PFKFB3 Mediated Changes in ROS/NO Balance Contribute to Endothelial Dysfunction in Obesity

Abstract

Obesity is a strong risk factor for cardiovascular disease, in large part due to an altered metabolic state. One of the earliest consequences of cardiovascular dysfunction in obesity is the loss of endothelial function and impaired nitric oxide (NO) signaling. In blood vessels, NO is synthesized by endothelial nitric oxide synthase (eNOS). The biological actions of NO can be compromised by rapid inactivation by reactive oxygen species (ROS) such as superoxide that is mainly generated by NADPH oxidases (NOXs). However, the signals coordinating the increased superoxide production leading to loss of NO with altered metabolism remain unknown.We have found that the expression of 6‐phosphofructo‐2‐kinase/fructose‐2, 6‐biphosphatase 3 (PFKFB3), which is a key glycolytic regulatory enzyme, is significantly increased in endothelial cells of obese animals. Overexpression of PFKFB3 within the endothelium of blood vessels is accompanied by the loss of vascular relaxation and in decreased NO production as a result of increased eNOS phosphorylation on the inhibitory T495 residue. PFKFB3 overexpression also blunted Akt‐S473 phosphorylation, reducing stimulus‐dependent phosphorylation and activation of eNOS at S1177. While PFKFB3 exerted negative effects on NO signaling, it increased the activity and mRNA levels of NOX1, a major contributor to endothelial dysfunction. Further, we have also found that pharmacological inhibition of NOX1 attenuates the decreased vasodilator responses in PFKFB3 overexpressing aortic rings.These results demonstrate a novel functional relationship between endothelial metabolism, ROS and NO production that may contribute to endothelial dysfunction in obesity.