Dataset Information

Competitive interactions of collagen and a jararhagin-derived disintegrin peptide with the integrin alpha2-I domain.

ABSTRACT: Integrin alpha2beta1 is a major receptor required for activation and adhesion of platelets, through the specific recognition of collagen by the alpha2-I domain (alpha2-I), which binds fibrillar collagen via Mg(2+)-bridged interactions. The crystal structure of a truncated form of the alpha2-I domain, bound to a triple helical collagen peptide, revealed conformational changes suggestive of a mechanism where the ligand-bound I domain can initiate and propagate conformational change to the full integrin complex. Collagen binding by alpha2-I and fibrinogen-dependent platelet activity can be inhibited by snake venom polypeptides. Here we describe the inhibitory effect of a short cyclic peptide derived from the snake toxin metalloprotease jararhagin, with specific amino acid sequence RKKH, on the ability of alpha2-I to bind triple helical collagen. Isothermal titration calorimetry measurements showed that the interactions of alpha2-I with collagen or RKKH peptide have similar affinities, and NMR chemical shift mapping experiments with (15)N-labeled alpha2-I, and unlabeled RKKH peptide, indicate that the peptide competes for the collagen-binding site of alpha2-I but does not induce a large scale conformational rearrangement of the I domain.

SUBMITTER: Lambert LJ

PROVIDER: S-EPMC2423259 | biostudies-literature | 2008 Jun

REPOSITORIES: biostudies-literature

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Competitive interactions of collagen and a jararhagin-derived disintegrin peptide with the integrin alpha2-I domain.

Lambert Lester J LJ Bobkov Andrey A AA Smith Jeffrey W JW Marassi Francesca M FM

The Journal of biological chemistry 20080416 24

Integrin alpha2beta1 is a major receptor required for activation and adhesion of platelets, through the specific recognition of collagen by the alpha2-I domain (alpha2-I), which binds fibrillar collagen via Mg(2+)-bridged interactions. The crystal structure of a truncated form of the alpha2-I domain, bound to a triple helical collagen peptide, revealed conformational changes suggestive of a mechanism where the ligand-bound I domain can initiate and propagate conformational change to the full int ...[more]

PMID: 18417478

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Project description:Previous reports demonstrate that the Î±2-integrin (Î±2) mediates pancreatic ductal adenocarcinoma (PDAC) cell interaction with collagens. We found that untransformed pancreatic ductal epithelial cells and well-differentiated PDAC cells use Î±2 exclusively to adhere and migrate on collagenI. In contrast, poorly-differentiated PT45P1 and MIAPaCa2 cells demonstrate reduced reliance on, or complete loss of Î±2, respectively. Further, well-differentiated PDAC lines exhibit reduced in vitro invasion compared to poorly-differentiated lines, and Î±2-blockade suppressed invasion of well-differentiated lines exclusively. Based on these data and the demonstrated role of Î±2 in maintaining tissue architecture in other organs, we hypothesized that Î±2 may actually suppress the malignant phenotype in PDAC. Accordingly, stable ectopic expression of Î±2 in MIAPaCa2 cells (MP2-Î±2) retarded in vitro invasion. MP2-Î±2 cells maintained on collagenI were more invasion-retarded than MP2-Î±2 cells maintained in standard tissue culture, and demonstrated higher Î±2Î²1 expression that was reflected in faster and more complete adhesion/migration on collagenI. Affymetrix gene expression profiling of Î±2-expressing and mock-transfected cells revealed that kallikrein-related peptidases (KLK)-5, 6 and 7 were specifically upregulated by Î±2. Accordingly, well-differentiated PDAC lines express KLK-5, 6 and 7 and KLK blockade increased invasion as well as collagenI-migration in KLK-positive lines. Importantly, an Î±2 cytoplasmic deletion mutant promoted KLK expression and retarded invasion, while an Î±9Î±2 chimera retarded invasion less efficiently, and did not impact KLK expression. These data demonstrate for the first time that the Î±2-ectodomain and KLKâ??s coordinately regulate a less invasive phenotype in PDAC cells. Experiment Overall Design: Affymetrix global gene arrays were used to analyse differences in gene expression patterns in MIAPaCa2 cells stably reexpressing the alpha2 integrin, a cytoplasmic deletion of the alpha2 integrin (dCYTO) or an alpha9 ectodomain and transmembrane domain/alpha2 cytoplasmic domain chimera, versus vector-only mock controls. RNA was harvested from cells passaged identically and maitained under standard tissue culture conditions or on collagenI- or tenascin FNIII-coated plates.. Experiment Overall Design: Genetic manipulation (stable transgene expression)

Dataset Information

Competitive interactions of collagen and a jararhagin-derived disintegrin peptide with the integrin alpha2-I domain.

Publications

Competitive interactions of collagen and a jararhagin-derived disintegrin peptide with the integrin alpha2-I domain.

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