Endothelial cell spreading on fibrin requires fibrinopeptide B cleavage and amino acid residues 15-42 of the beta chain.

Abstract

Adhesion and spreading ofcultured human umbilical vein endothelial cells on fibrin surfaces of varying structure were characterized to understand better the interactions occurring between endothelium and fibrin at sites of vascular injury. Fibrin prepared with reptilase, which cleaves only fibrinopeptide A from fibrinogen, and fibrin prepared with thrombin, which cleaves both fibrinopeptide A and fibrinopeptide B, equally supported endothelial cell adhesion. In contrast, only fibrin made with thrombin mediated endothelial cell spreading, as assessed by fluorescence microscopy of cells stained with rhodamine phalloidin to identify actin stress fibers or by scanning electron microscopy. Fibrin prepared with reptilase failed to support cell spreading. To further investigate the role of the amino terminus of the fibrin 6 chain after fibrinopeptide B cleavage in promoting cell spreading, protease III from Crotalus atrox venom was used to specifically cleave the amino-terminal 42 residues of the fibrinogen B,) chain. After clotting with thrombin, this fibrin derivative lacking B#1-42 failed to support significant cell spreading. Spreading on fibrin was unaffected by depletion of Weibel-Palade bodies from endothelial cells, indicating that the spreading was independent of stimulated von Willebrand factor release. We conclude that endothelial cell spreading on fibrin requires fibrinopeptide B cleavage and involves residues 1542 of the fibrin 8 chain. (J. Clin. Invest.

The VE‐cadherin binding domain of fibrinogen induces endothelial barrier permeability and enhances transendothelial migration of malignant breast epithelial cells

“…Both MoAbs T2G1 (anti-FgBb [15][16][17][18][19][20][21] ) and BV9 (anti-VE-cadherin EC3-EC4), but not MoAb 18C6 (anti-FPB Bb [1][2][3][4][5][6][7][8][9][10][11][12][13][14], partially inhibited Fg-induced FITCDextran Flux, implicating VE-cadherin and Fg-b in mechanisms of Fg-induced EC permeability. Fg is capable of inducing permeability of different types of barrier EC, as Fg also induced permeability of a microvascular EC barrier, whereas it did not induce permeability of an epithelial cell barrier.…”

“…10 Newly exposed residues, b15-GHRP-18, promote lateral aggregation of fibrin monomers during polymerization and insoluble clot formation in secondary hemostasis. 10 Furthermore, exposure of the b 15-42 domain mediates fibrin binding to EC surfaces, 11 promotes EC adhesion and spreading, 12 and stimulates proliferation of EC, fibroblasts and cancer cells. 13,14 Cadherins mediate homophilic cell-cell adhesion critical for the maintenance of barrier integrity of epithelium (E-cadherin) and endothelium (VE-cadherin).…”

Fibrin but Not Adsorbed Fibrinogen Supports Fibronectin Assembly by Spread Platelets

“…This interaction brings the peripheral D domains of two fibrin monomers together and drives formation of double-stranded twisting fibrils. The fibrinogen-to-fibrin conversion also exposes the ␤15-42 sequence that interacts with vascular endothelial cadherin to favor spreading of platelets, fibroblasts, and endothelial cells on fibrin (40,(43)(44)(45)(46).…”

Reactive carbonyl compounds (RCCs) cause aggregation and dysfunction of fibrinogen

“…They are also rich in lysinyl residues (40 Lys in Aα; 37 Lys in Bβ and 30 Lys in γ). Cleavage of the N-terminal regions of fibrinogen α (Arg19-Gly20) and β chains (Arg21-Gly22) catalyzed by thrombin releases fibrinopeptide A and B (∼1900 Da and ∼2400 Da) (Bunce et al, 1992) and is the most important step in the conversion of fibrinogen into fibrin. Fibrin monomers polymerize end to end to form protofibrils which in turn associate laterally to form fibrin fibers (Hantgan and Hermans, 1979).…”

“…(2) RCCs strongly induce fibrinogen aggregation and deposition and aggregated proteins dysfunction in the conversion of fibrinogen to fibrin in the presence of thrombin. (3) Since lysinyl residues in the N-terminal region of fibrinogen molecules modified by RCCs are blocked, it is difficult for thrombin to recognize the cleavage sites (Arg-Gly) (Bunce et al, 1992) and produce fibrin, thus disrupting fibrinogenesis. We believe the second mechanism provides the best explanation for our results.…”