Figure 4.
Effect of Rap1b transfection on the high glucose–induced altered mitochondrial morphology, membrane potential, and cell survival. (A) High-glucose (35 mM) treatment induced marked deformation of the mitochondria with dilation of the cristae (arrows), as observed by electron microscopy. With Rap1b overexpression, the aberrant cristae were not observed, but the swelling of the mitochondria persisted to a certain extent. (B) By confocal microscopy, a loss of TMRE staining, indicative of mitochondrial ΔΨm, was observed under high-glucose ambience in cells undergoing apoptosis (green arrowheads, middle subpanels). DAPI staining highlights the fragmented nuclei (blue staining) of apoptotic cells (arrowheads). Rap1b transfection restored the TMRE staining and ΔΨm (right subpanels). (C) FACS analyses revealed decreased cell survival under high-glucose (HG) ambience, which was restored to baseline with overexpression of Rap1b as in cells with low glucose (LG; 5 mM) culture media. (D) Quantification of FACS analyses of four experiments. *P < 0.01.