Arsenic signals through g‐proteins and NADPH Oxidase (NOX) to promote mouse liver sinusoidal endothelial cell capillarization

Abstract

Arsenic is a global health hazard that may cause disease in over 100 million people world‐wide. Liver disease including portal hypertension, non‐cirrhotic portal fibrosis, and vascular shunting and oxidative injury are associated drinking water with elevated arsenic levels. Liver sinusoidal endothelial cell (LSEC) capillarization with loss of fenestrations and increased surface expression of PECAM‐1 is an early event in these diseases. Drinking water containing 10 ppb or more of arsenic promotes LSEC capillarization in mice through unknown mechanisms. Therefore, the hypothesis that arsenic signals through NOX to promote LSEC capillarization was tested in primary mouse LSEC cultures. Ex Vivo arsenic exposures (0.5–5 μM) for 8 h recapitulated in vivo effects on capillarization. The ex vivo exposures increased superoxide generation that was prevented by pre‐incubating cells with the scavenger tempol or a selective NOX2 inhibitory peptide, gp91‐tat. Both tempol and gp91‐tat prevented arsenic‐stimulated capillarization. Finally, inhibition of either Gai or Rac1 GTPase also blocked arsenic‐stimulated oxidant generation and capillarization. These data are first demonstrating that environmental levels of arsenic stimulate LSEC capillarization through a g‐protein coupled, NOX‐mediated signaling cascade. Sponsored by EPA STAR grant FP‐91654201 and NIEHS grant R01ES013781.