Multiple Roles for the Non-Coding RNA SRA in Regulation of Adipogenesis and Insulin Sensitivity

Bin Xu,Craig N Johnson,Hongzhi Miao,Ruichuan Xu,Isabelle Gerin,William P Cawthorn,Ormond A Macdougald,Dang Vu-Phan,Ronald J Koenig,Xiao-Wei Chen,Gian Paolo Fadini

doi:10.1371/journal.pone.0014199

Bin Xu, Craig N Johnson + Show 9 more

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https://doi.org/10.1371/journal.pone.0014199

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Journal: PloS one	Publication Date: Dec 2, 2010
Citations: 200	License type: CC BY 4.0

Affiliation: University of Michigan–Ann Arbor

Abstract

Peroxisome proliferator-activated receptor-γ (PPARγ) is a master transcriptional regulator of adipogenesis. Hence, the identification of PPARγ coactivators should help reveal mechanisms controlling gene expression in adipose tissue development and physiology. We show that the non-coding RNA, Steroid receptor RNA Activator (SRA), associates with PPARγ and coactivates PPARγ-dependent reporter gene expression. Overexpression of SRA in ST2 mesenchymal precursor cells promotes their differentiation into adipocytes. Conversely, knockdown of endogenous SRA inhibits 3T3-L1 preadipocyte differentiation. Microarray analysis reveals hundreds of SRA-responsive genes in adipocytes, including genes involved in the cell cycle, and insulin and TNFα signaling pathways. Some functions of SRA may involve mechanisms other than coactivation of PPARγ. SRA in adipocytes increases both glucose uptake and phosphorylation of Akt and FOXO1 in response to insulin. SRA promotes S-phase entry during mitotic clonal expansion, decreases expression of the cyclin-dependent kinase inhibitors p21Cip1 and p27Kip1, and increases phosphorylation of Cdk1/Cdc2. SRA also inhibits the expression of adipocyte-related inflammatory genes and TNFα-induced phosphorylation of c-Jun NH2-terminal kinase. In conclusion, SRA enhances adipogenesis and adipocyte function through multiple pathways.

Highlights

Obesity is a prevalent health hazard closely associated with a number of pathological disorders, including type 2 diabetes, cardiovascular disease, hypertension, cancer, and gallbladder disease
The finding that steroid receptor RNA activator (SRA) binds to peroxisome proliferator-activated receptor gamma (PPARc) in vitro prompted us to test for its functional relevance to PPARc target gene transcription
A reporter plasmid containing three copies of the acyl-CoA oxidase PPAR response element linked to the luciferase gene (PPRE-luc) was co-transfected with PPARc, RXRa, pRL-TK Renilla luciferase as an internal control, and increasing quantities of SRA in JEG-3 cells

Summary

Introduction

Obesity is a prevalent health hazard closely associated with a number of pathological disorders, including type 2 diabetes, cardiovascular disease, hypertension, cancer, and gallbladder disease. Adipogenesis is a complex process that is highly regulated by positive and negative stimuli, including a variety of hormones and nutritional signals [2,3,4,5]. Fibroblast-like preadipocytes differentiate into lipid-laden and insulin-responsive adipocytes. This process occurs in several stages (growth arrest, mitotic clonal expansion and terminal differentiation) and is driven by the coordinated effects of a number of transcription factors and signaling molecules, including peroxisome proliferator-activated receptor gamma (PPARc), the CCAAT/enhancer-binding proteins (C/EBPs) [4,8], Kruppel-like factors (KLFs) [9,10], Wingless proteins (Wnt) [11,12], GATA2 [13,14] and cell cycle proteins [15,16,17]

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