Fig. 3

USP22 is a target of miR-144-3p and exerts a suppressive function on the ferroptosis of pancreatic β cells. A The expression of USP22 in pancreatic tissues between the control and T2DM model groups. B The expression level of USP22 in INS-1 cells after 24, 48, 72 h cultivation of HG was detected by RT-qPCR. C Dual-luciferase reporter assay confirmed the putative binding site for miR-144-3p in the 3′-UTR of USP22 (right), as predicted by the TargetScan (left). D The expression of USP22 in INS-1 cells transfected with miR-144-3p mimics at mRNA (left) and protein (right) levels. E The correlation analysis between the expression of miR-144-3p and USP22 in the pancreas of the T2DM model. F RT-qPCR detected the transfection efficiency of USP22 overexpression vector (USP22 OE). Before treating with HG, INS-1 cells transfected with or without USP22 OE alone, or together with miR-144-3p mimic or NC mimic. G Cell viability of HG-induced INS-1 cells was detected by CCK-8 assay. H GSH content, I MDA levels, and J iron content were measured using the corresponding detection kits. K Lipid ROS level was determined by the BODIPY™ 581/591 C11 method. L The levels of USP22 and ferroptosis-related proteins (GPX4 and TFR1) were evaluated by western blot. M Glucose stimulated insulin secretion was detected to assess β cells’ function (^**P < 0.01 and ^***P < 0.005 vs. HG-induced INS-1 cells; ^#P < 0.05, ^##P < 0.01, ^###P < 0.005 vs. HG-induced INS-1 cells + USP22 OE)