Transglutaminase-mediated processing of fibronectin by endothelial cell monolayers

Abstract

We studied the interaction of [125I]fibronectin with human umbilical vein endothelial cells. Endothelial cell monolayers cross-linked [125I]fibronectin which had been preadsorbed to gelatin-coated dishes. The cross-linking of the substrate-immobilized [125I]fibronectin was mediated by cell-associated tissue transglutaminase and occurred more rapidly during the first 30 min after endothelial cell seeding but also continued for several hours after the cells were fully spread. The processing of the [125I]fibronectin was associated with the basolateral surface of the endothelial cell, as demonstrated by the finding that cross-linking did not occur when [125I]fibronectin was presented to the apical surface of confluent monolayers. Transglutaminase activity was not necessary for attachment and spreading of HUVEC on a fibronectin/gelatin matrix. The presence of a nonpeptidyl transglutaminase inactivator rendered the cells more susceptible to detachment by trypsin and destabilized the association of fibronectin with the subendothelial extracellular matrix. Thus, endothelial cells process fibronectin into cross-linked multimers due to the expression of tissue transglutaminase at the basal surface of the cell. This process may serve to stabilize the extracellular matrix and to firmly anchor the cells to the basement membrane.

Matrix changes induced by transglutaminase 2 lead to inhibition of angiogenesis and tumor growth

“…It has been suggested that TG2-mediated ECM crosslinking in HUVEC and the endothelial-like cell line ECV304 contributes to basement membrane assembly and cell adhesion. 8,12 We found abundant, endogenous TG2 in capillaries grown in vitro (Figure 1), with enzyme activity localized in the HUVEC ECM. Inhibition of the endogenous TG2 had little effect on tube formation, suggesting that the observed in situ extracellular activity of TG2 is not essential for tube formation.…”

“…6 Many ECM proteins are known substrates of the enzyme, 7 and the crosslinking of these proteins by endothelial cell TG2 is thought to play a role in the stabilization of the basement membrane. 8 However, in a number of different tissues, inappropriate crosslinking of the ECM by TG2 following continuous tissue insult can lead to ECM accumulation and fibrosis. 9,10 Cell surface TG2 is also thought to be involved in cell migration, 11 and cell adhesion, 12 by a mechanism that is independent of its transamidating activity.…”

Transglutaminase 2 inhibitor, KCC009, disrupts fibronectin assembly in the extracellular matrix and sensitizes orthotopic glioblastomas to chemotherapy

“…Cell surface TG2 crosslinks fibronectin, which acts to stabilize the ECM and anchor cells at the basement membrane (Martinez et al, 1994). TG2 binds with high affinity to fibronectin at the N-terminal 42-kDa gelatin binding domain of fibronectin via a novel recognition site within the NH 2 -terminal beta-sandwich domain of TG2 (Akimov and Belkin, 2001).…”

Localization of Tissue Transglutaminase in Human Carotid and Coronary Artery Atherosclerosis: Implications for Plaque Stability and Progression

“…This could potentially result in a more resilient barrier at the blood-vessel interface. Other substrates, such as vitronectin (Sane et al, 1990), osteopontin (Prince et al, 1991), thrombospondin (Bale and Mosher 1986), fibronectin (Martinez et al, 1994), dermatan sulfate proteoglycan (Kinsella and Wight, 1990), and apo(a) (Borth et al, 1991), are often increased in the atheromatous plaque (Dufourcq et al, 1998;Giachelli et al, 1995;Hajjar and Nachman, 1996;Riessen et al, 1994;Shekhonin et al, 1987;Wight et al, 1985).…”