Bcl-2 and Bcl-xL Suppress Glucose Signaling in Pancreatic β-Cells

(Downloading may take up to 30 seconds. If the slide opens in your browser, select File -> Save As to save it.)

Click on image to view larger version.

FIG. 1.
FIG. 1.

Small-molecule inhibition of Bcl-2/Bcl-xL rapidly displaces Bad and eventually induces mitochondrial apoptosis. A: Top: Western blot illustrating the loss of Bcl-xL coimmunoprecipitation with Bad in MIN6 β-cells treated with C6. Bottom: Densitometric quantification of the ratio of Bcl-xL to Bad protein in Bad immunoprecipitates after various durations of C6 exposure. Data (mean ± SEM) are normalized to control (n = 3–5; *P < 0.05 vs. time 0). B: Bcl-xL and Bad protein levels in MIN6 β-cells treated with 80 μmol/L C6 (n = 3; *P < 0.05 vs. time 0). C and D: PI incorporation in mouse islet cells and MIN6 β-cells during incubation with C6 (n = 3). E: Relative cell death (PI+ cells) in human islet cells treated with Bcl-2/Bcl-xL antagonists (n = 3 donor preparations). F: Western blots for Bax and cytochrome c (Cyto c) in mitochondrial and cytosolic fractions from MIN6 β-cells treated with 40 μmol/L C6 for 4 h (n = 3). G: Top: Caspase-3 activation (loss of MiCy-mKO FRET) imaged in four individual MIN6 β-cells during continued Bcl-2/Bcl-xL inhibition. Bottom: C6 (20 μmol/L) activated caspase-3 at an average time of 2.9 ± 0.3 h (n = 12 cells from two independent cultures). Staurosporine (STS; 10 μmol/L) activated caspase-3 after 1.65 ± 0.12 h (n = 10 cells from two independent cultures). H: Flow cytometric detection of mitochondrial membrane potential in MIN6 β-cells treated with 20 μmol/L C6, 20 μmol/L YC137, and 30 mmol/L glucose (30G). Reduction of TMRE intensity indicates a loss of ΔΨm (n = 3 cultures). (A high-quality color representation of this figure is available in the online issue.)

This Article

  1. Diabetes vol. 62 no. 1 170-182