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C-peptide prevents hyperglycemia-induced endothelial apoptosis through inhibition of reactive oxygen species-mediated transglutaminase 2 activation.

Bhatt MP, Lim YC, Hwang J, Na S, Kim YM, Ha KS - Diabetes (2012)

Bottom Line: 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).In addition, C-peptide prevented hyperglycemia-induced activation of transamidation activity and apoptosis in the heart and renal cortex of streptozotocin diabetic mice.Furthermore, TG2 may be a promising avenue of therapeutic investigation to treat diabetic vasculopathies.

View Article: PubMed Central - PubMed

Affiliation: Department of Molecular and Cellular Biochemistry, Kangwon National University School of Medicine, Chuncheon, Kangwon-do, Korea.

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.

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TG2 siRNA prevents high glucose (HG)–induced apoptotic cell death. Cells were transfected with the indicated concentrations of human TG2–specific siRNA (TG2 siRNA) or control (Ctrl) siRNA and incubated with HG (33 mmol/L d-glucose) for 72 h. A: TG2 siRNA inhibits TG2 expression in a concentration-dependent manner. Dose-dependent recovery of cell viability (B) and decrease in cell death rate (C) by TG2 siRNA. Results are expressed as mean ± SD from three independent experiments. **P < 0.01.
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Figure 2: TG2 siRNA prevents high glucose (HG)–induced apoptotic cell death. Cells were transfected with the indicated concentrations of human TG2–specific siRNA (TG2 siRNA) or control (Ctrl) siRNA and incubated with HG (33 mmol/L d-glucose) for 72 h. A: TG2 siRNA inhibits TG2 expression in a concentration-dependent manner. Dose-dependent recovery of cell viability (B) and decrease in cell death rate (C) by TG2 siRNA. Results are expressed as mean ± SD from three independent experiments. **P < 0.01.

Mentions: High glucose–induced cell death was significantly reversed by the transglutaminase inhibitors cystamine and monodansylcadaverine (P < 0.01; Fig. 1A). A similar inhibitory effect on apoptosis was observed with DiOC6/PI double-staining (Fig. 1B). TG2 siRNA suppressed TG2 expression in a dose-dependent manner (Fig. 2A). TG2 siRNA inhibited high glucose–induced cell death in a dose-dependent manner as estimated by MTT assay, with significant effect at 10 nmol/L (P < 0.01; Fig. 2B). TG2 siRNA also prevented the apoptosis observed with DiOC6/PI double-staining (Fig. 2C).


C-peptide prevents hyperglycemia-induced endothelial apoptosis through inhibition of reactive oxygen species-mediated transglutaminase 2 activation.

Bhatt MP, Lim YC, Hwang J, Na S, Kim YM, Ha KS - Diabetes (2012)

TG2 siRNA prevents high glucose (HG)–induced apoptotic cell death. Cells were transfected with the indicated concentrations of human TG2–specific siRNA (TG2 siRNA) or control (Ctrl) siRNA and incubated with HG (33 mmol/L d-glucose) for 72 h. A: TG2 siRNA inhibits TG2 expression in a concentration-dependent manner. Dose-dependent recovery of cell viability (B) and decrease in cell death rate (C) by TG2 siRNA. Results are expressed as mean ± SD from three independent experiments. **P < 0.01.
© Copyright Policy - creative-commons
Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC3526059&req=5

Figure 2: TG2 siRNA prevents high glucose (HG)–induced apoptotic cell death. Cells were transfected with the indicated concentrations of human TG2–specific siRNA (TG2 siRNA) or control (Ctrl) siRNA and incubated with HG (33 mmol/L d-glucose) for 72 h. A: TG2 siRNA inhibits TG2 expression in a concentration-dependent manner. Dose-dependent recovery of cell viability (B) and decrease in cell death rate (C) by TG2 siRNA. Results are expressed as mean ± SD from three independent experiments. **P < 0.01.
Mentions: High glucose–induced cell death was significantly reversed by the transglutaminase inhibitors cystamine and monodansylcadaverine (P < 0.01; Fig. 1A). A similar inhibitory effect on apoptosis was observed with DiOC6/PI double-staining (Fig. 1B). TG2 siRNA suppressed TG2 expression in a dose-dependent manner (Fig. 2A). TG2 siRNA inhibited high glucose–induced cell death in a dose-dependent manner as estimated by MTT assay, with significant effect at 10 nmol/L (P < 0.01; Fig. 2B). TG2 siRNA also prevented the apoptosis observed with DiOC6/PI double-staining (Fig. 2C).

Bottom Line: 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).In addition, C-peptide prevented hyperglycemia-induced activation of transamidation activity and apoptosis in the heart and renal cortex of streptozotocin diabetic mice.Furthermore, TG2 may be a promising avenue of therapeutic investigation to treat diabetic vasculopathies.

View Article: PubMed Central - PubMed

Affiliation: Department of Molecular and Cellular Biochemistry, Kangwon National University School of Medicine, Chuncheon, Kangwon-do, Korea.

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.

Show MeSH
Related in: MedlinePlus