TCDD alters essential transcriptional regulators of osteogenic differentiation in multipotent mesenchymal stem cells

Abstract

Differentiation of multipotent mesenchymal stem cells into bone-forming osteoblasts requires strict coordination of transcriptional pathways. Aryl hydrocarbon receptor (AhR) ligands, such as 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), have been shown to alter osteoblast differentiation in vitro and bone formation in multiple developmental in vivo models. The goal of the present study was to establish a global transcriptomic landscape during early, intermediate, and apical stages of osteogenic differentiation in vitro in response to TCDD exposure. Human bone-derived mesenchymal stem cells (hBMSC) were cultured in growth media (GM), osteogenic differentiation media (ODM), or osteogenic differentiation media containing 10 nM TCDD (ODM+TCDD), thus enabling a comparison of the transcriptomic profiles of undifferentiated, differentiated, and differentiated -TCDD-exposed hBMSCs, respectively. In this test system, exposure to TCDD attenuated differentiation of hBMSCs into osteoblasts as evidenced by reduced alkaline phosphatase activity and mineralization. At various timepoints, we observed altered expression of genes that play a role in the Wnt, FGF, BMP/TGF-β developmental pathways, as well as pathways related to extracellular matrix organization and deposition. Reconstruction of gene regulatory networks with the iDREM analysis revealed modulation of transcription factors (TF) including POLR3G, NR4A1, RDBP, GTF2B, POU2F2 and ZEB1, which may putatively influence osteoblast differentiation and the requisite deposition and mineralization of bone extracellular matrix. We demonstrate that the combination of RNA-Seq data in conjunction with the iDREM regulatory model, captures the transcriptional dynamics underlying mesenchymal stem cell differentiation under different conditions in vitro. Model predictions are consistent with existing knowledge and provides a new tool to identify novel pathways and transcription factors that may facilitate a better understanding of the osteoblast differentiation process, perturbation by exogenous agents, and potential intervention strategies targeting those specific pathways.

Integration of single‐cell and RNA‐seq data to explore the role of focal adhesion‐related genes in osteoporosis

“…The regulatory network of TF‐hub gene revealed that FAM129A and RNF24 could be regulated by POU2F2 and FOXC1. POU2F2 was shown to be an important transcription factor during the differentiation of MSCS into osteoblasts, 31 and FOXC1 was considered to be an important gene for bone marrow stem cell migration and adhesion to cortical bone. 32 , 33 This regulatory network provides a direction for future research into the role and regulatory mechanisms of FAM129A and RNF24 in OP.…”

Effects of Atrazine exposure on human bone marrow-derived mesenchymal stromal cells assessed by combinatorial assay matrix

“…Recent work by Behan Bush et al demonstrated the toxicity of xenobiotics Aroclor and Non-Aroclor mixtures of Polychlorinated Biphenyl exposure on Human Adipose MSCs (74). Another recent study has demonstrated that 2,3,7,8tetrachlorodibenzo-p-dioxin alters essential transcriptional regulators of osteogenic differentiation in bone marrow MSCs (75). Our present study further strengths this concept by molecular profiling of MSCs in their innate/native (Metabolic activity, Immunomodulatory secretome, Angiogenic secretome) and responsive functionality (Exogenous IFNg induced secretome, cell surface molecules, phosphorylation signals) post Atrazine exposure.…”