TGFβ-induced protein mediates lymphatic endothelial cell adhesion to the extracellular matrix under low oxygen conditions

TGF beta-induced protein (TGFBI) is an extracellular protein that mediates cell adhesion to collagen, laminin and fibronectin through its interaction with different beta integrins. We had previously reported that hypoxia-induced TGFBI mRNA expression in lymphatic endothelial cells (LEC). Here, we demonstrate that TGFBI can contribute to hypoxia-induced increases in LEC adhesion to the ECM. We show that while there are no changes in alpha(1), alpha(4), alpha v, beta(1), beta(2), beta(3), alpha(5)beta(1), alpha v beta(3), alpha v beta(5) integrin expression on the LEC surface after hypoxia exposure, there exists an accumulation of TGFBI adaptor protein in LEC supernatants. We also demonstrate that hypoxia driven TGBFI expression is dependent on TGF beta production by LEC. Furthermore, we show that TGFBI mediated LEC adhesion and migration through the ECM by its binding to the beta(3) integrin. The identification of the specific mechanisms regulating LEC-ECM interactions may help us design new terapeutic applications for diseases in which lymphatic vessel function is compromised.