CYP1B1 and Endothelial Nitric Oxide Synthase Combine to Sustain Proangiogenic Functions of Endothelial Cells under Hyperoxic Stress

Abstract

Lack of CYP1B1 expression is associated with attenuation of retinal endothelial cell (EC) capillary morphogenesis in vitro and angiogenesis in vivo. This is largely attributed to increased intracellular oxidative stress and increased production of thrombospondin‐2 (TSP2), an endogenous inhibitor of angiogenesis. Here we demonstrate that endothelium nitric oxide synthase (eNOS) expression is dramatically decreased in the EC prepared from retina, lung, heart, and aorta of CYP1B1‐deficient (CYP1B1−/−) mice compared to wild type (CYP1B1+/+) mice. The eNOS expression was also decreased in retinal vasculature of CYP1B1−/− mice. Inhibition of eNOS activity in cultured CYP1B1+/+ retinal EC blocked capillary morphogenesis concomitant with increased oxidative stress and reduced NO bioavailability. Furthermore, expression of a constitutively active eNOS in CYP1B1−/− retinal EC or their incubation with a NO donor reduced oxidative stress and improved cell migration and capillary morphogenesis. In addition, acute inhibition of CYP1B1 activity in the CYP1B1+/+ retinal EC resulted in increased oxidative stress, reduced NO bioavailability, and attenuation of capillary morphogenesis. Together our results suggest CYP1B1 constitutive expression produces long term effects on EC that favors eNOS expression and NO bioavailability by reducing oxidative stress and TSP2 expression. Supported by EY018179 and DK067120