Characterization of huJAM: evidence for involvement in cell-cell contact and tight junction regulation

Cell-cell interactions of the mucosal epithelia are important for the maint enance and establishment of epithelial barrier function. During events of i nflammation, such cell-cell interactions are often disrupted, resulting in a leaky epithelial barrier, which in turn can lead to various inflammatory and infective dysfunctions. Human junctional adhesion molecule (huJAM), fou nd on the mucosal epithelia and vascular endothelia of many major organ sys tems, is a membrane glycoprotein which resolves to a doublet band of simila r to 40 and similar to 37 kDa under SDS-PAGE analysis, representing differe ntially glycosylated forms of the same protein. huJAM was localized to the lateral membrane of Caco-2 cells (a human colonic epithelial cell line) mon olayers, in an area basolateral of the epithelial tight junctions (TJ). Thr ough functional and biochemical assays, we show huJAM to be able to homotyp ically associate and to participate in TJ restitution after trypsin-EDTA di sruption. Furthermore, we also observed a migration of huJAM expression tow ard areas of cell-cell contacts during events of cell adhesion and monolaye r formation. These qualities makes huJAM a likely player in the regulation of cell-cell contacts and the subsequent formation of TJs.