Upported by research illustrating that overexpression of exogenous occludin in fibroblasts was capable to induce the formation of TJ strands, but these TJ strands have been shorter and lesser in quantity when compared to those claudin-based TJ strands; and when fibroblasts had been cotransfected with occludin and claudins, occludin was recruited to the TJ strands formed by claudins, and with each other they formed continuous belt-like ultrastructures at the cell ell interface, which was in contrast towards the punctuate pattern when occludin was overexpressed alone (Furuse et al., 1998). Extra important, though young adult occludin knockout mice at 610 weeks of age have been fertile but when these mice reached adulthood by 30 weeks, apart from being infertile with seminiferous tubules were discovered to be devoid of spermatocytes and spermatids, calcification within the brain, and chronic gastritis within the gastric epithelium had been detected (Saitou et al., 2000), illustrating occludin, and possibly TJs, may perhaps be playing extra crucial cellular roles in addition to serving as an indispensable MASP-2 Proteins Accession protein in the TJ barrier. In this context, it can be of interest to note that studies have reported internalization of occludin by caveolae and/or clathrin-mediated endocytosis (Murakami et al., 2009; Schwarz et al., 2007; Shen and Turner, 2005), which includes the Sertoli cell TJ barrier (Wong et al., 2009; Yan et al., 2008c), illustrating occludin may be rapidly mobilized to other cellular domains to exert its function apart from the TJ barrier. two.1.three. Junctional Adhesion Molecules–JAMs are members from the immunoglobulin superTNF Superfamily Proteins medchemexpress family (IgSF) proteins; the extracellular region of these TJ-integral membrane proteins possess two Ig-like domains. Based on sequence homology, JAM family is composed of two subfamilies with among them comprises 3 closely connected members namely JAM-A (JAM-1), JAM-B (JAM-2) and JAM-C (JAM-3). One more subfamily, in which the members have a decrease polypeptide sequence similarity, includes Car, JAM-D (JAM-4) and JAMlike (JAM-L). Herein, we focus on the former subfamily considering that its members have been superior characterized and studied within the testis. JAMs differ from claudins and occludin topologically because each JAM molecule has only 1 extracellular domain, a single transmembrane region and a cytoplasmic tail that varies in length among diverse isoforms (Mandell and Parkos, 2005; Severson and Parkos, 2009). Unlike claudins and occludin, JAMs alone is insufficient to from TJ strands as no TJs were detected in lots of principal cultures of fibroblasts and established fibroblast cell lines that expressed either JAM-A or JAM-C. Nevertheless, JAMs are concentrated for the TJs when examined by immunofluorescence microscopy (Morris et al., 2006). JAMs are also distributed in and about TJ strands under electron microscopy, indicating their intimate association together with the TJ barrier (Itoh et al., 2001). The involvementNIH-PA Author Manuscript NIH-PA Author Manuscript NIH-PA Author ManuscriptInt Rev Cell Mol Biol. Author manuscript; accessible in PMC 2014 July 08.Mok et al.Pageof JAM proteins in TJ-barrier function has been revealed in quite a few research. For example, a study in T84 human intestinal epithelial cells utilizing anti-JAM-A antibody has shown that JAM-A is essential for recovery of Ca2+ depletion-induced TJ-barrier disruption as reestablishment of TJ barrier was disrupted due to the loss of JAM-A and occludin function following antibody therapy (Liu et al., 2000). JAMs are also needed for the resealing of.
