title: Promoter DNA demethylation of Keap1 gene in diabetic cardiomyopathy.
abstract: Researches have shown that the onset of diabetes is closely associated with oxidative stress and the chronic exposure leads to the development of complications such as diabetic cardiomyopathy. One of the central adaptive responses against the oxidative stresses is the activation of the nuclear transcriptional factor, NF-E2-related factor 2 (Nrf2), which then activates more than 20 different antioxidative enzymes. Kelch-like ECH associated protein 1 (Keap1) targets and binds to Nrf2 for proteosomal degradation. The aim of the present study was to investigate the status of Nrf2 mediated antioxidant system in myocardial biopsies of non-diabetic (NDM) and type-2 diabetic (DM-T2) cardiomyopathy patients. The western blot analysis of antioxidant proteins, real-time PCR analysis of Nrf2/Keap1 gene and bisulphate DNA sequencing analysis to study the methylation status of the CpG islands of Keap1 promoter DNA were performed. The immunoblot analysis showed the decreased level of antioxidant proteins other than Keap1 in the diabetic cardiopathy patients. Similarly, mRNA levels of Keap1 showed 5-fold increase in diabetic patients. Further analysis on promoter region of Keap1 gene revealed 80% demethylation in diabetic patients. Altogether, our results indicated that demethylation of the CpG islands in the Keap1 promoter will activate the expression of Keap1 protein, which then increases the targeting of Nrf2 for proteosomal degradation. Decreased Nrf2 activity represses the transcription of many antioxidant enzyme genes and alters the redox-balance up on diabetes. Thus, our study clearly demonstrates the failure of Nrf2 mediated antioxidant system revealed in biopsies of diabetic cardiomyopathy.
authors: Department of Cardiology, Qilu Hospital of Shandong University Shandong 250012, China ; Department of Cardiology, Liao Cheng People's Hospital Shandong 252000, China.
authors: Zhong-Zhi
authors: ZZ
authors: Liu
authors: Department of Cardiology, Liao Cheng People's Hospital Shandong 252000, China.
authors: Xiang-Zhi
authors: XZ
authors: Zhao
authors: Department of Cardiology, Liao Cheng People's Hospital Shandong 252000, China.
authors: Xue-Song
authors: XS
authors: Zhang
authors: Department of Cardiology, Qilu Hospital of Shandong University Shandong 250012, China.
authors: Mei
authors: M
authors: Zhang
mesh_terms: D000368:Aged; D015153:Blotting, Western; D018899:CpG Islands / Q000235:genetics; D019175:DNA Methylation; D003924:Diabetes Mellitus, Type 2 / Q000150:complications*; D058065:Diabetic Cardiomyopathies / Q000235:genetics*; D005260:Female; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins; D000072019:Kelch-Like ECH-Associated Protein 1; D008297:Male; D018384:Oxidative Stress / Q000502:physiology*; D011401:Promoter Regions, Genetic / Q000235:genetics; D060888:Real-Time Polymerase Chain Reaction
chemical_list: D047908:Intracellular Signaling Peptides and Proteins; C431364:KEAP1 protein, human; D000072019:Kelch-Like ECH-Associated Protein 1
keywords: CpG islands; Nrf2; antioxidant system; bisulphate sequencing