Effect of glucotoxicity on Lin28a expression, β-cell function and apoptosis in primary rat islet cells. Rat islet cells were cultured in high glucose (HG, 30 mM D-glucose) for the time shown. (A, C, D, F, G) RT-qPCR analysis for Lin28a, insulin-1, insulin-2, PDX-1, and BETA 2 in high glucose-incubated rat islets cells. Data are from three independent experiments and values are shown as the mean ± SEM. *P value < 0.001 and **P value < 0.01 vs. 0 h. (B, H, I) Western blot analysis for Lin28a, PDX-1, BETA2, Bax, Bcl-2, c-caspase3 (c-cas3) and pro-caspase3 (pro-cas3) in high glucose-incubated rat islet cells. Data are from three independent measurements and values are shown as the mean ± SEM. *P < 0.01, **P < 0.05 vs. 0 h. (E) Quantification of glucose-stimulated insulin secretion (GSIS) of rat islet cells incubated with high glucose containing medium for 48h. Data are from three independent experiments and values are shown as the mean ± SEM. *P value < 0.05 vs. 5 mM D-glucose. PDX-1, pancreatic and duodenal homeobox 1; BETA2, basic helix-loop-helix type of transcription factor; GSIS, glucose-stimulated insulin secretion.