Matrix association of latent TGF-beta binding protein-2 (LTBP-2) is dependent on fibrillin-1

J Cell Physiol. 2009 Dec;221(3):586-93. doi: 10.1002/jcp.21888.

Abstract

The components of the extracellular matrix (ECM) and their differential expression patterns play important roles in tissue formation. The deposition of latent TGF-beta binding proteins (LTBPs) to the ECM exhibit distinct distribution profiles. We have analyzed here the temporal and spatial ECM association of latent TGF-beta binding protein LTBP-2 in cultured human embryonic lung fibroblasts. We found that LTBP-2 was not assembled to the ECM until by confluency of cultures following the deposition of fibronectin (FN) and fibrillin-1. In 5-day-old cultures LTBP-2 was rapidly secreted from cells and it subsequently associated with the ECM as shown by metabolic labeling and immunoprecipitation. LTBP-2 colocalized transiently with fibronectin and failed to assemble to the ECM of FN deficient mouse fibroblasts. Analysis of different cultured human cell lines revealed partial colocalization of LTBP-2 and fibrillin-1 in the ECM of fibroblasts, MG-63 osteosarcoma cells and human vascular endothelial cells. Silencing of fibrillin-1 expression by lentiviral shRNAs profoundly disrupted the deposition of LTBP-2. Current results suggest that LTBP-2 is not an element of the provisional ECM of fibroblasts but is more likely a component of more mature ECM and indicate that matrix association of LTBP-2 depends on a pre-formed fibrillin-1 network.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adipokines
  • Animals
  • Cell Line
  • Cell Line, Tumor
  • Cells, Cultured
  • Embryo, Mammalian / cytology
  • Endothelial Cells / metabolism
  • Extracellular Matrix / metabolism*
  • Fibrillin-1
  • Fibrillins
  • Fibroblasts / metabolism
  • Fibronectins / metabolism
  • Gene Expression / genetics
  • Humans
  • Latent TGF-beta Binding Proteins / genetics
  • Latent TGF-beta Binding Proteins / metabolism*
  • Mice
  • Mice, Knockout
  • Microfilament Proteins / genetics
  • Microfilament Proteins / metabolism*
  • Protein Binding / physiology
  • RNA Interference

Substances

  • Fibrillin-1
  • Fibrillins
  • Fibronectins
  • Latent TGF-beta Binding Proteins
  • Microfilament Proteins
  • FBN1 protein, human
  • Adipokines
  • Fbn1 protein, mouse
  • LTBP2 protein, human