Mitochondrial Fragmentation By Hyperglycemia In Endothelial Cells Is Mediated By ROS-induced ROS Release Through OPA1 And OMA1

Background:Diabetes Mellitus contributes to the vasculopathy via the activation of glucose toxicity pathways,including polyol,hexosamine,advanced glycation end products(AGE)and protein kinase C(PKC)pathway.The activation of the glucose toxicity pathways induces intracellular reactive oxygen species(ROS)production under high glucose condition,leading to cell death and dysfunction.However,whether these glucose toxicity pathways works synergistically to tissue damage remains unclearMethods:In this study,we inhibited polyol,hexosamine,AGE and PKC pathway with epalrestat,azaserine,aminoguanidine,sotrastaurin,and the mitochondrial ROS special scavenger Mito-Tempo respectively in human umbilical vein endothelial cells(HUVECs)before and after high glucose treatment.Using flow cytometry analysis,confocal laser scanning and western blotting to determine HUVECs mitochondria ROS,fragmentation and the expression of OMA1,OPA1,phosphor mTOR(Ser2448)and phosphor Akt(Ser473)Results:Prior to high glucose incubation significantly attenuated the mitochondrial ROS level and fragmentation in HUVECs in epalrestat,azaserine,aminoguanidine and sotrastaurin groups,whereas the cells treated after high glucose incubation with the same inhibitors did not attenuate the mitochondrial ROS level and fragmentation.However,treatment of mitochondrial ROS scavenger Mito-Tempo after high glucose incubation still attenuated the mitochondrial ROS and fragmentation through regulating the expression of OMA1,OPA1,phosphor mTOR(Ser2448)and phosphor Akt(Ser473)Conclusion:The present study explains why the pharmacological inhibition of the glucose toxicity pathways cannot reverse or slow down the clinical progression of diabetic vascular complications.Reducing the mitochondrial fragmentation and ROS may be a better therapeutic strategy for the treatment of diabetic vascular complications.