Loss of voltage-gated proton channel Hv1 leads to diet-induced obesity in mice

OBJECTIVE: The voltage-gated proton channel Hv1 has been proposed to mediate NADPH oxidase (NOX) function by regulating intracellular pH during respiratory bursts. In our previous work, we showed that Hv1 is expressed in pancreatic β cells and positively regulates insulin secretion. Here, we investigated the role of Hv1 in adipose tissue differentiation, metabolic homeostasis and insulin sensitivity using Hv1 knockout (KO) mice. DESIGN: Mice with genetic deletion of Hv1 are treated with high-fat diet (HFD) similar to wild-type (WT) mice. Body weight gain, adiposity, insulin sensitivity and gene expressions in both adipose tissue and liver were analyzed. RESULTS: Mice with genetic deletion of Hv1 display overt obesity with higher body weight gain and accumulation of adipose tissue compared with similarly HFD-treated WT. Hv1-deficient mice develop more glucose intolerance than WT, but no significant difference in insulin resistance, after fed with HFD. Deficiency of Hv1 results in a remarkable increase in epididymal adipocyte weight and size, while the gene expressions of proinflammatory factors and cytokines are obviously enhanced in the HFD-fed mice. Furthermore, the gene expression of Hv1 is increased in the HFD-fed mice, which is accompanied by the increase of NOX2 and NOX4. In addition, there is more severely diet-induced steatosis and inflammation in liver in KO mice. CONCLUSION: Our data demonstrated that lacking of Hv1 results in diet-induced obesity in mice through inflammation and hepatic steatosis. This study suggested that Hv1 acts as a positive regulator of metabolic homeostasis and a potential target for antiobesity drugs in therapy and may serve as an adaptive mechanism in cooperating with NOX to mediate reactive oxygen species for adipogenesis and insulin sensitivity.