miR-223 Plays A Critical Role in Obesogen-Enhanced Adipogenesis in Mesenchymal Stem Cells and in Transgenerational Obesity

Exposure of pregnant F0 mouse dams to the obesogen tributyltin (TBT) predisposes unexposed male descendants to obesity and diverts mesenchymal stem cells (MSCs) toward the adipocytic lineage. TBT also promotes adipogenic commitment and differentiation of MSCs, in vitro. We sought to identify TBT-induced factors predisposing MSCs toward the adipocytic fate. We exposed mouse MSCs to TBT, the PPARγ-selective agonist rosiglitazone or the RXR-selective agonist LG-100268 and determined their transcriptomal profiles to determine candidate microRNAs (miR) regulating adipogenic commitment and differentiation. Of the top 10 candidate microRNAs predicted by Ingenuity Pathway Analysis, miR-21, miR-33 and miR-223 were expressed in a manner consistent with an ability to differentially regulate target genes during adipogenesis. After 24 hours exposure to 50 nM TBT, miR-223 levels in MSCs were increased and expression of its target genes ZEB1, NFIB, and FOXP1 was decreased. Both ROSI and TBT increased miR-223 levels, and this induction was inhibited by the PPARγ antagonist T0070907 but not by the RXR antagonists HX531 or UVI3003, placing miR-223 downstream of PPARγ. Chromatin immunoprecipitation confirmed TBT-induced binding of PPARγ to regulatory elements in the miR-223 promoter. miR-223 levels were elevated in white adipose tissue of F2 and F3 male descendants of pregnant F0 mouse dams exposed to 50 nM TBT throughout gestation. miR-223 levels were further induced in males fed with an increased fat diet. We infer that TBT induced miR-223 expression and increased adipogenesis in MSCs through the PPARγ pathway and that transgenerationally increased expression of miR-223 plays an important role in the development of obesity caused by TBT exposure. ### Competing Interest Statement B. Blumberg is a named inventor on U.S. patents 5,861,274; 6,200,802; 6,815,168; and 7,250,273 related to PPARγ. All other authors declare they have no actual or potential competing financial interests.