The extracellular glycoprotein SPARC interacts with platelet-derived growth factor (PDGF)-AB and -BB and inhibits the binding of PDGF to its receptors

Elaine W. Raines*, Timothy F Lane, M. Luisa Iruela-Arispe, Russell Ross, E. Helene Sage

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

316 Scopus citations

Abstract

Interactions among growth factors, cells, and extracellular matrix are critical to the regulation of directed cell migration and proliferation associated with development, wound healing, and pathologic processes. Here we report the association of PDGF-AB and -BB, but not PDGF-AA, with the extracellular glycoprotein SPARC. Complexes of SPARC and 125I-labeled PDGF-BB or -AB were specifically immunoprecipitated by anti-SPARC immunoglobulins. 125I-PDGF-BB and -AB also bound specifically to SPARC that was immobilized on microtiter wells or bound to nitrocellulose after transfer from SDS/polyacrylamide gels. The binding of PDGF-BB to SPARC was pH-dependent; significant binding was detectable only above pH 6.6. The interaction of SPARC with specific dimeric forms of PDGF affected the activity of this mitogen. SPARC inhibited the binding of PDGF-BB and PDGF-AB, but not PDGF-AA, to human dermal fibroblasts in a dose-dependent manner. The expression of SPARC and PDGF was minimal in most normal adult tissues but was increased after injury. Enhanced expression of both PDGF-B chain and SPARC was seen in advanced lesions of atherosclerosis. We suggest that the coordinate expression of SPARC and PDGF-B-containing dimers following vascular injury may regulate the activity of specific dimeric forms of PDGF in vivo.

Original languageEnglish (US)
Pages (from-to)1281-1285
Number of pages5
JournalProceedings of the National Academy of Sciences of the United States of America
Volume89
Issue number4
DOIs
StatePublished - Feb 15 1992

Keywords

  • Atherosclerosis
  • Extracellular matrix
  • Growth factors
  • Wound healing

ASJC Scopus subject areas

  • General

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