The Collagen-binding A-domains of Integrins α1β1 and α2β1Recognize the Same Specific Amino Acid Sequence, GFOGER, in Native (Triple-helical) Collagens

Abstract

We have previously assigned an integrin ␣ 2 ␤ 1 -recognition site in collagen I to the sequence, GFOGERGVEG-POGPA (O ‫؍‬ Hyp), corresponding to residues 502-516 of the ␣ 1 (I) chain and located in the fragment ␣ 1 (I)CB3 (Knight, C. G., Morton, L. F., Onley, D. J., Peachey, A. R., Messent, A. J., Smethurst, P. A., Tuckwell, D. S., Farndale, R. W., and Barnes, M. J. (1998) J. Biol. Chem. 273, 33287-33294). In this study, we show that recognition is entirely contained within the six-residue sequence GFOGER. This sequence, when in triple-helical conformation, readily supports ␣ 2 ␤ 1 -dependent cell adhesion and exhibits divalent cation-dependent binding of isolated ␣ 2 ␤ 1 and recombinant ␣ 2 A-domain, being at least as active as the parent collagen. Replacement of E by D causes loss of recognition. The same sequence binds integrin ␣ 1 A-domain and supports integrin ␣ 1 ␤ 1 -mediated cell adhesion. Triple-helical GFOGER completely inhibits ␣ 2 A-domain binding to collagens I and IV and ␣ 2 ␤ 1 -dependent adhesion of platelets and HT 1080 cells to these collagens. It also fully inhibits ␣ 1 A-domain binding to collagen I and strongly inhibits ␣ 1 ␤ 1 -mediated adhesion of Rugli cells to this collagen but has little effect on either ␣1 A-domain binding or adhesion of Rugli cells to collagen IV. We conclude that the sequence GFOGER represents a high-affinity binding site in collagens I and IV for ␣ 2 ␤ 1 and in collagen I for ␣ 1 ␤ 1 . Other high-affinity sites in collagen IV mediate its recognition of ␣ 1 ␤ 1 .The integrins are important receptors mediating both cellcell contact and cellular recognition of the extracellular matrix. They are heterodimers comprising an ␣ and a ␤ chain and are classified according to the identity of the latter (1). Integrin recognition sequences have been identified in a number of matrix proteins. RGDX 1 (where X is one of several possible amino acids) occurs in a wide variety of adhesive glycoproteins and recognizes several of the integrins. In fibronectin, for example, RGD recognizes a number of integrins, including ␣ 5 ␤ 1 , ␣ V ␤ 3 , and ␣ IIb ␤ 3 (2, 3).Integrins ␣ 1 ␤ 1 and ␣ 2 ␤ 1 are the major integrin collagen receptors (4 -6). Each recognizes a variety of collagens, including collagen I, the most abundant and widely distributed of all the collagens. Recognition of collagen IV by integrin ␣ 1 ␤ 1 has been reported to involve an aspartyl residue at position 461 in the ␣ 1 (IV) collagen chain and an arginyl residue at the same residue position in the ␣ 2 (IV) chain (7).Integrin ␣ 2 ␤ 1 plays an essential role in platelet adhesion to collagens in the blood vessel wall under flow conditions (8). This adhesion depends on collagen being in the triple-helical conformation (9) and is important in hemostasis, but it may also be a crucial initiator of thrombosis. Fragmentation of collagen I has indicated the presence of several ␣ 2 ␤ 1 -binding sites throughout the molecule recognized by platelets (9). In particular, fragment ␣ 1 (I)CB3 2 is as good as the parent collagen in supporting ...

Mammalian collagen IV

“…This interaction is critical for a variety of biological processes, including cell adhesion, migration, survival, proliferation, and differentiation. Cell culture studies have shown that collagen IV is the binding substrate for a large number of cell types including platelets (Santoro, 1986;Staatz et al, 1990), hepatocytes (Rubin et al, 1981), keratinocytes (Murray et al, 1979), endothelial (Cheng and Kramer, 1989;Herbst et al, 1988), mesangial (Setty et al, 1998), pancreatic (Kaido et al, 2004), and tumor cells such as breast and prostate carcinoma (Abecassis et al, 1987;Dedhar et al, 1993), melanoma (Chelberg et al, 1989), fibrosarcoma, and glioma (Aumailley and Timpl, 1986;Knight et al, 2000). Cell attachment to collagen IV is mediated by multiple binding sites within both triple-helical and NC1 domains, suggesting involvement of several adhesion receptors (Chelberg et al, 1989;Herbst et al, 1988;Wayner and Carter, 1987).…”

“…The α 2 β 1 integrin plays an important role in platelet adhesion to collagens and hemostasis in the blood vessel wall (Sixma et al, 1997). It has been shown that a short sequence of GFOGER peptide (O being hydroxyproline) represents a binding site for the α 2 β 1 integrin (Knight et al, 2000). The sequence represents a highaffinity binding site in both collagen I and IV, and is entirely dependent on the native triplehelical conformation.…”

Phagocytosis and remodeling of collagen matrices

“…With fibroblast cellular remodeling having such critical effects on healing and cancer applications, gaining a better understanding of the fibroblastic remodeling response is important. α1β1 and α2β1 integrins are involved in binding to native collagen type I while αvβ3 is activated in response to denatured collagen type I [56,[59][60][61][62]. The α2β1 integrin binds to the GFOGER sequence in native collagen type I and does not bind to denatured collagen type I [60,62,[63][64][65].…”

“…α1β1 and α2β1 integrins are involved in binding to native collagen type I while αvβ3 is activated in response to denatured collagen type I [56,[59][60][61][62]. The α2β1 integrin binds to the GFOGER sequence in native collagen type I and does not bind to denatured collagen type I [60,62,[63][64][65]. The αvβ3 integrin binds to denatured collagen type I almost exclusively via matricryptic RGD sequences that are exposed upon denaturation and unwinding of the triple helix [59,61,[66][67][68].…”

Human Podocytes Adhere to the KRGDS Motif of the α3α4α5 Collagen IV Network

“…4 Finally, the laminin receptor integrin ␣3␤1 has been reported to bind to the ␣1␣1␣2(IV) networks in certain cell types. 5,6 The sites for integrin ␣1␤1 and ␣2␤1 binding to the ␣1␣1␣2 collagen IV network resides within the triple-helical domain, [7][8][9] although integrin ␣1␤1 also interacts with recombinant ␣1(IV) and ␣2(IV) NC1 domains. 10,11 Integrins ␣v␤3 and ␣v␤5 have been shown to bind the ␣2(IV) NC1 domain.…”