The Functions and Mechanisms of TGF‐β3 Signalling in Controlling the Fate Determinations of Various Types of Stem Cells

The fate determinations of stem cells are governed by signalling molecules and pathways, and notably, the TGF-β superfamily members play pivotal roles in mediating these decisions. Significantly, TGF-β3 participates in affecting the development of stem cells and their microenvironment. In this review, we address the functions and regulatory networks of TGF-β3 in the fate decisions of several types of stem cells, including neural stem cells, haematopoietic stem cells, odontogenic stem cells, hair-follicle stem cells, adipose-derived stem cells, and mesenchymal stem cells. Specifically, we discuss the biosynthesis, activation, the roles, and mechanisms of TGF-β in influencing the proliferation, differentiation, and cell death of these stem cells, and we further highlight the perspective in this field. TGF-β signalling in stem cells begins with the activation of either integrin-dependent or integrin-independent pathways by binding to cell surface receptors TbRII and TbRI and co-receptor Betaglycan (TR3). TGF-β acts via both classical Smad signalling pathways and a variety of non-classical pathways. Notably, the biological functions of TGF-β3 depend primarily on specific cell type and the existing conditions of stem cells, reflecting the integration of multiple factors including the concentration, duration of action, interactions with other genes and/or non-coding RNAs. This review provides in-depth analyses of the molecular mechanisms through which TGF-β3 affects the fate decisions of adult stem cells, which lays a basis for identifying potential targets and developing future interventions for treating human diseases.