Junctional adhesion molecule, a novel member of the immunoglobulin superfamily that distributes at intercellular...

Area of Science:

• Cell Biology
• Immunology
• Molecular Biology

Background:

• Tight junctions are crucial for controlling paracellular permeability in endothelial and epithelial cells.
• Occludin is the only known integral membrane protein at tight junctions, linking them to intracellular networks.
• The precise molecular composition and function of tight junctions in regulating cell migration are not fully understood.

Purpose of the Study:

• To identify novel proteins localized at endothelial and epithelial cell junctions.
• To investigate the role of newly identified junctional proteins in cell migration, specifically monocyte transmigration.

Main Methods:

• Confocal and immunoelectron microscopy were used to determine the localization of the novel protein.
• cDNA cloning was employed to identify the gene encoding the novel protein.
• Monoclonal antibodies (mAbs) were used in in vitro and in vivo assays to assess the function of the novel protein in monocyte transmigration.

Main Results:

• A novel protein, junctional adhesion molecule (JAM), was identified and found to be selectively concentrated at intercellular junctions.
• JAM colocalizes with known tight junction components at the apical region of endothelial and epithelial cells.
• An anti-JAM mAb (BV11) inhibited both spontaneous and chemokine-induced monocyte transmigration in vitro and in vivo.

Conclusions:

• Junctional adhesion molecule (JAM) is a newly identified component of endothelial and epithelial cell junctions.
• JAM plays a significant role in regulating monocyte transmigration.
• JAM represents a potential therapeutic target for modulating inflammatory responses involving monocyte infiltration.