Abstract 18008: Post-Transcriptional Regulation of Adiponectin by Micro-RNA 378 in Human Visceral and Subcutaneous Adipose Tissue

Abstract

Purpose: MicroRNAs (miR), single-stranded non-protein coding gene products, regulate gene expression through post-transcriptional inhibition, and involved in essential biological processes including obesity and insulin resistance. miR-378/378*, which are encoded by PGC-1β gene and counterbalance the metabolic actions of PGC-1β. We conducted to elucidate the role of miR378 expression in human adiposity and adipose tissue inflammation. Methods: Study 1 (clinical study): Pair samples were obtained from subcutaneous (SAT) and visceral adipose tissue (VAT) during elective operation in 71 men and 42 women. MiRNA and adipocytokines levels were determined by qRT-PCR. Study 2 (in vitro study): We quantitated adipocytokine transcription during adipogenesis in 3T3-L1 cells overexpressing mimics or inhibitors of miR378 and assessed post-transcriptional regulation in HEK 293 cells expressing a renilla-luciferase-adiponectin-3’UTR sequence. Results: Study 1: The mean size, median and mode of adipocytes were negatively correlated with levels of adipose adiponectin in SAT and in VAT. CD68 was negatively, and TLR4, PPARγ2, PGC-1β, and ESRRG were positively correlated with adipose adiponectin. Study 2: Upon in silico search, we found a putative target site for miRNA378/378* in the 3 prime untranslated region (3’ UTR) of adiponectin gene. Expression levels of miR378 as well as adiponectin, ACSL1, GPAT6, PPARγ2 and PGC1β were increased in 3T3L1 during differentiation. The expression of adiponectin and ESRRG, a PGC-1β partner, were inhibited by miR378 mimics. Luminescence activity in HEK 293 cells expressing a renilla-luciferase-adiponectin-3’UTR sequence was inhibited by overexpressing mimics of miR378 and the decrease was recovered by adding the inhibitors of miR378, indicating that the posttranscriptional activity of adiponectin 3’UTR of was regulated via the miR378 binding site. Conclusion: There were depot- and size-dependent variations in adiponectin, miRNA378 and its related genes in SAT and VAT. Roles of miR378 and other possible miRNAs were warranted in adiponectin expression and its post-translational modification, which links to metabolic and cardiovascular abnormalities associated with obesity and insulin resistance.