α11β1 Integrin Recognizes the GFOGER Sequence in Interstitial Collagens

Abstract

The integrins ␣ 1 ␤ 1 , ␣ 2 ␤ 1 , ␣ 10 ␤ 1 , and ␣ 11 ␤ 1 are referred to as a collagen receptor subgroup of the integrin family. Recently, both ␣ 1 ␤ 1 and ␣ 2 ␤ 1 integrins have been shown to recognize triple-helical GFOGER (where single letter amino acid nomenclature is used, O ‫؍‬ hydroxyproline) or GFOGER-like motifs found in collagens, despite their distinct binding specificity for various collagen subtypes. In the present study we have investigated the mechanism whereby the latest member in the integrin family, ␣ 11 ␤ 1 , recognizes collagens using C2C12 cells transfected with ␣ 11 cDNA and the bacterially expressed recombinant ␣ 11 I domain. The ligand binding properties of ␣ 11 ␤ 1 were compared with those of ␣ 2 ␤ 1 . Mg 2؉ -dependent ␣ 11 ␤ 1 binding to type I collagen required micromolar Ca 2؉ but was inhibited by 1 mM Ca 2؉ , whereas ␣ 2 ␤ 1 -mediated binding was refractory to millimolar concentrations of Ca 2؉ . The bacterially expressed recombinant ␣ 11 I domain preference for fibrillar collagens over collagens IV and VI was the same as the ␣ 2 I domain. Despite the difference in Ca 2؉ sensitivity, ␣ 11 ␤ 1 -expressing cells and the ␣ 11 I domain bound to helical GFOGER sequences in a manner similar to ␣ 2 ␤ 1 -expressing cells and the ␣ 2 I domain. Modeling of the ␣ I domain-collagen peptide complexes could partially explain the observed preference of different I domains for certain GFOGER sequence variations. In summary, our data indicate that the GFOGER sequence in fibrillar collagens is a common recognition motif used by ␣ 1 ␤ 1 , ␣ 2 ␤ 1 , and also ␣ 11 ␤ 1 integrins. Although ␣ 10 and ␣ 11 chains show the highest sequence identity, ␣ 2 and ␣ 11 are more similar with regard to collagen specificity. Future studies will reveal whether ␣ 2 ␤ 1 and ␣ 11 ␤ 1 integrins also show overlapping biological functions.The collagen family currently includes at least 24 members (1, 2), and four different collagen-binding integrins ␣ 1 ␤ 1 , ␣ 2 ␤ 1 , ␣ 10 ␤ 1 (3) and ␣ 11 ␤ 1 (4) are known. The ␣ 3 ␤ 1 integrin does not interact directly with collagen, but it does act as a laminin receptor (5) that can affect the activity of the collagen receptor ␣ 2 ␤ 1 through receptor cross-talk (6).

Integrin Activation State Determines Selectivity for Novel Recognition Sites in Fibrillar Collagens

“…Collagen primary amino acid sequences GFOGER, GLOGER, and GASGER were previously shown to bind ␣ 2 ␤ 1 -containing cells, the purified integrin and recombinant ␣ 1 , ␣ 2 , and ␣ 11 I domains (13,14,16). A bioinformatic approach was taken to analyze the presence of GER sequences in human fibrillar collagens.…”

Complementary, Semiautomated Methods for Creating Multidimensional PEG-Based Biomaterials

“…It was not possible to synthesize these 3D As a proof-of-concept study, we encapsulated MDA-MB-231 or Hs578T cells in 3D PEG-MAL hydrogels with both manual pipetting (Figure 4c,e) and liquid handling robotics (Figure 4d-e). We chose three peptide sequences, RGD, GFOGER, and DGEA, that represent cell-adhesion sites in collagen I (GFOGER & DGEA) [42][43][44] and fibronectin/vitronectin/osteopontin (RGD). 43,45 Additionally, an enzymedegradable crosslinker (Pan-MMP, GPQGIWGQ) was incorporated into some of the hydrogels to allow the cells to degrade and move through the matrix.…”

Mammalian collagen IV

“…The α 11 I domain binds stronger to collagen I through the same GFOGER motif as α 2 β 1 integrin (Zhang et al, 2003), while binding of α 10 is more specific for collagen IV similar to α 1 I domain (Tulla et al, 2001b). Nevertheless, structure of binding sites for these two integrins on collagen IV remains unknown.…”