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Zhou Z, Gao P, Zhang T, Yang Y, Ding Q, Wu Z, Wang L. Functional analysis reveals calcium-sensing receptor gene regulating cell-cell junction in renal tubular epithelial cells. Int Urol Nephrol 2024; 56:2165-2177. [PMID: 38372840 DOI: 10.1007/s11255-024-03948-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2023] [Accepted: 01/04/2024] [Indexed: 02/20/2024]
Abstract
PURPOSE Calcium-sensing receptor (CASR) influences the expression pattern of multiple genes in renal tubular epithelial cells. The objective of this inquiry was to explore the molecular mechanisms of CASR in renal tubular epithelial cells and nephrolithiasis. METHODS HK-2 cells were transfected with lentiviruses carrying either CASR (named CASR) or an empty vector negative control (named NC), as well as shRNA intended to target CASR (named shCASR) or its corresponding negative control (named shNC). CCK-8 assay was used to detect the effect of CASR on the proliferation of HK-2 cells. RNA-Sequencing was applied to explore potential pathways regulated by CASR in HK-2 cells. RESULTS PCR and western blot results showed that CASR expression was significantly increased in CASR cells and was decreased in shCASR cells when compared to their corresponding negative control, respectively. CCK-8 assay revealed that CASR inhibited the proliferation of HK-2 cells. RNA-Sequencing results suggested that the shCASR HK-2 cells exhibited a significant up-regulation of 345 genes and a down-regulation of 366 genes. These differentially expressed genes (DEGs) were related to cell apoptosis and cell development. In CASR HK-2 cells, 1103 DEGs primarily functioned in mitochondrial energy metabolism, and amino acid metabolism. With the Venn diagram, 4 DEGs (Clorf116, ENPP3, IL20RB, and CLDN2) were selected as the hub genes regulated by CASR. Enrichment analysis revealed that these hub genes were involved in cell-cell junction, and epithelial cell development. CONCLUSIONS In summary, our investigation has the potential to offer novel perspectives on CASR regulating cell-cell junction in HK-2 cells.
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Affiliation(s)
- Zijian Zhou
- Department of Urology, Huashan Hospital, Fudan University, Shanghai, 200040, People's Republic of China
- Clinical Research Center of Urolithiasis, Shanghai Medical College, Fudan University, Shanghai, 200040, People's Republic of China
| | - Peng Gao
- Department of Urology, Huashan Hospital, Fudan University, Shanghai, 200040, People's Republic of China
- Clinical Research Center of Urolithiasis, Shanghai Medical College, Fudan University, Shanghai, 200040, People's Republic of China
| | - Tongtong Zhang
- Urology Centre, Shuguang Hospital Affiliated to Shanghai University of Traditional Chinese Medicine, Shanghai, 200040, People's Republic of China
| | - Yuanyuan Yang
- Department of Urology, Huashan Hospital, Fudan University, Shanghai, 200040, People's Republic of China
- Clinical Research Center of Urolithiasis, Shanghai Medical College, Fudan University, Shanghai, 200040, People's Republic of China
| | - Qiang Ding
- Department of Urology, Huashan Hospital, Fudan University, Shanghai, 200040, People's Republic of China
- Clinical Research Center of Urolithiasis, Shanghai Medical College, Fudan University, Shanghai, 200040, People's Republic of China
| | - Zhong Wu
- Department of Urology, Huashan Hospital, Fudan University, Shanghai, 200040, People's Republic of China.
- Clinical Research Center of Urolithiasis, Shanghai Medical College, Fudan University, Shanghai, 200040, People's Republic of China.
| | - Lujia Wang
- Department of Urology, Huashan Hospital, Fudan University, Shanghai, 200040, People's Republic of China.
- Clinical Research Center of Urolithiasis, Shanghai Medical College, Fudan University, Shanghai, 200040, People's Republic of China.
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Rungrasameviriya P, Santilinon A, Atichartsintop P, Hadpech S, Thongboonkerd V. Tight junction and kidney stone disease. Tissue Barriers 2024; 12:2210051. [PMID: 37162265 PMCID: PMC10832927 DOI: 10.1080/21688370.2023.2210051] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2023] [Accepted: 04/30/2023] [Indexed: 05/11/2023] Open
Abstract
Defects of tight junction (TJ) are involved in many diseases related to epithelial cell functions, including kidney stone disease (KSD), which is a common disease affecting humans for over a thousand years. This review provides brief overviews of KSD and TJ, and summarizes the knowledge on crystal-induced defects of TJ in renal tubular epithelial cells (RTECs) in KSD. Calcium oxalate (CaOx) crystals, particularly COM, disrupt TJ via p38 MAPK and ROS/Akt/p38 MAPK signaling pathways, filamentous actin (F-actin) reorganization and α-tubulin relocalization. Stabilizing p38 MAPK signaling, reactive oxygen species (ROS) production, F-actin and α-tubulin by using SB239063, N-acetyl-L-cysteine (NAC), phalloidin and docetaxel, respectively, successfully prevent the COM-induced TJ disruption and malfunction. Additionally, genetic disorders of renal TJ, including mutations and single nucleotide polymorphisms (SNPs) of CLDN2, CLDN10b, CLDN14, CLDN16 and CLDN19, also affect KSD. Finally, the role of TJ as a potential target for KSD therapeutics and prevention is also discussed.
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Affiliation(s)
- Papart Rungrasameviriya
- Nawamethee Project, Doctor of Medicine Program, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand
| | - Aticha Santilinon
- Nawamethee Project, Doctor of Medicine Program, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand
| | - Palita Atichartsintop
- Nawamethee Project, Doctor of Medicine Program, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand
| | - Sudarat Hadpech
- Medical Proteomics Unit, Research Department, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand
| | - Visith Thongboonkerd
- Medical Proteomics Unit, Research Department, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand
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Hong SY, Qin BL. The Protective Role of Dietary Polyphenols in Urolithiasis: Insights into Antioxidant Effects and Mechanisms of Action. Nutrients 2023; 15:3753. [PMID: 37686790 PMCID: PMC10490426 DOI: 10.3390/nu15173753] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2023] [Revised: 08/15/2023] [Accepted: 08/25/2023] [Indexed: 09/10/2023] Open
Abstract
Urolithiasis is a common urological disease with increasing prevalence and high recurrence rates around the world. Numerous studies have indicated reactive oxygen species (ROS) and oxidative stress (OS) were crucial pathogenic factors in stone formation. Dietary polyphenols are a large group of natural antioxidant compounds widely distributed in plant-based foods and beverages. Their diverse health benefits have attracted growing scientific attention in recent decades. Many literatures have reported the effectiveness of dietary polyphenols against stone formation. The antiurolithiatic mechanisms of polyphenols have been explained by their antioxidant potential to scavenge free radicals and ROS, modulate the expression and the activity of endogenous antioxidant and prooxidant enzymes, regulate signaling pathways associated with OS, and maintain cell morphology and function. In this review, we first describe OS and its pathogenic effects in urolithiasis and summarize the classification and sources of dietary polyphenols. Then, we focus on the current evidence defining their antioxidant potential against stone formation and put forward challenges and future perspectives of dietary polyphenols. To conclude, dietary polyphenols offer potential applications in the treatment and prevention of urolithiasis.
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Affiliation(s)
| | - Bao-Long Qin
- Department of Urology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China
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Nakashima M, Goda N, Tenno T, Kotake A, Inotsume Y, Amaya M, Hiroaki H. Pharmacologic Comparison of High-Dose Hesperetin and Quercetin on MDCK II Cell Viability, Tight Junction Integrity, and Cell Shape. Antioxidants (Basel) 2023; 12:antiox12040952. [PMID: 37107328 PMCID: PMC10135814 DOI: 10.3390/antiox12040952] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2023] [Revised: 04/05/2023] [Accepted: 04/12/2023] [Indexed: 04/29/2023] Open
Abstract
The modulation of tight junction (TJ) integrity with small molecules is important for drug delivery. High-dose baicalin (BLI), baicalein (BLE), quercetin (QUE), and hesperetin (HST) have been shown to open TJs in Madin-Darby canine kidney (MDCK) II cells, but the mechanisms for HST and QUE remain unclear. In this study, we compared the effects of HST and QUE on cell proliferation, morphological changes, and TJ integrity. HST and QUE were found to have opposing effects on the MDCK II cell viability, promotion, and suppression, respectively. Only QUE, but not HST, induced a morphological change in MDCK II into a slenderer cell shape. Both HST and QUE downregulated the subcellular localization of claudin (CLD)-2. However, only QUE, but not HST, downregulated CLD-2 expression. Conversely, only HST was shown to directly bind to the first PDZ domain of ZO-1, a key molecule to promote TJ biogenesis. The TGFβ pathway partially contributed to the HST-induced cell proliferation, since SB431541 ameliorated the effect. In contrast, the MEK pathway was not involved by both the flavonoids, since U0126 did not revert their TJ-opening effect. The results offer insight for using HST or QUE as naturally occurring absorption enhancers through the paracellular route.
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Affiliation(s)
- Mio Nakashima
- Laboratory of Structural Molecular Pharmacology, Graduate School of Pharmaceutical Sciences, Nagoya University, Furocho, Chikusa-ku, Nagoya 464-8601, Aichi, Japan
| | - Natsuko Goda
- Laboratory of Structural Molecular Pharmacology, Graduate School of Pharmaceutical Sciences, Nagoya University, Furocho, Chikusa-ku, Nagoya 464-8601, Aichi, Japan
| | - Takeshi Tenno
- Laboratory of Structural Molecular Pharmacology, Graduate School of Pharmaceutical Sciences, Nagoya University, Furocho, Chikusa-ku, Nagoya 464-8601, Aichi, Japan
- BeCerllBar, LLC, Business Incubation Building, Nagoya University, Furocho, Chikusa ku, Nagoya 464-8601, Aichi, Japan
| | - Ayaka Kotake
- Cosmetics Research Department, Nicca Chemical Co., Ltd., Fukui 910-8670, Fukui, Japan
| | - Yuko Inotsume
- Cosmetics Research Department, Nicca Chemical Co., Ltd., Fukui 910-8670, Fukui, Japan
| | - Minako Amaya
- Cosmetics Research Department, Nicca Chemical Co., Ltd., Fukui 910-8670, Fukui, Japan
| | - Hidekazu Hiroaki
- Laboratory of Structural Molecular Pharmacology, Graduate School of Pharmaceutical Sciences, Nagoya University, Furocho, Chikusa-ku, Nagoya 464-8601, Aichi, Japan
- BeCerllBar, LLC, Business Incubation Building, Nagoya University, Furocho, Chikusa ku, Nagoya 464-8601, Aichi, Japan
- Center for One Medicine Innovative Translational Research, Gifu University Institute for Advanced Study, Yanagito, Gifu 501-1112, Gifu, Japan
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Guo J, Chen X, Lin Z, Jin L, Hou Z, Dong W, Zhang Y. Tight junction disruption through activation of the PI3K/AKT pathways in the skin contributes to blister fluid formation after severe tibial plateau fracture. Front Bioeng Biotechnol 2022; 10:946261. [PMID: 36032734 PMCID: PMC9403793 DOI: 10.3389/fbioe.2022.946261] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2022] [Accepted: 07/04/2022] [Indexed: 11/13/2022] Open
Abstract
Background: Acute compartment syndrome (ACS) is an orthopedic emergency that commonly occurs after severe tibial plateau fracture. Fracture blisters form on the skin, and it was found in our previous study that when blisters form, the compartment pressure significantly decreases. However, the potential mechanism underlying this pressure decrease has not yet been elucidated. Methods: To obtain a comprehensive understanding of the changes that occur after blister formation on the skin, the changes in tight junction expression in the skin after tibial plateau fracture were observed. Blister samples and normal skin were collected from patients with bicondylar tibial plateau fractures with or without blisters. The epidermis thickness was measured, and the difference in the levels of K1, K5, K10, and skin barrier proteins such as claudin 1, claudin 2, and occludin between the two groups was evaluated by immunochemistry analysis, immunofluorescence, Western blotting, and qPCR. Results: The skin was thinner and the levels of K1, K5, and K10 were significantly decreased in blistered skin. Furthermore, the PI3K/AKT pathway was found to be activated, and the tight junction expression was significantly decreased in blistered skin. This indicates that the paracellular pathway, which is essential for accelerating fluid accumulation in blisters and indirectly decreases compartment pressure, was activated. Conclusion: Changes in the tight junction expression after blister formation may underlie blister fluid formation and indirectly explain the decrease in compartment pressure under blistered skin after severe tibial plateau fracture.
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Affiliation(s)
- Jialiang Guo
- The School of Medicine, Nankai University, Tianjin, China
- Department of Orthopaedics, The Third Hospital of Hebei Medical University, Shijiazhuang, China
| | - Xiaojun Chen
- Department of Orthopaedics, The Third Hospital of Hebei Medical University, Shijiazhuang, China
| | - Zhe Lin
- Department of Orthopaedics, The Third Hospital of Hebei Medical University, Shijiazhuang, China
| | - Lin Jin
- Department of Orthopaedics, The Third Hospital of Hebei Medical University, Shijiazhuang, China
| | - Zhiyong Hou
- Department of Orthopaedics, The Third Hospital of Hebei Medical University, Shijiazhuang, China
- *Correspondence: Zhiyong Hou, ; Yingze Zhang,
| | - Weichong Dong
- Department of Pharmacy, The Second Hospital of Hebei Medical University, Shijiazhuang, China
| | - Yingze Zhang
- Department of Orthopaedics, The Third Hospital of Hebei Medical University, Shijiazhuang, China
- Chinese Academy of Engineering, Beijing, China
- NHC Key Laboratory of Intelligent Orthopeadic Equipment (The Third Hospital of Hebei Medical University), Shijiazhuang, China
- *Correspondence: Zhiyong Hou, ; Yingze Zhang,
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Gomes TL, de Oliveira-Marques V, Hampson RJ, Jacinto A, de Moraes LV, Martinho RG. theLiTE™: A Screening Platform to Identify Compounds that Reinforce Tight Junctions. Front Pharmacol 2022; 12:752787. [PMID: 35069190 PMCID: PMC8771259 DOI: 10.3389/fphar.2021.752787] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2021] [Accepted: 11/24/2021] [Indexed: 11/13/2022] Open
Abstract
Tight junctions (TJ) are formed by transmembrane and intracellular proteins that seal the intercellular space and control selective permeability of epithelia. Integrity of the epithelial barrier is central to tissue homeostasis and barrier dysfunction has been linked to many pathological conditions. TJ support the maintenance of cell polarity through interactions with the Par complex (Cdc42-Par-6-Par-3-aPKC) in which Par-6 is an adaptor and links the proteins of the complex together. Studies have shown that Par-6 overexpression delays the assembly of TJ proteins suggesting that Par-6 negatively regulates TJ assembly. Because restoring barrier integrity is of key therapeutic and prophylactic value, we focus on finding compounds that have epithelial barrier reinforcement properties; we developed a screening platform (theLiTE™) to identify compounds that modulate Par-6 expression in follicular epithelial cells from Par-6-GFP Drosophila melanogaster egg chambers. Hits identified were then tested whether they improve epithelial barrier function, using measurements of transepithelial electrical resistance (TEER) or dye efflux to evaluate paracellular permeability. We tested 2,400 compounds, found in total 10 hits. Here we present data on six of them: the first four hits allowed us to sequentially build confidence in theLiTE™ and two compounds that were shortlisted for further development (myricetin and quercetin). We selected quercetin due to its clinical and scientific validation as a compound that regulates TJ; food supplement formulated on the basis of this discovery is currently undergoing clinical evaluation in gastroesophageal reflux disease (GERD) sufferers.
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Affiliation(s)
- Teresa Lopes Gomes
- Thelial Technologies SA, Parque Tecnológico de Cantanhede, Cantanhede, Portugal
| | | | - Richard John Hampson
- Thelial Technologies SA, Parque Tecnológico de Cantanhede, Cantanhede, Portugal
- Thelial BV (Epinutra), Wageningen, Netherlands
| | - António Jacinto
- iNOVA4Health, Chronic Diseases Research Centre - CEDOC, NOVA Medical School, NMS, Universidade Nova de Lisboa, Lisbon, Portugal
| | - Luciana Vieira de Moraes
- Thelial Technologies SA, Parque Tecnológico de Cantanhede, Cantanhede, Portugal
- Thelial BV (Epinutra), Wageningen, Netherlands
| | - Rui Gonçalo Martinho
- Thelial Technologies SA, Parque Tecnológico de Cantanhede, Cantanhede, Portugal
- Departamento de Ciências Biomédicas e Medicina, and Center for Biomedical Research, Universidade do Algarve, Faro, Portugal
- Department of Medical Sciences and Institute for Biomedicine (iBiMED), University of Aveiro, Aveiro, Portugal
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Nakashima M, Hisada M, Goda N, Tenno T, Kotake A, Inotsume Y, Kameoka I, Hiroaki H. Opposing Effect of Naringenin and Quercetin on the Junctional Compartment of MDCK II Cells to Modulate the Tight Junction. Nutrients 2020; 12:nu12113285. [PMID: 33120983 PMCID: PMC7693399 DOI: 10.3390/nu12113285] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2020] [Revised: 10/16/2020] [Accepted: 10/23/2020] [Indexed: 02/07/2023] Open
Abstract
Maintaining tight junction (TJ) integrity is important for epithelial cell barriers. Previously, the enhancement of TJ integrity, induced by citrus-derived flavonoids, naringin (NRG) and hesperidin (HSD), was demonstrated, but the effects of their aglycones naringenin (NAR) and hesperetin (HST), and the mechanisms, have not been systematically investigated. Here we compared three series of flavonoids related to NAR, HST, quercetin (QUE) and their glycosides with the Madin–Darby canine kidney (MDCK) II cell monolayers. The effect of flavonoids on the protein expression level of claudin (CLD)-2 and its subcellular localization were investigated. NAR, NRG, and HSD increased the CLD-2 localization at the TJ compartment, and its protein expression level. QUE and HST showed TJ-mitigating activity. Narirutin (NRT), neohesperidin (NHD) and rutin (RUT) did not affect the TJ. In addition, NAR and QUE induced an increase or decrease of the transepithelial electrical resistance (TEER) values of the MDCK II monolayers. Two known signaling pathways, phosphatidyl-inositol-3 kinase (PI3K) and 5′-AMP-activated protein kinase (AMPK), were further compared with NAR. Two-dimensional polyacrylamide electrophoresis (2D PAGE) analysis of whole-cell proteins treated with NAR, AICA-riboside (AMPK activator) and LY294002 (PI3K inhibitor) showed in both a distinct pattern. This suggests the target of NAR’s CLD-2 or zonula occludens-1 (ZO-1) modulation was unique.
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Affiliation(s)
- Mio Nakashima
- Graduate School of Pharmaceutical Sciences, Nagoya University, Furocho, Chikusa, Nagoya, Aichi 464-8601, Japan; (M.N.); (M.H.); (N.G.); (T.T.)
- Department of Biological Sciences, Faculty of Science, Nagoya University, Furocho, Chikusa, Nagoya, Aichi 464-8602, Japan
| | - Misaki Hisada
- Graduate School of Pharmaceutical Sciences, Nagoya University, Furocho, Chikusa, Nagoya, Aichi 464-8601, Japan; (M.N.); (M.H.); (N.G.); (T.T.)
| | - Natsuko Goda
- Graduate School of Pharmaceutical Sciences, Nagoya University, Furocho, Chikusa, Nagoya, Aichi 464-8601, Japan; (M.N.); (M.H.); (N.G.); (T.T.)
| | - Takeshi Tenno
- Graduate School of Pharmaceutical Sciences, Nagoya University, Furocho, Chikusa, Nagoya, Aichi 464-8601, Japan; (M.N.); (M.H.); (N.G.); (T.T.)
- BeCerllBar, LLC., Business Incubation Building, Nagoya University, Furocho, Chikusa-ku, Nagoya, Aichi 464-8601, Japan
| | - Ayaka Kotake
- Cosmetics Research Department, Nicca Chemical Co. Ltd., Fukui 910-8670, Japan; (A.K.); (Y.I.); (I.K.)
| | - Yuko Inotsume
- Cosmetics Research Department, Nicca Chemical Co. Ltd., Fukui 910-8670, Japan; (A.K.); (Y.I.); (I.K.)
| | - Ikuo Kameoka
- Cosmetics Research Department, Nicca Chemical Co. Ltd., Fukui 910-8670, Japan; (A.K.); (Y.I.); (I.K.)
| | - Hidekazu Hiroaki
- Graduate School of Pharmaceutical Sciences, Nagoya University, Furocho, Chikusa, Nagoya, Aichi 464-8601, Japan; (M.N.); (M.H.); (N.G.); (T.T.)
- Department of Biological Sciences, Faculty of Science, Nagoya University, Furocho, Chikusa, Nagoya, Aichi 464-8602, Japan
- BeCerllBar, LLC., Business Incubation Building, Nagoya University, Furocho, Chikusa-ku, Nagoya, Aichi 464-8601, Japan
- Correspondence: ; Tel.: +81-52-789-4535
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Special Issue on "The Tight Junction and Its Proteins: More than Just a Barrier". Int J Mol Sci 2020; 21:ijms21134612. [PMID: 32610530 PMCID: PMC7370070 DOI: 10.3390/ijms21134612] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2020] [Accepted: 06/26/2020] [Indexed: 12/12/2022] Open
Abstract
For a long time, the tight junction (TJ) was known to form and regulate the paracellular barrier between epithelia and endothelial cell sheets. Starting shortly after the discovery of the proteins forming the TJ—mainly, the two families of claudins and TAMPs—several other functions have been discovered, a striking one being the surprising finding that some claudins form paracellular channels for small ions and/or water. This Special Issue covers numerous dedicated topics including pathogens affecting the TJ barrier, TJ regulation via immune cells, the TJ as a therapeutic target, TJ and cell polarity, the function of and regulation by proteins of the tricellular TJ, the TJ as a regulator of cellular processes, organ- and tissue-specific functions, TJs as sensors and reactors to environmental conditions, and last, but not least, TJ proteins and cancer. It is not surprising that due to this diversity of topics and functions, the still-young field of TJ research is growing fast. This Editorial gives an introduction to all 43 papers of the Special Issue in a structured topical order.
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Tachibana K, Kondoh M. A Method to Prepare a Bioprobe for Regulatory Science of the Drug Delivery System to the Brain: An Angulin Binder to Modulate Tricellular Tight Junction-Seal. Methods Mol Biol 2020; 2367:291-304. [PMID: 32789775 DOI: 10.1007/7651_2020_317] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Epithelium acts as a barrier separating the interior and exterior of the body, and the epithelial and endothelial cells form tight junctions (TJs) by sealing the paracellular space. The blood-brain barrier (BBB) endothelial cells have well-developed TJs and express specific polarized transport systems to tightly control paracellular movements of solutes, ions, and water. Thus, more than 98% of small-molecular-weight drugs cannot pass the BBB. The tricellular TJ (tTJ) is a structure at contacts of three cells. Angulin-1, also known as lipolysis-stimulated lipoprotein receptor (LSR), is one of angulin family and is abundantly expressed in brain endothelial cells, which plays an important role in barrier function of the BBB. The C-terminal domain of a receptor-binding component of Clostridium perfringens iota-toxin (Ib421-664), also named as angubindin-1, binds to its receptors angulin-1 and angulin-3. This angubindin-1 modulates the tTJ barrier and is able to deliver a 16-mer gapmer antisense oligonucleotide (5.3 kDa) without adverse effects. Thus, angulin binders, such as angubindin-1, are useful tools for studying the safety assessment of tTJ-targeted drug delivery and BBB permeability modulation. Here, we provide a protocol for the expression and purification of recombinant angubindin-1 protein as angulin binders, an analysis method for angubindin-1 binding affinity, and a procedure for assessing the effect of modulating tight junction integrity.
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Affiliation(s)
- Keisuke Tachibana
- Graduate School of Pharmaceutical Sciences, Osaka University, Osaka, Japan.
| | - Masuo Kondoh
- Graduate School of Pharmaceutical Sciences, Osaka University, Osaka, Japan.
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Venugopal S, Anwer S, Szászi K. Claudin-2: Roles beyond Permeability Functions. Int J Mol Sci 2019; 20:ijms20225655. [PMID: 31726679 PMCID: PMC6888627 DOI: 10.3390/ijms20225655] [Citation(s) in RCA: 71] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2019] [Revised: 11/08/2019] [Accepted: 11/09/2019] [Indexed: 12/12/2022] Open
Abstract
Claudin-2 is expressed in the tight junctions of leaky epithelia, where it forms cation-selective and water permeable paracellular channels. Its abundance is under fine control by a complex signaling network that affects both its synthesis and turnover in response to various environmental inputs. Claudin-2 expression is dysregulated in many pathologies including cancer, inflammation, and fibrosis. Claudin-2 has a key role in energy-efficient ion and water transport in the proximal tubules of the kidneys and in the gut. Importantly, strong evidence now also supports a role for this protein as a modulator of vital cellular events relevant to diseases. Signaling pathways that are overactivated in diseases can alter claudin-2 expression, and a good correlation exists between disease stage and claudin-2 abundance. Further, loss- and gain-of-function studies showed that primary changes in claudin-2 expression impact vital cellular processes such as proliferation, migration, and cell fate determination. These effects appear to be mediated by alterations in key signaling pathways. The specific mechanisms linking claudin-2 to these changes remain poorly understood, but adapters binding to the intracellular portion of claudin-2 may play a key role. Thus, dysregulation of claudin-2 may contribute to the generation, maintenance, and/or progression of diseases through both permeability-dependent and -independent mechanisms. The aim of this review is to provide an overview of the properties, regulation, and functions of claudin-2, with a special emphasis on its signal-modulating effects and possible role in diseases.
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