2 '-deoxyguanosine oxidation is associated with decrease in the DNA-binding activity of the transcription factor Sp1 in liver and kidney from diabetic and insulin-resistant rats

Over the years, several lines of evidence have emerged supporting the role of oxidative stress in the development of diabetic complications. This coul d involve the increase in the production of reactive oxygen species and the decrease in antioxidative defense systems. Modulation of the level of intr acellular reactive oxygen species is likely to affect the intracellular red ox homeostasis, which is crucial for numerous biological events such as the transcriptional activation of genes. In this work we studied the binding o f the redox transcription factors Spl and NF-KB extracted from kidney and l iver of streptozotocin diabetic (STZ) and fructose-fed rats using electroph oretic mobility shift (EMSA) assay. In addition, the level in 8-oxo-7,8-dih ydro-2'-deoxyguanosine (8-oxodGuo) was assessed within DNA by high performa nce liquid chromatography with electrochemical detection (HPLC-EC). A decre ase in the affinity of Spl to DNA was observed in the kidney of STZ rats an d fructose-fed rats (15% +/- 8.3 and 54% +/- 6.9, respectively, versus cont rol 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 ox idation, were measured in the kidney of diabetic rats. Therefore, the modif ication in the binding efficiency of Spl or NF-KB could be related to react ive oxygen species-mediated DNA damage. (C) 2000 Elsevier Science Inc.