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HEMCAM/CD146 downregulates cell surface expression of beta1 integrins
Journal of Cell Science
|May 1, 2001
Summary
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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