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Med Sci Monit. 2012 Jul;18(7):BR281-5.

Altered expression of base excision repair genes in response to high glucose-induced oxidative stress in HepG2 hepatocytes.

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  • 1The Key Laboratory of Geriatrics, Beijing Hospital and Beijing Institute of Geriatrics, Ministry of Health, China.

Abstract

BACKGROUND:

It is widely accepted that chronic hyperglycemia induces DNA oxidative damage in type 2 diabetes, but little is known about the effect of hyperglycemia on the DNA repair system which plays a critical role in the maintenance of genomic DNA stability in diabetes.

MATERIAL/METHODS:

To investigate the alteration of base excision repair (BER) genes under hyperglycemia, the relative expression of the mRNAs of the BER genes--ogg1, polbeta, lig3, xrcc1, and parp1--were quantified using real-time PCR in HepG2 hepatocytes incubated with 5.5 mM or 30 mM glucose.

RESULTS:

High levels of glucose induced ROS accumulation and DNA damage, paralleling the dynamic alterations of BER mRNA expression. Compared to 5.5 mM glucose-treated cells, ogg1 and polbeta mRNA expression transiently increased at day 1 and decreased after day 4 in cells exposed to 30 mM glucose. Exposure to 30 mM glucose increased the activity of PARP1, which led to reduced cellular NAD content and insulin receptor phosphorylation.

CONCLUSIONS:

Exposure to high concentrations of glucose initially led to the increased expression of BER mRNAs to counteract hyperglycemia-induced DNA damage; however, long-term exposure to high glucose concentrations reduced the expression of mRNA from BER genes, leading to accumulated DNA damage.

PMID:
22739728
PMCID:
PMC3560773
[PubMed - indexed for MEDLINE]
Free PMC Article
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