C-Peptide Prevents Hyperglycemia-Induced Endothelial Apoptosis Through Inhibition of Reactive Oxygen Species–Mediated Transglutaminase 2 Activation

  1. Kwon-Soo Ha1
  1. 1Department of Molecular and Cellular Biochemistry, Kangwon National University School of Medicine, Chuncheon, Kangwon-do, Korea
  2. 2Department of Laboratory Medicine, Gandaki Medical College Charak Hospital, Pokhara, Nepal
  3. 3Department of Obstetrics and Gynecology, Kangwon National University School of Medicine, Chuncheon, Kangwon-do, Korea
  1. Corresponding author: Kwon-Soo Ha, ksha{at}kangwon.ac.kr.

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 Ca2+ 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 Ca2+ 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.

Footnotes

  • Received March 8, 2012.
  • Accepted June 27, 2012.

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  1. Diabetes vol. 62 no. 1 243-253
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