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Yadav R, Kumar Y, Dahiya D, Bhatia A. Claudins: The Newly Emerging Targets in Breast Cancer. Clin Breast Cancer 2022; 22:737-752. [PMID: 36175290 DOI: 10.1016/j.clbc.2022.09.001] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2022] [Accepted: 09/04/2022] [Indexed: 01/25/2023]
Abstract
Claudin-low breast cancers are recently described entities showing low expression of certain claudins and cell adhesion molecules. Claudins constitute the backbone of tight junctions (TJs) formed between 2 cells. Their dysregulation plays a vital role in tumorigenesis. First part of the article focuses on the role of claudins in the TJ organization, their structural-functional characteristics, and post-transcriptional and translational modifications. The latter part of the review attempts to summarize existing knowledge regarding the status of claudins in breast cancer. The article also provides an overview of the effect of claudins on tumor progression, metastasis, stemness, chemotherapy resistance, and their crosstalk with relevant signaling pathways in breast cancer. Claudins can act as 2-edged swords in tumors. Some claudins have either tumor-suppressive/ promoting action, while others work as both in a context-dependent manner. Claudins regulate many important events in breast cancer. However, the intricacies involved in their activity are poorly understood. Post-translational modifications in claudins and their impact on TJ integrity, function, and tumor behavior are still unclear. Although their role in adverse events in breast cancer is recognized, their potential to serve as relevant targets for future therapeutics, especially for difficult-to-treat subtypes of the above malignancy, remains to be explored.
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Affiliation(s)
- Reena Yadav
- Department of Experimental Medicine and Biotechnology, Postgraduate Institute of Medical Education and Research, Chandigarh, India
| | - Yashwant Kumar
- Department of Immunopathology, Postgraduate Institute of Medical Education and Research, Chandigarh, India
| | - Divya Dahiya
- Department of General Surgery, Postgraduate Institute of Medical Education and Research, Chandigarh, India
| | - Alka Bhatia
- Department of Experimental Medicine and Biotechnology, Postgraduate Institute of Medical Education and Research, Chandigarh, India.
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Kohno T, Kojima T. Atypical Macropinocytosis Contributes to Malignant Progression: A Review of Recent Evidence in Endometrioid Endometrial Cancer Cells. Cancers (Basel) 2022; 14:cancers14205056. [PMID: 36291839 PMCID: PMC9599675 DOI: 10.3390/cancers14205056] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2022] [Revised: 10/01/2022] [Accepted: 10/13/2022] [Indexed: 11/24/2022] Open
Abstract
Simple Summary A novel type of macropinocytosis has been identified as a trigger for the malignant progression of endometrial cancer. Transiently reducing epithelial barrier homeostasis leads to macropinocytosis by splitting between adjacent cells in endometrioid endometrial cancer. Macropinocytosis causes morphological changes in well-differentiated to poorly differentiated cancer cells. Inhibition of macropinocytosis promotes a persistent dormant state in the intrinsic KRAS-mutated cancer cell line Sawano. This review focuses on the mechanisms of atypical macropinocytosis and its effects on cellular function, and it describes the physiological processes involved in inducing resting conditions in endometrioid endometrial cancer cells. Abstract Macropinocytosis is an essential mechanism for the non-specific uptake of extracellular fluids and solutes. In recent years, additional functions have been identified in macropinocytosis, such as the intracellular introduction pathway of drugs, bacterial and viral infection pathways, and nutritional supplement pathway of cancer cells. However, little is known about the changes in cell function after macropinocytosis. Recently, it has been reported that macropinocytosis is essential for endometrial cancer cells to initiate malignant progression in a dormant state. Macropinocytosis is formed by a temporary split of adjacent bicellular junctions of epithelial sheets, rather than from the apical surface or basal membrane, as a result of the transient reduction of tight junction homeostasis. This novel type of macropinocytosis has been suggested to be associated with the malignant pathology of endometriosis and endometrioid endometrial carcinoma. This review outlines the induction of malignant progression of endometrial cancer cells by macropinocytosis based on a new mechanism and the potential preventive mechanism of its malignant progression.
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Meoli L, Günzel D. Channel functions of claudins in the organization of biological systems. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2020; 1862:183344. [PMID: 32442419 DOI: 10.1016/j.bbamem.2020.183344] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/17/2019] [Revised: 04/27/2020] [Accepted: 05/05/2020] [Indexed: 02/07/2023]
Abstract
Claudins are tight junction proteins mostly appreciated in their function of paracellular barrier-formation. Compared to a virtual absence of any tight junctions, their paracellular sealing role certainly stands out. Yet, it was recognized immediately after the discovery of the first claudins, that some members of the claudin protein family were able to convey size and charge selectivity to the paracellular pathway. Thus, paracellular permeability can be fine-tuned according to the physiological needs of a tissue by inserting these channel-forming claudins into tight junction strands. Precise permeability adjustment is further suggested by the presence of numerous isoforms of channel-forming claudins (claudin-10b-, -15-, -16-like isoforms) in various vertebrate taxa. Moreover, their expression and localization are controlled by multiple transcriptional and posttranslational mechanisms. Consequently, mutation or dysregulation of channel-forming claudins can cause severe diseases. The present review therefore aims at providing an up-to-date report of the current research on these aspects of channel-forming claudins and their possible implications on future developments.
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Affiliation(s)
- Luca Meoli
- Institute of Clinical Physiology/Nutritional Medicine, Medical Department, Division of Gastroenterology, Infectiology, Rheumatology, Charité - Universitätsmedizin Berlin, 12203 Berlin, Germany
| | - Dorothee Günzel
- Institute of Clinical Physiology/Nutritional Medicine, Medical Department, Division of Gastroenterology, Infectiology, Rheumatology, Charité - Universitätsmedizin Berlin, 12203 Berlin, Germany.
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Boivin FJ, Schmidt-Ott KM. Functional roles of Grainyhead-like transcription factors in renal development and disease. Pediatr Nephrol 2020; 35:181-190. [PMID: 30554362 DOI: 10.1007/s00467-018-4171-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/01/2018] [Revised: 11/07/2018] [Accepted: 12/06/2018] [Indexed: 12/11/2022]
Abstract
Proper renal function relies on the tightly regulated development of nephrons and collecting ducts. This process, known as tubulogenesis, involves dynamic cellular and molecular changes that instruct cells to form highly organized tubes of epithelial cells which compartmentalize the renal interstitium and tubular lumen via assembly of a selective barrier. The integrity and diversity of the various renal epithelia is achieved via formation of intercellular protein complexes along the apical-basal axis of the epithelial cells. In recent years, the evolutionarily conserved family of Grainyhead-like (GRHL) transcription factors which encompasses three mammalian family members (Grainyhead-like 1, 2, 3) has emerged as a group of critical regulators for organ development, epithelial differentiation, and barrier formation. Evidence from transgenic animal models supports the presence of Grainyhead-like-dependent transcriptional mechanisms that promote formation and maintenance of epithelial barriers in the kidney. In this review, we highlight different Grhl-dependent mechanisms that modulate epithelial differentiation in the kidney. Additionally, we discuss how disruptions in these mechanisms result in impaired renal function later in life.
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Affiliation(s)
- Felix J Boivin
- Max Delbrück Center for Molecular Medicine, Robert-Rössle-Strasse 10, 13125, Berlin, Germany
| | - Kai M Schmidt-Ott
- Max Delbrück Center for Molecular Medicine, Robert-Rössle-Strasse 10, 13125, Berlin, Germany. .,Department of Nephrology, Charité Medical University, Berlin, Germany.
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Ziemens A, Sonntag SR, Wulfmeyer VC, Edemir B, Bleich M, Himmerkus N. Claudin 19 Is Regulated by Extracellular Osmolality in Rat Kidney Inner Medullary Collecting Duct Cells. Int J Mol Sci 2019; 20:ijms20184401. [PMID: 31500238 PMCID: PMC6770061 DOI: 10.3390/ijms20184401] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2019] [Revised: 08/29/2019] [Accepted: 09/04/2019] [Indexed: 01/27/2023] Open
Abstract
The inner medullary collecting duct (IMCD) is subject to severe changes in ambient osmolality and must either allow water transport or be able to seal the lumen against a very high osmotic pressure. We postulate that the tight junction protein claudin-19 is expressed in IMCD and that it takes part in epithelial adaptation to changing osmolality at different functional states. Presence of claudin-19 in rat IMCD was investigated by Western blotting and immunofluorescence. Primary cell culture of rat IMCD cells on permeable filter supports was performed under different osmotic culture conditions and after stimulation by antidiuretic hormone (AVP). Electrogenic transepithelial transport properties were measured in Ussing chambers. IMCD cells cultivated at 300 mosm/kg showed high transepithelial resistance, a cation selective paracellular pathway and claudin-19 was mainly located in the tight junction. Treatment by AVP increased cation selectivity but did not alter transepithelial resistance or claudin-19 subcellular localization. In contrast, IMCD cells cultivated at 900 mosm/kg had low transepithelial resistance, anion selectivity, and claudin-19 was relocated from the tight junctions to intracellular vesicles. The data shows osmolality-dependent transformation of IMCD epithelium from tight and sodium-transporting to leaky, with claudin-19 expression in the tight junction associated to tightness and cation selectivity under low osmolality.
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Affiliation(s)
- Annalisa Ziemens
- Institute of Physiology, Christian-Albrecht-University Kiel, Hermann-Rodewald-Str. 5, 24118 Kiel, Germany.
| | - Svenja R Sonntag
- Institute of Physiology, Christian-Albrecht-University Kiel, Hermann-Rodewald-Str. 5, 24118 Kiel, Germany.
- Department of Ophthalmology, University of Lübeck, Ratzeburger Allee 160, 23538 Lübeck, Germany.
| | - Vera C Wulfmeyer
- Institute of Physiology, Christian-Albrecht-University Kiel, Hermann-Rodewald-Str. 5, 24118 Kiel, Germany.
- Department of Nephrology and Hypertension, Hannover Medical School, Carl-Neuberg-Str. 1, 30625 Hannover, Germany.
| | - Bayram Edemir
- Department of Internal Medicine IV, Hematology and Oncology, University Hospital Halle, Ernst-Grube-Str. 40, 06120 Halle (Saale), Germany.
| | - Markus Bleich
- Institute of Physiology, Christian-Albrecht-University Kiel, Hermann-Rodewald-Str. 5, 24118 Kiel, Germany.
| | - Nina Himmerkus
- Institute of Physiology, Christian-Albrecht-University Kiel, Hermann-Rodewald-Str. 5, 24118 Kiel, Germany.
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Kohno T, Konno T, Kojima T. Role of Tricellular Tight Junction Protein Lipolysis-Stimulated Lipoprotein Receptor (LSR) in Cancer Cells. Int J Mol Sci 2019; 20:E3555. [PMID: 31330820 PMCID: PMC6679224 DOI: 10.3390/ijms20143555] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2019] [Revised: 07/17/2019] [Accepted: 07/19/2019] [Indexed: 02/07/2023] Open
Abstract
Maintaining a robust epithelial barrier requires the accumulation of tight junction proteins, LSR/angulin-1 and tricellulin, at the tricellular contacts. Alterations in the localization of these proteins temporarily cause epithelial barrier dysfunction, which is closely associated with not only physiological differentiation but also cancer progression and metastasis. In normal human endometrial tissues, the endometrial cells undergo repeated proliferation and differentiation under physiological conditions. Recent observations have revealed that the localization and expression of LSR/angulin-1 and tricellulin are altered in a menstrual cycle-dependent manner. Moreover, it has been shown that endometrial cancer progression affects these alterations. This review highlights the differences in the localization and expression of tight junction proteins in normal endometrial cells and endometrial cancers and how they cause functional changes in cells.
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Affiliation(s)
- Takayuki Kohno
- Department of Cell Science, Research Institute for Frontier Medicine, Sapporo Medical University, Sapporo 060-8556, Japan.
| | - Takumi Konno
- Department of Cell Science, Research Institute for Frontier Medicine, Sapporo Medical University, Sapporo 060-8556, Japan
| | - Takashi Kojima
- Department of Cell Science, Research Institute for Frontier Medicine, Sapporo Medical University, Sapporo 060-8556, Japan
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Abstract
PURPOSE OF REVIEW The tight junction conductance made of the claudin-based paracellular channel is important in the regulation of calcium and magnesium reabsorption in the kidney. This review describes recent findings of the structure, the function, and the physiologic regulation of claudin-14, claudin-16, and claudin-19 channels that through protein interactions confer calcium and magnesium permeability to the tight junction. RECENT FINDINGS Mutations in two tight junction genes - claudin-16 and claudin-19 - cause the inherited renal disorder familial hypomagnesemia with hypercalciuria and nephrocalcinosis. A recent genome-wide association study has identified claudin-14 as a major risk gene of hypercalciuric nephrolithiasis. The crystal structure of claudin-19 has recently been resolved allowing the reconstruction of a claudin assembly model from cis-dimers made of claudin-16 and claudin-19 interaction. MicroRNAs have been identified as novel regulators of the claudin-14 gene. The microRNA-claudin-14 operon is directly regulated by the Ca sensing receptor gene in response to hypercalcemia. SUMMARY The paracellular pathway in the kidney is particularly important for mineral metabolism. Three claudin proteins - claudin-14, claudin-16, and claudin-19 - contribute to the structure and function of this paracellular pathway. Genetic mutations and gene expression changes in these claudins may lead to alteration of the paracellular permeability to calcium and magnesium, ultimately affecting renal mineral metabolism.
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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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Transcriptional regulators of claudins in epithelial tight junctions. Mediators Inflamm 2015; 2015:219843. [PMID: 25948882 PMCID: PMC4407569 DOI: 10.1155/2015/219843] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2014] [Revised: 09/22/2014] [Accepted: 10/03/2014] [Indexed: 02/06/2023] Open
Abstract
Human gastrointestinal tract is covered by a monolayer of specialized epithelial cells that constitute a protective barrier surface to external toxic and infectious agents along with metabolic and digestive functions. Intercellular junctions, among epithelial cells, such as desmosomes, adherens, gap, and tight junctions (TJs), not only provide mechanical integrity but also limit movement of molecules across the monolayer. TJ is a complex structure composed of approximately 35 different proteins that interact with each other at the apical side of two adjacent epithelial cells. Claudin family proteins are important members of TJ with so far 24 known isoforms in different species. Claudins are structural proteins of TJ that help to control the paracellular movement by forming fence and barrier across the epithelial monolayer. Altered function of claudins is implicated in different form of cancers, inflammatory bowel diseases (IBDs), and leaky diarrhea. Based on their significant role in the molecular architecture of TJ, diversity, and disease association, further understanding about claudin family proteins and their genetic/epigenetic regulators is indispensable.
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Krug SM, Schulzke JD, Fromm M. Tight junction, selective permeability, and related diseases. Semin Cell Dev Biol 2014; 36:166-76. [DOI: 10.1016/j.semcdb.2014.09.002] [Citation(s) in RCA: 173] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2014] [Revised: 08/29/2014] [Accepted: 09/04/2014] [Indexed: 02/09/2023]
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Abstract
The imbalance between bone formation and resorption during bone remodeling has been documented to be a major factor in the pathogenesis of osteoporosis. Recent evidence suggests a significant role for the tight junction proteins, Claudins (Cldns), in the regulation of bone remodeling processes. In terms of function, whereas Cldns act "canonically" as key determinants of paracellular permeability, there is considerable recent evidence to suggest that Cldns also participate in cell signaling, ie, a "noncanonical function". To this end, Cldns have been shown to regulate cell proliferation, differentiation, and gene expression in a variety of cell types. The present review will discuss Cldns' structure, their expression profile, regulation of expression, and their canonical and non- canonical functions in general with special emphasis on bone cells. In order to shed light on the noncanonical functions of Cldns in bone, we will highlight the role of Cldn-18 in regulating bone resorption and osteoclast differentiation. Collectively, we hope to provide a framework for guiding future research on understanding how Cldns modulate osteoblast and osteoclast function and overall bone homeostasis. Such studies should provide valuable insights into the pathogenesis of osteoporosis, and may highlight Cldns as novel targets for the diagnosis and therapeutic management of osteoporosis.
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Affiliation(s)
- Fatima Z Alshbool
- Musculoskeletal Disease Center (F.Z.A., S.M.), Jerry L. Pettis VA Medical Center, Loma Linda, CA 92357; Departments of Medicine (S.M.), Biochemistry (S.M.), Physiology (S.M.), and Pharmacology (F.Z.A., S.M.), Loma Linda University, Loma Linda, California 92354
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Hyperosmolarity-induced up-regulation of claudin-4 mediated by NADPH oxidase-dependent H2O2 production and Sp1/c-Jun cooperation. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2013; 1833:2617-2627. [DOI: 10.1016/j.bbamcr.2013.06.016] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/19/2013] [Revised: 06/12/2013] [Accepted: 06/21/2013] [Indexed: 12/11/2022]
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Abstract
Claudins are tight junction membrane proteins that are expressed in epithelia and endothelia and form paracellular barriers and pores that determine tight junction permeability. This review summarizes our current knowledge of this large protein family and discusses recent advances in our understanding of their structure and physiological functions.
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Affiliation(s)
- Dorothee Günzel
- Department of Clinical Physiology, Charité, Campus Benjamin Franklin, Berlin, Germany
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Dubé É, Cyr DG. The Blood-Epididymis Barrier and Human Male Fertility. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2013; 763:218-36. [DOI: 10.1007/978-1-4614-4711-5_11] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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Ortiz-Melo MT, Sánchez-Guzmán E, González-Robles A, Valdés J, Gómez-Flores E, Castro-Muñozledo F. Expression of claudins -2 and -4 and cingulin is coordinated with the start of stratification and differentiation in corneal epithelial cells: retinoic acid reversibly disrupts epithelial barrier. Biol Open 2012; 2:132-43. [PMID: 23429425 PMCID: PMC3575648 DOI: 10.1242/bio.20123145] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2012] [Accepted: 10/29/2012] [Indexed: 12/24/2022] Open
Abstract
Although tight junctions (TJ) have been extensively studied in simple epithelial cells, it is still unknown whether their organization is coupled to cell differentiation in stratified epithelia. We studied the expression of TJ in RCE1(5T5) cells, an in vitro model which mimics the sequential steps of rabbit corneal epithelial differentiation. RCE1(5T5) cells expressed TJ components which were assembled once cells constituted differentiated epithelia, as suggested by the increase of transepithelial electrical resistance (TER) which followed a similar kinetic to the expression of the early differentiation marker Pax-6. TJ were functional as indicated by the establishment of an epithelial barrier nonpermeable to ruthenium red or a biotin tracer. In immunostaining experiments, TJ were located at the superficial cells from the suprabasal layers; Western blot and RT-PCR suggested that TJ were composed of claudins (cldn) -1, -2, -4, cingulin (cgn), occludin (ocln) and ZO-1. Semi-quantitative RT-PCR and TER measurements showed that TJ became organized when cells began to form a 3–5 layers stratified epithelium; TER increased once cells reached confluence, with a time course comparable to the raise in the expression of cgn, cldn-2 and -4. Nevertheless, cldn-1, -2, ZO-1 and ocln were present in the cells from the beginning of cultivation, suggesting that TER increases mainly depend on TJ assembly. While EGF increased epithelial barrier strength, retinoic acid disrupted it, increasing paracellular flux about 2-fold; this effect was concentration dependent and completely reversible. Our results suggest that TJ assembly is tightly linked to the expression of corneal epithelial terminal phenotype.
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Affiliation(s)
- María Teresa Ortiz-Melo
- Departamento de Biología Celular, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional , Apartado Postal 14-740, México City 07000 , México ; Posgrado en Ciencias Biológicas, FES-Iztacala, Universidad Nacional Autónoma de México , México City 04510 , México
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Abstract
Claudins are tight junction integral membrane proteins that are key regulators of the paracellular pathway. The paracellular pathways in the inner ear and in the kidney are predominant routes for transepithelial cation transport. Mutations in claudin-14 cause nonsyndromic recessive deafness DFNB29. A recent genome-wide association study has identified claudin-14 as a major risk gene of hypercalciuric nephrolithiasis. In vitro analyses show that claudin-14 functions as a cation barrier in epithelial cells. The barrier function of claudin-14 is crucial for generating the K(+) gradient between perilymph and endolymph in the inner ear. However, neither homozygous individuals with DFNB29 mutations nor claudin-14 knockout mice show any renal dysfunction. In this short review, I discuss several possible mechanisms to integrate the physiological function of claudin-14 in the inner ear and the kidney.
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Affiliation(s)
- Jianghui Hou
- Renal Division, Washington University Medical School, St. Louis, Missouri, USA.
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Abstract
The physiology of paracellular permeation of ions and solutes in the kidney is pivotally important but poorly understood. Claudins are the key components of the paracellular pathway. Defects in claudin function result in a broad range of renal diseases, including hypomagnesemia, hypercalciuria and nephrolithiasis. This review describes recent findings on the physiological function of claudins underlying paracellular transport mechanisms with a focus on renal Ca(2+) handling. We have uncovered a molecular mechanism underlying paracellular Ca(2+) transport in the thick ascending limb of Henle (TAL) that involves the functional interplay of three important claudin genes: claudin-14, -16 and -19, all of which are associated with human kidney diseases with hypercalciuria, nephrolithiasis and bone mineral loss. The Ca(2+) sensing receptor (CaSR) signaling in the kidney has long been a mystery. By analyzing small non-coding RNA molecules in the kidney, we have uncovered a novel microRNA based signaling pathway downstream of CaSR that directly regulates claudin-14 gene expression and establishes the claudin-14 molecule as a key regulator for renal Ca(2+) homeostasis. The molecular cascade of CaSR-microRNAs-claudins forms a regulatory loop to maintain proper Ca(2+) homeostasis in the kidney.
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Affiliation(s)
- Jianghui Hou
- Renal Division, Washington University, St. Louis, MO, USA.
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Zhu R, Wong KF, Lee NPY, Lee KF, Luk JMC. HNF1α and CDX2 transcriptional factors bind to cadherin-17 (CDH17) gene promoter and modulate its expression in hepatocellular carcinoma. J Cell Biochem 2011; 111:618-26. [PMID: 20568120 DOI: 10.1002/jcb.22742] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Cadherin-17 (CDH17) belongs to the cell adhesion cadherin family with a prominent role in tumorigenesis. It is highly expressed in human hepatocellular carcinoma (HCC) and is proposed to be a biomarker and therapeutic molecule for liver malignancy. The present study aims to identify the transcription factors which interact and regulate CDH17 promoter activity that might contribute to the up-regulation of CDH17 gene in human HCC. A 1-kb upstream sequence of CDH17 gene was cloned and the promoter activity was studied by luciferase reporter assay. By bioinformatics analysis, deletion and mutation assays, and chromatin immunoprecipitation studies, we identified hepatic nuclear factor 1α (HNF1α) and caudal-related homeobox 2 (CDX2) binding sites at the proximal promoter region which modulate the CDH17 promoter activities in two HCC cell lines (Hep3B and MHCC97L). A consistent down-regulation of CDH17 and the two transcriptional activators (HNF1α and CDX2) expression was found in the liver of mouse during development, as well as in human liver cancer cells with less metastatic potential. Suppression of HNF1α and CDX2 expression by small interfering RNA (siRNA) significantly down-regulated expressions of CDH17 and its downstream target cyclin D1 and the viability of HCC cells in vitro. In summary, we identified the minimal promoter region of CDH17 that is regulated by HNF1α and CDX2 transcriptional factors. The present findings enhance our understanding on the regulatory mechanisms of CDH17 oncogene in HCC, and may shed new insights into targeting CDH17 expression as potential therapeutic intervention for cancer treatment.
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Affiliation(s)
- Rui Zhu
- Department of Surgery and Center for Cancer Research, The University of Hong Kong, Pokfulam, Hong Kong, China
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19
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Hou J, Renigunta A, Konrad M, Gomes AS, Schneeberger EE, Paul DL, Waldegger S, Goodenough DA. Claudin-16 and claudin-19 interact and form a cation-selective tight junction complex. J Clin Invest 2008; 118:619-28. [PMID: 18188451 DOI: 10.1172/jci33970] [Citation(s) in RCA: 143] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2007] [Accepted: 11/07/2007] [Indexed: 12/12/2022] Open
Abstract
Tight junctions (TJs) play a key role in mediating paracellular ion reabsorption in the kidney. Familial hypomagnesemia with hypercalciuria and nephrocalcinosis (FHHNC) is an inherited disorder caused by mutations in the genes encoding the TJ proteins claudin-16 (CLDN16) and CLDN19; however, the mechanisms underlying the roles of these claudins in mediating paracellular ion reabsorption in the kidney are not understood. Here we showed that in pig kidney epithelial cells, CLDN19 functioned as a Cl(-) blocker, whereas CLDN16 functioned as a Na(+) channel. Mutant forms of CLDN19 that are associated with FHHNC were unable to block Cl(-) permeation. Coexpression of CLDN16 and CLDN19 generated cation selectivity of the TJ in a synergistic manner, and CLDN16 and CLDN19 were observed to interact using several criteria. In addition, disruption of this interaction by introduction of FHHNC-causing mutant forms of either CLDN16 or CLDN19 abolished their synergistic effect. Our data show that CLDN16 interacts with CLDN19 and that their association confers a TJ with cation selectivity, suggesting a mechanism for the role of mutant forms of CLDN16 and CLDN19 in the development of FHHNC.
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Affiliation(s)
- Jianghui Hou
- Department of Cell Biology, Harvard Medical School, Boston, Massachusetts 02115, USA
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Sakai N, Chiba H, Fujita H, Akashi Y, Osanai M, Kojima T, Sawada N. Expression patterns of claudin family of tight-junction proteins in the mouse prostate. Histochem Cell Biol 2007; 127:457-62. [PMID: 17260152 DOI: 10.1007/s00418-007-0269-7] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/05/2007] [Indexed: 12/12/2022]
Abstract
Claudins are the transmembrane proteins forming the backbone of tight junctions, and consist of over 20 members of a gene family. Claudins are expressed in a tissue- and cell-type specific fashion, and changes in their abundance and/or distribution are proposed to play important roles in the pathophysiology of numerous disorders. In the prostate, claudin-1, -3, -4 and -7 transcripts are known to be expressed, but it is unknown regarding mRNA expression of other claudins or concerning expression and localization of claudin proteins in this organ. We herein show, by RT-PCR and Western blotting analyses, that not only these four claudins but also claudin-5, -8 and -10 are expressed in the normal mouse prostate. Claudin-3, -4, -5, -8 and -10 were primarily localized at the apicalmost sites of lateral membranes of luminal epithelial cells in the prostate gland, whereas claudin-1 and -7 were distributed along the basolateral membranes of the epithelium. These findings provide basic information for elucidating the significance of claudins in prostate diseases, including prostate cancers.
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Affiliation(s)
- Naoyuki Sakai
- Department of Pathology, Sapporo Medical University School of Medicine, South-1, West-17, Chuo-ku, Sapporo, 060-8556, Japan
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21
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Dufresne J, Cyr DG. Activation of an SP binding site is crucial for the expression of claudin 1 in rat epididymal principal cells. Biol Reprod 2007; 76:825-32. [PMID: 17251524 DOI: 10.1095/biolreprod.106.057430] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Claudin 1 (CLDN1) is a tight junctional protein present in the epididymis. Limited information exists regarding the regulation of Cldn1 transcription. In the epididymis, the regulation of the 5' flanking region of genes coding for tight junctional proteins is unknown. The present objectives were to investigate the transcriptional regulation of the Cldn1 gene in the rat epididymis. A 1.8-kb sequence of the 5' flanking region of the rat Cldn1 gene was cloned. The transcriptional start site is an adenine located at the -198 position relative to the first codon, and 26 bp downstream of the putative TATA box. It is the only start site for the Cldn1 gene transcription in the rat epididymis. The Cldn1 promoter was inserted into a luciferase gene expression vector and transfected into a rat caput epididymal cell line (RCE-1). Sequential deletion analysis revealed that minimal promoter activity was achieved with the construct containing -61 to +164 bp of the promoter. This sequence contained a TATA box and two consensus SP1 binding sites. Electrophoretic mobility shift and supershift assays confirmed that SP1 and SP3 were present in RCE-1 cells and epididymal nuclear extracts, and that they bind to the 5' SP1 binding motif of the promoter. Site-directed mutagenesis of the 5' SP1 binding site resulted in a 4-fold decrease in transactivation of the minimal promoter sequence. These findings indicate that SP1 and SP3 bind to the Cldn1 promoter region, and that this interaction influences the expression of Cldn1 in the rat epididymis.
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Affiliation(s)
- Julie Dufresne
- INRS-Institut Armand-Frappier, Université du Québec, Pointe Claire, Québec, Canada H9R 1G6
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22
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Abstract
Tight junctions form continuous intercellular contacts controlling solute movement through the paracellular pathway across epithelia. Paracellular barriers vary among epithelia in electrical resistance and behave as if they are lined with pores that have charge and size selectivity. Recent evidence shows that claudins, a large family (at least 24 members) of intercellular adhesion molecules, form the seal and its variable pore-like properties. This evidence comes from the study of claudins expressed in cultured epithelial cell models, genetically altered mice, and human mutants. We review information on the structure, function, and transcriptional and posttranslational regulation of the claudin family as well as of their evolutionarily distant relatives called the PMP22/EMP/MP20/claudin, or pfam00822, superfamily.
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Affiliation(s)
- Christina M Van Itallie
- Department of Medicine, Division of Gastroenterology and Hepatology, University of North Carolina, Chapel Hill, North Carolina 27599-7545, USA.
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Lui WY, Lee WM. Regulation of junction dynamics in the testis--transcriptional and post-translational regulations of cell junction proteins. Mol Cell Endocrinol 2006; 250:25-35. [PMID: 16431017 DOI: 10.1016/j.mce.2005.12.021] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Cell junctions are the sites at which cells attach to the neighboring cells. They do not only maintain tissue integrity, their turnover also plays a crucial role in cell development and morphogenesis. In the testis, tight junctions and adherens junctions are dynamically remodeled to allow the movement of post-meiotic germ cells across the seminiferous epithelium and the timely release of spermatids into the tubular lumen. There is growing evidence that this dynamic remodeling of cell junctions is mediated by several mechanisms at the transcriptional and post-translational levels. This review summarizes what is known about the transcriptional regulation, ubiquitination and endocytosis that are involved in modulating junction dynamics in epithelial cells. It also highlights the recent findings on the regulation of junction dynamics in the testis and the specific areas that require further research for a thorough understanding of the role of junction remodeling in spermatogenesis. Understanding the junction dynamics in the seminiferous epithelium may unfold new targets for non-hormonal male contraceptive development.
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Affiliation(s)
- Wing-Yee Lui
- Department of Zoology, The University of Hong Kong, Pokfulam, Hong Kong, China
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Fujita H, Chiba H, Yokozaki H, Sakai N, Sugimoto K, Wada T, Kojima T, Yamashita T, Sawada N. Differential expression and subcellular localization of claudin-7, -8, -12, -13, and -15 along the mouse intestine. J Histochem Cytochem 2006; 54:933-44. [PMID: 16651389 DOI: 10.1369/jhc.6a6944.2006] [Citation(s) in RCA: 186] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
Among tight-junction proteins, claudins, which play a key role in paracellular transport across epithelia, claudins 1 to 5 are expressed in the intestine, and changes in their abundance and/or distribution are considered to contribute to various gastrointestinal diseases. We investigated, by reverse transcription-PCR, immunoblot, and immunofluorescence analyses, which other claudin species were expressed in the mouse intestine, and whether they showed unique expression profiles. Rabbit polyclonal antibodies against mouse claudin-8, claudin-12, and claudin-15 were generated, and their specificity was verified by immunoblotting using COS-7 cells transfected with individual claudin cDNAs. Claudin-7, -8, -12, -13, and -15 appeared to be expressed in the duodenum, jejunum, ileum, and/or colon with remarkable variations in the expression levels along the intestinal tract, and had distinct subcellular localization in the intestinal epithelium. In addition, claudin-13 and -15 exhibited gradients along the crypt-surface axis of the colon. By contrast, claudin-6, -9, -10, -11, -14, -16, -18, and -19 were not observed in the intestine. Our results indicate that five additional species of claudins have very complex expression patterns along and within the intestine, and that this may reflect differences in paracellular permeable properties, providing valuable resources for studying the significance of these claudins in gastrointestinal disorders. This manuscript contains online supplemental material available at http://www.jhc.org. Please visit this article online to view these materials.
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Affiliation(s)
- Hiroki Fujita
- Dept. of Pathology, Sapporo Medical University School of Medicine, S1, W17, Sapporo 060-8556, Japan
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Lee NPY, Tong MK, Leung PP, Chan VW, Leung S, Tam PC, Chan KW, Lee KF, Yeung WSB, Luk JM. Kidney claudin-19: localization in distal tubules and collecting ducts and dysregulation in polycystic renal disease. FEBS Lett 2006; 580:923-31. [PMID: 16427635 DOI: 10.1016/j.febslet.2006.01.019] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2005] [Revised: 12/09/2005] [Accepted: 01/10/2006] [Indexed: 01/31/2023]
Abstract
Tight junction (TJ) constitutes the barrier by controlling the passage of ions and molecules via paracellular pathway and the movement of proteins and lipids between apical and basolateral domains of the plasma membrane. Claudins, occludin, and junctional adhesion molecules are the major three transmembrane proteins at TJ. This study focuses a newly identified mammalian TJ gene, claudin-19, in kidneys. Mouse claudin-19 composes of 224 amino acids and shares 98.2% and 95% amino acid homology with rat and human, respectively; the most evolutionary-related claudins are claudin-1 and -7, which share approximately 75% DNA sequence homology with claudin-19. Claudin-19 is abundantly expressed in the mouse and rat kidneys among the organs examined by Northern blots, and to a much less extent, also found in brain by RT-PCR. Claudin-19 and zonula occludens-1 (ZO-1) are localized at junctional regions of Madin-Darby canine kidney (MDCK) cells by immunofluorescent microscopy. In addition, ZO-1 is found in the claudin-19-associated protein complexes in MDCK cells by co-immunoprecipitation. Using aquaporin-1 and aquaporin-2 antibodies as markers for different renal segment, strong expression of claudin-19 was observed in distal tubules of the cortex as well as in the collecting ducts of the medulla. To less extent, claudin-19 is also present in the proximal tubules (cortex) and in the loop of Henle (medulla). Furthermore, intense claudin-19 immunoreactivity is found co-localized with the ZO-1 in kidneys from postnatal day 15, day 45, and adult rats and mice. Similar localizations of claudin-19 and ZO-1 are also observed in human kidneys. Since these renal segments are mainly for controlling the paracellular cation transport, it is suggested that claudin-19 may participate in these processes. In human polycystic kidneys, decreased expression and dyslocalization of claudin-19 are noticed, suggesting a possible correlation between claudin-19 and renal disorders. Taken together, claudin-19 is a claudin isoform that is highly and specifically expressed in renal tubules with a putative role in TJ homeostasis in renal physiology.
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Affiliation(s)
- Nikki P Y Lee
- Department of Surgery, Queen Mary Hospital, The University of Hong Kong, Pokfulam, Hong Kong, SAR, China
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