Fig. 3: Overexpression of miR-802 impairs β cell function.

qRT-PCR was used to evaluate the Ins1 and Ins2 levels, followed by immunostaining for DAPI (blue) and insulin (red) (Magnification: 40 ×, scale bar: 20 μm), (a) in islets (n = 3, 8 weeks old) and (b) in Min6 cells (n = 3 cell wells); then, insulin content was measured in islets (c), n = 5, 8 weeks old) and Min6 cells (d), n = 3 cell wells); and insulin secretion was analyzed in islets (e), n = 5, 8 weeks old) and Min6 cells (f), ***p < 0.001. g IPGTT (2 g kg⁻¹) in overnight fasted miR-802 KI and control mice at 10 weeks of age (n = 11 control group, n = 9 miR-802 KI). h In vivo insulin excursions at 15 weeks of age (n = 4). i Insulin content in the serum of miR-802 KI and control mice (n = 3, 10 weeks old). j Static insulin secretion was evaluated in islets from 15-week-old miR-802 KI and control mice (n = 5). k Islet organization in pancreas of miR-802 KI and control mice at 10 weeks of age (n = 3). Staining for insulin and glucagon is shown. Scale bar: 50 μm. Fasting insulin levels (FINS, (l) and HOMA-IR (m) at indicated time points of lentivirus-shFoxo1-treated, lentivirus-shFoxo1 and lentivirus-miR-802-treated mice fed an HFD diet compared with control mice (n = 7). HOMA-IR was calculated as HOMA-IR = (FBG (mmol L⁻¹) x FINS (mIU L⁻¹))/22.5. IPGTT (n) and IPITT (o) assays were performed to evaluate the insulin sensitivity of mice. Area under the curve (AUC) was calculated (n = 7). *p < 0.05; **p < 0.01; ***p < 0.001 versus control group; #p < 0.05, ##p < 0.01, ###p < 0.001 versus lentivirus-shFoxo1 group, insulin synthesis (p) and insulin secretion (q, n = 5) were analyzed. The p-values by two-tailed unpaired Student’s t test (c, d and I), one-way ANOVA (l, m) or two-way ANOVA (a, b, e–h, j, n–q) are indicated. All data are represented as mean ± SD except (g, h) and (l–o) (mean ± SEM). Source data are provided as a Source Data file.