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HEMCAM/CD146 downregulates cell surface expression of beta1 integrins

S Alais1, N Allioli, C Pujades

  • 1UMR-CNRS 7622, Université Pierre et Marie Curie, Paris, France.

Journal of Cell Science
|May 1, 2001
PubMed

Insights

HEMCAM/gicerin, an immunoglobulin superfamily protein, regulates fibroblast adhesion by controlling beta1 integrin expression. This protein impacts cell proliferation and adhesion properties to extracellular matrix proteins.

Area of Science:

  • Cell Biology
  • Molecular Biology
  • Biochemistry

Background:

  • HEMCAM/gicerin is an immunoglobulin superfamily protein involved in cell adhesion.
  • It interacts with neurite outgrowth factor (NOF) and exists in short (HEMCAM-s) and long (HEMCAM-l) cytoplasmic tail variants due to alternative splicing.

Purpose of the Study:

  • To investigate the cellular function of HEMCAM-s and HEMCAM-l isoforms.
  • To determine how HEMCAM expression affects fibroblast proliferation and adhesion properties.

Main Methods:

  • Stable transfection of murine fibroblasts with HEMCAM isoforms.
  • Assessing cell proliferation and adhesion to extracellular matrix proteins (laminin 1, fibronectin).
  • Flow cytometry, immunoprecipitation, semi-quantitative PCR, and northern blot analyses to study integrin expression and regulation.

Main Results:

  • HEMCAM expression delayed fibroblast proliferation and altered adhesion to extracellular matrix proteins.
  • Both HEMCAM isoforms inhibited integrin-dependent adhesion and spreading to laminin 1.
  • Adhesion to fibronectin was isoform-dependent.
  • HEMCAM downregulated cell surface expression of key integrins (α3β1, α6β1, α7β1, α5β1).
  • Regulation of α6β1 integrin expression by HEMCAM occurred at the translational or maturation level.

Conclusions:

  • HEMCAM regulates fibroblast adhesion by controlling beta1 integrin expression.
  • The cytoplasmic tail of HEMCAM is not essential for inhibiting laminin 1 adhesion but influences fibronectin adhesion.
  • HEMCAM plays a significant role in modulating cell-matrix interactions through integrin regulation.

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