PROMOTER METHYLATION LEADS TO DOWN REGULATION OF HEPATIC CATALASE GENE IN HYPOTHYROID RATS

PROMOTER METHYLATION LEADS TO DOWN REGULATION OF HEPATIC CATALASE GENE IN HYPOTHYROID RATS J. DANDAPAT, S. K. BUNKER AND G.B.N. CHAINY P.G. Department of Biotechnology, Utkal University, Bhubaneswar-751004 Email- jdandapat.nou@gmail.com Catalase (EC 1.11.1.6) is an important antioxidant enzyme associated with metabolism of hydrogen peroxides. Previous findings from our laboratory indicate that hypothyroidism (one of the world wide prevailing endocrine disorders) down-regulates expression of catalase gene in rat liver. However, the precise mechanism of this down regulation is not well known. Therefore, the objective of the present study is to correlate the status of catalase promoter methylation with its expression in hypothyroid rats to understand the mechanism of its down regulation.  Results showed that neonatal hypothyroidism resulted in down regulation of catalase expression in adulthood along with elevated oxidative stress. Further, the sequencing of the catalase promoter region (-184 to +52) indicated a permanent change in methylation pattern of individual CpG dinucleotides in hypothyroid rats in comparison to control. It is presumed that epigenetic modifications of DNA in catalase promoter might be one of the mechanisms to explain hypothyroidism-induced down-regulation of catalase in liver.