Global, neuronal or β cell-specific deletion of inceptor improves glucose homeostasis in male mice with diet-induced obesity.

Insulin resistance is an early complication of diet-induced obesity (DIO) 1 , potentially leading to hyperglycaemia and hyperinsulinaemia, accompanied by adaptive β cell hypertrophy and development of type 2 diabetes 2 . Insulin not only signals via the insulin receptor (INSR), but also promotes β cell survival, growth and function via the insulin-like growth factor 1 receptor (IGF1R) 3-6 . We recently identified the insulin inhibitory receptor (inceptor) as the key mediator of IGF1R and INSR desensitization 7 . But, although β cell-specific loss of inceptor improves β cell function in lean mice 7 , it warrants clarification whether inceptor signal inhibition also improves glycaemia under conditions of obesity. We assessed the glucometabolic effects of targeted inceptor deletion in either the brain or the pancreatic β cells under conditions of DIO in male mice. In the present study, we show that global and neuronal deletion of inceptor, as well as its adult-onset deletion in the β cells, improves glucose homeostasis by enhancing β cell health and function. Moreover, we demonstrate that inceptor-mediated improvement in glucose control does not depend on inceptor function in agouti-related protein-expressing or pro-opiomelanocortin neurons. Our data demonstrate that inceptor inhibition improves glucose homeostasis in mice with DIO, hence corroborating that inceptor is a crucial regulator of INSR and IGF1R signalling.