Coenzyme Q10 suppresses apoptosis of mouse pancreatic β-cell line MIN6

Background: In mitochondrial diabetes, apoptosis of beta-cells caused by mitochondrial stress plays an important role in impaired insulin secretion. Several studies have reported that coenzyme Q10 (CoQ10) has therapeutic effects on mitochondrial diabetes, but no reports have examined the fundamental effectiveness or mechanism of CoQ10 in mitochondrial diabetes. We previously reported in a Japanese article that CoQ10 has protective effects on pancreatic beta-cells against mitochondrial stress using mouse pancreatic beta-cell line MIN6 and staurosporine (STS). Here, we report that CoQ10 protects MIN6 cells against apoptosis caused by STS and describe the more detailed apoptotic cascade. Methods: Apoptosis of MIN6 cells was induced by 0.5 mu M STS treatment for specific periods with or without 30 mu M CoQ10. The apoptosis cascade in MIN6 cells was then investigated using WST-8 assays, annexin-V staining, western blotting, and DNA degradation analysis. Results: Sixteen hours of 0.5 mu M STS treatment led to 47% cell viability, but pretreatment with 30 mu M CoQ10 resulted in significantly higher viability of 76% (P <0.01). CoQ10 also prevented translocation of phosphatidylserine from the inner leaflet to the outer leaflet of the cell membrane. CoQ10 prevented cytochrome c release from mitochondria and activation of caspase-3. Conclusion: We concluded that CoQ10 protects pancreatic beta-cells through anti-apoptotic effects against STS treatment.