Faculty Collaboration Database

iso-DGR sequences do not mediate binding of fibronectin N-terminal modules to adherent fibronectin-null fibroblasts. J Biol Chem 2010 Mar 19;285(12):8563-71

Date

01/26/2010

Pubmed ID

20097751

Pubmed Central ID

PMC2838278

DOI

10.1074/jbc.M109.062646

Scopus ID

2-s2.0-77950573401 (requires institutional sign-in at Scopus site)   19 Citations

Abstract

Fibronectin (FN) without an RGD sequence (FN-RGE), and thus lacking the principal binding site for alpha5beta1 integrin, is deposited into the extracellular matrix of mouse embryos. Spontaneous conversion of (263)NGR and/or (501)NGR to iso-DGR possibly explains this enigma, i.e. ligation of iso-DGR by alphavbeta3 integrin may allow cells to assemble FN. Partial modification of (263)NGR to DGR or iso-DGR was detected in purified plasma FN by mass spectrometry. To test functions of the conversion, one or both NGR sequences were mutated to QGR in recombinant N-terminal 70-kDa construct of FN (70K), full-length FN, or FN-RGE. The mutations did not affect the binding of soluble 70K to already adherent fibroblasts or the ability of soluble 70K to compete with non-mutant FN or FN-RGE for binding to FN assembly sites. Non-mutant FN and FN-N263Q/N501Q with both NGRs mutated to QGRs were assembled equally well by adherent fibroblasts. FN-RGE and FN-RGE-N263Q/N501Q were also assembled equally well. Although substrate-bound 70K mediated cell adhesion in the presence of 1 mm Mn(2+) by a mechanism that was inhibited by cyclic RGD peptide, the peptide did not inhibit 70K binding to cell surface. Mutations of the NGR sequences had no effect on Mn(2+)-enhanced cell adhesion to adsorbed 70K but caused a decrease in cell adhesion to reduced and alkylated 70K. These results demonstrate that iso-DGR sequences spontaneously converted from NGR are cryptic and do not mediate the interaction of the 70K region of FN with the cell surface during FN assembly.

Author List

Xu J, Maurer LM, Hoffmann BR, Annis DS, Mosher DF

MESH terms used to index this publication - Major topics in bold

Animals
Binding Sites
Cell Adhesion
Cell Membrane
Extracellular Matrix
Fibroblasts
Fibronectins
Humans
Mass Spectrometry
Mice
Mutation
Oligopeptides
Protein Structure, Tertiary
Recombinant Proteins
Vitronectin