All-trans Retinoic Acid Inhibits Bone Marrow Mesenchymal Stem Cell Commitment To Adipocytes Via Upregulating Fra1 Signaling

Objective: To investigate the molecular mechanism of Fra1 regulating all-trans retinoic acid(atRA)induced inhibition of adipogenic differentiation of rat primary bone marrow mesenchymal stem cells(BMSCs).Methods: BMSCs were obtained from the bone marrow of 2-week-old male SD rats and induced adipogenesis.Grouped as follows: fra1 overexpression(ad-fra1)group,atRA intervention(vector+atRA),silence fra1(si-fra1)group and atRA intervention after silence fra1(si-fra1+atRA)group.Oil red O staining was used to identify the lipid droplets in each group.Quantitative real-time reverse transcription PCR(qRT-PCR)was used to detect the mRNA expression of fra1,rarg,peroxisome proliferator-activated receptor γ2(pparg2),CCAAT/enhancer binding protein(c/ebpa),CD36 molecule(cd36),fatty acid binding protein(fabp),lipoprotein lipase(lpl),and Perilipin(plin).Western blot was used to detect the expression of related proteins.Chromatin immunoprecipitation(ChIP)was used to detect the interaction between RARγ and fra1,FRA1 and pparg2,c/ebpa genes,respectively.Results: BMSCs overexpressing fra1 and treated with atRA showed decreased mRNA and protein levels of key adipogenic regulators(PPARγ2,C/EBPα)and related bio-makers(Cd36,Fabp,Lpl,and Plin);atRA had a stronger inhibitory effect on adipogenesis compared with ad-fra1 group.Adipogenic gene expression in fra1-silenced BMSCs was significantly upregulated.Compared with that in the atRA group,the si-fra1 + atRA also upregulated adipogenic gene expression.However,compared with si-fra1,si-fra1 + atRA significantly inhibited adipogenic differentiation.Chromatin immunoprecipitation showed that RARγ combined fra1 gene and FRA1 combined pparg2 and c/ebpa genes.Conclusion: atRA inhibits BMSCs adipogenesis partially through the RARγ-Fra1-PPARγ2 and/or C/EBPα axis.Thus,vitamin A might be used to treat or prevent obesity and its related diseases.