A novel extracellular role for tissue transglutaminase in matrix-bound VEGF-mediated angiogenesis

• Published in: Cell death & disease Vol. 4; no. 9; p. e808
• Main Authors: Wang, Z, Perez, M, Caja, S, Melino, G, Johnson, T S, Lindfors, K, Griffin, M
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 01.09.2013; Springer Nature B.V; Nature Publishing Group
• Subjects: Animals; Antibodies; Biochemistry; Biomedical and Life Sciences; Cell Biology; Cell Culture; Cell Movement - drug effects; Cell Shape - drug effects; Chick Embryo; Cross-Linking Reagents - metabolism; Disease Models, Animal; Enzyme Inhibitors - pharmacology; Extracellular Matrix - drug effects; Extracellular Matrix - metabolism; Extracellular Space - enzymology; Female; Fibronectins - metabolism; Gene Knockdown Techniques; GTP-Binding Proteins - antagonists & inhibitors; GTP-Binding Proteins - metabolism; HEK293 Cells; Human Umbilical Vein Endothelial Cells - drug effects; Human Umbilical Vein Endothelial Cells - enzymology; Humans; Immunology; In Vitro Techniques; Life Sciences; Mice; Neovascularization, Pathologic - enzymology; Neovascularization, Pathologic - pathology; Original; original-article; Protein Glutamine gamma Glutamyltransferase 2; Rats; Signal Transduction - drug effects; Transglutaminases - antagonists & inhibitors; Transglutaminases - metabolism; Vascular Endothelial Growth Factor A - metabolism; tissue transglutaminase; crosslinking; angiogenesis; tubule and VEGF
• ISSN: 2041-4889; 2041-4889
• DOI: 10.1038/cddis.2013.318

The importance of tissue transglutaminase (TG2) in angiogenesis is unclear and contradictory. Here we show that inhibition of extracellular TG2 protein crosslinking or downregulation of TG2 expression leads to inhibition of angiogenesis in cell culture, the aorta ring assay and in vivo models. In a human umbilical vein endothelial cell (HUVEC) co-culture model, inhibition of extracellular TG2 activity can halt the progression of angiogenesis, even when introduced after tubule formation has commenced and after addition of excess vascular endothelial growth factor (VEGF). In both cases, this leads to a significant reduction in tubule branching. Knockdown of TG2 by short hairpin (shRNA) results in inhibition of HUVEC migration and tubule formation, which can be restored by add back of wt TG2, but not by the transamidation-defective but GTP-binding mutant W241A. TG2 inhibition results in inhibition of fibronectin deposition in HUVEC monocultures with a parallel reduction in matrix-bound VEGFA, leading to a reduction in phosphorylated VEGF receptor 2 (VEGFR2) at Tyr 1214 and its downstream effectors Akt and ERK1/2, and importantly its association with β 1 integrin. We propose a mechanism for the involvement of matrix-bound VEGFA in angiogenesis that is dependent on extracellular TG2-related activity.