MicroRNA-27a/b-3p and PPARG regulate SCAMP3 through a feed- forward loop during adipogenesis

Agné Kulyté,Michiel De Hoon,Yoshihide Hayashizaki,Peter Arner,Erik Arner,Piero Carninci,Kelvin Ho Man Kwok

doi:10.1038/s41598-019-50210-3

Abstract

MicroRNAs (miRNA) modulate gene expression through feed-back and forward loops. Previous studies identified miRNAs that regulate transcription factors, including Peroxisome Proliferator Activated Receptor Gamma (PPARG), in adipocytes, but whether they influence adipogenesis via such regulatory loops remain elusive. Here we predicted and validated a novel feed-forward loop regulating adipogenesis and involved miR-27a/b-3p, PPARG and Secretory Carrier Membrane Protein 3 (SCAMP3). In this loop, expression of both PPARG and SCAMP3 was independently suppressed by miR-27a/b-3p overexpression. Knockdown of PPARG downregulated SCAMP3 expression at the late phase of adipogenesis, whereas reduction of SCAMP3 mRNA levels increased PPARG expression at early phase in differentiation. The latter was accompanied with upregulation of adipocyte-enriched genes, including ADIPOQ and FABP4, suggesting an anti-adipogenic role for SCAMP3. PPARG and SCAMP3 exhibited opposite behaviors regarding correlations with clinical phenotypes, including body mass index, body fat mass, adipocyte size, lipolytic and lipogenic capacity, and secretion of pro-inflammatory cytokines. While adipose PPARG expression was associated with more favorable metabolic phenotypes, SCAMP3 expression was linked to increased fat mass and insulin resistance. Together, we identified a feed-forward loop through which miR-27a/b-3p, PPARG and SCAMP3 cooperatively fine tune the regulation of adipogenesis, which potentially may impact whole body metabolism.

Highlights

Adipocytes are the specific cellular components of white adipose tissue (WAT), an organ important for energy balance as well as endocrine and paracrine signaling
In order to construct a list of potential Feed-forward loops (FFLs) consisting of Peroxisome Proliferator Activated Receptor Gamma (PPARG), a miRNA and a target gene, we searched FANTOM5 adipogenesis CAGE7 and miRNA13 time course data for highly expressed miRNAs (>=10000 tags per million (TPM)) and genes predicted to be targets of the miRNA according to the TargetScan method[14]
Considering that PPARG was chosen as the transcription factor central to the loop in this screening for FFL candidates, and that PPARG is a positive regulator of gene expression and is upregulated during adipogenesis, we required that the miRNA and the target gene were at least two-fold downregulated or upregulated during adipocyte differentiation, and that their expression profile correlation (r-value) across the time course was −0.95 or lower

Summary

Introduction

Adipocytes are the specific cellular components of white adipose tissue (WAT), an organ important for energy balance as well as endocrine and paracrine signaling. In many cell types miRNAs form feed-back or feed-forward loops to fine tune regulation of gene expression[6] The role of such loops in adipogenesis is less well understood. Feed-forward loops (FFLs) are a common feature of transcriptional networks[8], and FFLs involving miRNAs are recurring motifs in mammalian cells[9] that may serve as a way of controlling the levels of transcription factors (TFs) and their targets[10]. FFLs may play important roles in differentiation[11,12] but it is not clear to what extent www.nature.com/scientificreports/ This network motif is present in adipogenesis. With this in mind, we set up to identify and experimentally verify miRNA–TF–target gene feed-forward loops involving PPARG during human adipocyte differentiation in vitro

Methods

Results

Conclusion