FIG. 3.

Different effects of lipotoxicity and glucotoxicity on TXNIP knockout (bTKO) β-cells and mitochondria-mediated apoptosis. Isolated islets of bTKO and control (lox/lox) mice were incubated at (A) 11.1 mmol/l glucose ± palmitate (1 mmol/l) or (B) at 5 versus 25 mmol/l glucose for 24 h and analyzed by TUNEL. At least 12 islets and more than 700 β-cell nuclei were analyzed per group. Bars represent mean fold change ± SEM in β-cell apoptosis. C: Cytochrome c release from the mitochondria (M) into the cytosol (C) was measured by subcellular fractionation and immunoblotting in INS-1 cells incubated for 24 h at low glucose (LG; 5 mmol/l) or high glucose (HG; 25 mmol/l) with or without palmitate (FA). Bars represent means ± SEM of three independent experiments and a representative immunoblot is shown. *P < 0.01 (M) HG versus LG; **P < 0.01 (C) HG versus LG.