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Intermittent high glucose implements stress-induced senescence in human vascular endothelial cells: role of superoxide production by NADPH oxidase.

Maeda M, Hayashi T, Mizuno N, Hattori Y, Kuzuya M - PLoS ONE (2015)

Bottom Line: Impaired glucose tolerance characterized by postprandial hyperglycemia, which occurs frequently in elderly persons and represents an important preliminary step in diabetes mellitus, poses an independent risk factor for the development of atherosclerosis.Interestingly, in intermittent high glucose, this effect was more pronounced as well as increase of p21 and p16INK4a , senescence related proteins with DNA damage.However, telomerase was not activated and telomere length was not shortened, thus stress-induced senescence was shown.

View Article: PubMed Central - PubMed

Affiliation: Department of Geriatrics, Nagoya University Graduate School of Medicine, Nagoya 466-8550, Japan.

ABSTRACT
Impaired glucose tolerance characterized by postprandial hyperglycemia, which occurs frequently in elderly persons and represents an important preliminary step in diabetes mellitus, poses an independent risk factor for the development of atherosclerosis. Endothelial cellular senescence is reported to precede atherosclerosis. We reported that continuous high glucose stimulus causes endothelial senescence more markedly than hypertension or dyslipidemia stimulus. In the present study, we evaluated the effect of fluctuating glucose levels on human endothelial senescence. Constant high glucose increased senescence-associated-β-galactosidase (SA-β-gal) activity, a widely used marker for cellular senescence. Interestingly, in intermittent high glucose, this effect was more pronounced as well as increase of p21 and p16INK4a , senescence related proteins with DNA damage. However, telomerase was not activated and telomere length was not shortened, thus stress-induced senescence was shown. However, constant high glucose activated telomerase and shortened telomere length, which suggested replicative senescence. Intermittent but not constant high glucose strikingly up-regulated the expression of p22phox, an NADPH oxidase component, increasing superoxide. The small interfering RNA of p22phox undermined the increase in SA-β-gal activity induced by intermittent high glucose. Conclusively, intermittent high glucose can promote vascular endothelial senescence more than constant high glucose, which is in partially dependent on superoxide overproduction.

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Effect of high glucose on p53, p21, p16INKa, and DNA ladder on Apurinic/apyrimidinic (AP) sites.HUVECs were cultured with constant high glucose (HG) and intermittent glucose (N/HG) introduced in Fig 1. Namely, N/HG was stimulated twice with HG (at 4-hour intervals) for a total of 4 hours daily (9 a.m. to 11 a.m., 3 p.m. to 5 p.m.), and was cultured in NG in other time of the total 4-hour HG stimulation. (A)-(D): Effect of high glucose on p53, p21, p16INKa protein. (E): Effect of continuous and intermittent high glucose on endothelial DNA damage on Apurinic/apyrimidinic(AP) sites. *p<0.05; **p<0.01 vs. NG; #p<0.05 vs. HG. The values of the three independent experiments are mean ± S.D.
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pone.0123169.g003: Effect of high glucose on p53, p21, p16INKa, and DNA ladder on Apurinic/apyrimidinic (AP) sites.HUVECs were cultured with constant high glucose (HG) and intermittent glucose (N/HG) introduced in Fig 1. Namely, N/HG was stimulated twice with HG (at 4-hour intervals) for a total of 4 hours daily (9 a.m. to 11 a.m., 3 p.m. to 5 p.m.), and was cultured in NG in other time of the total 4-hour HG stimulation. (A)-(D): Effect of high glucose on p53, p21, p16INKa protein. (E): Effect of continuous and intermittent high glucose on endothelial DNA damage on Apurinic/apyrimidinic(AP) sites. *p<0.05; **p<0.01 vs. NG; #p<0.05 vs. HG. The values of the three independent experiments are mean ± S.D.

Mentions: Endothelial senescence related proteins such as p53, p21, p16INK4a and were measured by western blotting (Fig 3A, 3B, 3C and 3D). Intermittent high glucose stimulus (IHG) increased these proteins significantly compared with the condition of normal glucose and tended to increase them than those by continuous high glucose stimuli. We further quantificated DNA damage of endothelial cells. DNA damage was observed by the stimuli of inthermittent high glucose (Fig 3E) as well as continuous high glucose stimuli. These results show that intermittent high glucose condition induced endothelial senescence, which starts as early as 3 days after the start of the stimuli.


Intermittent high glucose implements stress-induced senescence in human vascular endothelial cells: role of superoxide production by NADPH oxidase.

Maeda M, Hayashi T, Mizuno N, Hattori Y, Kuzuya M - PLoS ONE (2015)

Effect of high glucose on p53, p21, p16INKa, and DNA ladder on Apurinic/apyrimidinic (AP) sites.HUVECs were cultured with constant high glucose (HG) and intermittent glucose (N/HG) introduced in Fig 1. Namely, N/HG was stimulated twice with HG (at 4-hour intervals) for a total of 4 hours daily (9 a.m. to 11 a.m., 3 p.m. to 5 p.m.), and was cultured in NG in other time of the total 4-hour HG stimulation. (A)-(D): Effect of high glucose on p53, p21, p16INKa protein. (E): Effect of continuous and intermittent high glucose on endothelial DNA damage on Apurinic/apyrimidinic(AP) sites. *p<0.05; **p<0.01 vs. NG; #p<0.05 vs. HG. The values of the three independent experiments are mean ± S.D.
© Copyright Policy
Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC4400006&req=5

pone.0123169.g003: Effect of high glucose on p53, p21, p16INKa, and DNA ladder on Apurinic/apyrimidinic (AP) sites.HUVECs were cultured with constant high glucose (HG) and intermittent glucose (N/HG) introduced in Fig 1. Namely, N/HG was stimulated twice with HG (at 4-hour intervals) for a total of 4 hours daily (9 a.m. to 11 a.m., 3 p.m. to 5 p.m.), and was cultured in NG in other time of the total 4-hour HG stimulation. (A)-(D): Effect of high glucose on p53, p21, p16INKa protein. (E): Effect of continuous and intermittent high glucose on endothelial DNA damage on Apurinic/apyrimidinic(AP) sites. *p<0.05; **p<0.01 vs. NG; #p<0.05 vs. HG. The values of the three independent experiments are mean ± S.D.
Mentions: Endothelial senescence related proteins such as p53, p21, p16INK4a and were measured by western blotting (Fig 3A, 3B, 3C and 3D). Intermittent high glucose stimulus (IHG) increased these proteins significantly compared with the condition of normal glucose and tended to increase them than those by continuous high glucose stimuli. We further quantificated DNA damage of endothelial cells. DNA damage was observed by the stimuli of inthermittent high glucose (Fig 3E) as well as continuous high glucose stimuli. These results show that intermittent high glucose condition induced endothelial senescence, which starts as early as 3 days after the start of the stimuli.

Bottom Line: Impaired glucose tolerance characterized by postprandial hyperglycemia, which occurs frequently in elderly persons and represents an important preliminary step in diabetes mellitus, poses an independent risk factor for the development of atherosclerosis.Interestingly, in intermittent high glucose, this effect was more pronounced as well as increase of p21 and p16INK4a , senescence related proteins with DNA damage.However, telomerase was not activated and telomere length was not shortened, thus stress-induced senescence was shown.

View Article: PubMed Central - PubMed

Affiliation: Department of Geriatrics, Nagoya University Graduate School of Medicine, Nagoya 466-8550, Japan.

ABSTRACT
Impaired glucose tolerance characterized by postprandial hyperglycemia, which occurs frequently in elderly persons and represents an important preliminary step in diabetes mellitus, poses an independent risk factor for the development of atherosclerosis. Endothelial cellular senescence is reported to precede atherosclerosis. We reported that continuous high glucose stimulus causes endothelial senescence more markedly than hypertension or dyslipidemia stimulus. In the present study, we evaluated the effect of fluctuating glucose levels on human endothelial senescence. Constant high glucose increased senescence-associated-β-galactosidase (SA-β-gal) activity, a widely used marker for cellular senescence. Interestingly, in intermittent high glucose, this effect was more pronounced as well as increase of p21 and p16INK4a , senescence related proteins with DNA damage. However, telomerase was not activated and telomere length was not shortened, thus stress-induced senescence was shown. However, constant high glucose activated telomerase and shortened telomere length, which suggested replicative senescence. Intermittent but not constant high glucose strikingly up-regulated the expression of p22phox, an NADPH oxidase component, increasing superoxide. The small interfering RNA of p22phox undermined the increase in SA-β-gal activity induced by intermittent high glucose. Conclusively, intermittent high glucose can promote vascular endothelial senescence more than constant high glucose, which is in partially dependent on superoxide overproduction.

Show MeSH
Related in: MedlinePlus