title: A deep investigation into the adipogenesis mechanism: profile of microRNAs regulating adipogenesis by modulating the canonical Wnt/beta-catenin signaling pathway.
abstract: BACKGROUND
  MicroRNAs (miRNAs) are a large class of tiny non-coding RNAs (approximately 22-24 nt) that regulate diverse biological processes at the posttranscriptional level by controlling mRNA stability or translation. As a molecular switch, the canonical Wnt/beta-catenin signaling pathway should be suppressed during the adipogenesis; However, activation of this pathway leads to the inhibition of lipid depots formation. The aim of our studies was to identify miRNAs that might be involved in adipogenesis by modulating WNT signaling pathway. Here we established two types of cell model, activation and repression of WNT signaling, and investigated the expression profile of microRNAs using microarray assay.
  
  
  RESULTS
  The high throughput microarray data revealed 18 miRNAs that might promote adipogenesis by repressing WNT signaling: miR-210, miR-148a, miR-194, miR-322 etc. Meanwhile, we also identified 29 miRNAs that might have negative effect on adipogenesis by activating WNT signaling: miR-344, miR-27 and miR-181 etc. The targets of these miRNAs were also analysed by bioinformatics. To validate the predicted targets and the potential functions of these identified miRNAs, the mimics of miR-210 were transfected into 3T3-L1 cells and enlarged cells with distinct lipid droplets were observed; Meanwhile, transfection with the inhibitor of miR-210 could markedly decrease differentiation-specific factors at the transcription level, which suggested the specific role of miR-210 in promoting adipogenesis. Tcf7l2, the predicted target of miR-210, is a transcription factor triggering the downstream responsive genes of WNT signaling, was blocked at transcription level. Furthermore, the activity of luciferase reporter bearing Tcf7l2 mRNA 3' UTR was decreased after co-transfection with miR-210 in HEK-293FT cells. Last but not least, the protein expression level of beta-catenin was increased in the lithium (LiCl) treated 3T3-L1 cells after transfection with miR-210. These findings suggested that miR-210 could promote adipogenesis by repressing WNT signaling through targeting Tcf7l2.
  
  
  CONCLUSIONS
  The results suggest the presence of miRNAs in two cell models, providing insights into WNT pathway-specific miRNAs that can be further characterized for their potential roles in adipogenesis. To our knowledge, present study represents the first attempt to unveil the profile of miRNAs involved in adipogenesis by modulating WNT signaling pathway, which contributed to deeper investigation of the mechanism of adipogenesis.
authors.affiliation: State Key Laboratory of Biocontrol, School of Life Science, Sun Yat-Sen University, Guangzhou, China.
authors.forename: Limei
authors.initials: L
authors.lastname: Qin
authors.forename: Yaosheng
authors.initials: Y
authors.lastname: Chen
authors.forename: Yuna
authors.initials: Y
authors.lastname: Niu
authors.forename: Weiquan
authors.initials: W
authors.lastname: Chen
authors.forename: Qiwei
authors.initials: Q
authors.lastname: Wang
authors.forename: Shuqi
authors.initials: S
authors.lastname: Xiao
authors.forename: Anning
authors.initials: A
authors.lastname: Li
authors.forename: Ying
authors.initials: Y
authors.lastname: Xie
authors.forename: Jing
authors.initials: J
authors.lastname: Li
authors.forename: Xiao
authors.initials: X
authors.lastname: Zhao
authors.forename: Zuyong
authors.initials: Z
authors.lastname: He
authors.forename: Delin
authors.initials: D
authors.lastname: Mo
mesh_terms: D041721:3T3-L1 Cells; D050156:Adipogenesis / Q000187:drug effects / Q000235:genetics*; D000818:Animals; D002454:Cell Differentiation / Q000187:drug effects / Q000235:genetics; D003907:Dexamethasone / Q000494:pharmacology; D020869:Gene Expression Profiling; D007328:Insulin / Q000494:pharmacology; D018021:Lithium Chloride / Q000494:pharmacology; D051379:Mice; D035683:MicroRNAs / Q000235:genetics*; D020411:Oligonucleotide Array Sequence Analysis; D010766:Phosphorylation / Q000187:drug effects; D015203:Reproducibility of Results; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction / Q000187:drug effects / Q000235:genetics*; D051820:TCF Transcription Factors / Q000235:genetics; D058118:Transcription Factor 7-Like 2 Protein; D051153:Wnt Proteins / Q000378:metabolism*; D014970:Xanthines / Q000494:pharmacology; D051176:beta Catenin / Q000378:metabolism*
chemical_list: D007328:Insulin; C549325:MIRN210 microRNA, mouse; D035683:MicroRNAs; D051820:TCF Transcription Factors; C544895:Tcf7l2 protein, mouse; D058118:Transcription Factor 7-Like 2 Protein; D051153:Wnt Proteins; D014970:Xanthines; D051176:beta Catenin; C008514:methylxanthine; D003907:Dexamethasone; D018021:Lithium Chloride