Expressions of mRNA and encoded proteins of mitochondrial uncoupling protein genes (UCP1, UCP2, and UCP3) in epicardial and mediastinal adipose tissue and associations with coronary artery disease

OBJECTIVE: To evaluate the expression of UCP1, UCP2, and UCP3 mRNA and encoded proteins in epicardial and mediastinal adipose tissues in patients with coronary artery disease (CAD). SUBJECTS AND METHODS: We studied 60 patients with CAD and 106 patients undergoing valve replacement surgery (controls). Expression levels of UCP1, UCP2, and UCP3 mRNA and encoded proteins were measured by quantitative real-time PCR and Western blot analysis, respectively. RESULTS: We found increased UCP1, UCP2, and UCP3 mRNA levels in the epicardial adipose tissue in the CAD versus the control group, and higher UCP1 and UCP3 mRNA expression in the epicardial compared with the mediastinal tissue in the CAD group. There was also increased expression of UCP1 protein in the epicardial tissue and UCP2 protein in the mediastinum tissue in patients with CAD. Finally, UCP1 expression was associated with levels of fasting plasma glucose, and UCP3 expression was associated with levels of high-density lipoprotein cholesterol and low-density cholesterol in the epicardial tissue. CONCLUSIONS: Our study supports the hypothesis that higher mRNA expression by UCP genes in the epicardial adipose tissue could be a protective mechanism against the production of reactive oxygen species and may guard the myocardium against damage. Thus, UCP levels are essential to maintain the adaptive phase of cardiac injury in the presence of metabolic disorders.