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Regulation of cell adhesion receptors by transforming growth factor-beta. Concomitant regulation of integrins that

J Heino1, R A Ignotz, M E Hemler

  • 1Department of Biochemistry, University of Massachusetts Medical School, Worcester 01655.

The Journal of Biological Chemistry
|January 5, 1989
PubMed

Insights

Transforming growth factor-beta 1 (TGF-beta 1) upregulates key integrin subunits (alpha1, alpha2, alpha3, alpha5, beta1) in human lung fibroblasts. This enhances cell adhesion to extracellular matrices, influencing cell migration and development.

Area of Science:

  • Cell Biology
  • Molecular Biology
  • Biochemistry

Background:

  • Cell adhesion to extracellular matrices is crucial for cell function and is mediated by integrin receptors.
  • Integrins are heterodimeric cell surface receptors composed of alpha and beta subunits.
  • Growth and differentiation factors, such as TGF-beta 1, may regulate integrin expression and function.

Purpose of the Study:

  • To investigate the effect of TGF-beta 1 on the expression of alpha beta 1 integrins in human cell lines.
  • To determine how TGF-beta 1 influences the synthesis, assembly, and cell surface exposure of integrin subunits.
  • To elucidate the mechanisms by which TGF-beta 1 regulates integrin expression.

Main Methods:

  • Utilized a panel of specific antibodies and cDNA probes to analyze integrin expression.
  • Quantified protein and mRNA levels of integrin subunits in response to TGF-beta 1 treatment.
  • Assessed the assembly and cell surface exposure of alpha beta 1 integrin complexes.
  • Investigated the kinetics of beta 1 subunit conversion from precursor to mature glycoprotein.

Main Results:

  • TGF-beta 1 significantly elevated the expression of alpha 1, alpha 2, alpha 3, alpha 5, and beta 1 integrin subunits in WI-38 lung fibroblasts at both protein and mRNA levels.
  • Increased expression led to enhanced assembly and cell surface exposure of alpha beta 1 integrin complexes.
  • TGF-beta 1 accelerated the maturation of the beta 1 subunit, suggesting a role in overcoming rate-limiting alpha subunit assembly.
  • TGF-beta 1 did not induce novel integrin subunits but regulated existing ones, indicating parallel and independent regulatory mechanisms.

Conclusions:

  • TGF-beta 1 modulates the expression of specific alpha beta 1 integrin subunits in human fibroblasts.
  • The regulation involves increased synthesis and accelerated maturation of integrin subunits, facilitating complex assembly and cell surface presentation.
  • Altered integrin profiles induced by TGF-beta 1 can influence cell adhesion, migration, and development by modifying interactions with the extracellular matrix.

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