Downregulated expression of integrin alpha6 by transforming growth factor-beta(1) on lens epithelial cells in vitro

Biochem Biophys Res Commun. 2001 Jun 1;284(1):33-41. doi: 10.1006/bbrc.2001.4942.


Integrins represent the main cell surface receptors that mediate cell-matrix and cell-cell interactions. They play critical roles in adhesion, migration, morphogenesis, and the differentiation of several cell types. Previous studies have demonstrated that members of the fibroblast growth factor (FGF)-2, transforming growth factor (TGF)-beta(1), and insulin growth factor (IGF)-1 play important roles in lens biology. In particularly, TGF-beta(1) appears to play a key role in extracellular matrix production, cell proliferation, and cell differentiation of lens epithelial cells. In this study we investigated the effects of FGF-2, TGF-beta(1), and IGF-1 on the modulation of integrin receptors using lens epithelial cell lines (HLE B-3 and alphaTN-4) and lens explants. We found that the expression of integrin alpha6 is downregulated by TGF-beta(1), but is not responsive to FGF-2 or IGF-1. The promoter activity of the integrin alpha6 gene decreased upon TGF-beta(1) treatment in a transient transfection assay, and flow cytometric analysis demonstrated the reduced expression of integrin alpha6 by TGF-beta(1), whereas significant changes were not observed in the level of integrin alpha6 after the addition of FGF-2. These findings suggest that the reduced expression of integrin alpha6 caused by TGF-beta(1) might play a role in the activation of the cell cycle genes required during the fiber differentiation of the lens.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Antigens, CD / genetics
  • Antigens, CD / metabolism*
  • Down-Regulation / drug effects*
  • Epithelial Cells / cytology
  • Epithelial Cells / drug effects
  • Epithelial Cells / metabolism*
  • Fibroblast Growth Factor 2 / pharmacology
  • Flow Cytometry
  • Fluorescent Antibody Technique, Indirect
  • Humans
  • Insulin-Like Growth Factor I / pharmacology
  • Integrin alpha5
  • Integrin alpha6
  • Integrin alphaV
  • Laminin / genetics
  • Laminin / metabolism
  • Lens, Crystalline / cytology
  • Lens, Crystalline / drug effects
  • Lens, Crystalline / metabolism*
  • Mice
  • Promoter Regions, Genetic / drug effects
  • Promoter Regions, Genetic / physiology
  • Protein Isoforms / genetics
  • Protein Isoforms / metabolism
  • RNA, Messenger / metabolism
  • Transfection
  • Transforming Growth Factor beta / pharmacology*
  • Transforming Growth Factor beta1


  • Antigens, CD
  • Integrin alpha5
  • Integrin alpha6
  • Integrin alphaV
  • Laminin
  • Protein Isoforms
  • RNA, Messenger
  • TGFB1 protein, human
  • Tgfb1 protein, mouse
  • Transforming Growth Factor beta
  • Transforming Growth Factor beta1
  • Fibroblast Growth Factor 2
  • Insulin-Like Growth Factor I