Circulating Microrna Profiling In Young Men With Central Obesity

Abstract

The prevalence of obesity among Malaysian adults is increasing as much as 15% from 1996 to 2008, leading to an increase in obesity-associated diseases. Studying the regulation of genes related to obesity could assist in understanding the pathogenesis of central obesity. MicroRNA (miRNA) is a short non-coding RNA that regulates the gene expression through post-transcriptional inhibition on the target messenger RNA (mRNA). A single miRNA could target hundreds of genes within the same pathway, making it a possible therapeutic target for many diseases. The aim of this study was to determine the miRNA profiling in plasma of young men with central obesity as compared to control subjects. Total RNA was extracted from blood plasma of 23 subjects (central obese = 14, control = 9) recruited from medical screening programme around Klang valley from 2011 until 2012. The extracts were assessed for haemolytic marker using quantitative polymerase chain reaction (qPCR) where ∆Ct of less than 7 was taken as the cut-off value and this has reduced the sample size to 6 (central obese = 4, control = 2). Then, the eligible extracts were subjected to cDNA synthesis and qPCR using miRCURY LNATM Universal RT microRNA PCR Panel. The profiling data were normalised and analysed using GenEx software. Five miRNAs were selected for validation using Pick-&-Mix microRNA PCR Panel. One hundred and seventy five miRNAs were noted to be significantly expressed in plasma of the central obese group compared to the control group (p<0.05). Among these, 92 miRNAs were up-regulated and 83 were down-regulated. The validation result confirmed the expression of up-regulated miRNAs, which were miR-34a, miR-192 and miR-10b.

However, the qPCR failed to confirm the down-regulated miRNAs, which were miR- 15b* and miR-485-3p. The up-regulated miR-34a in obesity has been found to

regulate lipid metabolism through sirtuin 1 activity. G protein-coupled receptor 22 (GPR22) was demonstrated to be responsible in the pathogenesis of heart failure and its expression was correlated with miR-192 expression. GPR22 mRNA consists of a binding site for miR-192. Meanwhile, miR-10b has been found to be involved in atherosclerosis by modulating ATP-binding cassette A1 and G1 genes in macrophages reversing the cholesterol transport. The down-regulated miR-15b* and miR-485-3p also have been found to correlate with obesity-associated diseases through their regulation of OSBPL11 and TRDN genes, respectively in the development cardiovascular diseases. In conclusion, this study has successfully identified a list of significant miRNAs which were differentially expressed in the plasma of central obese subjects compared to control subjects.