Junctional Adhesion Molecules (JAMs): Cell Adhesion Receptors With Pleiotropic Functions in Cell Physiology and Development.

Junctional adhesion molecules (JAM)-A, -B and -C are cell-cell adhesion molecules of the immunoglobulin superfamily which are expressed by a variety of tissues, both during development and in the adult organism. Through their extracellular domains, they interact with other adhesion receptors on opposing cells. Through their cytoplasmic domains, they interact with PDZ domain-containing scaffolding and signaling proteins. In combination, these two properties regulate the assembly of signaling complexes at specific sites of cell-cell adhesion. The multitude of molecular interactions has enabled JAMs to adopt distinct cellular functions such as the regulation of cell-cell contact formation, cell migration, or mitotic spindle orientation. Not surprisingly, JAMs regulate diverse processes such as epithelial and endothelial barrier formation, hemostasis, angiogenesis, hematopoiesis, germ cell development, and the development of the central and peripheral nervous system. This review summarizes the recent progress in the understanding of JAMs, including their characteristic structural features, their molecular interactions, their cellular functions, and their contribution to a multitude of processes during vertebrate development and homeostasis.

Junctional adhesion molecule-like protein promotes tumor progression via the Wnt/ß-catenin signaling pathway in lung adenocarcinoma.

BACKGROUND: Lung adenocarcinoma (LUAD) is a heavy social burden worldwide. Because the mechanisms involved in LUAD remain unclear, the prognosis of LUAD remains poor. Consequently, it is urgent to investigate the potential mechanisms of LUAD. Junctional adhesion molecule-like protein (JAML), is recognized as a tumorigenesis molecule in gastric cancer. However, the role of JAML in LUAD is still unclear. Here we aimed to evaluate the role of JAML in LUAD. METHODS: qRT-PCR, Western blotting and immunohistochemistry were conducted to investigate the expression of JAML in LUAD tissues. JAML was knocked down and overexpressed in LUAD cells using transient transfection by siRNA and plasmids or stable transfection by lentivirus. Proliferation potential of LUAD cells were detected by Cell Counting Kit-8, EdU incorporation and Colony formation assay. Migration and invasion abilities of LUAD cells were determined by wound healing, transwell migration and invasion assays. Cell cycle and cell apoptosis were detected by flow cytometry. The effects of JAML in vivo were studied in xenograft tumor models. Western blotting was used to explore the molecular mechanisms of JAML function. In addition, rescue experiments were performed to verify the possible mechanisms. RESULTS: JAML expression was elevated in LUAD tissues compared with peritumor tissues, and this upregulation was positively related to pT and pTNM. Furthermore, both in vitro and in vivo, JAML silencing markedly repressed malignant behaviors of LUAD cells and vice versa. Knockdown of JAML also mediated cell cycle arrest at G0/G1 phase and promoted apoptosis in LUAD cells. Mechanistically, silencing JAML repressed the process of epithelial-mesenchymal transition by inactivating the Wnt/ß-catenin pathway in LUAD cells. Effects of JAML can be rescued by Wnt/ß-catenin pathway activator in A549 cells. CONCLUSIONS: Our data reveal the oncogenic role of JAML in LUAD, indicating that JAML may be a predictive biomarker and novel therapeutic target for LUAD.

Endothelial Cell Junctional Adhesion Molecules: Role and Regulation of Expression in Inflammation.

Endothelial cells line the lumen of all blood vessels and play a critical role in maintaining the barrier function of the vasculature. Sealing of the vessel wall between adjacent endothelial cells is facilitated by interactions involving junctionally expressed transmembrane proteins, including tight junctional molecules, such as members of the junctional adhesion molecule family, components of adherence junctions, such as VE-Cadherin, and other molecules, such as platelet endothelial cell adhesion molecule. Of importance, a growing body of evidence indicates that the expression of these molecules is regulated in a spatiotemporal manner during inflammation: responses that have significant implications for the barrier function of blood vessels against blood-borne macromolecules and transmigrating leukocytes. This review summarizes key aspects of our current understanding of the dynamics and mechanisms that regulate the expression of endothelial cells junctional molecules during inflammation and discusses the associated functional implications of such events in acute and chronic scenarios.

L-Glutamine Enhances Tight Junction Integrity by Activating CaMK Kinase 2-AMP-Activated Protein Kinase Signaling in Intestinal Porcine Epithelial Cells.

BACKGROUND: The tight junctions (TJs) are essential for maintenance of the intestinal mucosal barrier integrity. Results of our recent work show that dietary l-glutamine (Gln) supplementation enhances the protein abundance of TJ proteins in the small intestine of piglets. However, the underlying mechanisms remain largely unknown. OBJECTIVE: This study was conducted to test the hypothesis that Gln regulates TJ integrity through calcium/calmodulin-dependent kinase 2 (CaMKK2)-AMP-activated protein kinase (AMPK) signaling which, in turn, contributes to improved intestinal mucosal barrier function. METHODS: Jejunal enterocytes isolated from a newborn pig were cultured in the presence of 0-2.0 mmol Gln/L for indicated time points. Cell proliferation, monolayer transepithelial electrical resistance (TEER), paracellular permeability, expression and distribution of TJ proteins, and phosphorylated AMPK were determined. RESULTS: Compared with 0 mmol Gln/L, 2.0 mmol Gln/L enhanced (P < 0.05) cell growth (by 31.9% at 48 h and 11.1% at 60 h). Cells treated with 2 mmol Gln/L increased TEER by 32.2% at 60 h, and decreased (P < 0.05) TJ permeability by 20.3-40.0% at 36-60 h. In addition, 2.0 mmol Gln/L increased (P < 0.05) the abundance of transmembrane proteins, such as occludin, claudin-4, junction adhesion molecule (JAM)-A, and the plaque proteins zonula occludens (ZO)-1, ZO-2, and ZO-3 by 1.8-6 times. In contrast, 0.5 mmol Gln/L had a moderate effect on TJ protein abundance (20.2-70.5%; P < 0.05) of occludin, claudin-3, claudin-4, JAM-A, and ZO-1. 2.0 mmol Gln/L treatment led to a greater distribution of claudin-1, claudin-4, and ZO-1 at plasma membranes compared with 0 mmol Gln/L. This effect of Gln was mediated by the activation of CaMKK2-AMPK signaling, because either depletion of calcium from the medium or the presence of an inhibitor of CaMKK2 abrogated the effect of Gln on epithelial integrity. CONCLUSION: Our findings indicate that activation of CaMKK2-AMPK signaling by Gln is associated with improved intestinal mucosal barrier function through enhancing the abundance of TJ proteins and altering their intracellular localization in intestinal porcine epithelial cells.

Nectin and junctional adhesion molecule are critical cell adhesion molecules for the apico-basal alignment of adherens and tight junctions in epithelial cells.

Tight junctions (TJs) and adherens junctions (AJs) form an apical junctional complex at the apical side of the lateral membranes of epithelial cells, in which TJs are aligned at the apical side of AJs. Many cell adhesion molecules (CAMs) and cell polarity molecules (CPMs) cooperatively regulate the formation of the apical junctional complex, but the mechanism for the alignment of TJs at the apical side of AJs is not fully understood. We developed a cellular system with which epithelial-like TJs and AJs were reconstituted in fibroblasts and analyzed the cooperative roles of CAMs and CPMs. We exogenously expressed various combinations of CAMs and CPMs in fibroblasts that express negligible amounts of these molecules endogenously. In these cells, the nectin-based cell-cell adhesion was formed at the apical side of the junctional adhesion molecule (JAM)-based cell-cell adhesion, and cadherin and claudin were recruited to the nectin-3- and JAM-based cell-cell adhesion sites to form AJ-like and TJ-like domains, respectively. This inversed alignment of the AJ-like and TJ-like domains was reversed by complementary expression of CPMs Par-3, atypical protein kinase C, Par-6, Crb3, Pals1 and Patj. We describe the cooperative roles of these CAMs and CPMs in the apico-basal alignment of TJs and AJs in epithelial cells.

The effect of hyperglycaemia on permeability and the expression of junctional complex molecules in human retinal and choroidal endothelial cells.

Diabetic retinopathy is the leading cause of preventable blindness in the working population and its prevalence continues to increase as the worldwide prevalence of diabetes grows. Diabetic choroidopathy is less well studied and occurs in the late stages of diabetic eye disease. The main cause of visual loss in diabetic eye disease is diabetic macular oedema caused by an increase in microvascular endothelial permeability. Endothelial cell permeability is influenced by multiple factors which have not been fully elucidated, particularly in human models. In addition, the gene and protein expression between retinal and choroidal endothelial cells, even in humans, has been shown to be heterogeneous. The aim of this project was to determine, in vitro, the effect of high glucose (25 mM) on human paracellular permeability in retinal and choroidal endothelial cells. The expression of selected tight junction molecules (Occludin, Claudin-5, JAM-A and JAM-C) and adheren junction (VE-Cadherin) molecules was also compared between retinal and choroidal endothelial cells and with high glucose. High glucose conditions significantly increased the permeability in both retinal and choroidal endothelial cells monolayers although the increase was higher in retinal endothelial cells. Under normal glucose culture conditions microarray analysis determined that occludin and claudin-5 gene expression was higher in retinal endothelial cells than choroidal endothelial cells, and western blotting indicated that claudin-5 protein expression was also higher in retinal endothelial cells whilst JAM-A, and C and VE-Cadherin levels were similar. In retinal endothelial cells exposed to high glucose claudin-5, occludin and JAM-A was found to be reduced, whereas the expression of VE-Cadherin and JAM-C was unchanged when evaluated with western blotting, immunofluorescence and qPCR. None of the proteins were significantly decreased by high glucose in choroidal endothelial cells. The increase in retinal endothelial cell permeability is likely caused by a decrease in selective tight junction protein expression, leading to increased paracellular permeability. This may indicate differences in junctional molecule regulation of permeability in retinal compared to choroidal endothelial cells.

Alterations in junctional proteins, inflammatory mediators and extracellular matrix molecules in eosinophilic esophagitis.

Eosinophilic esophagitis (EoE), an inflammatory atopic disease of the esophagus, causes massive eosinophil infiltration, basal cell hyperplasia, and sub-epithelial fibrosis. To elucidate cellular and molecular factors involved in esophageal tissue damage and remodeling, we examined pinch biopsies from EoE and normal pediatric patients. An inflammation gene array confirmed that eotaxin-3, its receptor CCR3 and interleukins IL-13 and IL-5 were upregulated. An extracellular matrix (ECM) gene array revealed upregulation of CD44 & CD54, and of ECM proteases (ADAMTS1 & MMP14). A cytokine antibody array showed a marked decrease in IL-1α and IL-1 receptor antagonist and an increase in eotaxin-2 and epidermal growth factor. Western analysis indicated reduced expression of intercellular junction proteins, E-cadherin and claudin-1 and increased expression of occludin and vimentin. We have identified a number of novel genes and proteins whose expression is altered in EoE. These findings provide new insights into the molecular mechanisms of the disease.

Junctional adhesion molecule-like protein as a novel target for kaempferol to ameliorate lung adenocarcinoma.

OBJECTIVE: Although there have been improvements in targeted therapy and immunotherapy, the majority of lung adenocarcinoma (LUAD) patients still lack effective therapies. Consequently, it is urgent to screen for new diagnosis biomarkers and pharmacological targets. Junctional adhesion molecule-like protein (JAML) was considered to be an oncogenic protein and may be a novel therapeutic target in LUAD. Kaempferol is a natural flavonoid that exhibits antitumor activities in LUAD. However, the effect of kaempferol on JAML is still unknown. METHODS: Small interfering RNA was used to knockdown JAML expression. The cell viability was determined using the cell counting kit-8 assay. The proliferation of LUAD cells was evaluated using the 5-ethynyl-2'-deoxyuridine incorporation assay. The migration and invasion of LUAD cells were evaluated by transwell assays. Molecular mechanisms were explored by Western blotting. RESULTS: JAML knockdown suppressed proliferation, migration and invasion of LUAD cells, and JAML deficiency restrained epithelial-mesenchymal transition (EMT) via inactivating the phosphoinositide 3-kinase/protein kinase B/mammalian target of rapamycin (PI3K/AKT/mTOR) pathway. Using a PI3K activator (740Y-P), rescue experiments showed that phenotypes to JAML knockdown in LUAD cells were dependent on the PI3K/AKT/mTOR pathway. Kaempferol also inhibited proliferation, migration and invasion of A549 and H1299 cells and partially suppressed EMT through the PI3K/AKT/mTOR pathway. Knockdown of JAML ameliorated the inhibitory effect of kaempferol on LUAD cells. Kaempferol exerted anticancer effects by targeting JAML. CONCLUSION: JAML is a novel target for kaempferol against LUAD cells. Please cite this article as: Wu Q, Wang YB, Che XW, Wang H, Wang W. Junctional adhesion molecule-like protein as a novel target for kaempferol to ameliorate lung adenocarcinoma. J Integr Med. 2023; 21(3): 268-276.

Regulation of the blood-testis barrier by coxsackievirus and adenovirus receptor.

The blood-testis barrier (BTB) divides the seminiferous epithelium into the basal and the adluminal compartment. It restricts paracellular diffusion of molecules between Sertoli cells, confers cell polarity, and creates a unique microenvironment in the adluminal compartment for spermatid development. However, it undergoes restructuring during the epithelial cycle so that preleptotene spermatocytes differentiated from type B spermatogonia residing in the basal compartment can traverse the BTB at stage VIII of the cycle, while the immunological barrier is maintained. Herein, coxsackievirus and adenovirus receptor (CAR), a tight junction (TJ) integral membrane protein in the testis and multiple epithelia and endothelia, was found to act as a regulatory protein at the BTB, besides serving as a structural adhesion protein. RNAi-mediated knockdown of CAR in a Sertoli cell epithelium with an established TJ-permeability barrier that mimicked the BTB in vivo resulted in a disruption of the TJ barrier and an increase in endocytosis of the TJ-protein occludin. Furthermore, such an enhancement in occludin endocytosis was accompanied by a downregulation of Thr-phosphorylation in occludin and an increase in the association of endocytosed occludin with early endosome antigen-1. These findings were confirmed by overexpressing CAR in Sertoli cells, which was found to "tighten" the Sertoli cell TJ barrier, promoting BTB function. These findings support the emerging concept that CAR is not only a structural protein, it is involved in conferring the phosphorylation status of other adhesion proteins at the BTB (e.g., occludin) possibly mediated via its structural interactions with nonreceptor protein kinases, thereby modulating endocytic vesicle-mediated protein trafficking.

Human intestinal epithelial cells exhibit a cellular response indicating a potential toxicity upon exposure to hematite nanoparticles.

This study examined the effects of different-sized nanoparticles on potential cytotoxicity in intestinal epithelia. Three sizes of hematite nanoparticles were used for the study at a 10 ppm concentration: 17, 53, and, 100 nm. Results indicate that, of the hematite nanoparticles tested, 17 nm was more toxic to the epithelial integrity than 53 or 100 nm. In addition, the epithelial integrity was affected by disruption of epithelial structures such as apical microvilli, and by disruption of the cell-cell junctions leading to reduction in transepithelial electrical resistance measurements (TEER). The drop in TEER was caused by disruption of the adhering junctions not by cell death, as determined by immunocytochemistry, and by using a cell viability assay. Epithelial integrity was also affected at the molecular level as shown by differential expression of genes related to cell junction maintenance, which was assessed by microarray analysis. In conclusion, the 17- and 100-nm hematite nanoparticles caused significant structural changes in the epithelium but not the 53 nm nanoparticles. Also, different-sized hematite nanoparticles each had different effects both at the cellular level and genetic level.

Physiological functions of junctional adhesion molecules (JAMs) in tight junctions.

Junctional adhesion molecules (JAMs) comprise a small subfamily of the immunoglobulin superfamily of adhesion receptors with a multitude of physiological functions in vertebrate development and homeostasis. Several members of the JAM family localize at tight junctions of epithelial and endothelial cells where they interact with PDZ domain-containing scaffolding proteins. For some JAM family members, molecular mechanisms have been elaborated through which they regulate cell-cell contact maturation and tight junction formation. For other members of this family our knowledge on their role in barrier-forming epithelia is still fragmentary. Here, we review our current understanding of the contribution of JAM family proteins to the barrier function of epithelial and endothelial cells with a major focus on epithelial tight junctions.

The mitochondrial outer membrane protein SYNJ2BP interacts with the cell adhesion molecule TMIGD1 and can recruit it to mitochondria.

BACKGROUND: Transmembrane and immunoglobulin domain-containing protein 1 (TMIGD1) is a recently identified cell adhesion molecule which is predominantly expressed by epithelial cells of the intestine and the kidney. Its expression is downregulated in both colon and renal cancer suggesting a tumor suppressive activity. The function of TMIGD1 at the cellular level is largely unclear. Published work suggests a protective role of TMIGD1 during oxidative stress in kidney epithelial cells, but the underlying molecular mechanisms are unknown. RESULTS: In this study, we address the subcellular localization of TMIGD1 in renal epithelial cells and identify a cytoplasmic scaffold protein as interaction partner of TMIGD1. We find that TMIGD1 localizes to different compartments in renal epithelial cells and that this localization is regulated by cell confluency. Whereas it localizes to mitochondria in subconfluent cells it is localized at cell-cell contacts in confluent cells. We find that cell-cell contact localization is regulated by N-glycosylation and that both the extracellular and the cytoplasmic domain contribute to this localization. We identify Synaptojanin 2-binding protein (SYNJ2BP), a PDZ domain-containing cytoplasmic protein, which localizes to both mitochondria and the plasma membrane, as interaction partner of TMIGD1. The interaction of TMIGD1 and SYNJ2BP is mediated by the PDZ domain of SYNJ2BP and the C-terminal PDZ domain-binding motif of TMIGD1. We also find that SYNJ2BP can actively recruit TMIGD1 to mitochondria providing a potential mechanism for the localization of TMIGD1 at mitochondria. CONCLUSIONS: This study describes TMIGD1 as an adhesion receptor that can localize to both mitochondria and cell-cell junctions in renal epithelial cells. It identifies SYNJ2BP as an interaction partner of TMIGD1 providing a potential mechanism underlying the localization of TMIGD1 at mitochondria. The study thus lays the basis for a better understanding of the molecular function of TMIGD1 during oxidative stress regulation.

Changes in the expression and distribution of junction and polarity proteins in the porcine endometrium during early pregnancy period.

The maternal endometrium undergoes transformations during early pregnancy period to regulate the paracellular permeability across the epithelium and to enable adhesion between the trophoblast and endometrial epithelial cells. These transformations, under the influence of ovarian hormones, are associated with a partial loss in polarity of epithelial cell that is regulated by tight junctions (TJ), adherens junctions (AJ) and associated polarity protein complexes. This study examined the change in expression and distribution of proteins associated with TJs, AJs and apical partition defective (PAR) complex in porcine endometrium on Days 10, 13 and 16 of estrous cycle and pregnancy. Moreover, effect of hormones, progesterone (P4) and 17-ß estradiol (E2) on polar phenotype of endometrial epithelial cells was also investigated in vitro. There was pregnancy induced increase in gene and protein expression of TJ associated claudin-1 (CLDN1) on Day 13 of pregnancy as compared to corresponding day of estrous cycle and a decrease in TJ protein, zona occludens-1 (ZO-1) and PAR complex associated PAR6 expression levels on Day 16 of pregnancy (P < 0.05). Immunofluorescence studies revealed that on Days 10 and 13, TJ proteins occludin (OCLN) and ZO-1were primarily present in the apical region of lateral epithelial membrane. On Day 16 of pregnancy, whereas, OCLN redistributed into cytoplasm, ZO-1 decreased apically but was found to localize in the basal epithelium. The AJ proteins cadherin and ß-catenin were located at the apical epithelium on Day 10 of estrous cycle and pregnancy and Day 13 of estrous cycle. On Days 13 and 16 of pregnancy both proteins were expressed in the lateral membrane and co-localization between these proteins was observed on Day 16. On Day 10, PAR complex proteins PAR3, cell division control protein 42 (CDC42) and atypical protein kinase C (aPKC) ζ were observed in apical epithelium and in lateral membrane and CDC42 was also present in the cytoplasm of epithelium. Pregnancy induced redistribution of aPKCζ to cytoplasm and CDC42 to apical surface of luminal epithelium was observed on Days 13 and 16. The in vitro P4 and E2 treatment of epithelial cells mimicked in vivo results. These results indicate that P4 and E2 regulate alterations in epithelium that may facilitate embryo implantation and given the role of cadherin, catenin and CDC42 in embryo invasion, change in distribution of these proteins may limit the invasiveness of porcine conceptuses into the stroma.

Baculovirus-assisted Reovirus Infection in Monolayer and Spheroid Cultures of Glioma cells.

The mammalian orthoreovirus Type 3 Dearing has great potential as oncolytic agent in cancer therapy. One of the bottlenecks that hampers its antitumour efficacy in vivo is the limited tumour-cell infection and intratumoural distribution. This necessitates strategies to improve tumour penetration. In this study we employ the baculovirus Autographa californica multiple nucleopolyhedrovirus as a tool to expand the reovirus' tropism and to improve its spread in three-dimensional tumour-cell spheroids. We generated a recombinant baculovirus expressing the cellular receptor for reovirus, the Junction Adhesion Molecule-A, on its envelope. Combining these Junction Adhesion Molecule-A-expressing baculoviruses with reovirus particles leads to the formation of biviral complexes. Exposure of the reovirus-resistant glioblastoma cell line U-118 MG to the baculovirus-reovirus complexes results in efficient reovirus infection, high reovirus yields, and significant reovirus-induced cytopathic effects. As compared to the reovirus-only incubations, the biviral complexes demonstrated improved penetration and increased cell killing of three-dimensional U-118 MG tumour spheroids. Our data demonstrate that reovirus can be delivered with increased efficiency into two- and three-dimensional tumour-cell cultures via coupling the reovirus particles to baculovirus. The identification of baculovirus' capacity to penetrate into tumour tissue opens novel opportunities to improve cancer therapy by improved delivery of oncolytic viruses into tumours.

Porcine circovirus 2 (PCV2) increases the expression of endothelial adhesion/junction molecules.

Porcine circovirus type 2 (PCV2) is the primary causative agent of porcine circovirus disease, a complex multisystem syndrome in domestic pigs. Despite the significant economic losses caused by porcine circovirus disease, the mechanisms of pathogenesis underlying the clinical findings remain largely unclear. As various reports have highlighted the potential key role of vascular lesions in the pathogenesis of porcine circovirus disease, the aim of this work was to investigate effects of PCV2 infection on vascular endothelial cells, focusing on cell viability and expression of adhesion/junction molecules. PCV2 infection reduced endothelial cell viability, while viral infection did not affected the viability of several other classical cell lines. Also, PCV2 infection in endothelial cells displayed a dual/biphasic effect: initially, infection increased ICAM-1 expression, which can favor leukocyte recruitment and emigration to tissues and possibly inducing characteristic porcine circovirus disease inflammatory lesions; then, secondarily, infection caused an increase in zonula occludens 1 tight junction protein (ZO-1) expression, which in turn can result in difficulties for cell traffic across the endothelium and a potential impairment the immune response in peripheral tissues. These virus-induced endothelial changes could directly impact the inflammatory process of porcine circovirus disease and associated vascular/immune system disturbances. Data suggest that, among the wide range of effects induced by PCV2 on the host, endothelial modulation can be a pivotal process which can help to explain PCV2 pathogenesis in some porcine circovirus disease presentations.

A novel junctional adhesion molecule A (CgJAM-A-L) from oyster (Crassostrea gigas) functions as pattern recognition receptor and opsonin.

Junctional adhesion molecule (JAM), a subfamily of immunoglobulin superfamily (IgSF) with a couple of immunoglobulin domains, can act as regulator in homeostasis and inflammation of vertebrates. In the present study, a structural homolog of JAM-A (designated CgJAM-A-L) was screened out from oyster, Crassostrea gigas, through a search of JAM-A D1 domain (N-terminal Ig domain in JAM-A). The cDNA of CgJAM-A-L was of 1188 bp encoding a predicted polypeptide of 395 amino acids. The immunoreactive area of CgJAM-A-L mainly distributed over the plasma membrane of hemocytes. After Vibro splendidus or tumor necrosis factor (CgTNF-1) stimulation, the mRNA transcripts of CgJAM-A-L in hemocytes increased significantly by 4.46-fold and 9.00-fold (p < 0.01) of those in control group, respectively. The recombinant CgJAM-A-L protein (rCgJAM-A-L) could bind multiple PAMPs including lipopolysaccharides (LPS), peptidoglycan (PGN), lipoteichoic acid (LTA), mannose (MAN), ß-glucan (GLU) and poly(I:C), and various microorganisms including Micrococcus luteus, Staphylococcus aureus, Escherichia coli, Vibro anguillarum, V. splendidus, Pastoris pastoris and Yarrowia lipolytica. The phagocytic rates of oyster hemocytes towards Gram-negative bacteria V. anguillarum and yeast P. pastoris were significantly enhanced after the incubation of rCgJAM-A-L, and even increased more significantly after the pre-incubation of rCgJAM-A-L with microbes (p < 0.01). The results collectively indicated that CgJAM-A-L functioned as an important pattern recognition receptor (PRR) and opsonin in the immune defense against invading pathogen in oyster. Moreover, as the most primitive specie with homolog of JAMs, the information of CgJAM-A-L in oyster would provide useful clues for the evolutionary study of JAMs and immunoglobulins.

'Special k' and a loss of cell-to-cell adhesion in proximal tubule-derived epithelial cells: modulation of the adherens junction complex by ketamine.

Ketamine, a mild hallucinogenic class C drug, is the fastest growing 'party drug' used by 16-24 year olds in the UK. As the recreational use of Ketamine increases we are beginning to see the signs of major renal and bladder complications. To date however, we know nothing of a role for Ketamine in modulating both structure and function of the human renal proximal tubule. In the current study we have used an established model cell line for human epithelial cells of the proximal tubule (HK2) to demonstrate that Ketamine evokes early changes in expression of proteins central to the adherens junction complex. Furthermore we use AFM single-cell force spectroscopy to assess if these changes functionally uncouple cells of the proximal tubule ahead of any overt loss in epithelial cell function. Our data suggests that Ketamine (24-48 hrs) produces gross changes in cell morphology and cytoskeletal architecture towards a fibrotic phenotype. These physical changes matched the concentration-dependent (0.1-1 mg/mL) cytotoxic effect of Ketamine and reflect a loss in expression of the key adherens junction proteins epithelial (E)- and neural (N)-cadherin and ß-catenin. Down-regulation of protein expression does not involve the pro-fibrotic cytokine TGFß, nor is it regulated by the usual increase in expression of Slug or Snail, the transcriptional regulators for E-cadherin. However, the loss in E-cadherin can be partially rescued pharmacologically by blocking p38 MAPK using SB203580. These data provide compelling evidence that Ketamine alters epithelial cell-to-cell adhesion and cell-coupling in the proximal kidney via a non-classical pro-fibrotic mechanism and the data provides the first indication that this illicit substance can have major implications on renal function. Understanding Ketamine-induced renal pathology may identify targets for future therapeutic intervention.

Genomic organisation, embryonic expression and biochemical interactions of the zebrafish junctional adhesion molecule family of receptors.

The mammalian JAM family is composed of three cell surface receptors. Interactions between the proteins have well-characterised roles in inflammation and tight junction formation, but little is known about their function in early development. Recently, we identified a role for jamb and jamc in zebrafish myocyte fusion. Genome duplication in the teleost lineage raised the possibility that additional JAM family paralogues may also function in muscle development. To address this, we searched the zebrafish genome to identify potential paralogues and confirmed their homology, bringing the total number of zebrafish jam family members to six. We then compared the physical binding properties of each paralogue by surface plasmon resonance and determined the gene expression patterns of all zebrafish jam genes at different stages of development. Our results suggest a significant sub-functionalisation of JAM-B and JAM-C orthologues with respect to binding strength (but not specificity) and gene expression. The paralogous genes, jamb2 and jamc2, were not detected in the somites or myotome of wild-type embryos. We conclude that it is unlikely that the paralogues have a function in primary myogenesis.

Porcine circovirus 2 (PCV2) increases the expression of endothelial adhesion/junction molecules

Abstract Porcine circovirus type 2 (PCV2) is the primary causative agent of porcine circovirus disease, a complex multisystem syndrome in domestic pigs. Despite the significant economic losses caused by porcine circovirus disease, the mechanisms of pathogenesis underlying the clinical findings remain largely unclear. As various reports have highlighted the potential key role of vascular lesions in the pathogenesis of porcine circovirus disease, the aim of this work was to investigate effects of PCV2 infection on vascular endothelial cells, focusing on cell viability and expression of adhesion/junction molecules. PCV2 infection reduced endothelial cell viability, while viral infection did not affected the viability of several other classical cell lines. Also, PCV2 infection in endothelial cells displayed a dual/biphasic effect: initially, infection increased ICAM-1 expression, which can favor leukocyte recruitment and emigration to tissues and possibly inducing characteristic porcine circovirus disease inflammatory lesions; then, secondarily, infection caused an increase in zonula occludens 1 tight junction protein (ZO-1) expression, which in turn can result in difficulties for cell traffic across the endothelium and a potential impairment the immune response in peripheral tissues. These virus-induced endothelial changes could directly impact the inflammatory process of porcine circovirus disease and associated vascular/immune system disturbances. Data suggest that, among the wide range of effects induced by PCV2 on the host, endothelial modulation can be a pivotal process which can help to explain PCV2 pathogenesis in some porcine circovirus disease presentations.