C-Peptide Activates AMPKα and Prevents ROS-Mediated Mitochondrial Fission and Endothelial Apoptosis in Diabetes

Abstract

Vasculopathy is a major complication of diabetes; however, molecular mechanisms mediating the development of vasculopathy and potential strategies for prevention have not been identified. We have previously reported that C-peptide prevents diabetic vasculopathy by inhibiting reactive oxygen species (ROS)-mediated endothelial apoptosis. To gain further insight into ROS-dependent mechanism of diabetic vasculopathy and its prevention, we studied high glucose–induced cytosolic and mitochondrial ROS production and its effect on altered mitochondrial dynamics and apoptosis. For the therapeutic strategy, we investigated the vasoprotective mechanism of C-peptide against hyperglycemia-induced endothelial damage through the AMP-activated protein kinase α (AMPKα) pathway using human umbilical vein endothelial cells and aorta of diabetic mice. High glucose (33 mmol/L) increased intracellular ROS through a mechanism involving interregulation between cytosolic and mitochondrial ROS generation. C-peptide (1 nmol/L) activation of AMPKα inhibited high glucose–induced ROS generation, mitochondrial fission, mitochondrial membrane potential collapse, and endothelial cell apoptosis. Additionally, the AMPK activator 5-aminoimidazole-4-carboxamide 1-β-d-ribofuranoside and the antihyperglycemic drug metformin mimicked protective effects of C-peptide. C-peptide replacement therapy normalized hyperglycemia-induced AMPKα dephosphorylation, ROS generation, and mitochondrial disorganization in aorta of diabetic mice. These findings highlight a novel mechanism by which C-peptide activates AMPKα and protects against hyperglycemia-induced vasculopathy.

Vagal nerve stimulation improves mitochondrial dynamics via an M3 receptor/CaMKKβ/AMPK pathway in isoproterenol‐induced myocardial ischaemia

“…Moreover, our previous research demonstrated that AMPK activation played an important role in VNS or ACh ability to protect from mitochondrial biogenesis and antioxidative stress, and provide autophagic cytoprotection during myocardial ischaemia 13, 60, 61. More interestingly, another study demonstrated that AMPK activation prevented mitochondrial fission by decreasing Drp1 and Fis‐1 levels in high glucose‐induced endothelial apoptosis 62. In this study, we showed that VNS treatment activated AMPK and ACC (the substrate of AMPK) in ISO‐induced myocardial damage.…”

AMPK activation by glucagon-like peptide-1 prevents NADPH oxidase activation induced by hyperglycemia in adult cardiomyocytes

“…AMPK also reduces the impact of ROS production on mitochondrial function by avoiding permeability transition pore opening (32) or by promoting mitochondrial biosynthesis through proliferatoractivated receptor-␥ coactivator-1␣. AMPK also inhibits ROSinduced mitochondrial fission and collapse of the mitochondrial membrane potential (7). Finally, AMPK promotes autophagy, minimizing oxidative stress-induced cellular damage by phosphorylating ULK-1 or inhibiting p70S6 kinase phosphorylation (38).…”

Essential Role of Transglutaminase 2 in Vascular Endothelial Growth Factor–Induced Vascular Leakage in the Retina of Diabetic Mice

“…Intracellular ROS generation was determined using 29,79-dichlorodihydrofluorescein diacetate (Molecular Probes, Eugene, OR) staining, as previously described (26). Cells were pretreated with the inhibitors for 30 min and incubated with 10 ng/mL VEGF and 10 mmol/L dichlorodihydrofluorescein diacetate in low-serum media (phenol red-free) for 10 min.…”