title: C-peptide prevents hyperglycemia-induced endothelial apoptosis through inhibition of reactive oxygen species-mediated transglutaminase 2 activation.
abstract: C-peptide is a bioactive peptide with a potentially protective role in diabetes complications; however, its molecular mechanism of protection against cardiovascular damage caused by hyperglycemia-induced apoptosis remains unclear. We investigated the protective mechanism of C-peptide against hyperglycemia-induced apoptosis using human umbilical vein endothelial cells and streptozotocin diabetic mice. High glucose (33 mmol/L) induced apoptotic cell death in endothelial cells via sequential elevation of intracellular Ca(2+) and reactive oxygen species (ROS) as well as subsequent activation of transglutaminase 2 (TG2). C-peptide (1 nmol/L) prevented endothelial cell death by inhibiting protein kinase C- and NADPH oxidase-dependent intracellular ROS generation and by abolishing high glucose-induced TG2 activation, without affecting intracellular Ca(2+) levels. Consistently, in the aorta of streptozotocin diabetic mice, hyperglycemia stimulated transamidating activity and endothelial cell apoptosis that was inhibited by C-peptide replacement therapy (35 pmol/min/kg) using osmotic pumps (control and diabetes, n = 8; diabetes + C-peptide, n = 7). In addition, C-peptide prevented hyperglycemia-induced activation of transamidation activity and apoptosis in the heart and renal cortex of streptozotocin diabetic mice. Thus, C-peptide protects endothelial cells from hyperglycemia-induced apoptotic cell death by inhibiting intracellular ROS-mediated activation of TG2. Furthermore, TG2 may be a promising avenue of therapeutic investigation to treat diabetic vasculopathies.
authors.affiliation: Department of Molecular and Cellular Biochemistry, Kangwon National University School of Medicine, Chuncheon, Kangwon-do, Korea.
authors.forename: Mahendra Prasad
authors.initials: MP
authors.lastname: Bhatt
authors.forename: Young-Cheol
authors.initials: YC
authors.lastname: Lim
authors.forename: JongYun
authors.initials: J
authors.lastname: Hwang
authors.forename: SungHun
authors.initials: S
authors.lastname: Na
authors.forename: Young-Myeong
authors.initials: YM
authors.lastname: Kim
authors.forename: Kwon-Soo
authors.initials: KS
authors.lastname: Ha
mesh_terms: D000818:Animals; D017209:Apoptosis; D002096:C-Peptide / Q000502:physiology*; D002118:Calcium / Q000378:metabolism; D002478:Cells, Cultured; D003921:Diabetes Mellitus, Experimental / Q000378:metabolism / Q000473:pathology; D004789:Enzyme Activation; D019204:GTP-Binding Proteins / Q000037:antagonists & inhibitors / Q000502:physiology*; D061307:Human Umbilical Vein Endothelial Cells / Q000473:pathology*; D006801:Humans; D006943:Hyperglycemia / Q000473:pathology*; D007672:Kidney Cortex / Q000473:pathology; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D009206:Myocardium / Q000473:pathology; D000091345:Protein Glutamine gamma Glutamyltransferase 2; D017382:Reactive Oxygen Species / Q000378:metabolism*; D013311:Streptozocin; D011503:Transglutaminases / Q000037:antagonists & inhibitors / Q000502:physiology*
chemical_list: D002096:C-Peptide; D017382:Reactive Oxygen Species; D013311:Streptozocin; D000091345:Protein Glutamine gamma Glutamyltransferase 2; D011503:Transglutaminases; D019204:GTP-Binding Proteins; D002118:Calcium