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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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C-peptide inhibits hyperglycemia-induced stimulation of transamidating activity and apoptosis in mice aortic segments. Transamidating activity (green) in aortic segments was double-stained with endothelial cell marker platelet endothelial cell adhesion molecule-I (red). A: Inhibition of hyperglycemia-induced stimulation of transamidating activity by ex vivo treatment of C-peptide (C-pep) or cystamine (Cys; n = 6 per group). B and C: C-peptide replacement therapy inhibits hyperglycemia-induced stimulation of transamidating activity and apoptosis in vivo (n = 8 for control and diabetes, n = 7 for diabetes + C-peptide). C: Apoptotic cells in aortic segments were stained by TUNEL (green, indicated by arrows) with nuclear counterstaining using Hoechst dye 33258 (blue). Bar: 50 μm. (A high-quality color representation of this figure is available in the online issue.)
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Figure 6: C-peptide inhibits hyperglycemia-induced stimulation of transamidating activity and apoptosis in mice aortic segments. Transamidating activity (green) in aortic segments was double-stained with endothelial cell marker platelet endothelial cell adhesion molecule-I (red). A: Inhibition of hyperglycemia-induced stimulation of transamidating activity by ex vivo treatment of C-peptide (C-pep) or cystamine (Cys; n = 6 per group). B and C: C-peptide replacement therapy inhibits hyperglycemia-induced stimulation of transamidating activity and apoptosis in vivo (n = 8 for control and diabetes, n = 7 for diabetes + C-peptide). C: Apoptotic cells in aortic segments were stained by TUNEL (green, indicated by arrows) with nuclear counterstaining using Hoechst dye 33258 (blue). Bar: 50 μm. (A high-quality color representation of this figure is available in the online issue.)

Mentions: Transamidating activity was activated in aortic segments of diabetic mice (Fig. 6A). Transamidating activity was observed in cells stained with platelet endothelial cell adhesion molecule, indicating transamidating activity in aortic endothelial cells. However, incubating the segments with 5 nmol/L C-peptide inhibited hyperglycemia-induced activation of transamidating activity. In addition, cystamine inhibited the transamidating activity stimulated by hyperglycemia. Thus, hyperglycemia elevates transamidating activity, and ex vivo treatment of C-peptide inhibits transamidating activity stimulated by hyperglycemia in aorta of diabetic mice.


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)

C-peptide inhibits hyperglycemia-induced stimulation of transamidating activity and apoptosis in mice aortic segments. Transamidating activity (green) in aortic segments was double-stained with endothelial cell marker platelet endothelial cell adhesion molecule-I (red). A: Inhibition of hyperglycemia-induced stimulation of transamidating activity by ex vivo treatment of C-peptide (C-pep) or cystamine (Cys; n = 6 per group). B and C: C-peptide replacement therapy inhibits hyperglycemia-induced stimulation of transamidating activity and apoptosis in vivo (n = 8 for control and diabetes, n = 7 for diabetes + C-peptide). C: Apoptotic cells in aortic segments were stained by TUNEL (green, indicated by arrows) with nuclear counterstaining using Hoechst dye 33258 (blue). Bar: 50 μm. (A high-quality color representation of this figure is available in the online issue.)
© Copyright Policy - creative-commons
Related In: Results  -  Collection

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

Figure 6: C-peptide inhibits hyperglycemia-induced stimulation of transamidating activity and apoptosis in mice aortic segments. Transamidating activity (green) in aortic segments was double-stained with endothelial cell marker platelet endothelial cell adhesion molecule-I (red). A: Inhibition of hyperglycemia-induced stimulation of transamidating activity by ex vivo treatment of C-peptide (C-pep) or cystamine (Cys; n = 6 per group). B and C: C-peptide replacement therapy inhibits hyperglycemia-induced stimulation of transamidating activity and apoptosis in vivo (n = 8 for control and diabetes, n = 7 for diabetes + C-peptide). C: Apoptotic cells in aortic segments were stained by TUNEL (green, indicated by arrows) with nuclear counterstaining using Hoechst dye 33258 (blue). Bar: 50 μm. (A high-quality color representation of this figure is available in the online issue.)
Mentions: Transamidating activity was activated in aortic segments of diabetic mice (Fig. 6A). Transamidating activity was observed in cells stained with platelet endothelial cell adhesion molecule, indicating transamidating activity in aortic endothelial cells. However, incubating the segments with 5 nmol/L C-peptide inhibited hyperglycemia-induced activation of transamidating activity. In addition, cystamine inhibited the transamidating activity stimulated by hyperglycemia. Thus, hyperglycemia elevates transamidating activity, and ex vivo treatment of C-peptide inhibits transamidating activity stimulated by hyperglycemia in aorta of diabetic mice.

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