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Junctional adhesion molecules (JAMs): more molecules with dual functions?
Klaus Ebnet1, Atsushi Suzuki, Shigeo Ohno
1Institute of Cell Biology, ZMBE, University of Münster, 48149 Münster, Germany.
Journal of Cell Science
|December 6, 2003
Summary
Junctional adhesion molecules (JAMs) regulate immune cell interactions and cell polarity. These immunoglobulin proteins are key to leukocyte-endothelial cell adhesion and tight junction formation in epithelial cells.
Area of Science:
- Cell Biology
- Immunology
- Molecular Biology
Background:
- Junctional adhesion molecules (JAMs) are immunoglobulin subfamily members expressed on leukocytes, platelets, epithelial, and endothelial cells.
- JAMs localize to cell-cell contacts, particularly at tight junctions.
Purpose of the Study:
- To elucidate the dual functions of JAMs in immune cell interactions and cell polarity.
- To identify extracellular ligands and intracellular binding proteins associated with JAMs.
Main Methods:
- Analysis of JAMs' extracellular domain interactions with leukocyte integrins (LFA-1, Mac-1, alpha4beta1).
- Investigation of JAMs' cytoplasmic domain associations with tight junction-associated proteins (ZO-1, AF-6, MUPP1, PAR-3).
- Examination of the PAR-3 protein complex involvement in cell polarity regulation.
Main Results:
- JAMs associate with leukocyte beta2 integrins (LFA-1, Mac-1) and beta1 integrin (alpha4beta1), influencing leukocyte-endothelial cell interactions.
- JAMs bind to tight junction proteins (ZO-1, AF-6, MUPP1) and the cell polarity protein PAR-3.
- The PAR-3 complex, including atypical protein kinase C and PAR-6, is conserved and regulates cell polarity.
Conclusions:
- JAMs possess dual roles in regulating immune cell interactions and establishing cell polarity in epithelial and endothelial cells.
- JAMs are critical mediators of both immune responses and the structural integrity of cellular barriers.