Hypothalamic Ventromedial Lin28a Enhances Glucose Metabolism in Diet-Induced Obesity
Kim JD, etc Diabetes,
The Lin28a/Let-7 axis has been studied in peripheral tissues for its role in metabolism regulation. However, its central function remains unclear. Here we found that Lin28a is highly expressed in the hypothalamus compared to peripheral tissues. Its expression is positively correlated with positive energy balance, suggesting a potential central role for Lin28a in metabolism regulation. Thus, we targeted the hypothalamic ventromedial nucleus (VMH) to selectively overexpress (Lin28aKIVMH ) or downregulate (Lin28aKDVMH ) Lin28a expression in mice. On a standard chow diet, body weight and glucose homeostasis were not affected in Lin28aKIVMH or Lin28aKDVMH mice. On high fat diet (HFD), although no difference in body weight and composition were observed, Lin28aKIVMH mice showed improved glucose tolerance and insulin sensitivity compared to their controls. Conversely, Lin28aKDVMH mice displayed glucose intolerance and insulin resistance. Changes in VMH AKT activation of diet-induced obese Lin28aKIVMH or Lin28aKDVMH mice were not associated with alterations in Let-7 levels or insulin receptor activation. Rather, we observed altered expression of TANK-binding kinase 1 (TBK-1), which was found to be a direct Lin28a target mRNA. VMH-specific inhibition of TBK-1 in diet-induced obese mice impaired glucose metabolism and AKT activation. Altogether, our data show a TBK-1-dependent role for central Lin28a in glucose homeostasis.