Circ_0000284 Is Involved in Arsenite-Induced Hepatic Insulin Resistance Through Blocking the Plasma Membrane Translocation of GLUT4 in Hepatocytes via IGF2BP2/PPAR-γ

Arsenic exposure can induce liver insulin resistance (IR) and diabetes (DM), but the underlying mechanisms are not yet clear. Circular RNAs (circRNAs) are involved in the regulation of the onset of diabetes, especially in the progression of IR. This study aimed to investigate the role of circRNAs in arsenic-induced hepatic IR and its underlying mechanism. Male C57BL/6J mice were given drinking water containing sodium arsenite (0, 0.5, 5, or 50 ppm) for 12 months. The results show that sodium arsenite increased circ_0000284 expression, decreased insulin-like growth factor 2 mRNA binding protein 2 (IGF2BP2) and peroxisome proliferator-activated receptor-γ (PPAR-γ), and inhibited cell membrane protein levels of insulin-responsive glucose transporter protein 4 (GLUT4) in the mouse livers, indicating that arsenic exposure causes liver damage and disruptions to glucose metabolism. Furthermore, sodium arsenite reduced glucose consumption and glycogen levels, increased the expression of circ_0000284, reduced the protein levels of IGF2BP2 and PPAR-γ, and inhibited GLUT4 protein levels in the cell membranes of insulin-treated HepG2 cells. However, a circ_0000284 inhibitor reversed arsenic exposure-induced reductions in IGF2BP2, PPAR-γ, and GLUT4 levels in the plasma membrane. These results indicate that circ_0000284 is involved in arsenite-induced hepatic insulin resistance through blocking the plasma membrane translocation of GLUT4 in hepatocytes via IGF2BP2/PPAR-γ. This study provides a scientific basis for finding early biomarkers for the control of arsenic exposure and type 2 diabetes mellitus (T2DM), and discovering new prevention and control measures.