The Role Of Mir-125a In Adipogenesis

Fat deposition in adipose tissue is contributed by both hypertrophy and hyperplasia ofadipocytes, the latter results from differentiation of new adipocytes from preadipocytes.This process, called adipogenesis, is highly orchestrated by many transcriptional factors,extracellular signaling pathways and miRNAs.A number of transcription factors are involved in the regulation of adipogenesis,among which peroxisome proliferator-activated receptor-γ (PPARγ) andCCAAT/enhancer-binding protein-α(C/EBPα), so-called adipogenic master genes, lie incenter. They activate expression of fatty acid-binding protein4(Fabp4), fatty acid synthase(FAS), lipoprotein lipase (LPL) and other genes encoding proteins responsible for matureadipocyte functions. Many other factors, like Kruppel-like factors (KLFs), GATA-bindingprotein2and3(GATA2and3), also affect adipogenesis mainly by interacting orinfluencing the activity of PPARγ and C/EBPα.Previous solexa sequencing during the development of porcine adipose tissue in ourlab showed that miR-125a is highly expressed in porcine adipose tissue; the expressionlevel in240-day-old adult pig backfat was nearly3times higher than7-day-old pigletbackfat. In this study, we first predicted target genes of miR-125a by Targetscan, PicTar andmiRanda in both mice and pigs, and luciferase reporter assay was used to validate it. Gainand loss of function studies were performed using agomir and antagomir to explore the roleof miR-125a in adipogenesis.The main results are as follows:1MiR-125a Inhibits Porcine Preadipocytes Differentiation by TargetingERRα1) ERRα was initially confirmed as the target of miR-125a Using Luciferase ReportAssay and further confirmed in porcine preadipocytes by overexpression of miR-125a.2) miR-125a was ubiquitously expressed and highly expressed in heart and adipose tissue.During porcine preadipocytes differentiation, miR-125a were rapidly suppressed inresponse to adipogenic stimuli, with around50%down-regulation after4dayspost-induction but began to increase until a higher level at terminal differentiation thanpre-induction. 3) Overexpression of miR-125a Using Agomir Inhibits Porcine PreadipocytesDifferentiation.4) Antagonism of miR-125a Using Antagomir Promotes Porcine PreadipocytesDifferentiation.2MiR-125a-5p is Implicated in3T3-L1Preadipocytes Differentiation1) MiR-125a-5p was highly expressed in kidney, heart, skeletal muscle and adiposetissue. The expression level in spleen and liver is much lower.2) The expression level of MiR-125a-5p decreased during3T3-L1preadipoctyesdifferentiation.3) Overexpression of miR-125a-5p Using Agomir Inhibits3T3-L1PreadipocytesDifferentiation.4) Antagonism of miR-125a-5p Using Antagomir Promotes3T3-L1PreadipocytesDifferentiation.All in all, our data revealed that overexpression of miR-125a inhibits while inhibitionof miR-125a promotes adipocyte differentiation in both porcine primary preadipocytes and3T3-L1Preadipocytes Differentiation, we also verified miR-125a inhibits porcinepreadipocytes differentiation through targeting ERRα for the first time, which may providenew insights in pork quality improvement and diabetes control.