MicroRNA network regulation of developmental bone toxicity in a human embryonic stem cell osteogenic model.

Developmental exposure to environmental toxicants is a cause of skeletal abnormalities. Yet the molecular mechanisms linking early exposure to impaired bone formation remain undefined. Skeletal tissues arise from both neural crest- and mesoderm-derived lineages that rely on shared osteogenic differentiation programs, suggesting that disruption of common regulatory processes may contribute to diverse skeletal outcomes. MicroRNAs (miRNAs) are key post-transcriptional regulators of gene networks and have appeared as indicators of toxicant-induced perturbation. In this study, we examined whether developmentally relevant toxicants are associated with miRNA regulatory networks during osteogenic differentiation. Using a human embryonic stem cell (hESC)-based osteogenic differentiation model, we assessed the effects of nine toxicants spanning distinct primary mechanisms. Toxicant exposure impaired osteogenic differentiation at their IC50, as reflected by altered expression of osteogenic markers and transcriptional remodeling. Global miRNA profiling revealed dysregulation of miRNAs enriched for bone-related biological processes, including regulators of osteogenic commitment and differentiation timing. Integrated miRNA-mRNA network analysis identified a subset of miRNAs linked to core osteogenic and lineage-associated pathways, including