Role of miR-181c in Diet-Induced Obesity Through Regulation of Lipid Synthesis in Liver
We recently identified a nuclear-encoded miRNA (miR-181c) in cardiomyocytes that can translocate into mitochondria to regulate mitochondrial gene (mt-COX1), and influence obesity-induced cardiac dysfunction through mitochondrial pathway. Liver plays a pivotal role during obesity. Therefore, we hypothesized that miR-181c plays an important role in pathophysiological complications associated with obesity. We used miR-181c/d-/- mice to study the miR-181c role in lipogenesis in hepatocytes during diet-induced obesity (DIO). Indirect calorimetric measurements were made during the 26 weeks high fat diet (HFD) exposure. qPCR was performed to examine the gene expression involved in lipid synthesis. Here, we show that miR-181c/d-/- mice are not protected against all metabolic consequences of HFD exposure. After 26 weeks of the HFD, miR-181c/d-/- mice had a significantly higher body fat (%) compared to WT. Glucose tolerance tests showed hyperinsulinemia and hyperglycemia, indicative of insulin insensitivity in the miR-181c/d-/- mice. HFD-fed miR-181c/d-/- mice had higher serum and liver triglyceride levels compared to HFD-fed WT mice. qPCR data demonstrated that several genes which are regulated by isocitrate dehydrogenase 1 (IDH1) were upregulated in miR-181c/d-/- liver compared to WT liver. Furthermore, an AAV-8 was used to deliver miR-181c, in vivo, to validate the potential role of miR-181c in the liver. miR-181c delivery attenuate the lipogenesis by downregulating the same lipid synthesis genes in the liver. In hepatocytes, miR-181c regulates lipid biosynthesis by targeting IDH1. Taken together, the data indicate that overexpression of miR-181c can be beneficial for various lipid metabolism disorders.