Fibronectin is required for integrin alphavbeta6-mediated activation of latent TGF-beta complexes containing LTBP-1

FASEB J. 2005 Nov;19(13):1798-808. doi: 10.1096/fj.05-4134com.


Transforming growth factor-betas (TGF-beta) are secreted as latent complexes consisting of the TGF-beta dimer, the TGF-beta propeptide dimer, and the latent TGF-beta binding protein (LTBP). Although the bonds between TGF-beta and its propeptide are cleaved intracellulary, the propeptide associates with TGF-beta by electrostatic interactions, thereby conferring latency to the complex. We reported that a specific sequence of LTBP-1 is required for latent TGF-beta activation by the integrin alphavbeta6. Here we describe a 24 amino acid sequence from the hinge domain required for activation. The LTBP-1 polypeptide rL1N, which includes the hinge, associates with fibronectin in binding assays. We present evidence that fibronectin null cells minimally activate latent TGF-beta and poorly incorporate the active hinge sequence into their matrix. In addition, cells missing the fibronectin receptor alpha5beta1 exhibit defective activation of latent TGF-beta by alphavbeta6 and decreased matrix incorporation. The results indicate specificity for integrin-mediated latent TGF-beta activation that include unique sequences in LTBP-1 and an appropriate matrix molecule.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Antigens, Neoplasm / chemistry*
  • Antigens, Neoplasm / metabolism
  • Biological Assay
  • Blotting, Western
  • CHO Cells
  • Collodion / chemistry
  • Cricetinae
  • Dimerization
  • Electrophoresis, Polyacrylamide Gel
  • Epitopes / chemistry
  • Fibronectins / chemistry
  • Fibronectins / physiology*
  • Genetic Vectors
  • Integrins / chemistry*
  • Integrins / metabolism
  • Intracellular Signaling Peptides and Proteins / chemistry*
  • Intracellular Signaling Peptides and Proteins / metabolism
  • Latent TGF-beta Binding Proteins
  • Luciferases / metabolism
  • Mice
  • Microscopy, Fluorescence
  • Molecular Sequence Data
  • Peptides / chemistry
  • Protein Binding
  • Protein Structure, Tertiary
  • RNA, Messenger / metabolism
  • Reverse Transcriptase Polymerase Chain Reaction
  • Time Factors
  • Transforming Growth Factor beta / metabolism*


  • Antigens, Neoplasm
  • Epitopes
  • Fibronectins
  • Integrins
  • Intracellular Signaling Peptides and Proteins
  • Latent TGF-beta Binding Proteins
  • Ltbp1 protein, mouse
  • Peptides
  • RNA, Messenger
  • Transforming Growth Factor beta
  • integrin alphavbeta6
  • Collodion
  • Luciferases