:Endothelial Cells / Q000378:metabolism*; D018841:HSP90 Heat-Shock Proteins / Q000378:metabolism; D006801:Humans; D007527:Isoenzymes / Q000378:metabolism; D052250:Nitric Oxide Synthase Type III / Q000037:antagonists & inhibitors / Q000378:metabolism*; D018272:Porins / Q000378:metabolism; D011485:Protein Binding; D013997:Time Factors
D051242:Caveolin 1; D018841:HSP90 Heat-Shock Proteins; D007527:Isoenzymes; D018272:Porins; D002097:C-Reactive Protein; D052250:Nitric Oxide Synthase Type III