JAM-A

Intestinal barrier function is regulated by epithelial tight junctions (TJs), structures that control paracellular permeability. Junctional adhesion molecule-A (JAM-A) is a TJ-associated protein that regulates barrier; however, mechanisms linking JAM-A to epithelial permeability are poorly understood. Here we report that JAM-A associates directly with ZO-2 and indirectly with afadin, and this complex, along with PDZ-GEF1, activates the small GTPase Rap2c. Supporting a functional link, small interfering RNA-mediated down-regulation of the foregoing regulatory proteins results in enhanced permeability similar to that observed after JAM-A loss...

Junctional adhesion molecule-A (JAM-A) is a tight junction-associated signaling protein that regulates epithelial cell proliferation, migration, and barrier function. JAM-A dimerization on a common cell surface (in cis) has been shown to regulate cell migration, and evidence suggests that JAM-A may form homodimers between cells (in trans). Indeed, transfection experiments revealed accumulation of JAM-A at sites between transfected cells, which was lost in cells expressing cis- or predicted trans-dimerization null mutants...

Epithelial tight junctions (TJs) seal off the intercellular space to generate a paracellular barrier as well as a selective transport pathway. They also maintain apicobasal polarization of cells. In addition, TJs serve as signaling platforms that orchestrate many epithelial functions. The past years have brought about a remarkable increase in our understanding of the structure and function of TJs. The overall aim of this review is to provide an update on this new knowledge, with special emphasis on TJs in the kidney tubular epithelium...

Junctional adhesion molecule-A (JAM-A) is one component of tight junctions which are involved in important processes like paracellular permeability, cell polarity, adhesion, migration, and angiogenesis. Here we describe JAM-A expression in distal convoluted tubule, connecting tubule, and in cells of the collecting duct of the healthy human kidney. In addition, JAM-A was weakly expressed in cells of the proximal tubule. Using immunofluorescence, FACS and Western blot analysis we investigated JAM-A expression in tubular cells in vitro...

Epithelial cells form a highly selective barrier and line many organs. The epithelial barrier is maintained by closely apposed cell-cell contacts containing tight junctions, the regulation of which is incompletely understood. Here we report the cloning, tissue localization and evidence for a role in epithelial barrier regulation of an immunoglobulin superfamily member that likely represents the human homolog of murine junction adhesion molecule (JAM). Analysis of the primary structure of human JAM, cloned from T84 epithelial cells, predicts a transmembrane protein with an extracellular domain that contains two IgV loops...