FIGURE 4.

Role of miR-200b in beta cell apoptosis. A, members of the miR-200 family were overexpressed in INS-1 beta cells by transfection. 48 h after transfection, cells were harvested, and cleaved caspase-3 was measured by immunoblotting and corrected for β-actin. The results of three independent experiments were used for the quantification shown. B, INS-1 beta cells transfected with negative control or pre-miR-200b for 48 h were analyzed by TUNEL staining. Representative pictures are shown; the red arrows point to TUNEL-positive apoptotic nuclei. For quantification of the percent TUNEL-positive beta cells, >500 nuclei were analyzed per group. C, INS-1 beta cells transfected with miR-200b were analyzed for the Bax/Bcl2 ratio by qRT-PCR. D, human islets were transfected with miR-200b or negative control, and after 72 h, the Bax/Bcl2 ratio was assessed as a marker of apoptosis. Error bars represent mean ± S.E. (n = 3).