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Heterologous expression of alpha 1-integrin cDNA generates variable ligand specificities and alterations in cell
L D Wong1, A B Sondheim, K R Zachow
1Department of Molecular and Cell Biology, University of California, Berkeley 94720-3200, USA.
Cell Adhesion and Communication
|September 1, 1996
Summary
Cellular context dictates integrin alpha 1 beta 1 ligand specificity, even with identical mRNA. This finding highlights the importance of the cellular environment in determining integrin function and cell differentiation.
Area of Science:
- Cell Biology
- Molecular Biology
- Biochemistry
Background:
- Integrins mediate diverse cellular functions through mechanisms not fully understood.
- Integrin alpha 1 beta 1 exhibits variable ligand specificity, binding laminin-1 and collagen in some cells but only collagen in others.
Purpose of the Study:
- To investigate the molecular basis for differential ligand specificity of integrin alpha 1 beta 1.
- To determine if identical integrin alpha 1 beta 1 mRNA can yield different ligand specificities in distinct cell types.
Main Methods:
- Transfection of three cell types (K562, MRC-5, RD) with rat alpha 1 subunit cDNA.
- Assessment of alpha 1 beta 1-dependent cell attachment to collagen IV and laminin-1.
- Analysis of cell morphology and alpha 1 subunit characteristics (antigenic, electrophoretic, glycosylation).
Main Results:
- K562 cells showed collagen IV but not laminin-1 attachment (without activation), unlike MRC-5 and RD cells which bound both.
- Collagen IV binding induced a differentiated megakaryocyte-like morphology in K562 cells.
- Differences in glycosylation of the alpha 1 subunit correlated with altered ligand specificity.
Conclusions:
- Identical integrin alpha 1 beta 1 mRNA can result in distinct ligand specificities based on the cellular context.
- Cellular context is crucial for determining integrin function and ligand selectivity.
- Integrins can influence the differentiation state of pluripotential cells.