Transforming Growth Factor-β and Endoglin Signaling Orchestrate Wound Healing

Physiological wound healing is a complex process requiring the temporal and spatial co-ordination of various signaling networks, biomechanical forces, and biochemical signaling pathways in both hypoxic and non-hypoxic conditions. Although a plethora of factors are required for successful physiological tissue repair, transforming growth factor beta (TGF-β) expression has been demonstrated throughout wound healing and shown to regulate many processes involved in tissue repair, including production of ECM, proteases, protease inhibitors, migration, chemotaxis, and proliferation of macrophages, fibroblasts of the granulation tissue, epithelial and capillary endothelial cells. TGF-β mediates these effects by stimulating signaling pathways through a receptor complex which contains Endoglin. Endoglin is expressed in a broad spectrum of proliferating and stem cells with elevated expression during hypoxia, and regulates important cellular functions such as proliferation and adhesion via Smad signaling. This review focuses on how the TGF-β family and Endoglin, regulate stem cell availability, and modulate cellular behavior within the wound microenvironment, includes current knowledge of the signaling pathways involved, and explores how this information may be applicable to inflammatory and/or angiogenic diseases such as fibrosis, rheumatoid arthritis and metastatic cancer.