Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The blood-brain barrier (BBB) is formed by brain capillary endothelial cells, astrocytes, pericytes, microglia, and neurons. BBB disruption under pathological conditions such as neurodegenerative disease and inflammation is observed in parallel with microglial activation. To test whether activation of microglia is linked to BBB dysfunction, we evaluated the effect of lipopolysaccharide (LPS) on BBB functions in an in vitro co-culture system with rat brain microvascular endothelial cells (RBEC) and microglia. When LPS was added for 6 h to the abluminal side of RBEC/microglia co-culture at a concentration showing no effects on the RBEC monolayer, transendothelial electrical resistance was decreased and permeability to sodium-fluorescein was increased in RBEC. Immunofluorescence staining for tight junction proteins demonstrated that zonula occludens-1-, claudin-5-, and occludin-like immunoreactivities at the intercellular borders of RBEC were fragmented in the presence of LPS-activated microglia. These functional changes induced by LPS-activated microglia were blocked by the nicotinamide adenine dinucleotide phosphate (NADPH) oxidase inhibitor, diphenyleneiodonium chloride. The present findings suggest that LPS activates microglia to induce dysfunction of the BBB by producing reactive oxygen species through NADPH oxidase.
Cell Mol Neurobiol 2010 Mar
PMID:Lipopolysaccharide-activated microglia induce dysfunction of the blood-brain barrier in rat microvascular endothelial cells co-cultured with microglia. 1972 78

Occludin is a self-associating transmembrane tight junction protein affected in oxidative stress. However, its function is unknown. The cytosolic C-terminal tail contains a coiled coil-domain forming dimers contributing to the self-association. Studying the hypothesis that the self-association is redox-sensitive, we found that the dimerization of the domain depended on the sulfhydryl concentration of the environment in low-millimolar range. Under physiological conditions, monomers and dimers were detected. Masking the sulfhydryl residues in the domain prevented the dimerization but affected neither its helical structure nor cylindric shape. Incubation of cell extracts containing full-length occludin with sulfhydryl reagents prevented the dimerization; a cysteine/alanine exchange mutant also did not show dimer formation. This demonstrates, for the first time, that disulfide bridge formation of the domain is involved in the occludin dimerization. It is concluded that the redox-dependent dimerization of occludin may play a regulatory role in the tight junction assembly under physiological and pathological conditions.
Cell Mol Life Sci 2009 Nov
PMID:Redox-sensitivity of the dimerization of occludin. 1975 80

Polyphenols in apples, such as various hydroxycinnamic acids and flavonoids, have positive health effects that strongly depend on their bioavailability. In order to show that the Ussing-type chamber is a useful model to study metabolism, transport, and tightness of cell monolayers in one experimental setup, monolayers of the T84 colon carcinoma cell line mounted in Ussing-type chambers were incubated in the presence of physiological concentrations of various hydroxycinnamic acids (including ferulic, isoferulic, cinnamic, and hydrocinnamic acids) and flavonoids for 4 h. Concentrations of each tested polyphenol in the apical chamber, basolateral chamber, and those associated with the cells were then determined using HPLC with DAD (HPLC-DAD). The transport studies showed that the amounts of the tested polyphenols that passed from the apical to the basolateral side of the T84 monolayers depended on their polarity. Metabolites, such as glucuronides and sulfates of ferulic acid, were also detected at measurable levels by HPLC-ESI-MS/MS in the model system, but only when they were supplied at supra-physiological concentrations (>100 microM). In addition, the transepithelial resistance (TER) of T84 monolayers was measured before and after the addition of polyphenols, with and without short-term exposure to apical sodium caprate (C10), a tight junction (TJ) modulator. Exposure to C10 induced a decrease in TER that was reversible by incubation with polyphenols. However, no increase in paracellular permeability of tested polyphenols was observed after apical C10 exposure, so C10 did not promote fluxes of hydroxycinnamic acids across the monolayers. Further, real-time PCR analysis of the T84 colon cell line showed that ferulic and isoferulic acids induced significant increases in expression of the TJ components zonula occludens-1 (ZO-1) and claudin-4 transcription, but reductions in occludin expression. In contrast, caffeic and p-coumaric acids had no significant effects on the transcription of either ZO-1 or occludin. Our results provide confirmation that T84 cells could be used as model system to simulate the intestinal mucosa, and that polyphenols are able to increase the TER of C10-treated and -untreated T84 monolayers.
Mol Nutr Food Res 2009 Oct
PMID:The Ussing type chamber model to study the intestinal transport and modulation of specific tight-junction genes using a colonic cell line. 1976 65

Surgery and infection are prominent risk factors for the development of obstructive cholestasis which in turn is associated with failure of the liver barrier. We studied the effects of oral Lactobacillus plantarum (LP) supplementation on endotoxemia, oxidative stress, apoptosis, and tight junctions of hepatocytes in an experimental model of obstructive jaundice. Fifty male Wistar rats were randomly divided into five groups of 10 each: group I, sham-operated; group II, ligation and division of the common bile duct (BDL); group III, BLD followed by oral LP treatment; group IV, BDL followed by internal biliary drainage (IBD); group V, BDL followed by IBD and oral LP treatment. Hepatocyte apoptosis, plasma reduced glutathione (GSH) and oxidized glutathione (GSSG) levels, and portal blood endotoxin levels were measured and changes in tight junction-associated proteins occludin, claudin-1, claudin-4, and ZO-1 were observed. Compared to the sham-operated group I, significant increases in endotoxemia, apoptosis, and GSSG were observed in group II and significant decreases were observed in group V. Tight junctions were destroyed in group II animals but were not in animals treated with oral LP (groups III and V). An increase in occludin, claudin-1, claudin-4, and ZO-1 mRNA and protein levels were detected in livers in LP-treated animals (group V) compared with group II levels. Oral LP treatment of rats with obstructive jaundice assisted in the return of active hepatic barrier function. These results may lead to treatments to prevent the deleterious effects of obstructive jaundice.
Mol Biol Rep 2010 Jul
PMID:Effects of oral Lactobacillus plantarum on hepatocyte tight junction structure and function in rats with obstructive jaundice. 1981 88

An important component of the pathogenic process of multiple sclerosis (MS) is the blood-brain barrier (BBB) damage. We recently set an in vitro model of BBB, based on a three-cell-type co-culture system, in which rat neurons and astrocytes synergistically induce brain capillary endothelial cells to form a monolayer with permeability properties resembling those of the physiological BBB. Herein we report that the serum from patients with secondary progressive multiple sclerosis (SPMS) has a damaging effect on isolated neurons. This finding suggests that neuronal damaging in MS could be a primary event and not only secondary to myelin damage, as generally assumed. SPMS serum affects the permeability of the BBB model, as indicated by the decrease of the transendothelial electrical resistance (TEER). Moreover, as shown by both immunofluorescence and Western blot analyses, BBB breaking is accompanied by a decrease of the synthesis as well as the peripheral localization of occludin, a structural protein of the tight junctions that are responsible for BBB properties.
Int J Mol Med 2009 Dec
PMID:Neuronal and BBB damage induced by sera from patients with secondary progressive multiple sclerosis. 1988 13

Crohn's disease is associated with increased permeability of the intestine even in quiescent patients. Increased intestinal permeability may cause dysregulated immunological responses in the intestinal mucosa that leads to chronic intestinal inflammation. Tight junction proteins contribute to intestinal permeability, and functional abnormality and dislocation of such proteins may cause increased intestinal permeability. We studied the expression of tight junction proteins Rab13, vasodilator-stimulated phosphoprotein (VASP), zonula occludin-1 (ZO-1), and F-actin in the intestinal epithelium of patients with inactive inflammatory bowel disease. Surgical samples were obtained from 10 controls (without inflammatory bowel disease), 10 patients with Crohn's disease and 7 patients with ulcerative colitis. F-actin was visualized with fluorescent phalloidin. Tight junction proteins were visualized by an immunofluorescence method. Rab13, VASP, and ZO-1 were found in apical tight junctions in normal epithelium but were dislocated to the basolateral position in patients with inactive Crohn's disease, whereas the structure of F-actin was maintained in inactive mucosa. In patients with ulcerative colitis, these tight junction proteins were not dislocated. Latent dislocation of tight junction proteins in the inactive mucosa of patients with Crohn's disease may permit the invasion of gut antigens to initiate and perpetuate altered immune response.
Int J Mol Med 2009 Dec
PMID:Dislocation of Rab13 and vasodilator-stimulated phosphoprotein in inactive colon epithelium in patients with Crohn's disease. 1988 26

Tricellulin was identified as the first marker of the tricellular tight junction, which forms at the meeting points of three cells, and it is required for the maintenance of the transepithelial barrier. Although it is also considered to be important for the mucosal barrier of the upper respiratory tract, little is known about its expression and localization. In the present study, we examined the expression and localization of tricellulin in normal human nasal epithelial cells in vivo and in vitro, especially using primary cultures and telomerase reverse transcriptase (hTERT)-transfected cells. In human nasal epithelial cells in vivo and in vitro, mRNA and protein of tricellulin were detected. It was localized not only at tricellular contacts but also at bicellular borders, and in part colocalized with occludin. In human nasal epithelium, by immunoelectron microscopy analysis, tricellulin-associated gold particles were observed around the junction-like structure of the uppermost region. By treatment with 10% fetal bovine serum (FBS), expression of tricellulin mRNA was weakly increased, whereas that of bicellular tight junction molecules was strongly increased, in real-time PCR. These results suggest that tricellulin is stably expressed in human nasal epithelial cells and may play an important role for the sealing of the corner at tricellular contacts to prevent infiltration by various inhaled viruses and antigens.
Med Mol Morphol 2009 Dec
PMID:Expression and localization of tricellulin in human nasal epithelial cells in vivo and in vitro. 2003 65

Junctional epithelium, a nonkeratinized stratified epithelium, extends apically in apposition to the surface of the enamel to form a seal between the epithelium and the tooth. Desmosomes and gap junctions adhere to the junctional epithelium through cell-cell contact, but no evidence of tight junctions has been found. Recently, tight junction hallmark proteins and tight junction-related structures have been identified in stratified squamous epithelium. The present study examined whether tight junction proteins were expressed in the junctional epithelium. We used immunohistochemical techniques to observe expression of claudin-1, -4, -5, -7, and occludin in porcine gingival junctional epithelium. Claudin-4 exhibited immunoreactivity in the intercellular spaces of all layers of the oral epithelium and the junctional epithelium. Stronger expression was observed in junctional epithelial cells adjacent to the inner and outer basal laminae than in the inner cell layers. Immunohistochemical positivity for claudin-7 was clearly observed in the junctional epithelium, but only a faint positivity was observed in the basal layer of the oral epithelium. No immunohistochemical positivity for claudin-1, -5, or occludin was observed in the junctional epithelium. RT-PCR assay confirmed expression of porcine claudin-4 and -7 mRNAs in the junctional epithelium. These findings indicate that claudin-4 and -7 may play a role in the junctional epithelium even in the absence of tight junctions.
Med Mol Morphol 2009 Dec
PMID:Expression of claudin-4 and -7 in porcine gingival junctional epithelium. 2003 66

Claudins (Cls) are a multigene family of transmembrane proteins with different tissue distribution, which have an essential role in the formation and sealing capacity of tight junctions (TJs). At the level of the blood-brain barrier (BBB), TJs are the main molecular structures which separate the neuronal milieu from the circulatory space, by a restriction of the paracellular flow of water, ions and larger molecules into the brain. Different studies suggested recently significant BBB alterations in both vascular and degenerative dementia types. In a previous study we found in Alzheimer's disease (AD) and vascular dementia (VaD) brains an altered expression of occludin, a molecular partner of Cls in the TJs structure. Therefore in this study, using an immunohistochemical approach, we investigated the expression of Cl family proteins (Cl-2, Cl-5 and Cl-11) in frontal cortex of aged control, AD and VaD brains. To estimate the number of Cl-expressing cells, we applied a random systematic sampling and the unbiased optical fractionator method. We found selected neurons, astrocytes, oligodendrocytes and endothelial cells expressing Cl-2, Cl-5 and Cl-11 at detectable levels in all cases studied. We report a significant increase in ratio of neurons expressing Cl-2, Cl-5 and Cl-11 in both AD and VaD as compared to aged controls. The ratio of astrocytes expressing Cl-2 and Cl-11 was significantly higher in AD and VaD as compared to aged controls. The ratio of oligodendrocytes expressing Cl-11 was significantly higher in AD and the ratio of oligodendrocytes expressing Cl-2 was significantly higher in VaD as compared to aged controls. Within the cerebral cortex, Cls were selectively expressed by pyramidal neurons, which are the ones responsible for cognitive processes and affected by AD pathology. Our findings suggest a new function of Cl family proteins which might be linked to response to cellular stress.
J Cell Mol Med 2010 May
PMID:Altered expression of claudin family proteins in Alzheimer's disease and vascular dementia brains. 2004 69

Protocadherin LKC (PLKC) is a member of the heterogeneous subgroup of protocadherins that was identified and described as a potential tumor-suppressor gene involved in contact inhibition (Okazaki, N., Takahashi, N., Kojima, S., Masuho, Y., and Koga, H. (2002) Carcinogenesis 23, 1139-1148 and Ose, R., Yanagawa, T., Ikeda, S., Ohara, O., and Koga, H. (2009) Mol. Oncol. 3, 54-66). Several aspects of the structure, posttranslational processing, targeting, and function of this new protocadherin are still not known. Here, we demonstrate that the expression of PLKC at the apical membrane domain and its concentration at regions of cell-cell contacts occur concomitantly with significant elevation of PLKC-mRNA levels. Furthermore, it can be found within the adherens junctions, but it does not colocalize with tight junctions proteins ZO-1 and occludin, respectively. Additionally, unlike E-cadherin, PLKC is not redistributed upon Ca(2+) removal. Biosynthetic labeling revealed N- and O-glycosylation as posttranslational modifications as well as a fast transport to the cell surface and a low turnover rate. During differentiation, PLKC associates with detergent-resistant membranes that trigger its redistribution from intracellular membranes to the cell surface. This association occurs concomitant with alterations in the glycosylation pattern. We propose a role for PLKC in the establishment of a proper epithelial cell polarity that requires O-linked glycosylation and association of the protein with detergent-resistant membranes.
 ...
PMID:Protocadherin of the liver, kidney, and colon associates with detergent-resistant membranes during cellular differentiation. 2015 71


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