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Intercellular Junctions (intercellular + junction)

Distribution by Scientific Domains

Medical Sciences	47%
Life Sciences	41%

Selected Abstracts

Intercellular Junctions in Rabbit Eye Ora Serrata

ANATOMIA, HISTOLOGIA, EMBRYOLOGIA, Issue 5 2006
L. Nobeschi
Summary The aim of this study was to describe and localize the intercellular junctions in the ora serrata region of albino and pigmented rabbit eyes. Eyes of albino and pigmented rabbits were fixed and processed for transmission electron microscopy. Light and electron microscope examination was carried out on semithin and ultrathin sections. The ora serrata region showed adherens, gap and tight junctions in the retinal and ciliary margins of albino and pigmented rabbit eyes. In the retinal margin, zonulae adherens between Müller cells and photoreceptors are associated with tight junctions. In the ciliary margin, epithelial cells are joined by adherens, gap and tight junctions localized between apical and apicolateral cell membranes. Tight junctions appear as zonulae occludens in the non-pigmented apicolateral cell membranes and as tight focal junctions between pigmented and non-pigmented apical cell membranes. Between the ciliary and retinal margins there are adherens and tight focal junctions which attach pigmented apical cell membranes to adjacent cells. There were no differences in the distribution of intercellular junctions between albino and pigmented rabbits. [source]

Larval development in the Homoscleromorpha (Porifera, Demospongiae)

INVERTEBRATE BIOLOGY, Issue 3 2003
Nicole Boury-Esnault
Abstract. Embryonic development from coeloblastula to fully developed larva was investigated in 8 Mediterranean homoscleromorph species: Oscarella lobularis, O. tuberculata, O. microlobata, O. imperialis, Plakina trilopha, P. jani, Corticium candelabrum, and Pseudocorticium jarrei. Morphogenesis of the larva is similar in all these species; however, cell proliferation is more active in species of Oscarella than in Plakina and C. candelabrum. The result of cell division is a wrinkled, flagellated larva, called a cinctoblastula. It is composed of a columnar epithelium of polarized, monoflagellated cells among which are scattered a few non-flagellated ovoid cells. The central cavity always contains symbiotic bacteria. Maternal cells are also present in O. lobularis, O. imperialis, and P. jarrei. In the fully developed larva, cell shape and dimensions are constant for each species. The cells of the anterior pole have large vacuoles with heterogeneous material; those of the postero-lateral zone have an intranuclear paracrystalline inclusion; and the flagellated cells of the posterior pole have large osmiophilic inclusions. Intercellular junctions join the apical parts of the cells, beneath which are other specialized cell junctions. A basement membrane underlying the flagellated cells lines the larval cavity. This is the first observation of a basement membrane in a poriferan larva. The basal apparatus of flagellated cells is characterized by an accessory centriole located exactly beneath the basal body. The single basal rootlet is cross striated. The presence of a basement membrane and a true epithelium in the larva of Homoscleromorpha,unique among poriferan clades and shared with Eumetazoa,suggests that Demospongiae could be paraphyletic. [source]

Microcystin extracts induce ultrastructural damage and biochemical disturbance in male rabbit testis

ENVIRONMENTAL TOXICOLOGY, Issue 1 2010
Ying Liu
Abstract In the present research, the changes of ultrastructures and biochemical index in rabbit testis were examined after i.p. injection with 12.5 ,g/kg microcystin (MC) extracts. Ultrastructural observation showed widened intercellular junction, distention of mitochondria, endoplasmic reticulum, and Golgi apparatus. All these changes appeared at 1, 3, and 12 h, but recovered finally. In biochemical analyses, the levels of lipid peroxidation (MDA) and H2O2 increased significantly at 1 h, indicating MC-caused oxidative stress. Finally, H2O2 decreased to the normal levels, while MDA remained at high levels. The antioxidative enzymes (CAT, SOD, GPx, GST) and antioxidants (GSH) also increased rapidly at 1 h, demonstrating a quick response of the defense systems to the oxidative stress. Finally, the activity of CAT, SOD, and GPX recovered to the normal level, while the activity of GST and the concentration of GSH remained at a high level. This suggests that the importance of MCs detoxification by GST via GSH, and the testis of rabbit contained abundant GSH. The final recovery of ultrastructure and some biochemical indexes indicates that the defense systems finally succeeded in protecting the testis against oxidative damage. In conclusion, these results indicate that the MCs are toxic to the male rabbit reproductive system and the mechanism underlying this toxicity might to be the oxidative stress caused by MCs. Although the negative effects of MCs can be overcome by the antioxidant system of testis in this study, the potential reproductive risks of MCs should not be neglected because of their wide occurrence. © 2009 Wiley Periodicals, Inc. Environ Toxicol 2010. [source]

Signal Transduction Pathways in Enhanced Microvascular Permeability

MICROCIRCULATION, Issue 6 2000
SARAH Y. YUAN
ABSTRACT We have been investigating the molecular mechanisms underlying pathophysiological regulation of microvascular permeability on isolated venules and cultured venular endothelial monolayers. Physiological approaches have been employed in combination with molecular analyses to probe the signal transduction pathways leading to enhanced microvascular permeability. A newly developed technique of protein transfection into cells and intact microvessels enables the correlation of functional reactions and signaling events at the molecular level in a direct and specific fashion. The results indicate that inflammatory mediators increase microvascular permeability via intracellular signaling pathways involving the activation of phospholipase C, cytosolic calcium, protein kinase C, nitric oxide synthase, guanylate cyclase, and protein kinase G. In response to the signaling stimulation, complex biochemical and conformational reactions occur at the endothelial structural proteins. Specifically, myosin light-chain activation-mediated myosin light-chain phosphorylation can result in cell contraction. VE-cadherin and ,-catenin phosphorylation may induce dissociation of the junctional proteins and their connection to the cytoskeleton, leading to a loose or opened intercellular junction. Focal adhesion phosphorylation and redistribution further provide an anchorage support for the conformational changes in the cells and at the cell junction. The three processes may act in concert to facilitate the flux of fluid and macromolecules across the microvascular endothelium. [source]

Solution structure of GOPC PDZ domain and its interaction with the C-terminal motif of neuroligin

PROTEIN SCIENCE, Issue 9 2006
Xiang Li
Abstract GOPC (Golgi-associated PDZ and coiled-coil motif-containing protein) represents a PDZ domain-containing protein associated with the Golgi apparatus, which plays important roles in vesicular trafficking in secretory and endocytic pathways. GOPC interacts with many other proteins, such as the Wnt receptors Frizzled 8 and neuroligin via its PDZ domain. Neuroligin is a neural cell-adhesion molecule of the post-synapse, which binds to the presynapse molecule neurexin to form a heterotypic intercellular junction. Here we report the solution structure of the GOPC PDZ domain by NMR. Our results show that it is a canonical class I PDZ domain, which contains two ,-helices and six ,-strands. Using chemical shift perturbation experiments, we further studied the binding properties of the GOPC PDZ domain with the C-terminal motif of neuroligin. The observations showed that the ensemble of the interaction belongs to fast exchange with low affinity. The 3D model of the GOPC PDZ domain/neuroligin C-terminal peptide complex was constructed with the aid of the molecular dynamics simulation method. Our discoveries provide insight into the specific interaction of the GOPC PDZ domain with the C-terminal peptide of Nlg and also provide a general insight about the possible binding mode of the interaction of Nlg with other PDZ domain-containing proteins. [source]

Desmocollin 1 expression and desmosomal remodeling during terminal differentiation of human anagen hair follicle: an electron microscopic study

EXPERIMENTAL DERMATOLOGY, Issue 5 2004
Elena Donetti
Abstract:, The terminal differentiation (TD) program of keratinocytes of the human hair follicle (HF) occurs with specific temporal and spatial features in the various layers of the inner root sheath (IRS) and in the innermost layer of the outer root sheath (companion layer). This process is characterized by complex nuclear and cytoplasmic morphological changes, accompanied by profound modifications in intercellular junctions. As no correlation exists between the structure and the molecular composition of desmosomes during TD of the IRS/companion unit, the aim of our study was to investigate by transmission electron microscopy the remodeling of desmosomes in keratinizing cells of these compartments. By immunogold post embedding technique, we studied in anagen HFs the modulation of the synthesis of desmocollin 1 (Dsc1), a transmembrane glycoprotein specifically synthesized in the IRS and in the companion layer. Dsc1 immunoreactivity was actually confined to these compartments and tended to increase just before the level of TD, particularly in the Henle's layer and in the IRS cuticle. In Huxley's layer, the immunolabeling was patchy and in the companion layer Dsc1 synthesis was detected above the level of keratinization of Huxley's layer. In the whole IRS, concomitantly with TD, there was an abrupt and almost complete disappearance of Dsc1 synthesis. An asymmetric distribution of Dsc1 was noticed (i) between cells at different stages of differentiation and (ii) between cells belonging to layers with different spatial/temporal features of TD. Our results show that the ultrastructural modifications of desmosomes during TD of HF are paralleled by the modulation of the synthesis of desmocollin 1. [source]

The role of dynamin 3 in the testis,

JOURNAL OF CELLULAR PHYSIOLOGY, Issue 3 2007
K.S. Vaid
We report here that dynamin 3 in the testis is associated with structures termed tubulobulbar complexes that internalize intact intercellular junctions during sperm release and turnover of the blood,testis barrier. The protein lies adjacent to an actin-Arp2/3 network that cuffs the double plasma membrane tubular invagination at the core of each complex. To explore the possible relationship between dynamin 3 and nectin-based adhesion junctions, we transiently transfected DsRed-tagged dynamin 3 into MDCK cells stably transfected with eGFP-tagged nectin 2, one of the adhesion molecules known to be expressed in Sertoli cells at adhesion junctions. Cells transfected with the dynamin 3 construct had less uniformly distributed nectin 2 at intercellular contacts when compared to control cells expressing only nectin 2 or transfected with the DsRed plasmid alone. Significantly, tubular extensions positive for nectin 2 were visible projecting into the cells from regions of intercellular contact. Our findings are consistent with the conclusion that dynamin 3 is involved with tubulobulbar morphogenesis. Dynamin 3 also occurs in concentrated deposits around the capitulum and striated columns in the connecting piece of sperm tails suggesting that the protein in these cells may function to stabilize the base of the tail or serve as a reservoir for use during or after fertilization. J. Cell. Physiol. 210: 644,654, 2007. © 2006 Wiley-Liss, Inc. [source]

Computer-assisted morphometric analysis of lymphatic vessel changes in hamster tongue carcinogenesis

JOURNAL OF ORAL PATHOLOGY & MEDICINE, Issue 7 2010
Dong Chen
J Oral Pathol Med (2010) 39: 518,524 Background:, To characterize lymphangiogenesis in early-stage hamster tongue carcinoma development, morphological features and spatial relationships of lymphatic vessels. Methods:, Lymphatic vessels were examined histochemically, using 5,-Nase-ALPase enzyme and combined light and electron microscopy to measure lymphatic vessel area (LVA) and lymphatic vessel density (LVD). Results:, In atypical hyperplastic tissues, LVA was found to be 1429.97 and LVD was found to be 39, in carcinoma in situ LVA was 2538.33 and LVD was 48, and in micro-invasive carcinoma LVA was 5733.74 and LVD was 59. Increased lymphangiogenesis was seen in pre-neoplastic states and in early-stage oral squamous cell carcinoma (OSCC). Small regular lymphatic vessels predominated in atypical hyperplasia, and large, irregular lymphatic vessels in early-stage OSCC. Lymphatic endothelial vessels were stretched and porous over large areas. Conclusions:, Newly formed lymphatics and patulous intercellular junctions may be optimally suited for tumor cell metastasis through lymphatic channels in early- and middle-phase carcinogenesis. Lymphatic capillary LVA and LVD became enlarged, and positively correlated, with malignancy, but show no correlation with 7,12-dimethylbenz[a]anthracene-induced time. [source]

Pores in the Sieve and Channels in the Wall: Control of Paracellular Permeability by Junctional Proteins in Endothelial Cells

MICROCIRCULATION, Issue 3 2001
GIANFRANCO BAZZONI
ABSTRACT Exchange of solutes and ions between the luminal and abluminal compartments of the circulation is critically dependent on the barrier properties of the vascular endothelium. Transport of solutes and fluids occurs along the transcellular and paracellular pathways that are mediated by intracellular vesicles and intercellular junctions, respectively. Although the ability of endothelial cells to dynamically regulate permeability has long been recognized, the precise mechanism and the signaling pathways involved have not been fully elucidated. Finally, current definition of the complex molecular composition of intercellular junctions is expected to explain the difference in permeability between diverse segments of the circulation and possibly to highlight the existence of specific junctional channels. The properties of junctional adhesion molecule-1 (JAM-1) and vascular endothelial cadherin (VE-cadherin), two transmembrane components of interendothelial junctions, are described in detail. [source]

Cytoskeletal response of microvessel endothelial cells to an applied stress force at the submicrometer scale studied by atomic force microscopy

MICROSCOPY RESEARCH AND TECHNIQUE, Issue 10 2006
Wanyun Ma
Abstract Cytoskeleton fibers form an intricate three-dimensional network to provide structure and function to microvessel endothelial cells. During accommodation to blood flowing, stress fiber bundles become more prominent and align with the direction of blood flow. This network either mechanically resists the applied shear stress (lateral force) or, if deformed, is dynamically remodeled back to a preferred architecture. However, the detailed response of these stress fiber bundles to applied lateral force at submicrometer scales are as yet poorly understood. In our in vitro study, the tip, topography probe in lateral force microscopy of atomic force microscopy, acted as a tool for exerting quantitative vertical and lateral force on the filaments of the cytoskeleton. Moreover, the authors developed a formula to calculate the value of lateral force exerted on every point of the filaments. The results show that cytoskeleton fibers of healthy tight junctions in rat cerebral microvessel endothelial cells formed a cross-type network, and were reinforced and elongated in the direction of scanning under lateral force of 15,42 nN. Under peroxidation (H2O2 of 300 ,mol/L), the cytoskeleton remodeled at intercellular junctions, and changed over the meshwork structures into a dense bundle, that redistributed the stress. Once mechanical forces were exerted on an area, the cells shrank and lost morphologic tight junctions. It would be useful in our understanding of certain pathological processes, such as cerebral ischemia/reperfusion injury, which maybe caused by biomechanical forces and which are overlooked in current disease models. Microsc. Res. Tech., 2006. © 2006 Wiley-Liss, Inc. [source]

Histochemical analysis of lymphatic endothelial cells in lymphostasis

MICROSCOPY RESEARCH AND TECHNIQUE, Issue 2 2001
Rui-Cheng Ji
Abstract The ultrastructure of endothelial cells of intestinal lymphatics and the thoracic duct (TD) and the relation to lymphostasis were examined in rats and monkeys. Localization of 5,-nucleotidase (5,-Nase) and endothelial nitric oxide synthase (eNOS) was studied. In normal lymphatic endothelial cells, 5,-Nase reaction product was evenly deposited on the cell surface in vivo and on cultured TD endothelial cells (TDECs), whereas eNOS was evenly distributed throughout the nucleus and cytoplasm. TDECs had a long filamentous process extending towards the subendothelial extracellular matrix but became flat and regular within 30,40 minutes after gastric perfusion with olive oil. According to their electron-density, two types of cells were found in the TD endothelial layer. The cells with low electron-density exhibited stronger 5,-Nase activity. Valves were bicuspid formations and the valvular endothelial surface of the convex side showed weaker 5,-Nase activity than the concave side. During TD blockage-induced lymphostasis in rats, the 5,-Nase product was almost not discernible in the TDECs within 2 weeks. Larger vesicles were found in the endothelial cytoplasm of the ligated TD. Their number decreased after 6,12 weeks. The small intestinal lymphatics in the mucosa and submucosa were dilated, with numerous open intercellular junctions. The endothelial lining appeared to have reduced activities for 5,-Nase and eNOS in 9 of 11 experimental animals. The results indicated that the inability of the open intercellular junctions, normally working as one-way endothelial flap valves, may be a key morphological feature after TD blockage. Reduced eNOS and 5,-Nase may functionally influence contractile activity and transport capability of the lymphatic vessels in the lymphostasis. Microsc. Res. Tech. 55:70,80, 2001. © 2001 Wiley-Liss, Inc. [source]

Establishment of cadherin-based intercellular junctions in the dermal papilla of the developing hair follicle

THE ANATOMICAL RECORD : ADVANCES IN INTEGRATIVE ANATOMY AND EVOLUTIONARY BIOLOGY, Issue 2 2003
Daisuke Nanba
Abstract During hair follicle development, mesenchymal cells aggregate to form the dermal papilla with hair-inducing activity. However, the cellular mechanisms underlying the aggregative behavior of dermal papilla cells are less known. The present study demonstrates that cadherin-based intercellular junctions interconnect dermal papilla cells in developing hair follicles of mice. It is shown that as mesenchymal cells aggregate to be surrounded by epithelium in developing hair follicles, cadherin-11 comes to exhibit the dotted patterns of distribution. The appearance of the dot-like distribution of the molecule is concomitant with the formation of intercellular junctions in the mesenchymal aggregate, which make a tightly packed population of cells with little extracellular space. At later stages of the development, although extracellular space reappears in the dermal papilla, the cells remain interconnected by well-developed intercellular junctions, where cadherin-11 as well as ,-catenin is localized. Taking into consideration the normal hair development in cadherin-11 mutant mice, it might be that multiple cadherins are responsible for the establishment of intercellular junctions in the dermal papilla and serve to maintain the aggregative behavior of the cells. Anat Rec Part A 270A:97,102, 2003. © 2003 Wiley-Liss, Inc. [source]

Rhinovirus infection-induced alteration of tight junction and adherens junction components in human nasal epithelial cells

THE LARYNGOSCOPE, Issue 2 2010
Nam-Kyung Yeo MD
Abstract Objectives/Hypothesis: Manifestations of rhinovirus (RV) infections include mucus overproduction, increased vascular permeability, and secondary bacterial infection. These effects may reflect disrupted epithelial barrier functions, which are mainly regulated by intercellular junctions, referred to as tight junctions (TJs) and adherens junctions (AJs). The objective of this study was to investigate changes in the components of TJs (ZO-1, occluding, and claudin-1) and AJs (E-cadherin) after RV infection in cultured nasal epithelial cells. Methods: Primary human nasal epithelial cells grown at an air-liquid interface were infected apically with RV. RV-induced changes in the expression of epithelial TJ and AJ proteins were determined using real-time reverse transcriptase-polymerase chain reaction, confocal microscopy, and Western blot analyses. Functional changes in the integrity of junctional proteins were assessed by measuring transepithelial resistance (TER) using a voltmeter. Results: RV infection decreased mRNA levels of ZO-1, occludin, claudin-1, and E-cadherin to 64.2%, 51.8%, 56.2%, and 56.3%, respectively, of those in controls (P < .05). Decreases in ZO-1, occludin, claudin-1, and E-cadherin protein levels in RV-infected cells were evident in immunofluorescent confocal microscopic images. Expression levels of these proteins were also lower in the RV-infected group in Western blot analyses. RV infection reduced the mean TER from 143.1 ,/cm2 (controls) to 122.6 ,/cm2. Conclusions: RV infection decreased the expression of TJ and AJ components and reduced TER in primary cultured human nasal epithelial cells, indicating that RV infection may exert a harmful effect on nasal epithelial barrier function. Laryngoscope, 2010 [source]

Intercellular Junctions in Rabbit Eye Ora Serrata

Modification of epithelial cell barrier permeability and intercellular junctions by Clostridium sordellii lethal toxins

CELLULAR MICROBIOLOGY, Issue 7 2006
Catherine Boehm
Summary Clostridium sordellii lethal toxin (LT) is a glucosyltransferase which inactivates small GTPases from the Rho and Ras families. In the present work, we studied the effects of two variants, LT82 and LT9048, on the integrity of epithelial cell barrier using polarized MCCD (Mouse Cortical Collecting Duct) and MDCK (Madin-Darby Canine Kidney) cells. Our results demonstrate for the first time that LTs have very limited effects on tight junctions. In contrast, we show that both toxins modified the paracellular permeability within 2,4 h. Concomitantly LT82 and LT9048 induced a disorganization of basolateral actin filaments, without modifying apical actin. Both toxins mainly altered adherens junctions by removing E-cadherin-catenin complexes from the membrane to the cytosol. Similar effects on adherens junctions have been observed with other toxins, which directly or indirectly depolymerize actin. Thereby, Rac, a common substrate of both LTs, might play a central role in LT-dependent adherens junction alteration. Here, we show that adherens junction perturbation induced by LTs results neither from a direct effect of toxins on adherens junction proteins nor from an actin-independent Rac pathway, but rather from a Rac-dependent disorganization of basolateral actin cytoskeleton. This further supports that a dynamic equilibrium of cortical actin filaments is essential for functional E-cadherin organization in epithelia. [source]

Transepithelial migration of Toxoplasma gondii involves an interaction of intercellular adhesion molecule 1 (ICAM-1) with the parasite adhesin MIC2

CELLULAR MICROBIOLOGY, Issue 4 2005
Antonio Barragan
Summary Toxoplasma gondii crosses non-permissive biological barriers such as the intestine, the blood,brain barrier and the placenta thereby gaining access to tissues where it most commonly causes severe pathology. Herein we show that in the process of migration Toxoplasma initially concentrates around intercellular junctions and probably uses a paracellular pathway to transmigrate across biological barriers. Parasite transmigration required viable and actively motile parasites. Interestingly, the integrity of host cell barriers was not altered during parasite transmigration. As intercellular adhesion molecule 1 (ICAM-1) is upregulated on cellular barriers during Toxoplasma infection, we investigated the role of this receptor in parasite transmigration. Soluble human ICAM-1 and ICAM-1 antibodies inhibited transmigration of parasites across cellular barriers implicating this receptor in the process of transmigration. Furthermore, human ICAM-1 immunoprecipitated the mature form of the parasite adhesin MIC2 present on the parasite surface, indicating that this interaction may contribute to cellular migration. These findings reveal that Toxoplasma exploits the natural cell trafficking pathways in the host to cross cellular barriers and disseminate to deep tissues. [source]

Vitreous surgery for macular hole in patients with Vogt-Koyanagi-Harada disease

CLINICAL & EXPERIMENTAL OPHTHALMOLOGY, Issue 9 2008
Izumi Kobayashi MD
Abstract We describe two patients with Vogt-Koyanagi-Harada (VKH) disease, both in the convalescent stage, who presented with unilateral macular holes together with clinically significant epi-retinal membranes. Vitreo-retinal surgery was performed on the affected eyes and the surgical technique involved a standard three-port vitrectomy, peeling of the epi-retinal and internal limiting membrane (ILM). In both cases the retinae were tamponaded with air resulting in anatomical closure of the macular holes. The histology of the excised membrane was available in one case and this revealed multiple layers of presumed retinal pigment epithelial cells with cytoplasmic processes and intercellular junctions forming a basal lamina attached to the smooth surface of the ILM. Our findings demonstrate that macular holes can develop in patients with VKH but that the hole can be successfully closed with vitreo-retinal surgery. The convalescent stage tends to occur several weeks after the acute stage when the uveitic process has subsided and is characterized by choroidal depigmentation, producing a sunset glow appearance to the ocular fundus. Patients may also demonstrate varying degrees of cutaneous hypopigmentation, poliosis and/or alopecia. Macular holes have also been reported previously in patients during the convalescent stage of VKH and this communication describes the outcome of two patients who underwent vitreo-retinal surgery for this problem. [source]