Depletion of regulator-of-G-protein signaling-10 in mice exaggerates high-fat diet-induced insulin resistance and inflammation, and this effect is mitigated by dietary green tea extract.

ABSTRACT

The interaction between insulin resistance and inflammation plays a central role in the development of chronic diseases, although the mechanism is not fully understood. We previously demonstrated that regulator of G-protein signaling-10 (RGS10) protein is a negative modulator of the inflammatory response in macrophages and microglia. Because inflammation is a critical component in the development of high fat diet-induced insulin resistance, in this study we investigated whether RGS10 is involved in the diet-dependent regulation of glucose tolerance and insulin sensitivity. We hypothesized that the absence of RGS10 would exaggerate high-fat diet (HFD)-induced insulin resistance and inflammation response. Our results showed that RGS10 knockout (KO) mice fed a HFD gained significantly more weight and developed severe insulin resistance compared to wild-type (WT) mice fed HFD. Furthermore, compared to WT HFD-fed mice, KO mice fed the HFD displayed inflammatory phenotypes such as decreased adipose tissue expression of the anti-inflammatory M2 markers YM1 and Fizz1 and increased expression of the proinflammatory M1 cytokine interleukin 6 in adipose and CD11b, CD68 and interleukin 1ß in liver tissues. The impact of RGS10 deficiency on the exaggeration of HFD-induced insulin resistance and inflammation was ameliorated by oral consumption of green tea extract. Our results demonstrate that RGS10 is an important part of a protective mechanism involved in in regulating metabolic homeostasis by reducing inflammatory responses, which could potentially lead to an innovative new approach targeting inflammation and insulin resistance.