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Upported by research illustrating that overexpression of exogenous occludin in fibroblasts was able to induce the formation of TJ strands, but these TJ strands had been shorter and lesser in quantity when in comparison to these claudin-based TJ strands; and when fibroblasts have 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 for the punctuate pattern when occludin was CK2 Purity & Documentation overexpressed alone (Furuse et al., 1998). Additional important, whilst young adult occludin knockout mice at 610 weeks of age had been fertile but when these mice reached adulthood by 30 weeks, besides getting infertile with seminiferous tubules have been discovered to be devoid of spermatocytes and spermatids, calcification inside the brain, and chronic gastritis inside the gastric epithelium had been detected (Saitou et al., 2000), illustrating occludin, and probably TJs, may be playing much more important cellular roles in addition to serving as an indispensable protein in the TJ barrier. Within this context, it can be of interest to note that research have reported internalization of occludin by caveolae and/or clathrin-mediated endocytosis (Murakami et al., 2009; Schwarz et al., 2007; Shen and Turner, 2005), such as the Sertoli cell TJ barrier (Wong et al., 2009; Yan et al., 2008c), illustrating occludin could be quickly mobilized to other cellular domains to exert its function besides the TJ barrier. 2.1.3. Junctional Adhesion Molecules–JAMs are members with the immunoglobulin superfamily (IgSF) proteins; the extracellular area of those TJ-integral membrane proteins possess two Ig-like domains. Depending on sequence homology, JAM family is composed of two subfamilies with certainly one of them comprises three closely connected members namely JAM-A (JAM-1), JAM-B (JAM-2) and JAM-C (JAM-3). One more subfamily, in which the members possess a lower polypeptide sequence similarity, involves Auto, JAM-D (JAM-4) and JAMlike (JAM-L). Herein, we concentrate around the former subfamily considering that its members have already been far better characterized and studied within the testis. JAMs differ from claudins and occludin topologically considering the fact that each JAM molecule has only 1 extracellular domain, a single transmembrane area along with a cytoplasmic tail that varies in length amongst various isoforms (Mandell and Parkos, 2005; Severson and Parkos, 2009). In contrast to claudins and occludin, JAMs alone is insufficient to from TJ strands as no TJs were detected in a lot of key cultures of fibroblasts and established fibroblast cell lines that expressed either JAM-A or JAM-C. On the other hand, JAMs are concentrated to 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; available in PMC 2014 July 08.Mok et al.Pageof JAM proteins in TJ-barrier function has been revealed in a number of studies. For example, a study in T84 human intestinal epithelial cells employing anti-JAM-A antibody has shown that JAM-A is vital for recovery of Ca2+ EGFR/ErbB1/HER1 MedChemExpress depletion-induced TJ-barrier disruption as reestablishment of TJ barrier was disrupted due to the loss of JAM-A and occludin function following antibody treatment (Liu et al., 2000). JAMs are also needed for the resealing of.