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Nikolakis D, de Voogd FAE, Pruijt MJ, Grootjans J, van de Sande MG, D’Haens GR. The Role of the Lymphatic System in the Pathogenesis and Treatment of Inflammatory Bowel Disease. Int J Mol Sci 2022; 23:ijms23031854. [PMID: 35163775 PMCID: PMC8836364 DOI: 10.3390/ijms23031854] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2021] [Revised: 01/26/2022] [Accepted: 02/01/2022] [Indexed: 02/04/2023] Open
Abstract
Although the number of therapeutic options for the treatment of inflammatory bowel disease (IBD) has increased in recent years, patients suffer from decreased quality of life due to non-response or loss of response to the currently available treatments. An increased understanding of the disease’s etiology could provide novel insights for treatment strategies in IBD. Lymphatic system components are generally linked to immune responses and presumably related to inflammatory diseases pathophysiology. This review aims to summarize findings on immune-mediated mechanisms in lymphoid tissues linked with IBD pathogenesis and (potential) novel treatments. Enhanced innate and adaptive immune responses were observed in mesenteric lymph nodes (MLNs) and other lymphoid structures, such as Peyer’s patches, in patients with IBD and in animal models. Furthermore, the phenomenon of lymphatic obstruction in the form of granulomas in MLNs and lymphatic vessels correlates with disease activity. There is also evidence that abnormalities in the lymphatic stromal components and lymph node microbiome are common in IBD and could be exploited therapeutically. Finally, novel agents targeting lymphocyte trafficking have been added to the treatment armamentarium in the field of IBD. Overall, gut-associated lymphoid tissue plays a key role in IBD immunopathogenesis, which could offer novel therapeutic targets.
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Affiliation(s)
- Dimitrios Nikolakis
- Department of Gastroenterology, Amsterdam Institute for Gastroenterology Endocrinology and Metabolism, Academic Medical Center, Amsterdam UMC, University of Amsterdam, Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands; (D.N.); (F.A.E.d.V.); (M.J.P.); (J.G.)
- Department of Rheumatology and Clinical Immunology, Amsterdam Rheumatology & Immunology Center (ARC), Amsterdam UMC, University of Amsterdam, Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands;
- Department of Experimental Immunology, Amsterdam Institute for Infection & Immunity, Amsterdam UMC, University of Amsterdam, Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands
- Onassis Foundation, 4 Aeschinou Street, 10558 Athens, Greece
| | - Floris A. E. de Voogd
- Department of Gastroenterology, Amsterdam Institute for Gastroenterology Endocrinology and Metabolism, Academic Medical Center, Amsterdam UMC, University of Amsterdam, Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands; (D.N.); (F.A.E.d.V.); (M.J.P.); (J.G.)
| | - Maarten J. Pruijt
- Department of Gastroenterology, Amsterdam Institute for Gastroenterology Endocrinology and Metabolism, Academic Medical Center, Amsterdam UMC, University of Amsterdam, Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands; (D.N.); (F.A.E.d.V.); (M.J.P.); (J.G.)
| | - Joep Grootjans
- Department of Gastroenterology, Amsterdam Institute for Gastroenterology Endocrinology and Metabolism, Academic Medical Center, Amsterdam UMC, University of Amsterdam, Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands; (D.N.); (F.A.E.d.V.); (M.J.P.); (J.G.)
| | - Marleen G. van de Sande
- Department of Rheumatology and Clinical Immunology, Amsterdam Rheumatology & Immunology Center (ARC), Amsterdam UMC, University of Amsterdam, Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands;
- Department of Experimental Immunology, Amsterdam Institute for Infection & Immunity, Amsterdam UMC, University of Amsterdam, Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands
| | - Geert R. D’Haens
- Department of Gastroenterology, Amsterdam Institute for Gastroenterology Endocrinology and Metabolism, Academic Medical Center, Amsterdam UMC, University of Amsterdam, Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands; (D.N.); (F.A.E.d.V.); (M.J.P.); (J.G.)
- Correspondence:
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Lucas R, Hadizamani Y, Gonzales J, Gorshkov B, Bodmer T, Berthiaume Y, Moehrlen U, Lode H, Huwer H, Hudel M, Mraheil MA, Toque HAF, Chakraborty T, Hamacher J. Impact of Bacterial Toxins in the Lungs. Toxins (Basel) 2020; 12:toxins12040223. [PMID: 32252376 PMCID: PMC7232160 DOI: 10.3390/toxins12040223] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2020] [Revised: 03/30/2020] [Accepted: 03/31/2020] [Indexed: 12/13/2022] Open
Abstract
Bacterial toxins play a key role in the pathogenesis of lung disease. Based on their structural and functional properties, they employ various strategies to modulate lung barrier function and to impair host defense in order to promote infection. Although in general, these toxins target common cellular signaling pathways and host compartments, toxin- and cell-specific effects have also been reported. Toxins can affect resident pulmonary cells involved in alveolar fluid clearance (AFC) and barrier function through impairing vectorial Na+ transport and through cytoskeletal collapse, as such, destroying cell-cell adhesions. The resulting loss of alveolar-capillary barrier integrity and fluid clearance capacity will induce capillary leak and foster edema formation, which will in turn impair gas exchange and endanger the survival of the host. Toxins modulate or neutralize protective host cell mechanisms of both the innate and adaptive immunity response during chronic infection. In particular, toxins can either recruit or kill central players of the lung's innate immune responses to pathogenic attacks, i.e., alveolar macrophages (AMs) and neutrophils. Pulmonary disorders resulting from these toxin actions include, e.g., acute lung injury (ALI), the acute respiratory syndrome (ARDS), and severe pneumonia. When acute infection converts to persistence, i.e., colonization and chronic infection, lung diseases, such as bronchitis, chronic obstructive pulmonary disease (COPD), and cystic fibrosis (CF) can arise. The aim of this review is to discuss the impact of bacterial toxins in the lungs and the resulting outcomes for pathogenesis, their roles in promoting bacterial dissemination, and bacterial survival in disease progression.
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Affiliation(s)
- Rudolf Lucas
- Pharmacology and Toxicology, Medical College of Georgia at Augusta University, Augusta, GA 30912, USA;
- Vascular Biology Center, Medical College of Georgia at Augusta University, Augusta, GA 30912, USA;
- Department of Medicine and Division of Pulmonary Critical Care Medicine, Medical College of Georgia at Augusta University, Augusta, GA 30912, USA;
- Correspondence: (R.L.); (J.H.); Tel.: +41-31-300-35-00 (J.H.)
| | - Yalda Hadizamani
- Lungen-und Atmungsstiftung, Bern, 3012 Bern, Switzerland;
- Pneumology, Clinic for General Internal Medicine, Lindenhofspital Bern, 3012 Bern, Switzerland
| | - Joyce Gonzales
- Department of Medicine and Division of Pulmonary Critical Care Medicine, Medical College of Georgia at Augusta University, Augusta, GA 30912, USA;
| | - Boris Gorshkov
- Vascular Biology Center, Medical College of Georgia at Augusta University, Augusta, GA 30912, USA;
| | - Thomas Bodmer
- Labormedizinisches Zentrum Dr. Risch, Waldeggstr. 37 CH-3097 Liebefeld, Switzerland;
| | - Yves Berthiaume
- Department of Medicine, Faculty of Medicine, Université de Montréal, Montréal, QC H3T 1J4, Canada;
| | - Ueli Moehrlen
- Pediatric Surgery, University Children’s Hospital, Zürich, Steinwiesstrasse 75, CH-8032 Zürch, Switzerland;
| | - Hartmut Lode
- Insitut für klinische Pharmakologie, Charité, Universitätsklinikum Berlin, Reichsstrasse 2, D-14052 Berlin, Germany;
| | - Hanno Huwer
- Department of Cardiothoracic Surgery, Voelklingen Heart Center, 66333 Voelklingen/Saar, Germany;
| | - Martina Hudel
- Justus-Liebig-University, Biomedical Research Centre Seltersberg, Schubertstr. 81, 35392 Giessen, Germany; (M.H.); (M.A.M.); (T.C.)
| | - Mobarak Abu Mraheil
- Justus-Liebig-University, Biomedical Research Centre Seltersberg, Schubertstr. 81, 35392 Giessen, Germany; (M.H.); (M.A.M.); (T.C.)
| | - Haroldo Alfredo Flores Toque
- Pharmacology and Toxicology, Medical College of Georgia at Augusta University, Augusta, GA 30912, USA;
- Vascular Biology Center, Medical College of Georgia at Augusta University, Augusta, GA 30912, USA;
| | - Trinad Chakraborty
- Justus-Liebig-University, Biomedical Research Centre Seltersberg, Schubertstr. 81, 35392 Giessen, Germany; (M.H.); (M.A.M.); (T.C.)
| | - Jürg Hamacher
- Lungen-und Atmungsstiftung, Bern, 3012 Bern, Switzerland;
- Pneumology, Clinic for General Internal Medicine, Lindenhofspital Bern, 3012 Bern, Switzerland
- Medical Clinic V-Pneumology, Allergology, Intensive Care Medicine and Environmental Medicine, Faculty of Medicine, Saarland University, University Medical Centre of the Saarland, D-66421 Homburg, Germany
- Institute for Clinical & Experimental Surgery, Faculty of Medicine, Saarland University, D-66421 Homburg, Germany
- Correspondence: (R.L.); (J.H.); Tel.: +41-31-300-35-00 (J.H.)
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Tutunea-Fatan E, Lee JC, Denker BM, Gunaratnam L. Heterotrimeric Gα 12/13 proteins in kidney injury and disease. Am J Physiol Renal Physiol 2020; 318:F660-F672. [PMID: 31984793 DOI: 10.1152/ajprenal.00453.2019] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Gα12 and Gα13 are ubiquitous members of the heterotrimeric guanine nucleotide-binding protein (G protein) family that play central and integrative roles in the regulation of signal transduction cascades within various cell types in the kidney. Gα12/Gα13 proteins enable the kidney to adapt to an ever-changing environment by transducing stimuli from cell surface receptors and accessory proteins to effector systems. Therefore, perturbations in Gα12/Gα13 levels or their activity can contribute to the pathogenesis of various renal diseases, including renal cancer. This review will highlight and discuss the complex and expanding roles of Gα12/Gα13 proteins on distinct renal pathologies, with emphasis on more recently reported findings. Deciphering how the different Gα12/Gα13 interaction networks participate in the onset and development of renal diseases may lead to the discovery of new therapeutic strategies.
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Affiliation(s)
- Elena Tutunea-Fatan
- Matthew Mailing Centre for Translational Transplant Studies, Lawson Health Research Institute, London, Ontario, Canada
| | - Jasper C Lee
- Department of Microbiology and Immunology, University of Western Ontario, London, Ontario, Canada
| | - Bradley M Denker
- Beth Israel Deaconess Medical Center and Department of Medicine, Harvard Medical School, Boston, Massachusetts
| | - Lakshman Gunaratnam
- Matthew Mailing Centre for Translational Transplant Studies, Lawson Health Research Institute, London, Ontario, Canada.,Department of Microbiology and Immunology, University of Western Ontario, London, Ontario, Canada.,Division of Nephrology, Department of Medicine, University of Western Ontario, London, Ontario, Canada
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Scanlon K, Skerry C, Carbonetti N. Association of Pertussis Toxin with Severe Pertussis Disease. Toxins (Basel) 2019; 11:toxins11070373. [PMID: 31252532 PMCID: PMC6669598 DOI: 10.3390/toxins11070373] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2019] [Revised: 06/17/2019] [Accepted: 06/20/2019] [Indexed: 12/26/2022] Open
Abstract
Pertussis, caused by respiratory tract infection with the bacterial pathogen Bordetella pertussis, has long been considered to be a toxin-mediated disease. Bacteria adhere and multiply extracellularly in the airways and release several toxins, which have a variety of effects on the host, both local and systemic. Predominant among these toxins is pertussis toxin (PT), a multi-subunit protein toxin that inhibits signaling through a subset of G protein-coupled receptors in mammalian cells. PT activity has been linked with severe and lethal pertussis disease in young infants and a detoxified version of PT is a common component of all licensed acellular pertussis vaccines. The role of PT in typical pertussis disease in other individuals is less clear, but significant evidence supporting its contribution to pathogenesis has been accumulated from animal model studies. In this review we discuss the evidence indicating a role for PT in pertussis disease, focusing on its contribution to severe pertussis in infants, modulation of immune and inflammatory responses to infection, and the characteristic paroxysmal cough of pertussis.
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Affiliation(s)
- Karen Scanlon
- Department of Microbiology & Immunology, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Ciaran Skerry
- Department of Microbiology & Immunology, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Nicholas Carbonetti
- Department of Microbiology & Immunology, University of Maryland School of Medicine, Baltimore, MD 21201, USA.
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González-Mariscal L, Raya-Sandino A, González-González L, Hernández-Guzmán C. Relationship between G proteins coupled receptors and tight junctions. Tissue Barriers 2018; 6:e1414015. [PMID: 29420165 DOI: 10.1080/21688370.2017.1414015] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Tight junctions (TJs) are sites of cell-cell adhesion, constituted by a cytoplasmic plaque of molecules linked to integral proteins that form a network of strands around epithelial and endothelial cells at the uppermost portion of the lateral membrane. TJs maintain plasma membrane polarity and form channels and barriers that regulate the transit of ions and molecules through the paracellular pathway. This structure that regulates traffic between the external milieu and the organism is affected in numerous pathological conditions and constitutes an important target for therapeutic intervention. Here, we describe how a wide array of G protein-coupled receptors that are activated by diverse stimuli including light, ions, hormones, peptides, lipids, nucleotides and proteases, signal through heterotrimeric G proteins, arrestins and kinases to regulate TJs present in the blood-brain barrier, the blood-retinal barrier, renal tubular cells, keratinocytes, lung and colon, and the slit diaphragm of the glomerulus.
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Affiliation(s)
- Lorenza González-Mariscal
- a Department of Physiology , Biophysics and Neuroscience, Center for Research and Advanced Studies (Cinvestav) , Mexico City , Mexico
| | - Arturo Raya-Sandino
- a Department of Physiology , Biophysics and Neuroscience, Center for Research and Advanced Studies (Cinvestav) , Mexico City , Mexico
| | - Laura González-González
- a Department of Physiology , Biophysics and Neuroscience, Center for Research and Advanced Studies (Cinvestav) , Mexico City , Mexico
| | - Christian Hernández-Guzmán
- a Department of Physiology , Biophysics and Neuroscience, Center for Research and Advanced Studies (Cinvestav) , Mexico City , Mexico
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Chishiki K, Kamakura S, Hayase J, Sumimoto H. Ric-8A, an activator protein of Gαi, controls mammalian epithelial cell polarity for tight junction assembly and cystogenesis. Genes Cells 2017; 22:293-309. [PMID: 28185378 DOI: 10.1111/gtc.12477] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2017] [Accepted: 01/11/2017] [Indexed: 01/04/2023]
Abstract
Correct cyst morphogenesis of epithelial cells requires apical-basal polarization, which is partly regulated by mitotic spindle orientation, a process dependent on the heterotrimeric G protein subunit Gαi and its binding protein LGN. Here, we show that in three-dimensional culture of mammalian epithelial Madin-Darby canine kidney (MDCK) cells, the Gαi-activating protein Ric-8A is crucial for orientation of the mitotic spindle and formation of normal cysts that comprise a single layer of polarized cells with their apical surfaces lining an inner lumen. Consistent with the involvement of LGN, cystogenesis can be well organized by ADP-ribosylated Gαi, retaining the ability to interact with LGN, but not by the interaction-defective mutant protein Gαi2 (N150I). In monolayer culture of MDCK cells, functional tight junction (TJ) assembly, a process associated with epithelial cell polarization, is significantly delayed in Ric-8A-depleted cells as well as in Gαi-depleted cells in a mitosis-independent manner. Ric-8A knockdown results in a delayed cortical delivery of Gαi and the apical membrane protein gp135, and an increased formation of intercellular lumens surrounded by membranes rich in Gαi3 and gp135. TJ development also involves LGN and its related protein AGS3. Thus, Ric-8A regulates mammalian epithelial cell polarity for TJ assembly and cystogenesis probably in concert with Gαi and LGN/AGS3.
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Affiliation(s)
- Kanako Chishiki
- Department of Biochemistry, Kyushu University Graduate School of Medical Sciences, Fukuoka, 812-8582, Japan
| | - Sachiko Kamakura
- Department of Biochemistry, Kyushu University Graduate School of Medical Sciences, Fukuoka, 812-8582, Japan
| | - Junya Hayase
- Department of Biochemistry, Kyushu University Graduate School of Medical Sciences, Fukuoka, 812-8582, Japan
| | - Hideki Sumimoto
- Department of Biochemistry, Kyushu University Graduate School of Medical Sciences, Fukuoka, 812-8582, Japan
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Ishii Y, Saeki K, Liu M, Sasaki F, Koga T, Kitajima K, Meno C, Okuno T, Yokomizo T. Leukotriene B
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receptor type 2 (BLT2) enhances skin barrier function by regulating tight junction proteins. FASEB J 2015; 30:933-47. [DOI: 10.1096/fj.15-279653] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2015] [Accepted: 10/19/2015] [Indexed: 01/20/2023]
Affiliation(s)
- Yumiko Ishii
- Department of Medical BiochemistryKyushu UniversityFukuokaJapan
- Research Institute for Diseases of the ChestKyushu UniversityFukuokaJapan
| | - Kazuko Saeki
- Department of Medical BiochemistryKyushu UniversityFukuokaJapan
- Department of BiochemistryJuntendo University School of MedicineTokyoJapan
| | - Min Liu
- Department of Medical BiochemistryKyushu UniversityFukuokaJapan
- Department of BiochemistryJuntendo University School of MedicineTokyoJapan
- Department of EndocrinologyShanghai Ninth People's HospitalShanghai Jiao Tong University School of MedicineShanghaiChina
| | - Fumiyuki Sasaki
- Department of Medical BiochemistryKyushu UniversityFukuokaJapan
- Department of BiochemistryJuntendo University School of MedicineTokyoJapan
| | - Tomoaki Koga
- Department of Medical BiochemistryKyushu UniversityFukuokaJapan
- Department of BiochemistryJuntendo University School of MedicineTokyoJapan
| | - Keiko Kitajima
- Department of Developmental BiologyGraduate School of Medical SciencesKyushu UniversityFukuokaJapan
| | - Chikara Meno
- Department of Developmental BiologyGraduate School of Medical SciencesKyushu UniversityFukuokaJapan
| | - Toshiaki Okuno
- Department of Medical BiochemistryKyushu UniversityFukuokaJapan
- Department of BiochemistryJuntendo University School of MedicineTokyoJapan
| | - Takehiko Yokomizo
- Department of Medical BiochemistryKyushu UniversityFukuokaJapan
- Department of BiochemistryJuntendo University School of MedicineTokyoJapan
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Sasaki K, Kakuwa T, Akimoto K, Koga H, Ohno S. Regulation of epithelial cell polarity by PAR-3 depends on Girdin transcription and Girdin-Gαi3 signaling. J Cell Sci 2015; 128:2244-58. [PMID: 25977476 DOI: 10.1242/jcs.160879] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2014] [Accepted: 05/07/2015] [Indexed: 12/31/2022] Open
Abstract
Epithelial apicobasal polarity has fundamental roles in epithelial physiology and morphogenesis. The PAR complex, comprising PAR-3, PAR-6 and atypical protein kinase C (aPKC), is involved in determining cell polarity in various biological contexts, including in epithelial cells. However, it is not fully understood how the PAR complex induces apicobasal polarity. In this study, we found that PAR-3 regulates the protein expression of Girdin (also known as GIV or CCDC88A), a guanine-nucleotide-exchange factor (GEF) for heterotrimeric Gαi subunits, at the transcriptional level by cooperating with the AP-2 transcription factor. In addition, we confirmed that PAR-3 physically interacts with Girdin, and show that Girdin, together with the Gαi3 (also known as GNAI3), controls tight junction formation, apical domain development and actin organization downstream of PAR-3. Taken together, our findings suggest that transcriptional upregulation of Girdin expression and Girdin-Gαi3 signaling play crucial roles in regulating epithelial apicobasal polarity through the PAR complex.
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Affiliation(s)
- Kazunori Sasaki
- Department of Molecular Biology, Yokohama City University Graduate School of Medical Science, 3-9 Fuku-ura, Kanazawa-ku, Yokohama 236-0004, Japan
| | - Taku Kakuwa
- Department of Molecular Biology, Yokohama City University Graduate School of Medical Science, 3-9 Fuku-ura, Kanazawa-ku, Yokohama 236-0004, Japan
| | - Kazunori Akimoto
- Department of Molecular Biology, Yokohama City University Graduate School of Medical Science, 3-9 Fuku-ura, Kanazawa-ku, Yokohama 236-0004, Japan Department of Molecular Medical Science, Faculty of Pharmaceutical Sciences, Tokyo University of Science, 2641 Yamazaki, Noda, Chiba 278-8510, Japan
| | - Hisashi Koga
- Department of Human Genome Research, Kazusa DNA Research Institute, 2-6-7 Kazusa-Kamatari, Kisarazu, Chiba 292-0818, Japan
| | - Shigeo Ohno
- Department of Molecular Biology, Yokohama City University Graduate School of Medical Science, 3-9 Fuku-ura, Kanazawa-ku, Yokohama 236-0004, Japan
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Bauer HC, Krizbai IA, Bauer H, Traweger A. "You Shall Not Pass"-tight junctions of the blood brain barrier. Front Neurosci 2014; 8:392. [PMID: 25520612 PMCID: PMC4253952 DOI: 10.3389/fnins.2014.00392] [Citation(s) in RCA: 165] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2014] [Accepted: 11/14/2014] [Indexed: 12/31/2022] Open
Abstract
The structure and function of the barrier layers restricting the free diffusion of substances between the central nervous system (brain and spinal cord) and the systemic circulation is of great medical interest as various pathological conditions often lead to their impairment. Excessive leakage of blood-borne molecules into the parenchyma and the concomitant fluctuations in the microenvironment following a transient breakdown of the blood-brain barrier (BBB) during ischemic/hypoxic conditions or because of an autoimmune disease are detrimental to the physiological functioning of nervous tissue. On the other hand, the treatment of neurological disorders is often hampered as only minimal amounts of therapeutic agents are able to penetrate a fully functional BBB or blood cerebrospinal fluid barrier. An in-depth understanding of the molecular machinery governing the establishment and maintenance of these barriers is necessary to develop rational strategies allowing a controlled delivery of appropriate drugs to the CNS. At the basis of such tissue barriers are intimate cell-cell contacts (zonulae occludentes, tight junctions) which are present in all polarized epithelia and endothelia. By creating a paracellular diffusion constraint TJs enable the vectorial transport across cell monolayers. More recent findings indicate that functional barriers are already established during development, protecting the fetal brain. As an understanding of the biogenesis of TJs might reveal the underlying mechanisms of barrier formation during ontogenic development numerous in vitro systems have been developed to study the assembly and disassembly of TJs. In addition, monitoring the stage-specific expression of TJ-associated proteins during development has brought much insight into the “developmental tightening” of tissue barriers. Over the last two decades a detailed molecular map of transmembrane and cytoplasmic TJ-proteins has been identified. These proteins not only form a cell-cell adhesion structure, but integrate various signaling pathways, thereby directly or indirectly impacting upon processes such as cell-cell adhesion, cytoskeletal rearrangement, and transcriptional control. This review will provide a brief overview on the establishment of the BBB during embryonic development in mammals and a detailed description of the ultrastructure, biogenesis, and molecular composition of epithelial and endothelial TJs will be given.
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Affiliation(s)
- Hans-Christian Bauer
- Institute of Tendon and Bone Regeneration, Paracelsus Medical University - Spinal Cord Injury and Tissue Regeneration Center Salzburg Salzburg, Austria ; Department of Traumatology and Sports Injuries, Paracelsus Medical University Salzburg, Austria ; Austrian Cluster for Tissue Regeneration Vienna, Austria
| | - István A Krizbai
- Biological Research Centre, Institute of Biophysics, Hungarian Academy of Sciences Szeged, Hungary ; Institute of Life Sciences, Vasile Goldis Western University of Arad Arad, Romania
| | - Hannelore Bauer
- Department of Organismic Biology, University of Salzburg Salzburg, Austria
| | - Andreas Traweger
- Institute of Tendon and Bone Regeneration, Paracelsus Medical University - Spinal Cord Injury and Tissue Regeneration Center Salzburg Salzburg, Austria ; Austrian Cluster for Tissue Regeneration Vienna, Austria
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Pastorelli L, De Salvo C, Mercado JR, Vecchi M, Pizarro TT. Central role of the gut epithelial barrier in the pathogenesis of chronic intestinal inflammation: lessons learned from animal models and human genetics. Front Immunol 2013; 4:280. [PMID: 24062746 PMCID: PMC3775315 DOI: 10.3389/fimmu.2013.00280] [Citation(s) in RCA: 312] [Impact Index Per Article: 28.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2013] [Accepted: 08/29/2013] [Indexed: 12/12/2022] Open
Abstract
The gut mucosa is constantly challenged by a bombardment of foreign antigens and environmental microorganisms. As such, the precise regulation of the intestinal barrier allows the maintenance of mucosal immune homeostasis and prevents the onset of uncontrolled inflammation. In support of this concept, emerging evidence points to defects in components of the epithelial barrier as etiologic factors in the pathogenesis of inflammatory bowel diseases (IBDs). In fact, the integrity of the intestinal barrier relies on different elements, including robust innate immune responses, epithelial paracellular permeability, epithelial cell integrity, as well as the production of mucus. The purpose of this review is to systematically evaluate how alterations in the aforementioned epithelial components can lead to the disruption of intestinal immune homeostasis, and subsequent inflammation. In this regard, the wealth of data from mouse models of intestinal inflammation and human genetics are pivotal in understanding pathogenic pathways, for example, that are initiated from the specific loss of function of a single protein leading to the onset of intestinal disease. On the other hand, several recently proposed therapeutic approaches to treat human IBD are targeted at enhancing different elements of gut barrier function, further supporting a primary role of the epithelium in the pathogenesis of chronic intestinal inflammation and emphasizing the importance of maintaining a healthy and effective intestinal barrier.
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Affiliation(s)
- Luca Pastorelli
- Department of Pathology, Case Western Reserve University School of Medicine , Cleveland, OH , USA ; Department of Biomedical Sciences for Health, University of Milan , Milan , Italy ; Gastroenterology and Digestive Endoscopy Unit, IRCCS Policlinico San Donato , San Donato Milanese , Italy
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Wang Y, Li Y, Shi G. The regulating function of heterotrimeric G proteins in the immune system. Arch Immunol Ther Exp (Warsz) 2013; 61:309-19. [PMID: 23563866 DOI: 10.1007/s00005-013-0230-5] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2012] [Accepted: 03/25/2013] [Indexed: 01/17/2023]
Abstract
Heterotrimeric guanine nucleotide-binding proteins (G proteins), which consist of an α-, a β- and a γ-subunit, have crucial roles as molecular switches in the regulation of the downstream effector molecules of multiple G protein-coupled receptor signalling pathways, such as phospholipase C and adenylyl cyclase. According to the structural and functional similarities of their α-subunits, G proteins can be divided into four subfamilies: Gαs, Gαi/o, Gαq/11 and Gα12/13. Most of the α- and the βγ-subunits are abundantly expressed on the surface of immune cells. Recent studies have demonstrated that G proteins are a group of important immunomodulatory factors that regulate the migration, activation, survival, proliferation, differentiation and cytokine secretion of immune cells. In this review, we summarise the recent findings on the functions of G proteins in immune regulation and autoimmunity.
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Affiliation(s)
- Yantang Wang
- Department of Immunology, Chengdu Medical College, Chengdu, China
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Götlind YY, Fritsch Fredin M, Kumawat AK, Strid H, Willén R, Rangel I, Bland PW, Hörnquist EH. Interplay between T(h)1 and T(h)17 effector T-cell pathways in the pathogenesis of spontaneous colitis and colon cancer in the Gαi2-deficient mouse. Int Immunol 2013; 25:35-44. [PMID: 22962436 DOI: 10.1093/intimm/dxs089] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Gαi2-deficient mice spontaneously develop colitis. Using xMAP technology and RT-PCR, we investigated cytokine/chemokine profiles during histologically defined phases of disease: (i) no/mild, (ii) moderate, (iii) severe colitis without dysplasia/cancer and (iv) severe colitis with dysplasia/cancer, compared with age-matched wild-type (WT) littermates. Colonic dysplasia was observed in 4/11 mice and cancer in 1/11 mice with severe colitis. The histology correlated with progressive increases in colon weight/cm and spleen weight, and decreased thymus weight, all more advanced in mice with dysplasia/cancer. IL-1β, IL-6, IL-12p40, IL-17, TNF-α, CCL2 and CXCL1 protein levels in colons, but not small intestines increased with colitis progression and were significantly increased in mice with moderate and severe colitis compared with WT mice, irrespective of the absence/presence of dysplasia/cancer. CCL5 did not change during colitis progression. Colonic IL-17 transcription increased 40- to 70-fold in all stages of colitis, whereas IFN-γ mRNA was gradually up-regulated 12- to 55-fold with colitis progression, and further to 62-fold in mice with dysplasia/cancer. IL-27 mRNA increased 4- to 15-fold during the course of colitis, and colonic IL-21 transcription increased 3-fold in mice with severe colitis, both irrespective of the absence/presence of dysplasia/cancer. FoxP3 transcription was significantly enhanced (3.5-fold) in mice with moderate and severe colitis, but not in mice with dysplasia/cancer, compared with WT mice. Constrained correspondence analysis demonstrated an association between increased protein levels of TNF-α, CCL2, IL-1β, IL-6 and CXCL1 and dysplasia/cancer. In conclusion, colonic responses are dominated by a mixed T(h)1/T(h)17 phenotype, with increasing T(h)1 cytokine transcription with progression of colitis in Gαi2(-/-) mice.
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Affiliation(s)
- Yu-Yuan Götlind
- Department of Microbiology and Immunology, Institute of Biomedicine and MIVAC, Sahlgrenska Academy, Göteborg University, Göteborg, Sweden
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Luissint AC, Artus C, Glacial F, Ganeshamoorthy K, Couraud PO. Tight junctions at the blood brain barrier: physiological architecture and disease-associated dysregulation. Fluids Barriers CNS 2012; 9:23. [PMID: 23140302 PMCID: PMC3542074 DOI: 10.1186/2045-8118-9-23] [Citation(s) in RCA: 390] [Impact Index Per Article: 32.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2012] [Accepted: 10/21/2012] [Indexed: 01/01/2023] Open
Abstract
The Blood–brain barrier (BBB), present at the level of the endothelium of cerebral blood vessels, selectively restricts the blood-to-brain paracellular diffusion of compounds; it is mandatory for cerebral homeostasis and proper neuronal function. The barrier properties of these specialized endothelial cells notably depend on tight junctions (TJs) between adjacent cells: TJs are dynamic structures consisting of a number of transmembrane and membrane-associated cytoplasmic proteins, which are assembled in a multimolecular complex and acting as a platform for intracellular signaling. Although the structural composition of these complexes has been well described in the recent years, our knowledge about their functional regulation still remains fragmentary. Importantly, pericytes, embedded in the vascular basement membrane, and perivascular microglial cells, astrocytes and neurons contribute to the regulation of endothelial TJs and BBB function, altogether constituting the so-called neurovascular unit. The present review summarizes our current understanding of the structure and functional regulation of endothelial TJs at the BBB. Accumulating evidence points to a correlation between BBB dysfunction, alteration of TJ complexes and progression of a variety of CNS diseases, such as stroke, multiple sclerosis and brain tumors, as well as neurodegenerative diseases like Parkinson’s and Alzheimer’s diseases. Understanding how TJ integrity is controlled may thus help improve drug delivery across the BBB and the design of therapeutic strategies for neurological disorders.
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Bal MS, Castro V, Piontek J, Rueckert C, Walter JK, Shymanets A, Kurig B, Haase H, Nürnberg B, Blasig IE. The hinge region of the scaffolding protein of cell contacts, zonula occludens protein 1, regulates interacting with various signaling proteins. J Cell Biochem 2012; 113:934-45. [PMID: 22371973 DOI: 10.1002/jcb.23422] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Zonula occludens protein 1 (ZO-1) is a ubiquitous scaffolding protein, but it is unknown why it functions in very different cellular contacts. We hypothesized that a specific segment, the unique hinge region, can be bound by very different regulatory proteins. Using surface plasmon resonance spectroscopy and binding assays to peptide libraries, we show, for the first time, that the hinge region directly interacts with disparate signal elements such as G-proteins alpha 12 and alpha i2, the regulator of G-protein signaling 5, multifunctional signaling protein ahnak1, and L-type Ca2+-channel beta-2-subunit. The novel binding proteins specifically bound to a coiled coil-helix predicted in the hinge region of ZO-. The interactions were modulated by phosphorylation in the hinge helix. Activation of the G-proteins influenced their association to ZO-1. In colon cells, G alpha i2 and ZO-1 were associated, as shown by coimmunoprecipitation. After cotransfection in kidney cells, G alpha i2 barely colocalized with ZO-1; the colocalization coefficient was significantly increased when epinephrine activated G-protein signaling. In conclusion, proteins with different regulatory potential adhere to and influence cellular functions of ZO-proteins, and the interactions can be modulated via its hinge region and/or the binding proteins.
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Affiliation(s)
- Manjot Singh Bal
- Leibniz-Institut für Molekulare Pharmakologie, Berlin-Buch, Germany
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Luissint AC, Federici C, Guillonneau F, Chrétien F, Camoin L, Glacial F, Ganeshamoorthy K, Couraud PO. Guanine nucleotide-binding protein Gαi2: a new partner of claudin-5 that regulates tight junction integrity in human brain endothelial cells. J Cereb Blood Flow Metab 2012; 32:860-73. [PMID: 22333621 PMCID: PMC3345908 DOI: 10.1038/jcbfm.2011.202] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The blood-brain barrier (BBB) selectively controls the exchanges between the blood and the brain: it is formed by tight junctions (TJs) between adjacent microvascular endothelial cells. The transmembrane protein claudin-5 is known as a key TJ protein at the BBB, although, the molecular mechanisms by which it regulates TJ tightness are poorly understood. To identify putative claudin-5 partners that contribute to TJ integrity, claudin-5-enriched membrane microdomains were prepared by cell fractionation, using the human brain endothelial cell line hCMEC/D3 and claudin-5 immunoprecipitates were submitted to tandem mass spectrometry. Because a high concentration of mannitol is known to transiently destabilize TJs, this analysis was performed in basal conditions, after mannitol treatment, and after recovery of TJ integrity. We here demonstrate that the G-protein subunit αi2 (Gαi2) interacts with claudin-5 and that association is correlated with TJ integrity in hCMEC/D3 cells; also, a selective expression of Gαi2 is observed in human brain vasculature in situ. Moreover, small interfering RNA-mediated depletion of Gαi2 or claudin-5 in hCMEC/D3 cells similarly increases their paracellular permeability and delays TJ recovery after mannitol treatment. Altogether, our results identify Gαi2 as a novel claudin-5 partner required for TJ integrity in brain endothelial cells.
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H2O2 activates G protein, α 12 to disrupt the junctional complex and enhance ischemia reperfusion injury. Proc Natl Acad Sci U S A 2012; 109:6680-5. [PMID: 22493269 DOI: 10.1073/pnas.1116800109] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The epithelial cell tight junction separates apical and basolateral domains and is essential for barrier function. Disruption of the tight junction is a hallmark of epithelial cell damage and can lead to end organ damage including renal failure. Herein, we identify Gα12 activation by H(2)O(2) leading to tight junction disruption and demonstrate a critical role for Gα12 activation during bilateral renal ischemia/reperfusion injury. Madin-Darby canine kidney (MDCK) cells with inducible Gα12 (Gα12-MDCK) and silenced Gα12 (shGα12-MDCK) were subjected to ATP depletion/repletion and H(2)O(2)/catalase as models of tight junction disruption and recovery by monitoring transepithelial resistance. In ATP depleted cells, barrier disruption and recovery was not affected by Gα12, but reassembly was accelerated by Gα12 depletion. In contrast, silencing of Gα12 completely protected cells from H(2)O(2)-stimulated barrier disruption, a response that rapidly occurred in control cells. H(2)O(2) activated Src and Rho, and Src inhibition (by PP2), but not Rho (by Y27632), protected cells from H(2)O(2)-mediated barrier disruption. Immunofluorescent and biochemical analysis showed that H(2)O(2) led to increased tyrosine phosphorylation of numerous proteins and altered membrane localization of tight junction proteins through Gα12/Src signaling pathway. Gα12 and Src were activated in vivo during ischemia/reperfusion injury, and transgenic mice with renal tubular QLα12 (activated mutant) expression were delayed in recovery and showed more extensive injury. Conversely, Gα12 knockout mice were nearly completely protected from ischemia/reperfusion injury. Taken together, these studies reveal that ROS stimulates Gα12 to activate injury pathways and identifies a therapeutic target for ameliorating ROS mediated injury.
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Yamagata K. Pathological alterations of astrocytes in stroke-prone spontaneously hypertensive rats under ischemic conditions. Neurochem Int 2011; 60:91-8. [PMID: 22100568 DOI: 10.1016/j.neuint.2011.11.002] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2011] [Revised: 10/27/2011] [Accepted: 11/04/2011] [Indexed: 11/18/2022]
Abstract
Stroke-prone spontaneously hypertensive rats (SHRSP/Izm) develop severe hypertension, and more than 95% of them die of cerebral stroke. We showed the vulnerability of neuronal cells of SHRSP/Izm rats. Furthermore, we analyzed the characteristics of SHRSP/Izm astrocytes during a stroke. It is known that the proliferating ability of SHRSP/Izm astrocytes is significantly enhanced compared with those in the normotensive Wistar Kyoto rats (WKY/Izm) strain. Conversely, the ability of SHRSP/Izm astrocytes to form tight junctions (TJ) was attenuated compared with astrocytes from WKY/Izm rats. During the stress of hypoxia and reoxygenation (H/R), lactate production, an energy source for neuronal cells, decreased in SHRSP/Izm astrocytes in comparison with the WKY/Izm strain. Moreover, during H/R, SHRSP/Izm astrocytes decreased their production of glial cell line-derived neurotrophic factor (GDNF) in comparison with WKY/Izm astrocytes. Furthermore, SHRSP/Izm rats decreased production of l-serine, compared with WKY/Izm rats following nitric oxide (NO) stimulation. Additionally, in H/R, astrocytes of SHRSP/Izm rats expressed adhesion molecules such as VCAM-1 at higher levels. It is possible that all of these differences between SHRSP/Izm and WKY/Izm astrocytes are not associated with the neurological disorders in SHRSP/Izm. However, attenuated production of lactate and reduced GDNF production in astrocytes may reduce required energy levels and weaken the nutritional status of SHRSP/Ism neuronal cells. We suggest that the attenuation of astrocytes' functions accelerates neuronal cell death during stroke, and may contribute to the development of strokes in SHRSP/Izm. In this review, we summarize the altered properties of SHRSP/Izm astrocytes during a stroke.
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Affiliation(s)
- Kazuo Yamagata
- Laboratory of Molecular Health Science of Food, Department of Food Bioscience and Biotechnology, College of Bioresource Sciences, Nihon University (NUBS), 1866 Kameino, Fujisawa-shi, Kanagawa 252-8510, Japan.
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CD4+FoxP3+ regulatory T cells from Gαi2-/- mice are functionally active in vitro, but do not prevent colitis. PLoS One 2011; 6:e25073. [PMID: 21966415 PMCID: PMC3178583 DOI: 10.1371/journal.pone.0025073] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2011] [Accepted: 08/26/2011] [Indexed: 12/18/2022] Open
Abstract
Background Mice deficient in the inhibitory G protein subunit Gαi2 spontaneously develop a T helper 1 dominated colitis. We examined whether a defect in CD4+FoxP3+ regulatory T cells (Treg) underpins the pathogenesis of colitis in the Gαi2−/− (Gαi2-deficient) colitis model. Methodology/Principal Findings Using flow cytometry, we found that thymus and colonic lamina propria, but not spleen and mesenteric lymph nodes, of colitic Gαi2−/− mice contained increased frequencies of Treg, whereas FoxP3 expression intensity was similar in Gαi2−/− compared to Gαi2+/− or Gαi2+/+ wild type (WT) mice. The frequency of CD4+FoxP3+ T cells expressing CD103 was significantly increased in Gαi2−/− compared to WT mice. Treg in colons from WT mice clustered in the T cell areas of colonic lymphoid patches (CLP), with relatively few Treg in the lamina propria, as demonstrated by immunohistochemistry. In Gαi2−/− mice, CLP were not observed but lamina propria Treg were increased in number and frequency within the CD4+ infiltrate, compared to WT mice. Using an in vitro co-culture system and flow cytometric analysis of cell division we could demonstrate that the in vitro suppressive function of WT and Gαi2−/− CD4+FoxP3+ regulatory T cells (WT-Treg and KO-Treg) was indistinguishable, but that T effector cells (CD4+25− T cells) from Gαi2−/− mice were less readily suppressed than WT effectors (WT-Teff) by Treg from either source. However, neither WT nor Gαi2−/− Treg was able to suppress colitis induced by adoptive transfer of Gαi2−/− effector T cells (KO-Teff) to RAG2−/− recipients. The enhanced inflammatory activity of Gαi2−/− effectors was accompanied by increased expression of an effector/memory T cell phenotype and increased cytokine secretion, especially IL-4, IL-6 and IFN-γ. Conclusions There is an increased frequency of Gαi2−/− Treg in the colon, and they demonstrate no endogenous functional defect. However, Gαi2−/− T effector cells are dramatically less susceptible to suppression in vitro, and in vivo, despite increased effective numbers of Treg, they cannot prevent disease.
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Agle KA, Vongsa RA, Dwinell MB. Calcium mobilization triggered by the chemokine CXCL12 regulates migration in wounded intestinal epithelial monolayers. J Biol Chem 2010; 285:16066-75. [PMID: 20348095 PMCID: PMC2871475 DOI: 10.1074/jbc.m109.061416] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2009] [Revised: 03/26/2010] [Indexed: 12/26/2022] Open
Abstract
Restitution of intestinal epithelial barrier damage involves the coordinated remodeling of focal adhesions in actively migrating enterocytes. Defining the extracellular mediators and the intracellular signaling pathways regulating those dynamic processes is a key step in developing restitution-targeted therapies. Previously we have determined that activation of the chemokine receptor CXCR4 by the cognate ligand CXCL12 enhances intestinal epithelial restitution through reorganization of the actin cytoskeleton. The aim of these studies was to investigate the role of calcium effectors in CXCL12-mediated restitution. CXCL12 stimulated release of intracellular calcium in a dose-dependent manner. Inhibition of intracellular calcium flux impaired CXCL12-mediated migration of IEC-6 and CaCo2 cells. Pharmacological blockade and specific shRNA depletion of the phospholipase-C (PLCbeta3) isoform attenuated CXCL12-enhanced migration, linking receptor activation with intracellular calcium flux. Immunoblot analyses demonstrated CXCL12 activated the calcium-regulated focal adhesion protein proline-rich tyrosine kinase-2 (Pyk2) and the effector proteins paxillin and p130(Cas). Interruption of Pyk2 signaling potently blocked CXCL12-induced wound closure. CXCL12-stimulated epithelial cell migration was enhanced on laminin and abrogated by intracellular calcium chelation. These results suggest CXCL12 regulates restitution through calcium-activated Pyk2 localized to active focal adhesions. Calcium signaling pathways may therefore provide a novel avenue for enhancing barrier repair.
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Affiliation(s)
- Kimberle A. Agle
- From the Department of Microbiology and Molecular Genetics, Medical College of Wisconsin, Milwaukee, Wisconsin 53226
| | - Rebecca A. Vongsa
- From the Department of Microbiology and Molecular Genetics, Medical College of Wisconsin, Milwaukee, Wisconsin 53226
| | - Michael B. Dwinell
- From the Department of Microbiology and Molecular Genetics, Medical College of Wisconsin, Milwaukee, Wisconsin 53226
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20
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Donato R, Wood SA, Saunders I, Gundsambuu B, Yan Mak K, Abbott CA, Powell BC. Regulation of epithelial apical junctions and barrier function by Gα13. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2009; 1793:1228-35. [DOI: 10.1016/j.bbamcr.2009.04.008] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/16/2008] [Revised: 04/06/2009] [Accepted: 04/21/2009] [Indexed: 01/18/2023]
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21
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Babbin BA, Sasaki M, Gerner-Schmidt KW, Nusrat A, Klapproth JMA. The bacterial virulence factor lymphostatin compromises intestinal epithelial barrier function by modulating rho GTPases. THE AMERICAN JOURNAL OF PATHOLOGY 2009; 174:1347-57. [PMID: 19286565 DOI: 10.2353/ajpath.2009.080640] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Lymphocyte inhibitory factor A (lifA) in Citrobacter rodentium encodes the large toxin lymphostatin, which contains two enzymatic motifs associated with bacterial pathogenesis, a glucosyltransferase and a protease. Our aim was to determine the effects of each lymphostatin motif on intestinal epithelial-barrier function. In-frame mutations of C. rodentium lifA glucosyltransferase (CrGlM21) and protease (CrPrM5) were generated by homologous recombination. Infection of both model intestinal epithelial monolayers and mice with C. rodentium wild type resulted in compromised epithelial barrier function and mislocalization of key intercellular junction proteins in the tight junction and adherens junction. In contrast, CrGlM21 was impaired in its ability to reduce barrier function and influenced the tight junction proteins ZO-1 and occludin. CrPrM5 demonstrated decreased effects on the adherens junction proteins beta-catenin and E-cadherin. Analysis of the mechanisms revealed that C. rodentium wild type differentially influenced Rho GTPase activation, suppressed Cdc42 activation, and induced Rho GTPase activation. CrGlM21 lost its suppressive effects on Cdc42 activation, whereas CrPrM5 was unable to activate Rho signaling. Rescue experiments using constitutively active Cdc42 or C3 exotoxin to inhibit Rho GTPase supported a role of Rho GTPases in the epithelial barrier compromise induced by C. rodentium. Taken together, our results suggest that lymphostatin is a bacterial virulence factor that contributes to the disruption of intestinal epithelial-barrier function via the modulation of Rho GTPase activities.
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Affiliation(s)
- Brian A Babbin
- Department of Pathology and Laboratory Medicine, Division of Digestive Diseases, Emory University, Atlanta, Georgia 30322, USA
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22
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Liew CW, Vockel M, Glassmeier G, Brandner JM, Fernandez-Ballester GJ, Schwarz JR, Schulz S, Buck F, Serrano L, Richter D, Kreienkamp HJ. Interaction of the human somatostatin receptor 3 with the multiple PDZ domain protein MUPP1 enables somatostatin to control permeability of epithelial tight junctions. FEBS Lett 2008; 583:49-54. [PMID: 19071123 DOI: 10.1016/j.febslet.2008.11.048] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2008] [Revised: 11/12/2008] [Accepted: 11/18/2008] [Indexed: 12/26/2022]
Abstract
The presence of heterotrimeric G-proteins at epithelial tight junctions suggests that these cellular junctions are regulated by so far unknown G-protein coupled receptors. We identify here an interaction between the human somatostatin receptor 3 (hSSTR3) and the multiple PDZ protein MUPP1. MUPP1 is a tight junction scaffold protein in epithelial cells, and as a result of the interaction with MUPP1 the hSSTR3 is targeted to tight junctions. Interaction with MUPP1 enables the receptor to regulate transepithelial permeability in a pertussis toxin sensitive manner, suggesting that hSSTR3 can activate G-proteins locally at tight junctions.
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Affiliation(s)
- Chong Wee Liew
- Institut für Zellbiochemie und klinische Neurobiologie, Universitätsklinikum Hamburg-Eppendorf, Hamburg, Germany
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23
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Wei B, McPherson M, Turovskaya O, Velazquez P, Fujiwara D, Brewer S, Braun J. Integration of B cells and CD8+ T in the protective regulation of systemic epithelial inflammation. Clin Immunol 2008; 127:303-12. [PMID: 18282744 PMCID: PMC2478703 DOI: 10.1016/j.clim.2008.01.001] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2007] [Revised: 12/29/2007] [Accepted: 01/01/2008] [Indexed: 01/12/2023]
Abstract
Mechanisms that control abnormal CD4(+) T cell-mediated tissue damage are a significant factor in averting and resolving chronic inflammatory epithelial diseases. B cells can promote such immunoregulation, and this is thought to involve interaction with MHC II- or CD1-restricted regulatory T cells. The purpose of this study is to genetically define the interacting cells targeted by protective B cells, and to elucidate their regulatory mechanisms in CD4(+) T cell inflammation. Transfer of G alpha i2-/- CD3(+) T cells into lymphopenic mice causes a dose-dependent multi-organ inflammatory disease including the skin, intestine, and lungs. Disease activity is associated with elevated levels of serum TNF-alpha and IFN-gamma, and an activated IL-17 producing CD4(+) T cell population. Mesenteric node B cells from wild type mice suppress disease activity, serum cytokine expression, and levels of CD4(+) T cells producing TNF-alpha IFN-gamma, and IL-17. The protective function of B cells requires genetic sufficiency of IL-10, MHC I and TAP1. Regulatory B cells induce the expansion and activation of CD8(+) T cells, which is correlated with disease protection. These results demonstrate that CD8(+) T cells can ameliorate lymphopenic systemic inflammatory disease, through peptide/MHC I-dependent B cell interaction.
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Affiliation(s)
- Bo Wei
- Department of Pathology and Laboratory Medicine, David Geffen School of Medicine at UCLA, 10833 Le Conte Ave, CHS 13-222, Los Angeles, CA 90095
| | - Michael McPherson
- Molecular Biology Institute, David Geffen School of Medicine at UCLA, 10833 Le Conte Ave, CHS 13-222, Los Angeles, CA 90095
| | - Olga Turovskaya
- La Jolla Institute for Allergy and Immunology, San Diego, CA 92121
| | - Peter Velazquez
- Department of Pathology and Laboratory Medicine, David Geffen School of Medicine at UCLA, 10833 Le Conte Ave, CHS 13-222, Los Angeles, CA 90095
| | - Daisuke Fujiwara
- Department of Pathology and Laboratory Medicine, David Geffen School of Medicine at UCLA, 10833 Le Conte Ave, CHS 13-222, Los Angeles, CA 90095
| | - Sarah Brewer
- Department of Pathology and Laboratory Medicine, David Geffen School of Medicine at UCLA, 10833 Le Conte Ave, CHS 13-222, Los Angeles, CA 90095
| | - Jonathan Braun
- Department of Pathology and Laboratory Medicine, David Geffen School of Medicine at UCLA, 10833 Le Conte Ave, CHS 13-222, Los Angeles, CA 90095
- Molecular Biology Institute, David Geffen School of Medicine at UCLA, 10833 Le Conte Ave, CHS 13-222, Los Angeles, CA 90095
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Sabath E, Negoro H, Beaudry S, Paniagua M, Angelow S, Shah J, Grammatikakis N, Yu ASL, Denker BM. Galpha12 regulates protein interactions within the MDCK cell tight junction and inhibits tight-junction assembly. J Cell Sci 2008; 121:814-24. [PMID: 18285450 DOI: 10.1242/jcs.014878] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
The polarized functions of epithelia require an intact tight junction (TJ) to restrict paracellular movement and to separate membrane proteins into specific domains. TJs contain scaffolding, integral membrane and signaling proteins, but the mechanisms that regulate TJs and their assembly are not well defined. Galpha12 (GNA12) binds the TJ protein ZO-1 (TJP1), and Galpha12 activates Src to increase paracellular permeability via unknown mechanisms. Herein, we identify Src as a component of the TJ and find that recruitment of Hsp90 to activated Galpha12 is necessary for signaling. TJ integrity is disrupted by Galpha12-stimulated Src phosphorylation of ZO-1 and ZO-2 (TJP2); this phosphorylation leads to dissociation of occludin and claudin 1 from the ZO-1 protein complex. Inhibiting Hsp90 with geldanamycin blocks Galpha12-stimulated Src activation and phosphorylation, but does not affect protein levels or the Galpha12-ZO-1 interaction. Using the calcium-switch model of TJ assembly and GST-TPR (GST-fused TPR domain of PP5) pull-downs of activated Galpha12, we demonstrate that switching to normal calcium medium activates endogenous Galpha12 during TJ assembly. Thrombin increases permeability and delays TJ assembly by activating Galpha12, but not Galpha13, signaling pathways. These findings reveal an important role for Galpha12, Src and Hsp90 in regulating the TJ in established epithelia and during TJ assembly.
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Affiliation(s)
- Ernesto Sabath
- Renal Division, Brigham and Women's Hospital and Harvard Medical School, Boston, MA 02115, USA
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25
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Wang Y, Zhang HX, Sun YP, Liu ZX, Liu XS, Wang L, Lu SY, Kong H, Liu QL, Li XH, Lu ZY, Chen SJ, Chen Z, Bao SS, Dai W, Wang ZG. Rig-I-/- mice develop colitis associated with downregulation of G alpha i2. Cell Res 2007; 17:858-68. [PMID: 17893708 DOI: 10.1038/cr.2007.81] [Citation(s) in RCA: 97] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
RIG-I (retinoid acid-inducible gene-I), a putative RNA helicase with a cytoplasmic caspase-recruitment domain (CARD), was identified as a pattern-recognition receptor (PRR) that mediates antiviral immunity by inducing type I interferon production. To further study the biological function of RIG-I, we generated Rig-I(-/-) mice through homologous recombination, taking a different strategy to the previously reported strategy. Our Rig-I(-/-) mice are viable and fertile. Histological analysis shows that Rig-I(-/-) mice develop a colitis-like phenotype and increased susceptibility to dextran sulfate sodium-induced colitis. Accordingly, the size and number of Peyer's patches dramatically decreased in mutant mice. The peripheral T-cell subsets in mutant mice are characterized by an increase in effector T cells and a decrease in naive T cells, indicating an important role for Rig-I in the regulation of T-cell activation. It was further found that Rig-I deficiency leads to the downregulation of G protein alpha i2 subunit (G alpha i2) in various tissues, including T and B lymphocytes. By contrast, upregulation of Rig-I in NB4 cells that are treated with ATRA is accompanied by elevated G alpha i2 expression. Moreover, G alpha i2 promoter activity is increased in co-transfected NIH3T3 cells in a Rig-I dose-dependent manner. All these findings suggest that Rig-I has crucial roles in the regulation of G alpha i2 expression and T-cell activation. The development of colitis may be, at least in part, associated with downregulation of G alpha i2 and disturbed T-cell homeostasis.
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Affiliation(s)
- Yi Wang
- Department of Medical Genetics, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
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Kügler S, Böcker K, Heusipp G, Greune L, Kim KS, Schmidt MA. Pertussis toxin transiently affects barrier integrity, organelle organization and transmigration of monocytes in a human brain microvascular endothelial cell barrier model. Cell Microbiol 2006; 9:619-32. [PMID: 17002784 DOI: 10.1111/j.1462-5822.2006.00813.x] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Encephalopathies and neurological disorders are sometimes associated with respiratory tract infections caused by Bordetella pertussis. For these complications to occur cerebral barriers have to be compromised. Therefore, the influence of pertussis toxin (PT), a decisive virulence determinant of B. pertussis, on endothelial barrier integrity was investigated. Human brain microvascular endothelial cells cultured on Transwell filter devices were used as model for the blood brain barrier. PT, but not its B-oligomer, induced a reduction of the transendothelial resistance and enhanced the permeability for the protein marker horseradish peroxidase. Moreover, transmigration of human monocytes was also elevated suggesting a PT-associated enhancement of the diapedesis of blood leucocytes. Uptake and trafficking of PT was followed by electron microscopy via clathrin-coated pits and accumulation in lysosomes and microvesicular bodies. The breach in barrier integrity was accompanied by a transient disintegration of Golgi structures. Interestingly, PT-induced effects were only transient and restoration of barrier function was observed after 24 h. In summary, intoxication by PT causes a transient destruction of the cellular organization in human brain-derived endothelial cells resulting in a transient disruption of barrier functions. We suggest that these findings reflect early steps in the development of neurological disorders associated with pertussis disease.
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Affiliation(s)
- Silke Kügler
- Institut für Infektiologie, Zentrum für Molekularbiologie der Entzündung (ZMBE), Westfälische Wilhelms-Universität/Universitätsklinikum Münster, 48149 Münster, Germany
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27
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Bjursten M, Willén R, Hultgren Hörnquist E. Transfer of colitis by Galphai2-deficient T lymphocytes: impact of subpopulations and tissue origin. Inflamm Bowel Dis 2005; 11:997-1005. [PMID: 16239846 DOI: 10.1097/01.mib.0000185401.27170.22] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
To elucidate the potential cell population(s) involved in the induction of colitis in inhibitory G protein Galphai2(-/-) mice, Galphai2-deficient or competent bone marrow or splenic and mesenteric lymph node (MLN) T cells were transferred into immunodeficient mice. The mice were followed up to 23 weeks after transfer, recording changes in body weight. Colitis was graded on hematoxylin and eosin-stained colonic tissue, and production of serum interleukin-18 and colon-derived interferon-gamma was measured using ELISA. After adoptive transfer of Galphai2(-/-) bone marrow, severe colitis developed in irradiated wild type recipients, whereas irradiated Galphai2(-/-) mice increased their life span more than 3 times after transfer of wild type bone marrow, accompanied by significant amelioration of colitis. Neither purified Galphai2(-/-) CD4(+), nor CD8(+) splenic or MLN-derived T cells could induce colitis in recombination-activating gene V(RAG) 2(-/-) recipient mice, whereas transfer of splenic Galphai2(-/-) CD3(+) T cells induced severe colitis. In contrast, transfer of Galphai2(-/-) CD3(+) T cells from the MLN caused only minor histopathological changes in the intestinal mucosa. Finally, serum levels of interleukin-18 and interferon-gamma production from colonic tissue cultures correlated well with disease severity. Our results show that bone marrow transplantation can prolong the life of Galphai2(-/-) mice and ameliorate intestinal inflammation. Splenic CD4(+) or CD8(+) T cells on their own were poor inducers of colitis, whereas the combination of both was highly involved in the induction of intestinal inflammation. Furthermore, we show that the tissue origin of CD3(+) T cells is critical for their potency to induce colitis.
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Affiliation(s)
- Malin Bjursten
- Department of Clinical Immunology, Göteborg University, Gothenburg, Sweden
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28
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Hawkins BT, Davis TP. The blood-brain barrier/neurovascular unit in health and disease. Pharmacol Rev 2005; 57:173-85. [PMID: 15914466 DOI: 10.1124/pr.57.2.4] [Citation(s) in RCA: 1802] [Impact Index Per Article: 94.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
The blood-brain barrier (BBB) is the regulated interface between the peripheral circulation and the central nervous system (CNS). Although originally observed by Paul Ehrlich in 1885, the nature of the BBB was debated well into the 20th century. The anatomical substrate of the BBB is the cerebral microvascular endothelium, which, together with astrocytes, pericytes, neurons, and the extracellular matrix, constitute a "neurovascular unit" that is essential for the health and function of the CNS. Tight junctions (TJ) between endothelial cells of the BBB restrict paracellular diffusion of water-soluble substances from blood to brain. The TJ is an intricate complex of transmembrane (junctional adhesion molecule-1, occludin, and claudins) and cytoplasmic (zonula occludens-1 and -2, cingulin, AF-6, and 7H6) proteins linked to the actin cytoskeleton. The expression and subcellular localization of TJ proteins are modulated by several intrinsic signaling pathways, including those involving calcium, phosphorylation, and G-proteins. Disruption of BBB TJ by disease or drugs can lead to impaired BBB function and thus compromise the CNS. Therefore, understanding how BBB TJ might be affected by various factors holds significant promise for the prevention and treatment of neurological diseases.
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Affiliation(s)
- Brian T Hawkins
- Department of Medical Pharmacology, University of Arizona College of Medicine, Tucson, Arizona, USA
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29
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Bjursten M, Bland PW, Willén R, Hörnquist EH. Long-term treatment with anti-α4 integrin antibodies aggravates colitis in Gαi2-deficient mice. Eur J Immunol 2005; 35:2274-83. [PMID: 16052630 DOI: 10.1002/eji.200526022] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
Targeted deletion of the heterotrimeric G protein, Galphai2, in mice induces lethal colitis closely resembling ulcerative colitis. In chronic colitis, migration of circulating leukocytes into the intestinal mucosa is partially dependent on alpha4 integrins. In previous studies, short-term administration of anti-alpha4 integrin antibodies has been shown to attenuate intestinal inflammation, and here we elucidate the effect of long-term administration of anti-alpha4 integrin antibodies on colitis in Galphai2(-/- )mice. Long-term blockade of alpha4 integrin significantly increased the severity of colitis in Galphai2(-/-) mice. The inflammation was confined to the colon, associated with increased cancer in situ, destruction of crypt architecture, and increased production of IL-1beta, TNF-alpha and IFN-gamma. Blockade of alpha4 integrin reduced the recruitment of activated T cells to the small intestine. In strong contrast, there were significantly higher numbers of activated T cells in the colonic lamina propria and epithelium, most probably due to in situ proliferation. Furthermore, treatment with alpha4 integrin antibodies induced decreased levels of total IgA and IgG in sera, whereas total IgM levels were unchanged. These new findings may have implications in the understanding of the progression of chronic intestinal inflammation.
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MESH Headings
- Animals
- Antibodies, Blocking/adverse effects
- Antibodies, Blocking/therapeutic use
- Antibodies, Monoclonal/adverse effects
- Antibodies, Monoclonal/therapeutic use
- Colitis/immunology
- Colitis/pathology
- Colon/drug effects
- Colon/immunology
- Disease Models, Animal
- Female
- GTP-Binding Protein alpha Subunit, Gi2
- GTP-Binding Protein alpha Subunits, Gi-Go/deficiency
- GTP-Binding Protein alpha Subunits, Gi-Go/genetics
- Immunoglobulin A/blood
- Immunoglobulin G/blood
- Inflammatory Bowel Diseases/genetics
- Inflammatory Bowel Diseases/immunology
- Inflammatory Bowel Diseases/therapy
- Integrin alpha4/immunology
- Lymphoid Tissue/drug effects
- Lymphoid Tissue/immunology
- Male
- Mice
- Mice, Inbred C57BL
- Mice, Knockout
- Proto-Oncogene Proteins/deficiency
- Proto-Oncogene Proteins/genetics
- Spleen/drug effects
- Spleen/immunology
- T-Lymphocytes/drug effects
- T-Lymphocytes/immunology
- Time Factors
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Affiliation(s)
- Malin Bjursten
- Department of Clinical Immunology, Göteborg University, Gothenburg, Sweden
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30
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Zhou Y, Yokel RA. The Chemical Species of Aluminum Influences Its Paracellular Flux across and Uptake into Caco-2 Cells, a Model of Gastrointestinal Absorption. Toxicol Sci 2005; 87:15-26. [PMID: 15933224 DOI: 10.1093/toxsci/kfi216] [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: 11/12/2022] Open
Abstract
Aluminum (Al) can cause neurotoxicity, a low-turnover osteomalacia, and microcytic anemia. To test the null hypothesis that the chemical form (species) of Al does not influence its mechanism or rate of absorption from the gastrointestinal tract, Al flux across and uptake into Caco-2 cells was investigated. Caco-2 cells were grown on porous membranes mounted in vertical diffusion chambers or in 35-mm-diameter plastic cell culture dishes. When 8 mM 27Al was introduced as the ion, citrate, maltolate, fluoride, or hydroxide, the apical to basolateral apparent permeability (Papp) of Al correlated highly with the Papp of lucifer yellow (LY), a paracellular marker, except when introduced as Al hydroxide. The uptake rate of Al when introduced as the fluoride was > when introduced as the ion > maltolate > citrate > hydroxide. The activation energy of Al introduced as the ion, citrate, maltolate, and fluoride, determined from Arrhenius plots, was 13-22 KJ/mol, suggesting diffusion-mediated uptake. With exposure to 2 microM Al (containing 26Al as a tracer) introduced as the ion, hydroxide, citrate, and fluoride, Al and LY Papp were consistent with results obtained with 8 mM Al, but were not Al species dependent. Approximately 0.015% of the 26Al fluxed across the cell monolayer; 0.75% was associated with cells. Lumogallion staining imaged by confocal laser microscopy showed Al co-localized with DAPI in the nucleus. The results suggest that (1) soluble Al species predominantly diffuse through the paracellular pathway, (2) the ligand-dependent flux rate of Al is due to an effect on the tight junctions, (3) Caco-2 cell uptake of Al is a diffusion process, and (4) the ligand can influence the rate of cellular Al uptake.
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Affiliation(s)
- Yuzhao Zhou
- Graduate Center for Toxicology, University of Kentucky Medical Center, Lexington, Kentucky 40536-0305, USA
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31
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Hunt JL, Pollak MR, Denker BM. Cultured podocytes establish a size-selective barrier regulated by specific signaling pathways and demonstrate synchronized barrier assembly in a calcium switch model of junction formation. J Am Soc Nephrol 2005; 16:1593-602. [PMID: 15843471 DOI: 10.1681/asn.2004080679] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Abstract
Podocytes form unique cell-cell junctions (slit diaphragms) that are central to glomerular selectivity, although regulation and mechanisms of slit diaphragm assembly are poorly understood. With the use of cultured podocytes, a paracellular permeability flux assay was established to characterize properties of the size-selective barrier. Paracellular flux of differentiated podocytes was measured using anionic fluorescent dextrans of 3, 10, 40, and 70 kD. Podocytes form a highly selective barrier with a 160-fold difference in flux from the 3-kD dextran (11 pmol/min) to the 70-kD dextran (0.06 pmol/min). Barrier development was dependent on podocyte differentiation and not affected by dextran charge. Puromycin, a known podocyte toxin, increased flux 250% in a dose-dependent manner without affecting cell viability. Screening with modulators of specific signaling pathways identified reversible increases in flux with Src tyrosine and Rho kinase inhibition. The calcium switch model of epithelial junction assembly was modified to determine whether podocytes regulate barrier assembly. When cultured in low calcium for 90 min, flux increased by 300% and consistently returned to baseline 24 to 48 h after switching to normal calcium. Similar to classical epithelial junctions, barrier recovery occurred in the presence of cyclohexamide, an inhibitor of protein synthesis. During the calcium switch, there were reversible changes in localization and detergent solubility of the slit diaphragm protein ZO-1 and alpha-actinin-4, whereas nephrin and podocin solubility were unchanged. Taken together, these findings demonstrate that cultured podocytes develop a selective size barrier that is regulated by specific signaling pathways, and similar to classical epithelial junctions, podocytes demonstrate synchronized assembly of the barrier.
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Affiliation(s)
- Jennifer L Hunt
- Renal Division, Department of Medicine, Brigham and Women's Hospital, Boston, MA, USA
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32
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Wei B, Velazquez P, Turovskaya O, Spricher K, Aranda R, Kronenberg M, Birnbaumer L, Braun J. Mesenteric B cells centrally inhibit CD4+ T cell colitis through interaction with regulatory T cell subsets. Proc Natl Acad Sci U S A 2005; 102:2010-5. [PMID: 15684084 PMCID: PMC548553 DOI: 10.1073/pnas.0409449102] [Citation(s) in RCA: 144] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Inflammatory bowel disease reflects an aberrant mucosal CD4+ T cell response to commensal enteric bacteria. In addition to regulatory T cell subsets, recent studies have revealed a protective role of B cells in murine CD4+ T cell colitis, but the relationship of their action to T cell immunoregulation is unknown. Here we report that mesenteric lymph node (MLN) B cells protect mice from colitis induced by Galphai2-/- CD4+ T cells. Protection required the transfer of both B cells and CD8alpha+ T cells; neither cell type alone was sufficient to inhibit CD4+ T cell-mediated colitis. Similar results were also observed in colitis induced by CD4+CD45RBhi T cells. Immunoregulation was associated with localization of B cells and expansion of CD4-CD8- CD3+NK1.1+ T cells in the secondary lymphoid compartment, as well as expansion of CD4+CD8alpha+ T cells in the intestinal intraepithelial compartment. MLN B cells from Galphai2-/- mice were deficient in a phenotypic subset and failed to provide cotransfer colitis protection. These findings indicate that protective action of B cells is a selective trait of MLN B cells acquired through a Galphai2-dependent developmental process and link B cells with the formation of regulatory T cells associated with mucosal immune homeostasis.
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Affiliation(s)
- Bo Wei
- Department of Pathology and Laboratory Medicine and Molecular Biology Institute, University of California, Los Angeles, CA 90095, USA
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33
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Harhaj NS, Antonetti DA. Regulation of tight junctions and loss of barrier function in pathophysiology. Int J Biochem Cell Biol 2004; 36:1206-37. [PMID: 15109567 DOI: 10.1016/j.biocel.2003.08.007] [Citation(s) in RCA: 404] [Impact Index Per Article: 20.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2003] [Accepted: 08/21/2003] [Indexed: 12/16/2022]
Abstract
The mechanism by which epithelial and endothelial cells interact to form polarized tissue is of fundamental importance to multicellular organisms. Dysregulation of these barriers occurs in a variety of diseases, destroying the normal cellular environments and leading to organ failure. Increased levels of growth factors are a common characteristic of diseases exhibiting tissue permeability, suggesting that growth factors play a direct role in elevating permeability. Of particular concern for this laboratory, increased expression of vascular endothelial growth factor may enhance vascular permeability in diabetic retinopathy, leading to vision impairment and blindness. However, the mechanism by which growth factors increase permeability is unclear. Polarized cells form strong barriers through the development of tight junctions, which are specialized regions of the junctional complex. Tight junctions are composed of three types of transmembrane proteins, a number of peripheral membrane structural proteins, and are associated with a variety of regulatory proteins. Recent data suggest that growth factor-stimulated alterations in tight junctions contribute to permeability in a variety of disease states. The goal of this review was to elucidate potential mechanisms by which elevated growth factors elicit deregulated paracellular permeability via altered regulation of tight junctions, with particular emphasis on the tight junction proteins occludin and ZO-1, protein kinase C signaling, and endocytosis of junctional proteins. Understanding the molecular mechanisms underlying growth factor-mediated regulation of tight junctions will facilitate the development of novel treatments for diseases such as brain tumors, diabetic retinopathy and other diseases with compromised tight junction barriers.
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Affiliation(s)
- Nicole S Harhaj
- Penn State Retina Research Group, Penn State College of Medicine, 500 University Drive, Hershey, PA 17033, USA
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34
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Mruk DD, Cheng CY. Sertoli-Sertoli and Sertoli-germ cell interactions and their significance in germ cell movement in the seminiferous epithelium during spermatogenesis. Endocr Rev 2004; 25:747-806. [PMID: 15466940 DOI: 10.1210/er.2003-0022] [Citation(s) in RCA: 596] [Impact Index Per Article: 29.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Spermatogenesis is the process by which a single spermatogonium develops into 256 spermatozoa, one of which will fertilize the ovum. Since the 1950s when the stages of the epithelial cycle were first described, reproductive biologists have been in pursuit of one question: How can a spermatogonium traverse the epithelium, while at the same time differentiating into elongate spermatids that remain attached to the Sertoli cell throughout their development? Although it was generally agreed upon that junction restructuring was involved, at that time the types of junctions present in the testis were not even discerned. Today, it is known that tight, anchoring, and gap junctions are found in the testis. The testis also has two unique anchoring junction types, the ectoplasmic specialization and tubulobulbar complex. However, attention has recently shifted on identifying the regulatory molecules that "open" and "close" junctions, because this information will be useful in elucidating the mechanism of germ cell movement. For instance, cytokines have been shown to induce Sertoli cell tight junction disassembly by shutting down the production of tight junction proteins. Other factors such as proteases, protease inhibitors, GTPases, kinases, and phosphatases also come into play. In this review, we focus on this cellular phenomenon, recapping recent developments in the field.
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Affiliation(s)
- Dolores D Mruk
- Population Council, Center for Biomedical Research, New York, New York 10021, USA.
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35
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Cereijido M, Contreras RG, Shoshani L. Cell Adhesion, Polarity, and Epithelia in the Dawn of Metazoans. Physiol Rev 2004; 84:1229-62. [PMID: 15383651 DOI: 10.1152/physrev.00001.2004] [Citation(s) in RCA: 89] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Transporting epithelia posed formidable conundrums right from the moment that Du Bois Raymond discovered their asymmetric behavior, a century and a half ago. It took a century and a half to start unraveling the mechanisms of occluding junctions and polarity, but we now face another puzzle: lest its cells died in minutes, the first high metazoa (i.e., higher than a sponge) needed a transporting epithelium, but a transporting epithelium is an incredibly improbable combination of occluding junctions and cell polarity. How could these coincide in the same individual organism and within minutes? We review occluding junctions (tight and septate) as well as the polarized distribution of Na+-K+-ATPase both at the molecular and the cell level. Junctions and polarity depend on hosts of molecular species and cellular processes, which are briefly reviewed whenever they are suspected to have played a role in the dawn of epithelia and metazoan. We come to the conclusion that most of the molecules needed were already present in early protozoan and discuss a few plausible alternatives to solve the riddle described above.
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Affiliation(s)
- M Cereijido
- Center For Research and Advanced Studies, Dept. of Physiology, Biophysics, and Neurosciences, Avenida Instituto Politécnico Nacional 2508, Código Postal 07360, México D.F., Mexico.
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36
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Bazzoni G, Dejana E. Endothelial cell-to-cell junctions: molecular organization and role in vascular homeostasis. Physiol Rev 2004; 84:869-901. [PMID: 15269339 DOI: 10.1152/physrev.00035.2003] [Citation(s) in RCA: 913] [Impact Index Per Article: 45.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Intercellular junctions mediate adhesion and communication between adjoining endothelial and epithelial cells. In the endothelium, junctional complexes comprise tight junctions, adherens junctions, and gap junctions. The expression and organization of these complexes depend on the type of vessels and the permeability requirements of perfused organs. Gap junctions are communication structures, which allow the passage of small molecular weight solutes between neighboring cells. Tight junctions serve the major functional purpose of providing a "barrier" and a "fence" within the membrane, by regulating paracellular permeability and maintaining cell polarity. Adherens junctions play an important role in contact inhibition of endothelial cell growth, paracellular permeability to circulating leukocytes and solutes. In addition, they are required for a correct organization of new vessels in angiogenesis. Extensive research in the past decade has identified several molecular components of the tight and adherens junctions, including integral membrane and intracellular proteins. These proteins interact both among themselves and with other molecules. Here, we review the individual molecules of junctions and their complex network of interactions. We also emphasize how the molecular architectures and interactions may represent a mechanistic basis for the function and regulation of junctions, focusing on junction assembly and permeability regulation. Finally, we analyze in vivo studies and highlight information that specifically relates to the role of junctions in vascular endothelial cells.
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Affiliation(s)
- Gianfranco Bazzoni
- Istituto di Ricerche Farmacologiche "Mario Negri," Via Eritrea 62, I-20157 Milan, Italy.
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37
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Bruewer M, Hopkins AM, Hobert ME, Nusrat A, Madara JL. RhoA, Rac1, and Cdc42 exert distinct effects on epithelial barrier via selective structural and biochemical modulation of junctional proteins and F-actin. Am J Physiol Cell Physiol 2004; 287:C327-35. [PMID: 15044152 DOI: 10.1152/ajpcell.00087.2004] [Citation(s) in RCA: 180] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Epithelial intercellular junctions regulate cell-cell contact and mucosal barrier function. Both tight junctions (TJs) and adherens junctions (AJs) are regulated in part by their affiliation with the F-actin cytoskeleton. The cytoskeleton in turn is influenced by Rho family small GTPases such as RhoA, Rac1, and Cdc42, all of which constitute eukaryotic targets for several pathogenic organisms. With a tetracycline-repressible system to achieve regulated expression in Madin-Darby canine kidney (MDCK) epithelial cells, we used dominant-negative (DN) and constitutively active (CA) forms of RhoA, Rac1, and Cdc42 as tools to evaluate the precise contribution of each GTPase to epithelial structure and barrier function. All mutant GTPases induced time-dependent disruptions in epithelial gate function and distinct morphological alterations in apical and basal F-actin pools. TJ proteins occludin, ZO-1, claudin-1, claudin-2, and junctional adhesion molecule (JAM)-1 were dramatically redistributed in the presence of CA RhoA or CA Cdc42, whereas only claudins-1 and -2 were redistributed in response to CA Rac1. DN Rac1 expression also induced selective redistribution of claudins-1 and -2 in addition to JAM-1, whereas DN Cdc42 influenced only claudin-2 and DN RhoA had no effect. AJ protein localization was unaffected by any mutant GTPase, but DN Rac1 induced a reduction in E-cadherin detergent solubility. All CA GTPases increased the detergent solubility of claudins-1 and -2, but CA RhoA alone reduced claudin-2 and ZO-1 partitioning to detergent-insoluble membrane rafts. We conclude that Rho family GTPases regulate epithelial intercellular junctions via distinct morphological and biochemical mechanisms and that perturbations in barrier function reflect any imbalance in active/resting GTPase levels rather than simply loss or gain of GTPase activity.
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Affiliation(s)
- Matthias Bruewer
- Epithelial Pathobiology Research Unit, Department of Pathology and Lab Medicine, Emory University, Atlanta, GA 30322, USA.
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38
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Alvarado JA, Betanzos A, Franse-Carman L, Chen J, González-Mariscal L. Endothelia of Schlemm's canal and trabecular meshwork: distinct molecular, functional, and anatomic features. Am J Physiol Cell Physiol 2004; 286:C621-34. [PMID: 14613887 DOI: 10.1152/ajpcell.00108.2003] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The purpose of this study was to compare human endothelial cells from Schlemm's canal (SCEs) and the trabecular meshwork (TMEs) in terms of ZO-1 isoform expression, hydraulic conductivity (HC) properties, and “giant” vacuole (GV) formation. The principal study methods were Western blot, RT-PCR, immunofluorescence, and perfusion chambers. Blot signals for α+-and α--isoforms were similar in SCEs but less intense for the α+-relative to the α--signal in TMEs. With the anti-α+antibody used at 1/50 dilution, binding occurred at cell borders of both cell types, but only to SCEs when used at a ≥1/200 dilution in vitro and in vivo. SCEs were more resistive than TMEs (HC = 0.66 vs. 1.32 μl·min-1·mmHg-1·cm-2; P < 0.001) when perfused from apex to base. When perfused in the other direction, SCEs were again more resistive (5.23 vs. 9.04 μl·min-1·mmHg-1·cm-2; P < 0.01). GV formation occurred only in SCEs as a function of flow direction, perfusion pressure, and time. We conclude that SCEs and TMEs have distinctive phenotypic properties involving their content of ZO-1 isoforms, barrier function, and GV formation.
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Affiliation(s)
- Jorge A Alvarado
- Department of Ophthalmology, University of California, San Francisco, California 94143-0730, USA.
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39
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Meyer TN, Hunt J, Schwesinger C, Denker BM. Galpha12 regulates epithelial cell junctions through Src tyrosine kinases. Am J Physiol Cell Physiol 2003; 285:C1281-93. [PMID: 12890651 DOI: 10.1152/ajpcell.00548.2002] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Regulation and assembly of the epithelial cell junctional complex involve multiple signaling mechanisms, including heterotrimeric G proteins. Recently, we demonstrated that Galpha12 binds to the tight junction scaffolding protein ZO-1 through the SH3 domain and that activated Galpha12 increases paracellular permeability in Madin-Darby canine kidney (MDCK) cells (Meyer et al. J Biol Chem 277: 24855-24858, 2002). In the present studies, we explore the effects of Galpha12 expression on tight and adherens junction proteins and examine downstream signaling pathways. By confocal microscopy, we detect disrupted tight and adherens junction proteins with increased actin stress fibers in constitutively active Galpha12 (QLalpha12)-expressing MDCK cells. The normal distribution of ZO-1 and Na-K-ATPase was altered in QLalpha12-expressing MDCK cells, consistent with loss of polarity. We found that the tyrosine kinase inhibitor genistein and the Src-specific inhibitor PP-2 reversibly abrogated the QLalpha12 phenotype on the junctional complex. Junctional protein localization was preserved in PP-2- or genistein-treated QLalpha12-expressing cells, and the increase in paracellular permeability as measured by transepithelial resistance and [3H]mannitol flux was prevented by the inhibitors. Src activity was increased in QLalpha12-expressing MDCK cells as assessed by Src autophosphorylation, and beta-catenin tyrosine phosphorylation was also increased, although there was no detectable increase in Rho activity. Taken together, these results indicate that Galpha12 regulates MDCK cell junctions, in part through Src tyrosine kinase pathways.
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Affiliation(s)
- Tobias N Meyer
- Renal Division, Brigham and Women's Hospital and Harvard Medical School, Harvard Institutes of Medicine, 77 Avenue Louis Pasteur, Boston, MA 02115, USA
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40
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Rubenstein NM, Guan Y, Woo PL, Firestone GL. Glucocorticoid down-regulation of RhoA is required for the steroid-induced organization of the junctional complex and tight junction formation in rat mammary epithelial tumor cells. J Biol Chem 2003; 278:10353-60. [PMID: 12525486 DOI: 10.1074/jbc.m213121200] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
In Con8 mammary epithelial tumor cells, we have documented previously that the synthetic glucocorticoid dexamethasone induces the reorganization of the tight junction and adherens junction (apical junction) and stimulates the monolayer transepithelial electrical resistance (TER), which is a reliable in vitro measurement of tight junction sealing. Western blots demonstrated that dexamethasone treatment down-regulated the level of the RhoA small GTPase prior to the stimulation of the monolayer TER. To test the role of RhoA in the steroid regulation of apical junction dynamics functionally, RhoA levels were altered in Con8 cells by transfection of either constitutively active (RhoA.V14) or dominant negative (RhoA.DN19) forms of RhoA. Ectopic expression of constitutively active RhoA disrupted the dexamethasone-stimulated localization of zonula occludens-1 and beta-catenin to sites of cell-cell contact, inhibited tight junction sealing, and prevented the complete formation of the F-actin ring structure at the apical side of the cell monolayer. In a complementary manner, dominant negative RhoA caused a precocious organization of the tight junction, adherens junction, and the F-actin rings in the absence of steroid, whereas the monolayer TER remained glucocorticoid-responsive. Taken together, our results demonstrate that the glucocorticoid down-regulation of RhoA is a required step in the steroid signaling pathway which controls the organization of the apical junctional complex and the actin cytoskeleton in mammary epithelial cells.
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Affiliation(s)
- Nicola M Rubenstein
- Department of Molecular and Cell Biology and the Cancer Research Laboratory, University of California at Berkeley, 94720-3200, USA
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41
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Copin JC, Gasche Y. [Morphology and physiology of the blood-brain barrier]. ANNALES FRANCAISES D'ANESTHESIE ET DE REANIMATION 2003; 22:202-14. [PMID: 12747988 DOI: 10.1016/s0750-7658(03)00040-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The blood-brain barrier (BBB) is a complex biological system that consists of endothelial cells, pericytes and astrocytes, which are involved in the induction and maintenance of its physiological and ultrastructural characteristics. The BBB plays a primordial role in isolating the cerebral parenchyma as well as in controlling brain homeostasis by its selective permeability to nutriments and other molecules flowing through the cerebral microcapillaries. A better knowledge of this system is crucial in order to improve the efficiency of brain penetration by drugs, and in order to prevent BBB opening, leading to brain edema, in physiopathological situations such as brain ischemia, trauma or inflammatory processes.
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Affiliation(s)
- J C Copin
- Divisions des soins intensifs de chirurgie et de médecine, division d'investigations anesthésiologiques, hôpitaux universitaires de Genève, 1211 Genève, Suisse.
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42
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González-Mariscal L, Betanzos A, Nava P, Jaramillo BE. Tight junction proteins. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2003; 81:1-44. [PMID: 12475568 DOI: 10.1016/s0079-6107(02)00037-8] [Citation(s) in RCA: 802] [Impact Index Per Article: 38.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
A fundamental function of epithelia and endothelia is to separate different compartments within the organism and to regulate the exchange of substances between them. The tight junction (TJ) constitutes the barrier both to the passage of ions and molecules through the paracellular pathway and to the movement of proteins and lipids between the apical and the basolateral domains of the plasma membrane. In recent years more than 40 different proteins have been discovered to be located at the TJs of epithelia, endothelia and myelinated cells. This unprecedented expansion of information has changed our view of TJs from merely a paracellular barrier to a complex structure involved in signaling cascades that control cell growth and differentiation. Both cortical and transmembrane proteins integrate TJs. Among the former are scaffolding proteins containing PDZ domains, tumor suppressors, transcription factors and proteins involved in vesicle transport. To date two components of the TJ filaments have been identified: occludin and claudin. The latter is a protein family with more than 20 members. Both occludin and claudins are integral proteins capable of interacting adhesively with complementary molecules on adjacent cells and of co-polymerizing laterally. These advancements in the knowledge of the molecular structure of TJ support previous physiological models that exhibited TJ as dynamic structures that present distinct permeability and morphological characteristics in different tissues and in response to changing natural, pathological or experimental conditions.
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Affiliation(s)
- L González-Mariscal
- Department of Physiology, Biophysics and Neuroscience, Center for Research and Advanced Studies (CINVESTAV), Ave. Politécnico Nacional 2508, México DF, 07000, Mexico.
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43
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Baker SF, Yin Y, Runswick SK, Stewart GA, Thompson PJ, Garrod DR, Robinson C. Peptidase allergen Der p 1 initiates apoptosis of epithelial cells independently of tight junction proteolysis. Mol Membr Biol 2003; 20:71-81. [PMID: 12745920 DOI: 10.1080/0968768021000061150] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Loss of epithelial cell polarity, which can arise following disruption of tight junctions (TJs), is a precursor to the care-fully orchestrated removal of moribund cells from epithelia in apoptosis. Ordinarily, this cycle of events has minimally disruptive effects on the function of the epithelial barrier, but some agents have been identified that induce apoptosis and promote epithelial leakiness. The allergen Der p 1 is a cysteine peptidase that cleaves TJ adhesion proteins and induces apoptosis in epithelial cells. This suggests the possibility that, at least for some inducers of apoptosis, these events might be causally linked. We report here that Der p 1 induces epithelial apoptosis before outright cell detachment and that apoptosis occurs within the same time span as increased paracellular permeability in polarized epithelial monolayers. Whilst TJ-deficient BEAS-2B cells were resistant to Der p 1-induced apoptosis, the cell line 1HAEo-, which was also TJ deficient, was sensitive to Der p 1, providing evidence against TJ proteolysis as a cause of apoptosis. To provide direct evidence, we propagated cells that normally express TJs in low calcium medium that prevented intercellular junction assembly. These cells retained full susceptibility to Der p 1, indicating that Der p 1-induced apoptosis is independent from TJ proteolysis.
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Affiliation(s)
- Sharon F Baker
- Department of Pharmacology & Clinical Pharmacology, St George's Hospital Medical School, London, UK
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Adamson P, Wilbourn B, Etienne-Manneville S, Calder V, Beraud E, Milligan G, Couraud PO, Greenwood J. Lymphocyte trafficking through the blood-brain barrier is dependent on endothelial cell heterotrimeric G-protein signaling. FASEB J 2002; 16:1185-94. [PMID: 12153986 DOI: 10.1096/fj.02-0035com] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
We have previously shown that the engagement of ICAM-1 on brain endothelial cells (EC) results in the propagation of EC signaling pathways that are necessary for efficient lymphocyte migration across the tight vascular barriers of the brain. Signaling via this receptor alone, however, is unlikely to explain the differential recruitment of leukocytes at different vascular beds. In this study, we investigated the role of EC heterotrimeric G-protein-mediated signaling in supporting transendothelial migration of T lymphocytes. Treatment of brain EC monolayers with pertussis toxin (PTX) resulted in ADP-ribosylation of G-protein alpha subunits and inhibition (>80%) of lymphocyte migration without affecting lymphocyte adhesion. Aortic and high endothelial venule EC treated identically resulted in only partial inhibition of lymphocyte migration (<40%). Expression of ribosylation-resistant (PTX-insensitive) G-protein alpha subunits in brain EC restored their ability to support lymphocyte migration after pretreatment with PTX. Treatment of brain EC with PTX did not inhibit ICAM-1-stimulated tyrosine phosphorylation of focal adhesion kinase, suggesting the effects of PTX in inhibiting EC facilitation of lymphocyte migration are distinct from activation of EC through ICAM-1. We conclude that a heterotrimeric G-protein-mediated signaling pathway in brain EC is essential for efficient transendothelial migration of T lymphocytes into the brain.
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Affiliation(s)
- Peter Adamson
- Endothelial and Epithelial Cell Biology Research Unit, Division of Cell Biology, Institute of Ophthalmology, University College London, London EC1V 9EL, UK.
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Meyer TN, Schwesinger C, Denker BM. Zonula occludens-1 is a scaffolding protein for signaling molecules. Galpha(12) directly binds to the Src homology 3 domain and regulates paracellular permeability in epithelial cells. J Biol Chem 2002; 277:24855-8. [PMID: 12023272 DOI: 10.1074/jbc.c200240200] [Citation(s) in RCA: 91] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Zonula occludens proteins are multidomain proteins usually localized at sites of intercellular junctions, yet little is known about their role in regulating junctional properties. Multiple signaling proteins regulate the junctional complex, and several (including G proteins) have been co-localized with zonula occludens-1 (ZO-1) in the tight junction of epithelial cells. However, evidence for direct interactions between signaling proteins and tight junction proteins has been lacking. In these studies, we constructed Galpha-glutathione S-transferase (GST) fusion proteins and tested for interactions with [(35)S]methionine-labeled in vitro translated ZO-1 and ZO-2. Only Galpha(12) directly interacted with in vitro translated ZO-1 and ZO-2. Using a series of ZO-1 domains expressed as GST fusion proteins and in vitro translated [(35)S]methionine-labeled Galpha(12), we found that Galpha(12) and constitutively active (Q229L) alpha(12) (QLalpha(12)) bind to the Src homology 3 (SH3) domain of ZO-1. This binding was not detected with SH3 domains from other proteins. Inducible expression of wild-type alpha(12) and QLalpha(12) in Madin-Darby canine kidney (MDCK) cells was established using the Tet-Off system. In Galpha(12)-expressing cells, we found that ZO-1 and Galpha(12) co-localize by confocal microscopy and co-immunoprecipitate. Galpha(12) from MDCK cell lysates bound to the GST-ZO-1-SH3 domain, and expression of QLalpha(12) in MDCK cells reversibly increased paracellular permeability. These studies indicated that ZO-1 directly interacts with Galpha(12) and that Galpha(12) regulates barrier function of MDCK cells.
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Affiliation(s)
- Tobias N Meyer
- Renal Division, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts 02115, USA
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Wolburg H, Lippoldt A. Tight junctions of the blood-brain barrier: development, composition and regulation. Vascul Pharmacol 2002; 38:323-37. [PMID: 12529927 DOI: 10.1016/s1537-1891(02)00200-8] [Citation(s) in RCA: 779] [Impact Index Per Article: 35.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
1. The blood-brain barrier is essential for the maintenance and regulation of the neural microenvironment. The main characteristic features of blood-brain barrier endothelial cells are an extremely low rate of transcytotic vesicles and a restrictive paracellular diffusion barrier. 2. Endothelial blood-brain barrier tight junctions differ from epithelial tight junctions, not only by distinct morphological and molecular properties, but also by the fact that endothelial tight junctions are more sensitive to microenvironmental than epithelial factors. 3. Many ubiquitous molecular tight junction components have been identified and characterized including claudins, occludin, ZO-1, ZO-2, ZO-3, cingulin and 7H6. Signaling pathways involved in tight junction regulation include G-proteins, serine-, threonine- and tyrosine-kinases, extra and intracellular calcium levels, cAMP levels, proteases and cytokines. Common to most of these pathways is the modulation of cytoskeletal elements and the connection of tight junction transmembrane molecules to the cytoskeleton. Additionally, crosstalk between components of the tight junction- and the cadherin-catenin system of the adherens junction suggests a close functional interdependence of the two cell-cell contact systems. 4. Important new molecular aspects of tight junction regulation were recently elucidated. This review provides an integration of these new results.
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Affiliation(s)
- Hartwig Wolburg
- Institute of Pathology, University of Tübingen, Liebermeisterstr. 8, D-72076 Tübingen, Germany.
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Blumer JB, Chandler LJ, Lanier SM. Expression analysis and subcellular distribution of the two G-protein regulators AGS3 and LGN indicate distinct functionality. Localization of LGN to the midbody during cytokinesis. J Biol Chem 2002; 277:15897-903. [PMID: 11832491 DOI: 10.1074/jbc.m112185200] [Citation(s) in RCA: 97] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Activator of G-protein signaling 3 (AGS3) and LGN have a similar domain structure and contain four G-protein regulatory motifs that serve as anchors for the binding of the GDP-bound conformation of specific G-protein alpha subunits. As an initial approach to define further the different functional roles of AGS3 and LGN, we determined their expression profile and subcellular distribution. AGS3- and LGN-specific antisera indicated a widespread tissue distribution of LGN, whereas AGS3 is primarily enriched in brain. Brain punch biopsies of 13 discrete brain regions indicated that both AGS3 and LGN are expressed in all areas tested but are differentially regulated during development. LGN is expressed in neuronal, astroglial, and microglial cultures, whereas AGS3 expression is restricted to neurons. In primary neuronal cultures as well as in dividing cultures of PC12 cells, immunocytochemistry indicated distinct subcellular locations of AGS3 and LGN. The subcellular locations of the two proteins were differentially regulated by external stimuli and the cell cycle. In PC12 and COS7 cells, LGN moves from the nucleus to the midbody structure separating daughter cells during the later stages of mitosis, suggesting a role for G-proteins in cytokinesis. Thus, although AGS3 and LGN share a similar overall motif structure and both bind G-proteins, nature has endowed these proteins with different regulatory elements that allow functional diversity by virtue of tissue-specific expression and subcellular positioning.
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Affiliation(s)
- Joe B Blumer
- Department of Pharmacology and Experimental Therapeutics, Louisiana State University Health Sciences Center, New Orleans, Louisiana 70112, USA
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48
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Chen YH, Lu Q, Goodenough DA, Jeansonne B. Nonreceptor tyrosine kinase c-Yes interacts with occludin during tight junction formation in canine kidney epithelial cells. Mol Biol Cell 2002; 13:1227-37. [PMID: 11950934 PMCID: PMC102264 DOI: 10.1091/mbc.01-08-0423] [Citation(s) in RCA: 137] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Occludin is an integral membrane protein that is tyrosine phosphorylated when localized at tight junctions. When Ca(2+) was depleted from the culture medium, occludin tyrosine phosphorylation was diminished from Madin-Darby canine kidney epithelial cells in 2 min. This dephosphorylation was correlated with a significant reduction in transepithelial electrical resistance (TER), indicating a global loss of the tight junction barrier function. Reconstitution of Ca(2+) resulted in a robust tyrosine rephosphorylation of occludin that was temporally associated with an increase in TER. Moreover, we demonstrate in this study that occludin was colocalized with the nonreceptor tyrosine kinase c-Yes at cell junction areas and formed an immunoprecipitable complex with c-Yes in vivo. This complex dissociated when the cells were incubated in medium without Ca(2+) or treated with a c-Yes inhibitor, CGP77675. In the presence of CGP77675 after Ca(2+) repletion, occludin tyrosine phosphorylation was completely abolished and both tight junction formation and the increase of the TER were inhibited. Our study thus provides strong evidence that occludin tyrosine phosphorylation is tightly linked to tight junction formation in epithelial cells, and that the nonreceptor tyrosine kinase c-Yes is involved in the regulation of this process.
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Affiliation(s)
- Yan-Hua Chen
- Department of Anatomy and Cell Biology, East Carolina University School of Medicine, Greenville, NC 27858, USA.
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49
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Chen ML, Pothoulakis C, LaMont JT. Protein kinase C signaling regulates ZO-1 translocation and increased paracellular flux of T84 colonocytes exposed to Clostridium difficile toxin A. J Biol Chem 2002; 277:4247-54. [PMID: 11729192 DOI: 10.1074/jbc.m109254200] [Citation(s) in RCA: 130] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Clostridium difficile toxin A increases paracellular permeability in colonic epithelial T84 cells by mechanisms involving RhoA glucosylation and actin depolymerization. However, we previously observed that toxin A-mediated decline in transepithelial electrical resistance preceded changes in cell morphology and tight junction ultrastructure (Hecht, G., Pothoulakis, C., LaMont, J. T., and Madara, J. L. (1988) J. Clin. Invest. 82, 1516-1524). Recent studies also showed that C. difficile toxins induce early cellular responses, including activation of mitogen-activated protein kinases, generation of reactive oxygen metabolites, and calcium influx. The aim of this study was to investigate whether toxin A-induced early cellular responses contribute to the permeability changes. We found that toxin A stimulated the activities of membrane and cytosolic protein kinase Calpha (PKCalpha) and cytosolic PKCbeta. A specific PKCalpha/beta antagonist (myristoylated PKCalpha/beta peptide) blocked toxin A-mediated RhoA glucosylation. Furthermore, decreased transepithelial electrical resistance and increased translocation of ZO-1 from tight junction occurred within 2-3 h of toxin A exposure and were also inhibited by PKCalpha/beta antagonist. During this time period, toxin exposure did not induce translocation of ZO-2, dephosphorylation or translocation of occludin, or cell rounding. Our data indicate that PKC signaling regulates toxin A-mediated paracellular permeability changes and ZO-1 translocation.
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Affiliation(s)
- Ming L Chen
- Division of Gastroenterology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts 02215, USA
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50
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Huber JD, Egleton RD, Davis TP. Molecular physiology and pathophysiology of tight junctions in the blood-brain barrier. Trends Neurosci 2001; 24:719-25. [PMID: 11718877 DOI: 10.1016/s0166-2236(00)02004-x] [Citation(s) in RCA: 552] [Impact Index Per Article: 24.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Disruption of the tight junctions (TJs) of the blood-brain barrier (BBB) is a hallmark of many CNS pathologies, including stroke, HIV encephalitis, Alzheimer's disease, multiple sclerosis and bacterial meningitis. Furthermore, systemic-derived inflammation has recently been shown to cause BBB tight junctional disruption and increased paracellular permeability. The BBB is capable of rapid modulation in response to physiological stimuli at the cytoskeletal level, which enables it to protect the brain parenchyma and maintain a homeostatic environment. By allowing the "loosening" of TJs and an increase in paracellular permeability, the BBB is able to "bend without breaking"; thereby, maintaining structural integrity.
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Affiliation(s)
- J D Huber
- Department of Pharmacology, The University of Arizona College of Medicine, Tucson, AZ 85724, USA
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