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2'-deoxyguanosine oxidation is associated with decrease in the DNA-binding activity of the transcription factor Sp1
1Laboratoire du Stress Cardiovasculaire et Pathologies Associées, Faculté de Pharmacie de Grenoble, La Tronche, France.
Abstract:
Over the years, several lines of evidence have emerged supporting the role of oxidative stress in the development of diabetic complications. This could involve the increase in the production of reactive oxygen species and the decrease in antioxidative defense systems. Modulation of the level of intracellular reactive oxygen species is likely to affect the intracellular redox homeostasis, which is crucial for numerous biological events such as the transcriptional activation of genes. In this work we studied the binding of the redox transcription factors Sp1 and NF-kappaB extracted from kidney and liver of streptozotocin diabetic (STZ) and fructose-fed rats using electrophoretic mobility shift (EMSA) assay. In addition, the level in 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodGuo) was assessed within DNA by high performance liquid chromatography with electrochemical detection (HPLC-EC). A decrease in the affinity of Sp1 to DNA was observed in the kidney of STZ rats and fructose-fed rats (15% +/- 8.3 and 54% +/- 6.9, respectively, versus control group set to 100%). This was also found to occur to a lower extent, in the liver. Interestingly, higher levels of 8-oxodGuo, a biomarker of DNA oxidation, were measured in the kidney of diabetic rats. Therefore, the modification in the binding efficiency of Sp1 or NF-kappaB could be related to reactive oxygen species-mediated DNA damage.
Insights
Oxidative stress in diabetes impairs DNA binding of transcription factors Sp1 and NF-kappaB. This damage, indicated by 8-oxodGuo, may drive diabetic complications.
Area of Science:
- Biochemistry
- Molecular Biology
- Diabetology
Background:
- Oxidative stress is implicated in diabetic complications, involving increased reactive oxygen species (ROS) and reduced antioxidant defenses.
- Intracellular ROS levels impact redox homeostasis, crucial for gene transcription.
- Redox-active transcription factors like Sp1 and NF-kappaB regulate gene expression and are potentially affected by oxidative stress.
Purpose of the Study:
- To investigate the binding affinity of Sp1 and NF-kappaB transcription factors in diabetic rat models.
- To assess the level of DNA oxidation, specifically 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodGuo), in diabetic kidneys.
- To explore the relationship between oxidative stress, DNA damage, and transcription factor binding in diabetic complications.
Main Methods:
- Electrophoretic mobility shift assay (EMSA) was used to study Sp1 and NF-kappaB binding to DNA in kidney and liver extracts from streptozotocin (STZ)-induced diabetic and fructose-fed rats.
- High-performance liquid chromatography with electrochemical detection (HPLC-EC) was employed to quantify 8-oxodGuo levels in DNA.
Main Results:
- A significant decrease in Sp1 DNA binding affinity was observed in the kidneys of both STZ-treated rats (15% +/- 8.3) and fructose-fed rats (54% +/- 6.9) compared to controls.
- Reduced Sp1 binding was also noted, to a lesser extent, in the liver of these diabetic models.
- Elevated levels of 8-oxodGuo, a marker of DNA oxidation, were detected in the kidneys of diabetic rats.
Conclusions:
- The study demonstrates that oxidative stress in diabetes, particularly in the kidney, impairs the DNA binding activity of transcription factor Sp1.
- These alterations in transcription factor binding efficiency may be linked to reactive oxygen species-mediated DNA damage.
- The findings suggest a potential mechanism by which oxidative stress contributes to the pathogenesis of diabetic complications.