β1 Integrin-mediated collagen gel contraction is stimulated by PDGF

Donald Gullberg, Anders Tingström, Ann Charlotte Thuresson, Lennart Olsson, Louis Terracio, Thomas K. Borg, Kristofer Rubin

Research output: Contribution to journalArticle

Abstract

The attachment of primary rat hepatocytes and fibroblasts to collagen type I is mediated by non-RGD-dependent β1 integrin matrix receptors. In this report we describe a novel 96-well microtiter plate assay for the quantification of fibroblast-mediated contraction of floating collagen type I gels. Fetal calf serum and platelet-derived growth factor (PDGF), but not transforming growth factor-β1, stimulated primary rat heart fibroblasts and normal human diploid fibroblasts (AG 1518) to contract collagen gels to less than 10% of the initial gel volume within a 24-h incubation period. Rabbit polyclonal antibodies directed to the rat hepatocyte integrin β1-chain inhibited the PDGF-stimulated collagen gel contraction. The inhibitory activity on contraction of the anti-β1 integrin IgG could be overcome by adding higher doses of PDGF. The contraction process was not blocked by anti-fibronectin IgG nor by synthetic peptides containing the tripeptide Arg-Gly-Asp (RGD), in concentrations that readily blocked fibroblast attachment to fibronectin-coated planar substrates. Autologous fibronectin or control peptides containing the tripeptide Arg-Gly-Glu were without effect. Immunofluorescence microscopy on fibroblasts grown within collagen gels revealed a punctate distribution of the β1 integrin and a lack of detectable levels of endogenously produced fibronectin. Collectively these data suggest a role for integrin collagen receptors with affinity for collagen fibers, distinct from the previously described RGD-dependent fibronectin receptors, in the fibronectin-independent PDGF-stimulated collagen gel contraction process.

Original languageEnglish (US)
Pages (from-to)264-272
Number of pages9
JournalExperimental Cell Research
Volume186
Issue number2
DOIs
StatePublished - Feb 1990

ASJC Scopus subject areas

  • Cell Biology

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