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Abstract
Gap junction (GJ) intercellular communication (GJIC) is vital to ensure proper cell and tissue function. GJ are multimeric structures composed of proteins called connexins. Modifications on stability or subcellular distribution of connexins have a direct impact on the extent of GJIC. In this study we have investigated the role of the proteasome in regulation of connexin 43 (Cx43) internalization. Although the participation of both the proteasome and lysosome has long been suggested in Cx43 degradation, the molecular mechanisms whereby proteasome contributes to regulate Cx43 internalization and intercellular communication are still unclear. The results presented in this study envision a new mechanism whereby proteasome regulates GJIC by modulating interaction between Cx43 and ZO-1. Immunoprecipitation experiments, in the presence of proteasome inhibitors, together with immunofluorescence data indicate that the proteasome regulates interaction between Cx43 and ZO-1. Overexpression of the PDZ2 domain of ZO-1 and the expression of Cx-43 fused in frame with a V5/HIS tag, suggest that interaction between the two proteins occurs through the PDZ2 domain of ZO-1 and the C-terminus of Cx43. When interaction between Cx43 and ZO-1 is reduced, as in the presence of proteasome inhibitors, Cx43 accumulates, forming large GJ plaques at plasma membrane. Data presented in this article suggest a new pathway whereby alterations in proteasome activity may impact on GJIC as well as on non-junctional communication with extracellular environment, contributing to cell and tissue dysfunction.
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Affiliation(s)
- Henrique Girao
- Centre of Ophthalmology, Biomedical Institute for Research in Light and Image (IBILI), Faculty of Medicine, University of Coimbra, 3000-354 Coimbra, Portugal
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352
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Zhao S, Jia L, Gao P, Li Q, Lu X, Li J, Xu G. Study on the effect of eicosapentaenoic acid on phospholipids composition in membrane microdomains of tight junctions of epithelial cells by liquid chromatography/electrospray mass spectrometry. J Pharm Biomed Anal 2008; 47:343-50. [PMID: 18280689 DOI: 10.1016/j.jpba.2008.01.005] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2007] [Revised: 12/24/2007] [Accepted: 01/03/2008] [Indexed: 11/20/2022]
Abstract
Tight junctions of epithelial cells determine epithelial membrane integrity and play an important role in selective paracellular permeability to ions and macromolecules. In this work, we investigated the effect of one of n-3 series polyunsaturated fatty acids, eicosapentaenoic acid (EPA) on the phospholipid composition of membrane microdomains of tight junctions. After treated by EPA, membrane microdomains of tight junctions were isolated by discontinuous sucrose density gradient ultracentrifugation, and raft phospholipids were extracted. The PE, PI, PS, PC and SM were separated and determined by high-performance liquid chromatography/quadrupole-linear ion trap mass spectrometry (HPLC Qtrap-MS), and were further identified by HPLC-MS/MS. It was found that EPA altered the fatty acyl substitution of phospholipids that constituted membrane microdomains of tight junctions by enriching the unsaturated fatty acyl chains of the phospholipids. It provides a new visual angle to explaining the intracellular mechanism involved in n-3 polyunsaturated fatty acids (PUFAs) modulation of intestinal tight junction barrier.
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Affiliation(s)
- Sumin Zhao
- National Chromatographic R&A Center, Dalian Institute of Chemical Physics, The Chinese Academy of Sciences, Dalian, China
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353
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354
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Foerg C, Merkle HP. On The Biomedical Promise of Cell Penetrating Peptides: Limits Versus Prospects. J Pharm Sci 2008; 97:144-62. [PMID: 17763452 DOI: 10.1002/jps.21117] [Citation(s) in RCA: 110] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The cell membrane poses a substantial hurdle to the use of pharmacologically active biomacromolecules that are not per se actively translocated into cells. An appealing approach to deliver such molecules involves tethering or complexing them with so-called cell penetrating peptides (CPPs) that are able to cross the plasma membrane of mammalian cells. The CPP approach is currently a major avenue in engineering delivery systems that are hoped to mediate the non-invasive import of problematic cargos into cells. The large number of different cargo molecules that have been efficiently delivered by CPPs ranges from small molecules to proteins and even liposomes and particles. With respect to the involved mechanism(s) there is increasing evidence for endocytosis as a major route of entry. Moreover, in terms of intracellular trafficking, current data argues for the transport to acidic early endosomal compartments with cytosolic release mediated via retrograde delivery through the Golgi apparatus and the endoplasmic reticulum. The focus of this review is to revisit the performance of cell penetrating peptides for drug delivery. To this aim we cover both accomplishments and failures and report on new prospects of the CPP approach. Besides a selection of successful case histories of CPPs we also review the limitations of CPP mediated translocation. In particular, we comment on the impact of (i) metabolic degradation, (ii) the cell line and cellular differentiation state dependent uptake of CPPs, as well as (iii) the regulation of their endocytic traffic by Rho-family GTPases. Further on, we aim at the identification of promising niches for CPP application in drug delivery. In this context, as inspired by current literature, we focus on three principal areas: (i) the delivery of antineoplastic agents, (ii) the delivery of CPPs as antimicrobials, and (iii) the potential of CPPs to target inflammatory tissues.
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Affiliation(s)
- Christina Foerg
- Department of Chemistry and Applied Biosciences, Institute of Pharmaceutical Sciences, ETH Zurich, Wolfgang-Pauli-Strasse 10, CH-8093 Zurich, Switzerland
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355
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Junction restructuring and spermatogenesis: the biology, regulation, and implication in male contraceptive development. Curr Top Dev Biol 2007; 80:57-92. [PMID: 17950372 DOI: 10.1016/s0070-2153(07)80002-0] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Spermatogenesis that occurs in the seminiferous epithelium of adult mammalian testes is associated with extensive junction restructuring at the Sertoli-Sertoli cell, Sertoli-germ cell, and Sertoli-basement membrane interface. While this morphological phenomenon is known and has been described in great details for decades, the biochemical and molecular changes as well as the mechanisms/signaling pathways that define changes at the cell-cell and cell-matrix interface remain largely unknown until recently. In this chapter, we summarize and discuss findings in the field regarding the coordinated efforts of the anchoring [e.g., adherens junction (AJ), such as basal ectoplasmic specialization (basal ES)] and tight junctions (TJs) that are present in the same microenvironment, such as at the blood-testis barrier (BTB), or at distinctly opposite ends of the Sertoli cell epithelium, such as between apical ectoplasmic specialization (apical ES) in the apical compartment, and the BTB adjacent to the basal compartment of the epithelium. These efforts, in turn, regulate and coordinate different cellular events that occur during the seminiferous epithelial cycle. For instance, the events of spermiation and of preleptotene spermatocyte migration across the BTB both take place concurrently at stage VIII of the epithelial cycle of spermatogenesis. Recent findings suggest that these events are coordinated by protein complexes found at the apical and basal ES and TJ, which are located at different ends of the Sertoli cell epithelium. Besides, we highlight important areas of research that can now be undertaken, and functional studies that can be designed to tackle different issues pertinent to junction restructuring during spermatogenesis.
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356
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Rajasekaran SA, Beyenbach KW, Rajasekaran AK. Interactions of tight junctions with membrane channels and transporters. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2007; 1778:757-69. [PMID: 18086552 DOI: 10.1016/j.bbamem.2007.11.007] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/20/2007] [Revised: 11/02/2007] [Accepted: 11/09/2007] [Indexed: 12/22/2022]
Abstract
Tight junctions are unique organelles in epithelial cells. They are localized to the apico-lateral region and essential for the epithelial cell transport functions. The paracellular transport process that occurs via tight junctions is extensively studied and is intricately regulated by various extracellular and intracellular signals. Fine regulation of this transport pathway is crucial for normal epithelial cell functions. Among factors that control tight junction permeability are ions and their transporters. However, this area of research is still in its infancy and much more needs to be learned about how these molecules regulate tight junction structure and functions. In this review we have attempted to compile literature on ion transporters and channels involved in the regulation of tight junctions.
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Affiliation(s)
- Sigrid A Rajasekaran
- The Department of Pathology and Laboratory Medicine, David Geffen School of Medicine at UCLA, University of California, Los Angeles, CA 90095, USA
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357
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El Mokhtari NE, Ott SJ, Nebel A, Schäfer A, Rosenstiel P, Förster M, Nothnagel M, Simon R, Schreiber S. Role of NOD2/CARD15 in coronary heart disease. BMC Genet 2007; 8:76. [PMID: 17980027 PMCID: PMC2204032 DOI: 10.1186/1471-2156-8-76] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2007] [Accepted: 11/02/2007] [Indexed: 01/07/2023] Open
Abstract
BACKGROUND Bacterial DNA has been repeatedly detected in atheromatous lesions of coronary heart disease (CHD) patients. Phylogenetic signatures in the atheroma lesions that are similar to those of bacterial biofilms on human barrier organs, including the respiratory or gastrointestinal tract, raise the question of a defective barrier function in CHD. NOD2 plays a major role in defense against bacterial invasion. Genetic variation in the CARD15 gene, which encodes NOD2, was previously shown to result in a barrier defect that causes chronic inflammatory disorders (e.g. Crohn disease). In the present study, we investigated the possible involvement of NOD2/CARD15 in the pathology of CHD by i) analyzing the local expression of NOD2 in atherectomy versus healthy tissue (n = 5 each) using histochemical immunofluorescence and ii) by testing the three major functional CARD15 variants (R702W, G908R and 1007fs) for association with early-onset CHD in 900 German patients and 632 healthy controls. RESULTS In atherectomy tissue of CHD patients, NOD2 was detected in inflammatory cells at the luminal sides of the lesions. However, the allele and genotype frequencies of the three major CARD15 polymorphisms did not differ between CHD patients and controls. CONCLUSION The NOD2 up-regulation in atheroma lesions indicates an involvement of this protein in the pathology of CHD. Although NOD2 could be important in local immune response mechanisms, none of the analyzed CARD15 variants seem to play a significant role in the etiology of CHD.
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358
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Murphy EF, Hooiveld GJ, Muller M, Calogero RA, Cashman KD. Conjugated linoleic acid alters global gene expression in human intestinal-like Caco-2 cells in an isomer-specific manner. J Nutr 2007; 137:2359-65. [PMID: 17951470 DOI: 10.1093/jn/137.11.2359] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Conjugated linoleic acid (CLA) exhibits isomer-specific effects on transepithelial calcium (Ca) transport as well as on cell growth in human intestinal-like Caco-2 cells. However, the molecular mechanisms of action are still unclear. Therefore, this study used a transcriptomic approach to help elucidate the molecular mechanisms underlying such isomer-specific effects. Caco-2 cells were treated with 80 micromol/L linoleic acid (control), 80 micromol/L trans-10, cis-12 CLA, or 80 micromol/L cis-9, trans-11 CLA for 12 d. Ca transport was measured radio-isotopically. RNA was isolated from the cells, labeled, and hybridized to the Affymetrix U133 2.0 Plus arrays (n = 3). Data and functional analysis was preformed using Bioconductor. Using a minimum fold-change criterion of 1.6 and a false discovery rate criterion of P-value <or= 0.05, trans-10, cis-12 CLA altered the expression of 918 genes, whereas, cis-9, trans-11 CLA had no effect on gene expression. Gene ontology analysis revealed that trans-10, cis-12 CLA strongly modulated a number of processes inherently related to carcinogenesis, such as cell cycle, cell proliferation, and DNA metabolism. Trans-10, cis-12 CLA, but not cis-9, trans-11 CLA, increased transepithelial Ca transport in Caco-2 cells, which corresponded to changes in molecular mediators of paracellular (including claudin 2 and 4) and transcellular (calbindin D(9)k and vitamin D receptor) Ca transport. This microarray-based study highlighted a number of gene expression patterns of relevance to 2 important intestinal processes (carcinogenesis and Ca transport), which were modulated by trans-10, cis-12 CLA. These may help our mechanistic understanding of the role of CLA in promoting gut function and health.
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Affiliation(s)
- Eileen F Murphy
- Department of Food and Nutritional Sciences, University College, Cork, Ireland
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359
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Peters S, Cree IA, Alexander R, Turowski P, Ockrim Z, Patel J, Boyd SR, Joussen AM, Ziemssen F, Hykin PG, Moss SE. Angiopoietin modulation of vascular endothelial growth factor: Effects on retinal endothelial cell permeability. Cytokine 2007; 40:144-50. [PMID: 17959386 DOI: 10.1016/j.cyto.2007.09.001] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2006] [Revised: 07/18/2007] [Accepted: 09/06/2007] [Indexed: 10/22/2022]
Abstract
PURPOSE Vascular permeability is important at many sites, but particularly so in diabetic retinopathy where macular oedema is the major cause of blindness. Angiopoietin-2 (Ang-2) and vascular endothelial growth factor (VEGF) are important factors involved in neovascularization and vascular leakage, but there is little data on their interaction to promote increased vascular permeability. METHODS Porcine retinal endothelial cells (PREC) were seeded into permeable inserts and cultured in 24-well plates that permit measurement of permeability using fluorescent dextrans. Cell purity was assessed immunohistochemically. At confluency, PREC were treated with increasing concentrations of VEGF (20-100ng/ml) and Ang-2 (15-75ng/ml). The effect on tight junctions was assessed by visualization with an anti-ZO-1 antibody. RESULTS Immunohistochemistry showed high purity of isolated PREC. Permeability of untreated PREC monolayers was low. The increase in permeability in Ang-2 treated cells (25-30% compared with non-treated cells) was less than that for cells treated with VEGF only (20-100% compared with untreated cells). Highest permeability was seen with a combination of Ang-2 and VEGF (100-400% compared with untreated cells). Permeability increased with time after growth factor application. Preliminary ZO-1 immunohistochemistry appeared to demonstrate the presence of tight junctions between untreated PREC, and loss of tight junctions after treatment with VEGF and Ang-2. CONCLUSIONS VEGF alone is twice as potent in interrupting tight junctions in an endothelial cell monolayer as Ang-2. However, both growth factors acting together increase permeability three times as much as VEGF alone. Treatments designed to reduce vascular permeability in diabetic macular oedema should consider that crosstalk between growth factors including VEGF and the Ang-2/Tie-2 system can multiply their effects.
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Affiliation(s)
- Swaantje Peters
- University College of London, Institute of Ophthalmology, Departments of Cell Biology and Pathology, 11-43 Bath Street, London, UK
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360
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Wallez Y, Huber P. Endothelial adherens and tight junctions in vascular homeostasis, inflammation and angiogenesis. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2007; 1778:794-809. [PMID: 17961505 DOI: 10.1016/j.bbamem.2007.09.003] [Citation(s) in RCA: 322] [Impact Index Per Article: 18.9] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Received: 05/25/2007] [Revised: 09/03/2007] [Accepted: 09/05/2007] [Indexed: 11/25/2022]
Abstract
Endothelial cells lining the vessel wall are connected by adherens, tight and gap junctions. These junctional complexes are related to those found at epithelial junctions but with notable changes in terms of specific molecules and organization. Endothelial junctional proteins play important roles in tissue integrity but also in vascular permeability, leukocyte extravasation and angiogenesis. In this review, we will focus on specific mechanisms of endothelial tight and adherens junctions.
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Affiliation(s)
- Yann Wallez
- Vascular Pathophysiology Laboratory, Inserm U882 38054 Grenoble, France
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361
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Alvarez JI, Teale JM. Evidence for differential changes of junctional complex proteins in murine neurocysticercosis dependent upon CNS vasculature. Brain Res 2007; 1169:98-111. [PMID: 17686468 PMCID: PMC2754301 DOI: 10.1016/j.brainres.2007.07.010] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2007] [Revised: 06/29/2007] [Accepted: 07/02/2007] [Indexed: 10/23/2022]
Abstract
The delicate balance required to maintain homeostasis of the central nervous system (CNS) is controlled by the blood-brain barrier (BBB). Upon injury, the BBB is disrupted compromising the CNS. BBB disruption has been represented as a uniform event. However, our group has shown in a murine model of neurocysticercosis (NCC) that BBB disruption varies depending upon the anatomical site/vascular bed analyzed. In this study further understanding of the mechanisms of BBB disruption was explored in blood vessels located in leptomeninges (pial vessels) and brain parenchyma (parenchymal vessels) by examining the expression of junctional complex proteins in murine brain infected with Mesocestoides corti. Both pial and parenchymal vessels from mock infected animals showed significant colocalization of junctional proteins and displayed an organized architecture. Upon infection, the patterned organization was disrupted and in some cases, particular tight junction and adherens junction proteins were undetectable or appeared to be undergoing proteolysis. The extent and timing of these changes differed between both types of vessels (pial vessel disruption within days versus weeks for parenchymal vessels). To approach potential mechanisms, the expression and activity of matrix metalloproteinase-9 (MMP-9) were evaluated by in situ zymography. The results indicated an increase in MMP-9 activity at sites of BBB disruption exhibiting leukocyte infiltration. Moreover, the timing of MMP activity in pial and parenchymal vessels correlated with the timing of permeability disruption. Thus, breakdown of the BBB is a mutable process despite the similar structure of the junctional complex between pial and parenchymal vessels and involvement of MMP activity.
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Affiliation(s)
| | - Judy M. Teale
- Corresponding author: Judy M. Teale, Ph.D. Department of Biology, University of Texas at San Antonio, One UTSA Circle, San Antonio, TX 78249, Voice: (210) 4587025, Fax: (210) 4587025, Email address:
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362
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Morgan L, Shah B, Rivers LE, Barden L, Groom AJ, Chung R, Higazi D, Desmond H, Smith T, Staddon JM. Inflammation and dephosphorylation of the tight junction protein occludin in an experimental model of multiple sclerosis. Neuroscience 2007; 147:664-73. [PMID: 17560040 DOI: 10.1016/j.neuroscience.2007.04.051] [Citation(s) in RCA: 81] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2007] [Revised: 03/30/2007] [Accepted: 04/04/2007] [Indexed: 01/09/2023]
Abstract
Multiple sclerosis (MS) is a disease of the CNS in which inflammation, demyelination and neurodegeneration contribute to its initiation and progression. A frequently employed model of MS is experimental autoimmune encephalomyelitis (EAE). Here, to gain new insights into the disease process, an analysis of proteins in extracts of lumbar spinal cord from naïve and EAE rats was undertaken. The data mainly confirm that inflammation and blood-brain barrier (BBB) breakdown are the major hallmarks of disease in this model. Given their importance in the BBB, junctional proteins were further investigated. Occludin, a protein localizing to tight junctions in brain endothelial cells, showed strikingly increased migration in EAE when analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). This increased migration was mimicked by in vitro phosphatase treatment, implying its dephosphorylation in EAE. Occludin dephosphorylation coincided with the onset of inflammation, slightly preceding visible signs of disease, and was just prior to apparent changes in BBB permeability. These findings suggest occludin is a target for signaling processes in EAE, perhaps regulating the response of the BBB to the inflammatory environment as seen in MS.
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MESH Headings
- Animals
- Disease Models, Animal
- Electrophoresis, Gel, Two-Dimensional/methods
- Encephalitis/etiology
- Encephalitis/metabolism
- Encephalitis/pathology
- Encephalomyelitis, Autoimmune, Experimental/complications
- Encephalomyelitis, Autoimmune, Experimental/metabolism
- Encephalomyelitis, Autoimmune, Experimental/pathology
- Endothelial Cells/cytology
- Female
- Immunoprecipitation/methods
- Mass Spectrometry/methods
- Membrane Proteins/metabolism
- Occludin
- Phosphoric Monoester Hydrolases/pharmacology
- Phosphorylation/drug effects
- Rats
- Rats, Inbred Lew
- Spinal Cord/pathology
- Tight Junctions/metabolism
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Affiliation(s)
- L Morgan
- Eisai London Research Laboratories Ltd., University College London, London, UK
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363
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Eiselein L, Wilson DW, Lamé MW, Rutledge JC. Lipolysis products from triglyceride-rich lipoproteins increase endothelial permeability, perturb zonula occludens-1 and F-actin, and induce apoptosis. Am J Physiol Heart Circ Physiol 2007; 292:H2745-53. [PMID: 17259442 DOI: 10.1152/ajpheart.00686.2006] [Citation(s) in RCA: 78] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
Products generated from lipoprotein lipase-mediated hydrolysis of triglyceride-rich lipoproteins (TGRL) are reported to increase endothelial layer permeability. We hypothesize that these increases in permeability result from the active rearrangement and dissolution of the junctional barrier in human aortic endothelial cells, as well as induction of the apoptotic cascade. Human aortic endothelial cells were treated with TGRL lipolysis products generated from coincubation of human TGRL plus lipoprotein lipase. Measurement of transendothelial electrical resistance demonstrated a time-dependent decrease in endothelial barrier function in response to TGRL lipolysis products. Immunofluorescent localization of zonula occludens-1 (ZO-1) showed radial rearrangement along cell borders after 1.5 h of treatment with lipolysis products. A concurrent redistribution of F-actin from the cell body to the cell margins was observed via rhodamine phalloidin staining. Immunofluorescent imaging for occludin and vascular endothelial cadherin showed that these proteins relocalize as well, although these changes are less prominent than for ZO-1. Western analysis of cells exposed to lipolysis products for 3 h revealed the fragmentation of ZO-1, a reduction in occludin, and no change of vascular endothelial cadherin. Lipolysis products also increased caspase-3 activity and induced nuclear fragmentation. Treatments did not cause oncosis in cells at any point during the incubation. These results demonstrate that TGRL lipolysis products play an important role in the regulation of endothelial permeability, the organization of the actin cytoskeleton, the localization and expression of junctional proteins, especially ZO-1, and the induction of apoptosis.
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Affiliation(s)
- Larissa Eiselein
- Division of Endocrinology, University of California, Davis, CA 95616, USA
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364
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Jadhav V, Matchett G, Hsu FPK, Zhang JH. Inhibition of Src tyrosine kinase and effect on outcomes in a new in vivo model of surgically induced brain injury. J Neurosurg 2007; 106:680-6. [PMID: 17432722 DOI: 10.3171/jns.2007.106.4.680] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
OBJECT Brain tissue at the periphery of a neurosurgical resection site is vulnerable to injury by a variety of mechanisms including direct trauma, edema, hemorrhage, retractor stretch, and electrocautery. The goal in the present study was to develop an in vivo model of surgically induced brain injury and to test an Src tyrosine kinase inhibitor for neuroprotective properties in this model. METHODS The authors developed a new surgically induced brain injury model in rats. This model involves resection of part of the frontal lobe. Sprague-Dawley male rats weighing between 300 and 350 g were divided randomly into four groups: Group 1, surgical injury with vehicle treatment; Group 2, surgical injury after treatment with PP1 (an Src tyrosine kinase inhibitor with known neuroprotective properties); Group 3, sham surgery; and Group 4, control. Postoperative assessment included blood-brain barrier (BBB) permeability studies, and histological, immunohistochemical, and Western blot analyses. The authors found that surgical injury caused localized edema and disruption of the BBB compared with findings in the sham surgery group. Treatment with PP1 was associated with decreased edema, decreased breakdown of the BBB, decreased expression of both vascular endothelial growth factor and phosphorylated extracellular signal-regulated kinase 1 and 2, and preservation of ZO-1 expression. CONCLUSIONS In this study the authors describe a simple and reproducible in vivo animal model of surgically induced brain injury. Pretreatment with PP1 results in improved outcomes in this model, which suggests a possible role for Src tyrosine kinase inhibitors as preoperative therapy for planned neurosurgical procedures.
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Affiliation(s)
- Vikram Jadhav
- Department of Physiology and Pharmacology, Loma Linda University School of Medicine, Loma Linda, California 92354, USA
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365
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Prozialeck WC, Edwards JR. Cell adhesion molecules in chemically-induced renal injury. Pharmacol Ther 2007; 114:74-93. [PMID: 17316817 PMCID: PMC1913814 DOI: 10.1016/j.pharmthera.2007.01.001] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2007] [Accepted: 01/05/2007] [Indexed: 01/15/2023]
Abstract
Cell adhesion molecules are integral cell-membrane proteins that maintain cell-cell and cell-substrate adhesion and in some cases act as regulators of intracellular signaling cascades. In the kidney, cell adhesion molecules, such as the cadherins, the catenins, the zonula occludens protein-1 (ZO-1), occludin and the claudins are essential for maintaining the epithelial polarity and barrier integrity that are necessary for the normal absorption/excretion of fluid and solutes. A growing volume of evidence indicates that these cell adhesion molecules are important early targets for a variety of nephrotoxic substances including metals, drugs, and venom components. In addition, it is now widely appreciated that molecules, such as intracellular adhesion molecule-1 (ICAM-1), integrins, and selectins play important roles in the recruitment of leukocytes and inflammatory responses that are associated with nephrotoxic injury. This review summarizes the results of recent in vitro and in vivo studies indicating that these cell adhesion molecules may be primary molecular targets in many types of chemically-induced renal injury. Some of the specific agents that are discussed include cadmium (Cd), mercury (Hg), bismuth (Bi), cisplatin, aminoglycoside antibiotics, S-(1,2-dichlorovinyl)-l-cysteine (DCVC), and various venom toxins. This review also includes a discussion of the various mechanisms, by which these substances can affect cell adhesion molecules in the kidney.
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Affiliation(s)
- Walter C Prozialeck
- Department of Pharmacology, Midwestern University, 555 31st Street, Downers Grove, IL 60515, United States.
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366
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Chen YS, Chen KH, Liu CC, Lee CT, Yang CH, Chuang KC, Lin CR. Propofol-induced vascular permeability change is related to the nitric oxide signaling pathway and occludin phosphorylation. J Biomed Sci 2007; 14:629-36. [PMID: 17394100 DOI: 10.1007/s11373-007-9164-4] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2006] [Accepted: 02/28/2007] [Indexed: 01/22/2023] Open
Abstract
The present study was undertaken to elucidate the mechanism of intra-arterial propofol-induced vascular permeability change resulting in tissue edema. The mechanism of propofol-induced hyperpermeability was examined in a rat femoral artery injection model. Vascular permeability was determined by measuring the Evans blue content of the dorsal skin of the infused limb at 15, 30, 45 and 60 min after propofol injection. The total content of the tight junction proteins occludin, ZO-1 and claudin-5 under experimental conditions was also determined by western blotting. Intra-arterial injection with propofol resulted in a marked dose-dependent increase in vascular permeability of the rat hindpaw. Pretreatment with 10 mg/kg of N-nitro-L: -arginine methyl ester (L: -NAME) but not aminoguanidine significantly inhibited the change in vascular permeability after challenge with propofol. Pretreatment with L: -arginine and nitroprusside increased the propofol-induced permeability change. Intra-arterial injection of propofol significantly increased occludin phosphorylation after 15 min, which was consistent with the time profile of the vascular permeability change. L: -NAME partially reversed the change in occludin phosphorylation, whereas aminoguanidine had no effect compared with that in the controls. Our observations indicate that nitric oxide (NO) is an important mediator in the induction of vascular permeability induced by propofol. Occludin phosphorylation is a determining factor in the vascular permeability change induced by propofol. NO synthase (NOS) inhibitors might be useful in the treatment of accidental intra-arterial injection of propofol, in the reduction of any adverse effects.
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Affiliation(s)
- Yi-Shen Chen
- Department of Anesthesiology, Chang Gung Memorial Hospital-Kaohsiung Medical Center, Chang Gung University, 123 Ta-Pei Rd, Niao-Sung Hsian, Kaohsiung, 833, Taiwan, ROC
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367
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Brent L, Cohen IR, Doherty PC, Feldmann M, Matzinger P, Holgate ST, Lachmann P, Mitchison NA, Nossal G, Rose NR, Zinkernagel R. Crystal-ball gazing--the future of immunological research viewed from the cutting edge. Clin Exp Immunol 2007; 147:1-10. [PMID: 17177957 PMCID: PMC1810455 DOI: 10.1111/j.1365-2249.2006.03234.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Affiliation(s)
- L Brent
- 30 Hugo Road, London N195EU, UK
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368
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Abstract
Transcellular transport affects the paracellular flux through 2 distinct mechanisms: by determining the driving force and by altering the permeability of the paracellular pathway. Such coordination ensures efficient transepithelial transport by preventing the build-up of large electrical and osmotic gradients. The regulation of paracellular permeability was originally recognized as increased paracellular flux of water and solutes upon the activation of the intestinal Na+-coupled glucose uptake. Despite great advances in the molecular characterization of the tight junctions that form the structural basis of epithelial barrier functions, the mechanisms whereby apical transporters alter the paracellular pathways remains unresolved. Recent studies suggest that myosin-based contractility is central to this coupling. In this minireview, we summarize our current knowledge of paracellular permeability, its regulation by contractility, and the various signaling events that link apical Na+-glucose cotransport to myosin phosphorylation. While the role of myosin phosphorylation appears to be universal, the mechanism(s) whereby apical transport triggers this process is likely cell specific. The current model suggests that in intestinal cells, a key factor is a p38 MAP kinase-induced Na+/H+-exchanger-mediated alkalinization. We propose an alternative, nonexclusive mechanism in kidney tubular cells, in which the key event may be a Na+-cotransport-triggered plasma membrane depolarization, which in turn leads to Rho-mediated myosin phosphorylation.
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Affiliation(s)
- András Kapus
- The St. Michael's Hospital Research Institute and Department of Surgery, University of Toronto, 30 Bond Street, Queen Wing 7009, Toronto, ON M5B 1W8, Canada
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369
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Maher S, Feighery L, Brayden DJ, McClean S. Melittin as an epithelial permeability enhancer I: investigation of its mechanism of action in Caco-2 monolayers. Pharm Res 2007; 24:1336-45. [PMID: 17373574 DOI: 10.1007/s11095-007-9288-2] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2006] [Accepted: 01/19/2007] [Indexed: 02/07/2023]
Abstract
PURPOSE Melittin is an amphipathic antimicrobial peptide which has been shown to enhance the permeability of mannitol and reduce transepithelial electrical resistance (TER) across Caco-2 monolayers. The aim of this work was to further examine the potential of melittin as a paracellular permeability enhancer and to investigate the mechanism of interaction with tight junction proteins in Caco-2. MATERIALS AND METHODS The permeability of a range of fluorescent markers of differing molecular weights across monolayers was examined and immunofluorescence and western blotting analysis of tight junction proteins were also carried out. The mechanism of TER reduction was also examined using cell signalling inhibitors. RESULTS Apical but not basolateral addition of melittin increased the permeability of a range FITC-dextrans (4-70 kDa) across monolayers. Melittin effects were reversible and no cytotoxicity was evident in polarized Caco-2 epithelia at the concentrations used. Altered expression of ZO-1, E-cadherin and F-actin was also detected. The phospholipase A2 inhibitors, aristolochic acid and indomethacin and the cyclooxygenase inhibitor, piroxicam, partially attenuated melittin-induced TER reduction, suggesting that part of the mechanism by which melittin opens tight junctions involves prostaglandin signalling. CONCLUSIONS Apically-added melittin opens tight junctions, causing dramatic TER reductions with significant increases in flux of dextrans. These effects appear mediated in part via PLA2 and involve alterations in specific tight junction proteins.
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Affiliation(s)
- Sam Maher
- Institute of Technology Tallaght Dublin, Belgard Road, Tallaght, Dublin, Ireland
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370
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Tominaga M, Ozawa S, Ogawa H, Takamori K. A hypothetical mechanism of intraepidermal neurite formation in NC/Nga mice with atopic dermatitis. J Dermatol Sci 2007; 46:199-210. [PMID: 17350228 DOI: 10.1016/j.jdermsci.2007.02.002] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2006] [Revised: 01/20/2007] [Accepted: 02/02/2007] [Indexed: 11/17/2022]
Abstract
BACKGROUND Pruritus is a symptom in atopic dermatitis (AD). Previous studies have reported that increased intraepidermal neurites are observed in AD, suggesting that the neuritogenesis is related to itching in the skin. OBJECTIVE This study was conducted to reveal the mechanism of intraepidermal neurite formation in AD. METHODS In this study, we used conventional (Conv) NC/Nga mice with AD. NC/Nga mice maintained in specific pathogen-free (SPF) condition were used as a control with no AD. Distribution of intraepidermal neurites and expression patterns of growth factors (NGF and amphiregulin (AR)) and cell-cell junctional molecules (E-cadherin, zona occludens 1 (ZO-1) and desmoglein 3 (Dsg3)) were examined in the skins by immunohistochemistry or quantitative RT-PCR. Furthermore, detection of gelatinase activity was performed with in situ zymography. The same experiments were conducted in ICR mice for comparison with NC/Nga mice. RESULTS Neurite density and expression levels of growth factors and gelatinase were remarkably increased in the epidermis of Conv-NC/Nga mice compared with those of SPF-NC/Nga mice. Decreased expression of E-cadherin and ZO-1 and misexpression of Dsg3 were also observed in the atopic skins. In comparison with ICR mice, increases of neurite density and gelatinase activity were found in the skins of SPF-NC/Nga mice but expression levels of growth factors and cell-cell junctional molecules were unchanged. CONCLUSIONS Increases of growth factors and gelatinase activity may be related to neurite outgrowth in the epidermis of atopic NC/Nga mice. Additionally, abnormal expressions of cell-cell junctional molecules in the epidermis may provide intercellular spaces for the neurite formation.
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Affiliation(s)
- Mitsutoshi Tominaga
- Institute for Environmental and Gender Specific Medicine, Juntendo University Graduate School of Medicine, 2-1-1 Tomioka, Urayasu, Chiba 279-0021, Japan
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371
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Foerg C, Ziegler U, Fernandez-Carneado J, Giralt E, Merkle HP. Differentiation restricted endocytosis of cell penetrating peptides in MDCK cells corresponds with activities of Rho-GTPases. Pharm Res 2007; 24:628-42. [PMID: 17334941 DOI: 10.1007/s11095-006-9212-1] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2006] [Accepted: 12/08/2006] [Indexed: 01/19/2023]
Abstract
PURPOSE Cellular entry of biomacromolecules is restricted by the barrier function of cell membranes. Tethering such molecules to cell penetrating peptides (CPPs) that can translocate cell membranes has opened new horizons in biomedical research. Here, we investigate the cellular internalization of hCT(9-32)-br, a human calcitonin derived branched CPP, and SAP, a gamma-zein related sequence. METHODS Internalization of fluorescence labelled CPPs was performed with both proliferating and confluent MDCK cells by means of confocal laser scanning microscopy (CLSM) and fluorescence activated cell sorting (FACS) using appropriate controls. Internalization was further elaborated in an inflammatory, IFN-gamma/TNF-alphaa induced confluent MDCK model mimicking inflammatory epithelial pathologies. Activities of active form Rho-GTPases (Rho-A and Rac-1) in proliferating and confluent MDCK cells were monitored by pull-down assay and Western blot analysis. RESULTS We observed marked endocytic uptake of the peptides into proliferating MDCK by a process suggesting both lipid rafts and clathrin-coated pits. In confluent MDCK, however, we noted a massive but compound-unspecific slow-down of endocytosis. This corresponded with a down-regulation of endocytosis by Rho-GTPases, previously identified to be intimately involved in endocytic traffic. In fact, we found endocytic internalization to relate with active Rho-A; vice versa, MDCK cell density, degree of cellular differentiation and endocytic slow-down were found to relate with active Rac-1. To our knowledge, this is the first study to cast light on the previously observed differentiation restricted internalization of CPPs into epithelial cell models. In the inflammatory IFN-gamma/TNF-alphaa induced confluent MDCK model mimicking inflammatory epithelial pathologies, CPP internalization was enhanced in a cytokine concentration-dependent way resulting in maximum enhancement rates of up to 90%. We suggest a cytokine induced redistribution of lipid rafts in confluent MDCK to cause this enhancement. CONCLUSION Our findings emphasize the significance of differentiated cell models in the study of CPP internalization and point towards inflammatory epithelial pathologies as potential niche for the application of CPPs for cellular delivery.
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Affiliation(s)
- Christina Foerg
- Institute of Pharmaceutical Sciences, ETH Zurich, Zurich, Switzerland
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372
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Campbell SJ, Carare-Nnadi RO, Losey PH, Anthony DC. Loss of the atypical inflammatory response in juvenile and aged rats. Neuropathol Appl Neurobiol 2007; 33:108-20. [PMID: 17239013 DOI: 10.1111/j.1365-2990.2006.00773.x] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Epidemiological evidence indicates that the severity of many human neuropathologies is often age-related, and this also appears true in rodent models of human disease. In this study, we examined the inflammatory response within the brain to the archetypal pro-inflammatory cytokines interleukin-1beta (IL-1beta) or tumour necrosis factor-alpha (TNF-alpha). We assessed how the cerebral vasculature changes with age and whether any structural alterations are associated with altered cytokine sensitivities. Six hours after equivalent microinjections of IL-1beta or TNF-alpha, 3-week-old juvenile and 18-month-old aged rats displayed increased leucocyte recruitment, blood-brain barrier (BBB) breakdown, and a loss of specificity in the populations of leucocytes recruited when compared with the restricted profile observed in 2-month-old young adult rat brain. The expression of the tight junction protein claudin-1 was absent in those vessels where neutrophils were being actively recruited. To determine whether changes in the structure of the BBB might be responsible for the increased susceptibility observed at either end of the age spectrum, we compared the number of claudin-1 positive vessels in the unchallenged brain to the total number of vessels. Virtually all vessels in the young adult brain express claudin-1, but a significant proportion of vessels are claudin-1 negative in the juvenile rat brain. In the aged rat brain, the overall number of vessels is markedly reduced, but the majority of these still appear to be claudin-1 positive. The pattern of claudin-1 expression together with the change in vessel density indicates that the properties of the BBB change with age, and, despite similarities, the underlying cause of the heightened inflammatory response in the juvenile and in the aged brain is likely to differ. Indeed, the spatial characteristics of the cytokine-induced BBB breakdown are different at either end of the age spectrum. These studies identify two periods within the lifespan of a rat where susceptibility to pro-inflammatory mediators is dramatically increased.
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Affiliation(s)
- S J Campbell
- Experimental Neuropathology, Department of Pharmacology, University of Oxford, Mansfield Road, Oxfordshire, UK.
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373
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Yan HHN, Mruk DD, Lee WM, Cheng CY. Ectoplasmic specialization: a friend or a foe of spermatogenesis? Bioessays 2007; 29:36-48. [PMID: 17187371 PMCID: PMC2804921 DOI: 10.1002/bies.20513] [Citation(s) in RCA: 118] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The ectoplasmic specialization (ES) is a testis-specific, actin-based hybrid anchoring and tight junction. It is confined to the interface between Sertoli cells at the blood-testis barrier, known as the basal ES, as well as between Sertoli cells and developing spermatids designated the apical ES. The ES shares features of adherens junctions, tight junctions and focal contacts. By adopting the best features of each junction type, this hybrid nature of ES facilitates the extensive junction-restructuring events in the seminiferous epithelium during spermatogenesis. For instance, the alpha6beta1-integrin-laminin 333 complex, which is usually limited to the cell-matrix interface in other epithelia to facilitate cell movement, is a putative apical ES constituent. Furthermore, JAM-C and CAR, two tight junction integral membrane proteins, are also components of apical ES involving in spermatid orientation. We discuss herein the mechanisms that maintain the cross-talk between ES and blood-testis barrier to facilitate cell movement and orientation in the seminiferous epithelium.
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Affiliation(s)
- Helen H N Yan
- Center for Biomedical Research, Population Council, New York, NY 10021, USA.
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374
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Rajasekaran SA, Barwe SP, Gopal J, Ryazantsev S, Schneeberger EE, Rajasekaran AK. Na-K-ATPase regulates tight junction permeability through occludin phosphorylation in pancreatic epithelial cells. Am J Physiol Gastrointest Liver Physiol 2007; 292:G124-33. [PMID: 16959951 DOI: 10.1152/ajpgi.00297.2006] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Tight junctions are crucial for maintaining the polarity and vectorial transport functions of epithelial cells. We and others have shown that Na-K-ATPase plays a key role in the organization and permeability of tight junctions in mammalian cells and analogous septate junctions in Drosophila. However, the mechanism by which Na-K-ATPase modulates tight junctions is not known. In this study, using a well-differentiated human pancreatic epithelial cell line HPAF-II, we demonstrate that Na-K-ATPase is present at the apical junctions and forms a complex with protein phosphatase-2A, a protein known to be present at tight junctions. Inhibition of Na-K-ATPase ion transport function reduced protein phosphatase-2A activity, hyperphosphorylated occludin, induced rearrangement of tight junction strands, and increased permeability of tight junctions to ionic and nonionic solutes. These data suggest that Na-K-ATPase is required for controlling the tight junction gate function.
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Affiliation(s)
- Sigrid A Rajasekaran
- Department of Pathology and Laboratory Medicine, Rm. 13-344 CHS, University of California, Los Angeles, Los Angeles, CA 90095, USA.
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375
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Abstract
The specialized cerebral microvascular endothelium interacts with the cellular milieu of the brain and extracellular matrix to form a neurovascular unit, one aspect of which is a regulated interface between the blood and central nervous system (CNS). The concept of this blood-brain barrier (BBB) as a dynamically regulated system rather than a static barrier has wide-ranging implications for pathophysiology of the CNS. While in vitro models of the BBB are useful for screening drugs targeted to the CNS and indispensable for studies of cerebral endothelial cell biology, the complex interactions of the neurovascular unit make animal-based models and methods essential tools for understanding the pathophysiology of the BBB. BBB dysfunction is a complication of neurodegenerative disease and brain injury. Studies on animal models have shown that diseases of the periphery, such as diabetes and inflammatory pain, have deleterious effects on the BBB which may contribute to neurological complications associated with these conditions. Furthermore, genetic and/or epigenetic abnormalities in constituents of the BBB may be significant contributing factors in disease etiology. Research that approaches the BBB as a dynamic system integrated with both the CNS and the periphery is therefore critical to understanding and treating diseases of the CNS. Herein, we review various methodological approaches used to study BBB function in the context of disease. These include measurement of transport between blood and brain, imaging-based technologies, and genomic/proteomic approaches.
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376
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Kaneda KI, Miyamoto K, Nomura S, Horiuchi T. Intercellular localization of occludins and ZO-1 as a solute transport barrier of the mesothelial monolayer. J Artif Organs 2006; 9:241-50. [PMID: 17171403 DOI: 10.1007/s10047-006-0350-3] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2006] [Accepted: 07/03/2006] [Indexed: 11/29/2022]
Abstract
A hyperpermeable state has been observed in patients on long-term peritoneal dialysis. To understand the causes of the structural or functional changes and the progression of the fibrotic process, it is important to determine which region of the peritoneum exhibits these changes. The objectives of this study were to determine the solute permeability associated with cell-cell adhesion of human peritoneal mesothelial cells (HPMCs), to study the relationship between solute permeability and localizations of tight junction-associated proteins (TJPs: occludins and ZO-1), and to assess the effect of exogenous H2O2 supplementation. HPMCs were cultured on a Transwell until the transmesothelial electrical resistance (TER) reached a plateau. Solute permeation tests were conducted using fluorescein isothiocyanate - labeled dextran (molecular weight: 4, 10, 70, and 150 kDa) to calculate the solute permeability coefficient (SPC). Localization of TJPs was observed by a confocal laser scanning microscope after immunofluorescent staining. TER levels increased steadily, beginning at 97.5 +/- 0.7 ohms.cm2 and leveling off at 128 +/- 3.6 ohms.cm2 (n = 4). This was accompanied by the confluence of cells and the appearance of localized TJPs. SPC levels of the HPMC monolayer on the Transwell were reduced compared to those of the Transwell itself, indicating that the HPMC monolayer provided resistance against solute permeation. Exogenous H2O2 supplementation revealed an increased permeability accompanied with delocalization of TJPs, particularly occludins. The delocalization of occludins and ZO-1 at the intercellular space led to a decrease in intercellular binding capacity and thus triggered an increase in the solute permeability.
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Affiliation(s)
- Ken-ichi Kaneda
- Department of Chemistry for Materials, Graduate School of Engineering, Mie University, Tsu, Mie 514-8507, Japan
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377
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Selvatici R, Falzarano S, Franceschetti L, Cavallini S, Marino S, Siniscalchi A. Differential activation of protein kinase C isoforms following chemical ischemia in rat cerebral cortex slices. Neurochem Int 2006; 49:729-36. [PMID: 16963162 DOI: 10.1016/j.neuint.2006.06.003] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2006] [Accepted: 06/13/2006] [Indexed: 11/23/2022]
Abstract
The aim of the current study was to characterize the effects of chemical ischemia and reperfusion at the transductional level in the brain. Protein kinase C isoforms (alpha, beta(1), beta(2), gamma, delta and epsilon) total levels and their distribution in the particulate and cytosolic compartments were investigated in superfused rat cerebral cortex slices: (i) under control conditions; (ii) immediately after a 5-min treatment with 10mM NaN(3), combined with 2mM 2-deoxyglucose (chemical ischemia); (iii) 1h after chemical ischemia (reperfusion). In control samples, all the PKC isoforms were detected; immediately after chemical ischemia, PKC beta(1), delta and epsilon isoforms total levels (cytosol+particulate) were increased by 2.9, 2.7 and 9.9 times, respectively, while alpha isoform was slightly reduced and gamma isoform was no longer detectable. After reperfusion, the changes displayed by alpha, beta(1), gamma, delta and epsilon were maintained and even potentiated, moreover, an increase in beta(2) (by 41+/-12%) total levels became significant. Chemical ischemia-induced a significant translocation to the particulate compartment of PKC alpha isoform, which following reperfusion was found only in the cytosol. PKC beta(1) and delta isoforms particulate levels were significantly higher both in ischemic and in reperfused samples than in the controls. Conversely, following reperfusion, PKC beta(2) and epsilon isoforms displayed a reduction in their particulate to total level ratios. The intracellular calcium chelator, 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid, 1mM, but not the N-methyl-d-asparate receptor antagonist, MK-801, 1muM, prevented the translocation of beta(1) isoform observed during ischemia. Both drugs were effective in counteracting reperfusion-induced changes in beta(2) and epsilon isoforms, suggesting the involvement of glutamate-induced calcium overload. These findings demonstrate that: (i) PKC isoforms participate differently in neurotoxicity/neuroprotection events; (ii) the changes observed following chemical ischemia are pharmacologically modulable; (iii) the protocol of in vitro chemical ischemia is suitable for drug screening.
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Affiliation(s)
- Rita Selvatici
- Department of Experimental and Diagnostic Medicine, Medical Genetics Section, University of Ferrara, Via Fossato di Mortara 74, 44100 Ferrara, Italy.
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378
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Riazuddin S, Ahmed ZM, Fanning AS, Lagziel A, Kitajiri SI, Ramzan K, Khan SN, Chattaraj P, Friedman PL, Anderson JM, Belyantseva IA, Forge A, Riazuddin S, Friedman TB. Tricellulin is a tight-junction protein necessary for hearing. Am J Hum Genet 2006; 79:1040-51. [PMID: 17186462 PMCID: PMC1698716 DOI: 10.1086/510022] [Citation(s) in RCA: 207] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2006] [Accepted: 10/04/2006] [Indexed: 12/13/2022] Open
Abstract
The inner ear has fluid-filled compartments of different ionic compositions, including the endolymphatic and perilymphatic spaces of the organ of Corti; the separation from one another by epithelial barriers is required for normal hearing. TRIC encodes tricellulin, a recently discovered tight-junction (TJ) protein that contributes to the structure and function of tricellular contacts of neighboring cells in many epithelial tissues. We show that, in humans, four different recessive mutations of TRIC cause nonsyndromic deafness (DFNB49), a surprisingly limited phenotype, given the widespread tissue distribution of tricellulin in epithelial cells. In the inner ear, tricellulin is concentrated at the tricellular TJs in cochlear and vestibular epithelia, including the structurally complex and extensive junctions between supporting and hair cells. We also demonstrate that there are multiple alternatively spliced isoforms of TRIC in various tissues and that mutations of TRIC associated with hearing loss remove all or most of a conserved region in the cytosolic domain that binds to the cytosolic scaffolding protein ZO-1. A wild-type isoform of tricellulin, which lacks this conserved region, is unaffected by the mutant alleles and is hypothesized to be sufficient for structural and functional integrity of epithelial barriers outside the inner ear.
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Affiliation(s)
- Saima Riazuddin
- Section on Human Genetics, Laboratory of Molecular Genetics, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Rockville, MD 20850, USA
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379
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Song L, Ge S, Pachter JS. Caveolin-1 regulates expression of junction-associated proteins in brain microvascular endothelial cells. Blood 2006; 109:1515-23. [PMID: 17023578 PMCID: PMC1794065 DOI: 10.1182/blood-2006-07-034009] [Citation(s) in RCA: 137] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Recent evidence from this laboratory indicated that reduced expression of caveolin-1 accompanied the diminished expression of tight junction (TJ)-associated proteins occludin and zonula occludens-1 (ZO-1) following stimulation of brain microvascular endothelial cells (BMECs) with the chemokine CCL2 (formerly called MCP-1). Because attenuated caveolin-1 levels have also been correlated with heightened permeability of other endothelia, the objective of this study was to test the hypothesis that reduced caveolin-1 expression is causally linked to the action of CCL2 on BMEC junctional protein expression and barrier integrity. This was achieved using adenovirus to nondestructively deliver caveolin-1 siRNA (Ad-siCav-1) to BMEC monolayers, which model the blood-brain barrier (BBB). Treatment with siRNA reduced the caveolin-1 protein level as well as occludin and ZO-1. Additionally, occludin exhibited dissociation from the cytoskeletal framework. These changes were attended by comparable alterations in adherens junction (AJ)-associated proteins, VE-cadherin and beta-catenin, increased BMEC paracellular permeability, and facilitated the ability of CCL2 to stimulate monocytic transendothelial migration. Furthermore, treating BMECs with cavtratin, a synthetic cell-permeable peptide encoding the caveolin-1 scaffolding domain, antagonized effects of both Ad-siCav-1 and CCL2. These results collectively highlight caveolin-1 loss as a critical step in CCL2-induced modulation of BMEC junctional protein expression and integrity, and possibly serve a crucial role in regulating inflammation at the BBB.
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Affiliation(s)
- Li Song
- Blood-Brain Barrier Laboratory, Department of Pharmacology, University of Connecticut Health Center, Farmington 06030, USA
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380
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Yamagata M, Rook SL, Sassa Y, Ma RC, Geraldes P, Goddard L, Clermont A, Gao B, Salti H, Gundel R, White M, Feener EP, Aiello LP, King GL. Bactericidal/permeability‐increasing protein's signaling pathways and its retinal trophic and anti‐angiogenic effects. FASEB J 2006; 20:2058-67. [PMID: 17012258 DOI: 10.1096/05-5662com] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Bactericidal/permeability-increasing protein (BPI) was originally identified as a lipopolysaccharide (LPS) binding protein with gram-negative bactericidal activity in the leukocytes. In this study, we characterized the previously unknown effects of BPI in the eye and the molecular mechanisms involved in its action. BPI mRNA was detected in bovine retina; retinal pigment epithelium; and primary cultures of bovine retinal pigment epithelial cells (RPE), pericytes (RPC), and endothelial cells (REC); while BPI protein was measured in human vitreous and plasma. BPI, but not control protein thaumatin, activated extracellular regulated kinase (ERK) and AKT, and increased DNA synthesis in RPE and RPC but not in REC. A human recombinant 21 kDa modified amino-terminal fragment of BPI (rBPI21) reduced H2O2-induced apoptosis in RPE and inhibited vascular endothelial growth factor (VEGF)-stimulated ERK phosphorylation in REC when preincubated with VEGF. Intraperitoneal (i.p.)-injected rBPI21 reduced ischemia-induced retinal neovascularization and diabetes-induced retinal permeability. Since BPI has unusual dual properties of promoting RPC and RPE growth while suppressing VEGF-induced REC growth and vascular permeability, the mechanistic understanding of BPI's action may provide novel therapeutic opportunities for diabetic retinopathy and age-related macular degeneration.
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Affiliation(s)
- Michiko Yamagata
- Research Division, Joslin Diabetes Center, Harvard Medical School, Boston, Massachusetts 02215, USA
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381
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Abstract
New approaches for enhancing intranasal drug delivery based on recent discoveries on the molecular biology of tight junctions (TJ) are significantly improving the bioavailability of 'non-Lipinsky' small molecules, and peptide, protein and oligonucleotide drugs. As knowledge of the structure and function of the TJ has developed, so has the ability to identify mechanism-based TJ modulators using high-throughput molecular biology-based screening methods. The present review focuses on recent developments on the TJ protein complex as a lipid raft-like membrane microdomain, the emerging role of unique endocytic pathways in regulating TJ dynamics, and the utility of techniques such as RNA interference and phage display to study TJ components and identify novel peptides and related molecules that can modulate their function. Experimental and statistical methodologies used for the identification of new classes of TJ modulators are described, which are capable of reversibly opening TJ barriers with broad potential to significantly improve intranasal and, eventually, oral drug delivery. The development of an advanced intranasal formulation for the obesity therapeutic PYY(3-36), the endogenous Y2 receptor agonist is also reviewed.
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Affiliation(s)
- Paul H Johnson
- Nastech Pharmaceutical Company, Inc., Bothell, WA 98021, USA.
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382
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Chen Y, Tachibana O, Hasegawa M, Xu R, Hamada JI, Yamashita J, Hashimoto N, Takahashi JA. Absence of Tight Junctions between Microvascular Endothelial Cells in Human Cerebellar Hemangioblastomas. Neurosurgery 2006; 59:660-70; discussion 660-70. [PMID: 16955048 DOI: 10.1227/01.neu.0000223372.18607.d7] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Abstract
OBJECTIVE:
Endothelial tight junctions form the main barrier of the blood-brain barrier (BBB). In human hemangioblastomas, cyst formation is a common and important clinical manifestation. Although most researchers consider that the cyst formation in hemangioblastomas may be caused by the breakdown of the BBB, the underlying molecular mechanisms for cyst formation remain unknown. At present, there are few reports about the change of tight junctions in microvessel endothelium of human hemangioblastomas. The purpose of this research is to investigate the change of tight junction and its major molecular components in microvessel endothelium of human hemangioblastomas.
METHODS:
Twenty-four consecutive patients with cerebellar hemangioblastomas were studied. Tight junctions in the microvessels of hemangioblastomas and the control brain were examined by electron microscopy. Immunohistochemistry and double immunofluorescent microscopy were used to analyze the expression of CLN5 and its relationship with astrocytic endfeet in the control brain and hemangioblastomas. Quantitative real-time reverse-transcriptase polymerase chain reaction and Western blots were used to investigate the expression level of CLN5 in hemangioblastomas. Triple immunofluorescent microscopy was used to analyze the coexpression of vascular endothelial growth factor, vascular endothelial growth factor-R1, and placenta growth factor on microvessels of hemangioblastomas. Clinical and experimental data were correlated and analyzed by the one-way analysis of variance, Kruskal-Wallis test, and Spearman rank correlation test.
RESULTS:
In the control brain, the paracellular cleft between adjacent endothelial cells is sealed by continuous strands of tight junctions. In cystic hemangioblastomas, a significant paracellular cleft could be found between adjacent endothelial cells. Some endothelial cells were connected with adherens junction and no tight junction was found between them. Compared with the control brain, expression of CLN5 was decreased in cystic hemangioblastomas (P < 0.05). Phosphorylated CLN5 was detected in most hemangioblastomas, but not in the control brain. Microvessels in hemangioblastomas showed a significant absence of astrocytic endfeet. Coexpression of vascular endothelial growth factor, vascular endothelial growth factor-R1, and placenta growth factor was detected in the endothelial cells. The Spearman rank correlation test showed a significant correlation between a greater degree of CLN5 expression and less morphological cystic formation in these patients studied (correlation coefficient = −0.520; P = 0.009).
CONCLUSION:
The continuity of tight junctions of the BBB is interrupted in human cerebellar hemangioblastomas. Significant absence of astrocytic endfeet and tight junctions can be found in microvessels of hemangioblastomas, which may lead to the breakdown of the BBB in these tumors. These findings suggest that the absence of tight junctions might play a role in cyst formation of hemangioblastomas.
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Affiliation(s)
- Yizhao Chen
- Department of Neurosurgery, Graduate School of Medicine, Kanazawa University, Kanazawa, Japan
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383
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Cummins PM, von Offenberg Sweeney N, Killeen MT, Birney YA, Redmond EM, Cahill PA. Cyclic strain-mediated matrix metalloproteinase regulation within the vascular endothelium: a force to be reckoned with. Am J Physiol Heart Circ Physiol 2006; 292:H28-42. [PMID: 16951049 DOI: 10.1152/ajpheart.00304.2006] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
The vascular endothelium is a dynamic cellular interface between the vessel wall and the bloodstream, where it regulates the physiological effects of humoral and biomechanical stimuli on vessel tone and remodeling. With respect to the latter hemodynamic stimulus, the endothelium is chronically exposed to mechanical forces in the form of cyclic circumferential strain, resulting from the pulsatile nature of blood flow, and shear stress. Both forces can profoundly modulate endothelial cell (EC) metabolism and function and, under normal physiological conditions, impart an atheroprotective effect that disfavors pathological remodeling of the vessel wall. Moreover, disruption of normal hemodynamic loading can be either causative of or contributory to vascular diseases such as atherosclerosis. EC-matrix interactions are a critical determinant of how the vascular endothelium responds to these forces and unquestionably utilizes matrix metalloproteinases (MMPs), enzymes capable of degrading basement membrane and interstitial matrix molecules, to facilitate force-mediated changes in vascular cell fate. In view of the growing importance of blood flow patterns and mechanotransduction to vascular health and pathophysiology, and considering the potential value of MMPs as therapeutic targets, a timely review of our collective understanding of MMP mechanoregulation and its impact on the vascular endothelium is warranted. More specifically, this review primarily summarizes our current knowledge of how cyclic strain regulates MMP expression and activation within the vascular endothelium and subsequently endeavors to address the direct and indirect consequences of this on vascular EC fate. Possible relevance of these phenomena to vascular endothelial dysfunction and pathological remodeling are also addressed.
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Affiliation(s)
- Philip M Cummins
- Vascular Health Research Centre, Faculty of Science and Health, Dublin City Univ., Dublin, Ireland.
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384
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Groten T, Fraser HM, Duncan WC, Konrad R, Kreienberg R, Wulff C. Cell junctional proteins in the human corpus luteum: changes during the normal cycle and after HCG treatment. Hum Reprod 2006; 21:3096-102. [PMID: 16923746 DOI: 10.1093/humrep/del286] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
BACKGROUND Regulation of tissue remodelling and ovarian permeability by intercellular adhesion complexes may be involved in normal and pathological ovarian function. Therefore, the occurrence, distribution and hormonal control of the adherens junction protein vascular endothelial cadherin (VE-cadherin) and the tight junction proteins occludin and claudin in the human corpus luteum (CL) were investigated. METHODS CLs from patients undergoing hysterectomy for benign reasons were enucleated during early, mid- and late stages of the functional luteal phase and after HCG rescue in vivo. Immunostaining for occludin, claudins 1 and 5 and VE-cadherin was carried out on fixed tissue. Endothelial cells, granulosa lutein cells and theca lutein cells were identified by reference to serial sections immunostained for CD34, 17alpha-hydroxylase and 3beta-hydroxy-steroid-dehydrogenase. Quantitative analyses were performed using image analyses. RESULTS Occludin was localized to the plasma membrane of granulosa lutein cells and endothelial cells but was absent in theca lutein cells. Claudin 1 was exclusively localized to the plasma membrane of steroidogenic cells. Claudin 5 and VE-cadherin were only present in endothelial cells. After HCG administration in vivo, adherens and tight junction proteins were significantly down-regulated (P < 0.05). CONCLUSIONS The decrease of junctional proteins after HCG treatment suggests a hormonal control of tight and adherens junctions in the CL associated with tissue remodelling and an increase in luteal permeability during early pregnancy.
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Affiliation(s)
- T Groten
- Department of Obstetrics and Gynecology, University of Ulm, Ulm, Germany
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385
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Boehm C, Gibert M, Geny B, Popoff MR, Rodriguez P. Modification of epithelial cell barrier permeability and intercellular junctions by Clostridium sordellii lethal toxins. Cell Microbiol 2006; 8:1070-85. [PMID: 16819961 DOI: 10.1111/j.1462-5822.2006.00687.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
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.
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Affiliation(s)
- Catherine Boehm
- Unité des Bactéries anaérobies et Toxines, Institut Pasteur, 28 rue du Dr Roux, 75724, Paris Cedex 15, France
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386
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Yan S, Wang X, Chai H, Wang H, Yao Q, Chen C. Secretoneurin increases monolayer permeability in human coronary artery endothelial cells. Surgery 2006; 140:243-51. [PMID: 16904976 DOI: 10.1016/j.surg.2006.04.001] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2006] [Revised: 04/27/2006] [Accepted: 04/28/2006] [Indexed: 01/22/2023]
Abstract
BACKGROUND Secretoneurin (SN), a novel neuropeptide, may play a role in inflammation in the vascular system. However, the interaction between SN and endothelial cells is largely unknown. This study's objective is to investigate the effects of SN on endothelial permeability and its associated molecular mechanisms in human coronary artery endothelial cells (HCAECs). METHODS HCAECs were treated with SN. Monolayer permeability was assayed with a transwell system and a Texas Red-labeled dextran tracer. The mRNA and protein levels of endothelial junctional molecules were determined by real-time reverse transcriptase polymerase chain reaction (RT-PCR) and Western blot analysis, respectively. Superoxide anion was determined by fluorescent dye dihydroethidium-based flow cytometry detection. Mitogen-activated protein kinase (MAPK) activation was determined by Bio-Plex immunoassay. RESULTS HCAECs were treated with SN (15, 30, and 60 ng/ml) for 24 hours and showed a significant increase of monolayer permeability by 12%, 33%, and 47%, respectively, compared with controls (P < 0.05). SN-treated cells showed a significant reduction of zonula occludens-1 (ZO-1) and occludin at both mRNA and protein levels (P < 0.05). In addition, SN significantly increased superoxide anion in HCAECs (P < 0.05). Furthermore, SN activated MAPKs (JNK and ERK1/2) but not p38. Both antioxidant seleno-L-methionine (SeMet) and specific inhibitors of JNK and ERK1/2 effectively blocked SN-induced monolayer permeability increase in HCAECs. CONCLUSIONS SN significantly increases monolayer permeability and reduces the expression of ZO-1 and occludin through oxidative stress and the activation of JNK and ERK1/2 in HCAECs. This study provides direct evidence that SN impairs endothelial barrier function.
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Affiliation(s)
- Shaoyu Yan
- Molecular Surgeon Research Center, Division of Vascular Surgery and Endovascular Therapy, Michael E. DeBakey Department of Surgery, Baylor College of Medicine, Houston, TX 77030, USA
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387
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Buffington CAT, Westropp JL, Chew DJ, Bolus RR. Clinical evaluation of multimodal environmental modification (MEMO) in the management of cats with idiopathic cystitis. J Feline Med Surg 2006; 8:261-8. [PMID: 16616567 PMCID: PMC10822542 DOI: 10.1016/j.jfms.2006.02.002] [Citation(s) in RCA: 94] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/12/2006] [Indexed: 11/25/2022]
Abstract
This prospective observational study evaluated client-reported recurrence of lower urinary tract signs (LUTS) and other signs of abnormalities in cats with idiopathic cystitis after institution of multimodal environmental modification (MEMO). Forty-six client-owned indoor-housed cats with idiopathic cystitis, diagnosed based on a history of recurrent LUTS and evidence of absence of urolithiasis or bacterial urinary tract infection were studied. In addition to their usual care, clients were offered recommendations for MEMO based on a detailed environmental history. Cases were followed for 10 months by client contact to determine the effect of MEMO on LUTS and other signs. Significant (P<0.05) reductions in LUTS, fearfulness, nervousness, signs referable to the respiratory tract, and a trend (P<0.1) toward reduced aggressive behavior and signs referable to the lower intestinal tract were identified. These results suggest that MEMO is a promising adjunctive therapy for indoor-housed cats with LUTS, and should be followed up with prospective controlled clinical trials.
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Affiliation(s)
- C A Tony Buffington
- Department of Veterinary Clinical Sciences, The Ohio State University Veterinary Hospital, 601 Vernon L. Tharp Street, Columbus, OH 43210-1089, USA.
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388
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Sergent T, Parys M, Garsou S, Pussemier L, Schneider YJ, Larondelle Y. Deoxynivalenol transport across human intestinal Caco-2 cells and its effects on cellular metabolism at realistic intestinal concentrations. Toxicol Lett 2006; 164:167-76. [PMID: 16442754 DOI: 10.1016/j.toxlet.2005.12.006] [Citation(s) in RCA: 148] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2005] [Revised: 12/15/2005] [Accepted: 12/15/2005] [Indexed: 01/01/2023]
Abstract
Deoxynivalenol (DON) is a mycotoxin of the trichothecenes family to which human exposure levels can be high. Epidemiological studies suggest a link between DON and gastrointestinal illness. We investigated the interaction of DON with Caco-2 cells, a widely used in vitro model of the human intestinal barrier. The apical to basolateral (absorption) and basolateral to apical (excretion) transports of DON were found strictly proportional to both the initial concentration and the duration of the incubation. The absorption and excretion mean rates were similar to those of mannitol and were increased in the presence of EGTA, a calcium chelator. These data suggest that DON crosses the intestinal mucosa by a paracellular pathway through the tight junctions although some passive transcellular diffusion may not be ruled out. The DON transport was not affected by P-glycoprotein (PgP) or multidrug resistance-associated proteins (MRPs) inhibitors. A prolonged exposure to DON provokes the phosphorylation of the mitogen-activated protein kinases (MAPKs) Erk1/2, p38 and SAPK/JNK, as well as a decrease of the transepithelial resistance, suggesting that DON could trigger intestinal inflammation. These data imply that a chronic exposure to DON contaminated foods may negatively affect human health by altering the intestinal mucosa integrity and by inducing the MAPKs implicated in inflammation.
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Affiliation(s)
- Thérèse Sergent
- Laboratoire de Biochimie Cellulaire, Croix du Sud, 5, Institut des Sciences de la Vie & Université Catholique de Louvain, B-1348 Louvain-la-Neuve, Belgium
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389
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Li B, Zhao WD, Tan ZM, Fang WG, Zhu L, Chen YH. Involvement of Rho/ROCK signalling in small cell lung cancer migration through human brain microvascular endothelial cells. FEBS Lett 2006; 580:4252-60. [PMID: 16828752 DOI: 10.1016/j.febslet.2006.06.056] [Citation(s) in RCA: 116] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2006] [Revised: 05/02/2006] [Accepted: 06/21/2006] [Indexed: 01/28/2023]
Abstract
Small cell lung cancer (SCLC) cells migration across human brain microvascular endothelial cells (HBMECs) is an essential step of brain metastases. Here we investigated signalling pathways in HBMECs contributing to the process. Inhibition of endothelial Rho kinase (ROCK) with Y27632 and overexpression of ROCK dominant-negative mutant prevented SCLC cells, NCI-H209, transendothelial migration and the concomitant changes of tight junction. Conversely, inhibition of phosphatidylinositol 3-kinase (PI3K) and protein kinase C (PKC) had no effects. Furthermore, endothelial RhoA protein was activated during NCI-H209 cells transendothelial migration. Rho/ROCK participated in NCI-H209 cells transendothelial migration through regulating actin cytoskeleton reorganization. These results suggested that Rho/ROCK was required for SCLC cells transendothelial migration.
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Affiliation(s)
- Bo Li
- Department of Developmental Biology, Key Laboratory of Cell Biology, Ministry of Public Health of China, China Medical University, 92 Bei Er Road, Shenyang, Liaoning 110001, PR China
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390
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Murphy EF, Jewell C, Hooiveld GJ, Muller M, Cashman KD. Conjugated linoleic acid enhances transepithelial calcium transport in human intestinal-like Caco-2 cells: an insight into molecular changes. Prostaglandins Leukot Essent Fatty Acids 2006; 74:295-301. [PMID: 16650747 DOI: 10.1016/j.plefa.2006.03.003] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/23/2005] [Accepted: 03/12/2006] [Indexed: 10/24/2022]
Abstract
Conjugated linoleic acid (CLA) has been shown to enhance paracellular and transcellular Ca transport across human intestinal-like Caco-2 cell monolayers. The mechanisms of action, however, are still unclear. Therefore, this study investigated the molecular mechanisms underlying CLA-induced stimulation of Ca transport by use of preliminary microarray data together with more detailed and comprehensive quantitative reverse transcriptase-PCR analysis. While molecular expression of junctional adhesion molecule (JAM), ZO-2, ZO-3, claudin 2 and claudin 3 were unaltered, ZO-1, occludin, and claudin 4 were all up-regulated (1.6, 1.6, 2.4-fold, respectively; P<0.001-0.01) and claudin 1 down-regulated (2.5-fold; P<0.05) by trans-10, cis-12 CLA, which may underpin its effects on tight-junction function and paracellular Ca transport. On the other hand, expression of key genes involved in transcellular Ca transport (CaT1, ECaC1, calbindin D(9k), vitamin D receptor and PMCA) were unaffected by trans-10, cis-12 CLA. The mechanism by which CLA enhances transcellular Ca transport remains unclear.
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Affiliation(s)
- Eileen F Murphy
- Department of Food and Nutritional Sciences, University College, Cork, Ireland
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391
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Dolfini E, Roncoroni L, Elli L, Fumagalli C, Colombo R, Ramponi S, Forlani F, Bardella MT. Cytoskeleton reorganization and ultrastructural damage induced by gliadin in a three-dimensional in vitro model. World J Gastroenterol 2006; 11:7597-601. [PMID: 16437684 PMCID: PMC4727224 DOI: 10.3748/wjg.v11.i48.7597] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
AIM To evaluate the interplay between gliadin and LoVo cells and the direct effect of gliadin on cytoskeletal patterns. METHODS We treated LoVo multicellular spheroids with digested bread wheat gliadin in order to investigate their morphology and ultrastructure (by means of light microscopy and scanning electron microscopy), and the effect of gliadin on actin (phalloidin fluorescence) and the tight-junction protein occludin and zonula occluden-1. RESULTS The treated spheroids had deep holes and surface blebs, whereas the controls were smoothly surfaced ovoids. The incubation of LoVo spheroids with gliadin decreased the number of intracellular actin filaments, impaired and disassembled the integrity of the tight-junction system. CONCLUSION Our data obtained from an "in vivo-like" polarized culture system confirm the direct noxious effect of gliadin on the cytoskeleton and tight junctions of epithelial cells. Unlike two-dimensional cell culture systems, the use of multicellular spheroids seems to provide a suitable model for studying cell-cell interactions.
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Affiliation(s)
- Ersilia Dolfini
- Department of Biology and Genetics for Health Sciences, Via Viotti 3/5, 20131 Milano, Italy.
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392
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Sohrabji F, Bake S. Age-related changes in neuroprotection: is estrogen pro-inflammatory for the reproductive senescent brain? Endocrine 2006; 29:191-7. [PMID: 16785595 DOI: 10.1385/endo:29:2:191] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/25/2005] [Revised: 11/30/1999] [Accepted: 10/25/2005] [Indexed: 11/11/2022]
Abstract
Estrogen replacement therapy (ERT) is widely prescribed to postmenopausal women for relief from the adverse vasomotor effects of menopause, to reduce bone loss, to improve cardiovascular health, and to protect against metabolic disorders. However, there is now greater awareness of the increased risk to benefit ratio from the recently concluded Women's Health Initiative Memory Study (WHIMS), which reported that ERT increased the risk of cognitive impairment and dementia in elderly women. Studies from the experimental literature indicate that while estrogen is neuroprotective in many instances, estrogen replacement can be deleterious in some cases. These differences may be partly due to the age and species of the experimental model. The majority of the experimental data comes from studies where the age or endocrine status of the animal model is not comparable to that of menopausal or postmenopausal women, such as those in the WHIMS study. In this review, we will focus on age-related changes in estrogen's neuroprotective effects and evidence that reproductive senescence-related changes in the blood-brain barrier and the immune system may result in deleterious consequences for ERT.
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Affiliation(s)
- Farida Sohrabji
- Neuroscience and Experimental Therapeutics, Department of Human Anatomy & Medical Neurobiology, TAMHSC College of Medicine, College Station, TX 77843-1114, USA.
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393
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Alvarez JI, Teale JM. Breakdown of the blood brain barrier and blood–cerebrospinal fluid barrier is associated with differential leukocyte migration in distinct compartments of the CNS during the course of murine NCC. J Neuroimmunol 2006; 173:45-55. [PMID: 16406118 DOI: 10.1016/j.jneuroim.2005.11.020] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2005] [Accepted: 11/21/2005] [Indexed: 10/25/2022]
Abstract
Brain homeostasis is normally protected by the blood brain barrier (BBB) and the blood-cerebrospinal fluid barrier (BCB), barriers that function in distinct CNS compartments and consist of different types of blood vessels including pial (subarachnoid spaces, leptomeninges), parenchymal (cerebral cortex) and ventricular vessels. In this study, a mouse model of neurocysticercosis was used to distinguish between changes in the permeability of the BBB and the BCB and determine the association of such alterations on leukocyte infiltration. Mice were intracranially infected with the parasite Mesocestoides corti and sacrificed at various times post infection. Different anatomical areas of infected brain were analyzed by three color immunofluoresence utilizing antibodies against serum proteins to assess brain barrier permeability, glial fibrillary acidic protein (GFAP) to detect astrocytes, and specific cell surface markers to determine the subpopulations of leukocytes infiltrating the CNS at particular sites. The results indicate increased permeability of all three types of vessels/structural sites as a result of infection evidenced by serum proteins and leukocyte extravasation but with considerable differences in the timing and extent of these permeability changes. Parenchymal vessels were the most resilient to changes in permeability whereas pial vessels were the least. Choroid plexus vessels of the ventricles also appeared less susceptible to increased permeability compared with pial vessels. In addition, parenchymal vessels appeared impermeable to particular types of immune cells even after extended periods of infection. Additionally, alterations in reactive astrocytes juxtaposed to blood vessels that exhibited increased permeability displayed increased expression of cytokines known to regulate brain barrier function. The results suggest that access of leukocytes and serum derived factors into the infected brain depend on several parameters including the anatomical area, type of vascular bed, cell phenotype and cytokine microenvironment.
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Affiliation(s)
- Jorge I Alvarez
- Department of Microbiology and Immunology, University of Texas Health Science Center at San Antonio, 7703 Floyd Curl Drive, San Antonio, TX 78229-3900, USA
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394
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Lund CV, Nguyen MT, Owens GC, Pakchoian AJ, Shaterian A, Kruse CA, Eliceiri BP. Reduced glioma infiltration in Src-deficient mice. J Neurooncol 2006; 78:19-29. [PMID: 16552622 PMCID: PMC4002283 DOI: 10.1007/s11060-005-9068-y] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2005] [Accepted: 10/31/2005] [Indexed: 02/07/2023]
Abstract
Malignant brain tumors, such as glioblastoma, are characterized by extensive angiogenesis and permeability of the blood-brain barrier (BBB). The infiltration of glioma cells away from the primary tumor mass is a pathological characteristic of glial tumors. The infiltrating tumor cells represent a significant factor in tumor recurrence following surgical debulking, radiation, and chemotherapy treatments. Vascular endothelial growth factor (VEGF)-mediated vascular permeability (VP) has been associated with the progression of glioma tumor growth and infiltration into surrounding normal brain parenchyma. While VEGF induces a robust VP response in control mice (src+/+ or src+/-), the VP response is blocked in src-/- mice that demonstrate a 'leakage-resistant phenotype' in the brain. We used the Src-deficient mouse model to determine the role of Src in the maintenance of the BBB following orthotopic implantation and growth of glioma cells in the brain. Although solid tumor growth was the same in control and src-/- mice, the infiltrating component of glioma growth was reduced in src-/- mice. Characterization of the expression and localization of the extracellular matrix (ECM) protein fibrinogen was evaluated to determine the effect of a Src-mediated VP defect in the host compartment. These studies indicate that the reduced VP of host brain blood vessels of src-/- mice mediates a reduction in glioma cell invasion in a mouse brain tumor xenograft model.
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Affiliation(s)
- Caren V. Lund
- Division of Cancer Biology La Jolla Institute for Molecular Medicine, San Diego, CA, 92121, USA
- The Neurosciences Institute, 92121, San Diego, CA, USA
| | - Mai T.N. Nguyen
- Division of Cancer Biology La Jolla Institute for Molecular Medicine, San Diego, CA, 92121, USA
- The Neurosciences Institute, 92121, San Diego, CA, USA
| | - Geoffrey C. Owens
- Division of Cancer Biology La Jolla Institute for Molecular Medicine, San Diego, CA, 92121, USA
- The Neurosciences Institute, 92121, San Diego, CA, USA
| | - Andrew J. Pakchoian
- Division of Cancer Biology La Jolla Institute for Molecular Medicine, San Diego, CA, 92121, USA
- The Neurosciences Institute, 92121, San Diego, CA, USA
| | - Ashkaun Shaterian
- Division of Cancer Biology La Jolla Institute for Molecular Medicine, San Diego, CA, 92121, USA
- The Neurosciences Institute, 92121, San Diego, CA, USA
| | - Carol A. Kruse
- Division of Cancer Biology La Jolla Institute for Molecular Medicine, San Diego, CA, 92121, USA
- The Neurosciences Institute, 92121, San Diego, CA, USA
| | - Brian P. Eliceiri
- Division of Cancer Biology La Jolla Institute for Molecular Medicine, San Diego, CA, 92121, USA
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395
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Stamatovic SM, Dimitrijevic OB, Keep RF, Andjelkovic AV. Protein Kinase Cα-RhoA Cross-talk in CCL2-induced Alterations in Brain Endothelial Permeability. J Biol Chem 2006; 281:8379-88. [PMID: 16439355 DOI: 10.1074/jbc.m513122200] [Citation(s) in RCA: 140] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Monocyte chemoattractant protein-1 (MCP-1 or CCL2) regulates blood-brain barrier permeability by inducing morphological and biochemical alterations in the tight junction (TJ) complex between brain endothelial cells. The present study used cultured brain endothelial cells to examine the signaling networks involved in the redistribution of TJ proteins (occludin, ZO-1, ZO-2, claudin-5) by CCL2. The CCL2-induced alterations in the brain endothelial barrier were associated with de novo Ser/Thr phosphorylation of occludin, ZO-1, ZO-2, and claudin-5. The phosphorylated TJ proteins were redistributed/localized in Triton X-100-soluble as well as Triton X-100-insoluble cell fractions. Two protein kinase C (PKC) isoforms, PKCalpha and PKCzeta, had a significant impact on this event. Inhibition of their activity using dominant negative mutants PKCalpha-DN and PKCzeta-DN diminished CCL2 effects on brain endothelial permeability. Previous data indicate that Rho/Rho kinase signaling is involved in CCL2 regulation of brain endothelial permeability. The interactions between the PKC and Rho/Rho kinase pathways were therefore examined. Rho, PKCalpha, and PKCzeta activities were knocked down using dominant negative mutants (T17Rho, PKCalpha-DN, and PKCzeta-DN, respectively). PKCalpha and Rho, but not PKCzeta and Rho, interacted at the level of Rho, with PKCalpha being a downstream target for Rho. Double transfection experiments using dominant negative mutants confirmed that this interaction is critical for CCL2-induced redistribution of TJ proteins. Collectively these data suggest for the first time that CCL2 induces brain endothelial hyperpermeability via Rho/PKCalpha signal pathway interactions.
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Affiliation(s)
- Svetlana M Stamatovic
- Department of Neurosurgery, University of Michigan Medical School, Ann Arbor, Michigan 48109, USA
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396
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Simard A, Di Pietro E, Young CR, Plaza S, Ryan AK. Alterations in heart looping induced by overexpression of the tight junction protein Claudin-1 are dependent on its C-terminal cytoplasmic tail. Mech Dev 2006; 123:210-27. [PMID: 16500087 DOI: 10.1016/j.mod.2005.12.004] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2005] [Revised: 12/21/2005] [Accepted: 12/21/2005] [Indexed: 10/25/2022]
Abstract
In vertebrates, the positioning of the internal organs relative to the midline is asymmetric and evolutionarily conserved. A number of molecules have been shown to play critical roles in left-right patterning. Using representational difference analysis to identify genes that are differentially expressed on the left and right sides of the chick embryo, we cloned chick Claudin-1, an integral component of epithelial tight junctions. Here, we demonstrate that retroviral overexpression of Claudin-1, but not Claudin-3, on the right side of the chick embryo between HH stages 4 and 7 randomizes the direction of heart looping. This effect was not observed when Claudin-1 was overexpressed on the left side of the embryo. A small, but reproducible, induction of Nodal expression in the perinodal region on the right side of the embryo was noted in embryos that were injected with Claudin-1 retroviral particles on their right sides. However, no changes in Lefty,Pitx2 or cSnR expression were observed. In addition, Flectin expression remained higher in the left dorsal mesocardial folds of embryos with leftwardly looped hearts resulting from Claudin-1 overexpression on the right side of the embryo. We demonstrated that Claudin-1's C-terminal cytoplasmic tail is essential for this effect: mutation of a PKC phosphorylation site in the Claudin-1 C-terminal cytoplasmic domain at threonine-206 eliminates Claudin-1's ability to randomize the direction of heart looping. Taken together, our data provide evidence that appropriate expression of the tight junction protein Claudin-1 is required for normal heart looping and suggest that phosphorylation of its cytoplasmic tail is responsible for mediating this function.
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Affiliation(s)
- Annie Simard
- Departments of Pediatrics and Human Genetics, McGill University, Montréal, Que., Canada
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397
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398
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Collins NT, Cummins PM, Colgan OC, Ferguson G, Birney YA, Murphy RP, Meade G, Cahill PA. Cyclic strain-mediated regulation of vascular endothelial occludin and ZO-1: influence on intercellular tight junction assembly and function. Arterioscler Thromb Vasc Biol 2005; 26:62-8. [PMID: 16269664 DOI: 10.1161/01.atv.0000194097.92824.b3] [Citation(s) in RCA: 72] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
OBJECTIVE The vascular endothelium constitutes a highly effective fluid/solute barrier through the regulated apposition of intercellular tight junction complexes. Because endothelium-mediated functions and pathology are driven by hemodynamic forces (cyclic strain and shear stress), we hypothesized a dynamic regulatory link between endothelial tight junction assembly/function and hemodynamic stimuli. We, therefore, examined the effects of cyclic strain on the expression, modification, and function of 2 pivotal endothelial tight junction components, occludin and ZO-1. METHODS AND RESULTS For these studies, bovine aortic endothelial cells were subjected to physiological levels of equibiaxial cyclic strain (5% strain, 60 cycles/min, 24 hours). In response to strain, both occludin and ZO-1 protein expression increased by 2.3+/-0.1-fold and 2.0+/-0.3-fold, respectively, concomitant with a strain-dependent increase in occludin (but not ZO-1) mRNA levels. These changes were accompanied by reduced occludin tyrosine phosphorylation (75.7+/-8%) and increased ZO-1 serine/threonine phosphorylation (51.7+/-9% and 82.7+/-25%, respectively), modifications that could be completely blocked with tyrosine phosphatase and protein kinase C inhibitors (dephostatin and rottlerin, respectively). In addition, there was a significant strain-dependent increase in endothelial occludin/ZO-1 association (2.0+/-0.1-fold) in parallel with increased localization of both occludin and ZO-1 to the cell-cell border. These events could be completely blocked by dephostatin and rottlerin, and they correlated with a strain-dependent reduction in transendothelial permeability to FITC-dextran. CONCLUSIONS Overall, these findings indicate that cyclic strain modulates both the expression and phosphorylation state of occludin and ZO-1 in vascular endothelial cells, with putative consequences for endothelial tight junction assembly and barrier integrity.
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Affiliation(s)
- Nora T Collins
- Vascular Health Research Centre, Faculty of Science and Health, Dublin City University, Glasnevin, Dublin 9, Ireland
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399
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Ivanov AI, Nusrat A, Parkos CA. Endocytosis of the apical junctional complex: mechanisms and possible roles in regulation of epithelial barriers. Bioessays 2005; 27:356-65. [PMID: 15770686 DOI: 10.1002/bies.20203] [Citation(s) in RCA: 124] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Tight junctions (TJ) and adherens junctions (AJ) regulate cell-cell adhesion and barrier function of simple polarized epithelia. These junctions are positioned in the apical end of the lateral plasma membrane and form the so-called apical junctional complex (AJC). Although initially seen as purely structural features, the AJC is now known to play important roles in cell differentiation and proliferation. The AJC is a highly dynamic entity, undergoing rapid remodeling during normal epithelial morphogenesis and under pathologic conditions. There is growing evidence that remodeling of the AJC is mediated by internalization of junctional proteins. This review summarizes what is known about endocytic pathways, intracellular destinations and signaling cascades involved in internalization of AJC proteins. Potential biological roles for AJC endocytosis in maintaining functional apical junctions, reversible opening of epithelial barrier and disruption of intercellular adhesion are also discussed.
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Affiliation(s)
- Andrei I Ivanov
- Epithelial Pathobiology Research Unit, Department of Pathology and Laboratory Medicine, Emory University, Room 115, 615 Michael Street, Atlanta, GA 30322, USA.
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400
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Schiera G, Sala S, Gallo A, Raffa MP, Pitarresi GL, Savettieri G, Di Liegro I. Permeability properties of a three-cell type in vitro model of blood-brain barrier. J Cell Mol Med 2005; 9:373-9. [PMID: 15963256 PMCID: PMC6740205 DOI: 10.1111/j.1582-4934.2005.tb00362.x] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
We previously found that RBE4.B brain capillary endothelial cells (BCECs) form a layer with blood-brain barrier (BBB) properties if co-cultured with neurons for at least one week. As astrocytes are known to modulate BBB functions, we further set a culture system that included RBE4.B BCECs, neurons and astrocytes. In order to test formation of BBB, we measured the amount of 3H-sucrose able to cross the BCEC layer in this three-cell type model of BBB. Herein we report that both neurons and astrocytes induce a decrease in the permeability of the BCEC layer to sucrose. These effects are synergic as if BCECs are cultured with both neurons and astrocytes for 5 days, permeability to sucrose decreases even more. By Western analysis, we also found that, in addition to the canonical 60 kDa occludin, anti-occludin antibodies recognize a smaller protein of 48 kDa which accumulates during rat brain development. Interestingly this latter protein is present at higher amounts in endothelial cells cultured in the presence of both astrocytes and neurons, that is in those conditions in which sucrose permeation studies indicate formation of BBB.
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Affiliation(s)
- Gabriella Schiera
- Dipartimento di Biologia Cellulare e dello Sviluppo Alberto Monroy, Università degli Studi di Palermo, Palermo, 90128, Italy
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