LAUSR

Abstract Introduction: Mesenchymal stem cells (MSCs) are multipotent progenitor cells that can differentiate in to osteoblast, adipocytes and chondrocytes. Lineage specification of MSC is governed by various systemic hormones, systemic and local growth factors and cytokines. TNF-α is an inflammatory cytokine produced at the site of tissue injuries and known to regulates MSC migration and differentiation. However, its role on lineage specification and differentiation of MSCs remain complex and elusive. In this study we explored the same utilizing human bone marrow and adipocyte derived MSCs. Experimental Methods: Human MSCs derived from bone marrow and adipocytes were differentiated in to osteoblast and adipocytes in the presence or absence of TNF-α. Expressions of osteoblast and adipocyte differentiation markers were assessed by qRT-PCR. The key epigenetic factor of lineage specification JMJD3 was depleted in MSCs utilizing lentiviral ShRNA. Results: TNF-α promoted the osteoblastic and inhibited the adipogenic differentiation of MSC as assessed by Alizarin and oil red O staining, respectively. Consistently, while inducing the key osteogenic factors, TNF- α repressed the adipogenic markers in MSCs. Mechanistically, TNF-α regulates MSC fate by inducing lysine-specific demethylase JMJD3/KDM6B, which is a key epigenetic factor that determines mesenchymal stem cell lineage specification. ShRNA mediated knockdown of JMD3 in MSCs inhibited TNF- α mediated activation and inhibition of osteogenic and adipogenic differentiation, respectively. Conclusion: Our study uncovers the novel mechanisms of TNF-α mediated MSC lineage commitment and differentiation and thus highlight JMJD3 as mediator of TNF-α actions in MSCs.