Figure 4. Mpv17 knockdown in cultured β-cell, MIN6, protected the cells against STZ-induced injury and apoptosis.

(A) qPCR and immunoblotting analysis of MPV17 levels in the Mpv17 siRNA-and scramble-treated MIN6 cells. (B) Immunoblotting showing MPV17 protein knockdown efficiency by the si-Mpv17. (C) CCK8 assay showed attenuated decrease of cell viability of the Mpv17 knockdown cells. (D) Cell real-time assay showed that Mpv17 knockdown attenuated the decrease of cell viability in the treatment of STZ. *P<0.05, statistically significant; **P<0.01, statistically very significant. The blue stars refer to the Scr+Veh vs. Scr+STZ, yellow stars to si-Mpv17+Veh vs. si-Mpv17+STZ, turquoise stars to Scr+STZ vs. si-Mpv17+STZ, and red stars to Scr+Veh vs. si-Mpv17+Veh. (E) Condensation nuclei counting showed that STZ-induced MIN6 apoptosis was alleviated by Mpv17 knockdown. (F) Immunoblotting showed the cleaved caspase 3 was increased by STZ treatment, which was attenuated in the cells treated with si-Mpv17. Quantification of the result is shown on the right. The quantification result in each panel is presented with mean ± SD of the data from three independent experiments except (E) in which the quantification is presented with mean ± SD of the counts of condensation nuclei from 20 random high-power fields. The comparisons between two groups were performed using two-tailed, unpaired Student’s t-test (A,B) and the multiple comparison tests between groups were performed using two-way ANOVA followed by Bonferroni’s post-hoc test (C–F). *P<0.05, statistically significant; **P<0.01, statistically very significant.