scholarly journals Tricellulin constitutes a novel barrier at tricellular contacts of epithelial cells

2005 ◽  
Vol 171 (6) ◽  
pp. 939-945 ◽  
Author(s):  
Junichi Ikenouchi ◽  
Mikio Furuse ◽  
Kyoko Furuse ◽  
Hiroyuki Sasaki ◽  
Sachiko Tsukita ◽  
...  
Keyword(s):  
Rna Interference ◽  
Epithelial Cells ◽  
Membrane Protein ◽  
Tight Junctions ◽  
Intercellular Space ◽  
First Integral ◽  
Integral Membrane Protein ◽  
Epithelial Barrier ◽  
Critical Function ◽  
Weak Points

For epithelia to function as barriers, the intercellular space must be sealed. Sealing two adjacent cells at bicellular tight junctions (bTJs) is well described with the discovery of the claudins. Yet, there are still barrier weak points at tricellular contacts, where three cells join together. In this study, we identify tricellulin, the first integral membrane protein that is concentrated at the vertically oriented TJ strands of tricellular contacts. When tricellulin expression was suppressed with RNA interference, the epithelial barrier was compromised, and tricellular contacts and bTJs were disorganized. These findings indicate the critical function of tricellulin for formation of the epithelial barrier.

scholarly journals Occludin-deficient Embryonic Stem Cells Can Differentiate into Polarized Epithelial Cells Bearing Tight Junctions

1998 ◽  
Vol 141 (2) ◽  
pp. 397-408 ◽  
Author(s):  
Mitinori Saitou ◽  
Kazushi Fujimoto ◽  
Yoshinori Doi ◽  
Masahiko Itoh ◽  
Toyoshi Fujimoto ◽  
...  
Keyword(s):  
Epithelial Cells ◽  
Membrane Protein ◽  
Tight Junctions ◽  
Time Course ◽  
Es Cells ◽  
Embryonic Stem ◽  
Freeze Fracture ◽  
Integral Membrane Protein ◽  
Embryoid Bodies ◽  
Wild Type

Occludin is the only known integral membrane protein of tight junctions (TJs), and is now believed to be directly involved in the barrier and fence functions of TJs. Occludin-deficient embryonic stem (ES) cells were generated by targeted disruption of both alleles of the occludin gene. When these cells were subjected to suspension culture, they aggregated to form simple, and then cystic embryoid bodies (EBs) with the same time course as EB formation from wild-type ES cells. Immunofluorescence microscopy and ultrathin section electron microscopy revealed that polarized epithelial (visceral endoderm-like) cells were differentiated to delineate EBs not only from wild-type but also from occludin-deficient ES cells. Freeze fracture analyses indicated no significant differences in number or morphology of TJ strands between wild-type and occludin-deficient epithelial cells. Furthermore, zonula occludens (ZO)-1, a TJ-associated peripheral membrane protein, was still exclusively concentrated at TJ in occludin-deficient epithelial cells. In good agreement with these morphological observations, TJ in occludin-deficient epithelial cells functioned as a primary barrier to the diffusion of a low molecular mass tracer through the paracellular pathway. These findings indicate that there are as yet unidentified TJ integral membrane protein(s) which can form strand structures, recruit ZO-1, and function as a barrier without occludin.

scholarly journals Angulin-1 seals tricellular contacts independently of tricellulin and claudins

2021 ◽  
Vol 220 (9) ◽  
Author(s):  
Taichi Sugawara ◽  
Kyoko Furuse ◽  
Tetsuhisa Otani ◽  
Tomohiko Wakayama ◽  
Mikio Furuse
Keyword(s):  
Plasma Membrane ◽  
Epithelial Cells ◽  
Genome Editing ◽  
Tight Junctions ◽  
Barrier Function ◽  
Intercellular Space ◽  
Epithelial Barrier ◽  
Epithelial Barrier Function ◽  
C Terminus ◽  
Membrane Contact

Tricellular tight junctions (tTJs) are specialized tight junctions (TJs) that seal the intercellular space at tricellular contacts (TCs), where the vertices of three epithelial cells meet. Tricellulin and angulin family membrane proteins are known constituents of tTJs, but the molecular mechanism of tTJ formation remains elusive. Here, we investigated the roles of angulin-1 and tricellulin in tTJ formation in MDCK II cells by genome editing. Angulin-1–deficient cells lost the plasma membrane contact at TCs with impaired epithelial barrier function. The C terminus of angulin-1 bound to the TJ scaffold protein ZO-1, and disruption of their interaction influenced the localization of claudins at TCs, but not the tricellular sealing. Strikingly, the plasma membrane contact at TCs was formed in tricellulin- or claudin-deficient cells. These findings demonstrate that angulin-1 is responsible for the plasma membrane seal at TCs independently of tricellulin and claudins.

scholarly journals Angulin-1 seals tricellular contacts independently of tricellulin and claudins

2020 ◽  
Author(s):  
Taichi Sugawara ◽  
Kyoko Furuse ◽  
Tetsuhisa Otani ◽  
Mikio Furuse
Keyword(s):  
Plasma Membrane ◽  
Epithelial Cells ◽  
Genome Editing ◽  
Tight Junctions ◽  
Molecular Mechanism ◽  
Barrier Function ◽  
Intercellular Space ◽  
Epithelial Barrier ◽  
Epithelial Barrier Function ◽  
Membrane Contact

AbstractTricellular tight junctions (tTJs) are specialized tight junctions (TJs) that seal the intercellular space at tricellular contacts (TCs), where the vertices of three epithelial cells meet. Tricellulin and angulin family membrane proteins are known constituents of tTJs, but the molecular mechanism of tTJ formation remains elusive. Here, we investigated the roles of angulin-1 and tricellulin in tTJ formation in MDCK II cells by genome editing. Angulin-1-deficient cells lost the plasma membrane contact at TCs with impaired epithelial barrier function. The COOH-terminus of angulin-1 bound to the TJ scaffold protein ZO-1 and disruption of their interaction influenced the localization of claudins at TCs, but not the tricellular sealing. Strikingly, the plasma membrane contact at TCs was formed in tricellulin- or claudin-deficient cells. These findings demonstrate that angulin-1 is responsible for the plasma membrane seal at TCs independently of tricellulin and claudins.

Human junction adhesion molecule regulates tight junction resealing in epithelia

2000 ◽  
Vol 113 (13) ◽  
pp. 2363-2374 ◽  
Author(s):  
Y. Liu ◽  
A. Nusrat ◽  
F.J. Schnell ◽  
T.A. Reaves ◽  
S. Walsh ◽  
...  
Keyword(s):  
Epithelial Cells ◽  
Tight Junction ◽  
Tight Junctions ◽  
Adhesion Molecule ◽  
Transmembrane Protein ◽  
Extracellular Domain ◽  
Cell Junctions ◽  
Human Neutrophils ◽  
Epithelial Barrier ◽  
Cell Cell

Epithelial cells form a highly selective barrier and line many organs. The epithelial barrier is maintained by closely apposed cell-cell contacts containing tight junctions, the regulation of which is incompletely understood. Here we report the cloning, tissue localization and evidence for a role in epithelial barrier regulation of an immunoglobulin superfamily member that likely represents the human homolog of murine junction adhesion molecule (JAM). Analysis of the primary structure of human JAM, cloned from T84 epithelial cells, predicts a transmembrane protein with an extracellular domain that contains two IgV loops. Monoclonal antibodies generated against the putative extracellular domain were reactive with a 35–39 kDa protein from both T84 epithelial cells and human neutrophils. By immunofluorescence, JAM mAbs labeled epithelial cells from intestine, lung, and kidney, prominently in the region of tight junctions (co-localization with occludin) and also along lateral cell membranes below the tight junctions. Flow cytometric studies confirmed predominant JAM expression in epithelial cells but also revealed expression on endothelial and hematopoietic cells of all lineages. Functional studies demonstrated that JAM specific mAbs markedly inhibited transepithelial resistance recovery of T84 monolayers after disruption of intercellular junctions (including tight junctions) by transient calcium depletion. Morphologic analysis revealed that, after disassembly of cell-cell junctions, anti-JAM inhibition of barrier function recovery correlated with a loss of both occludin and JAM, but not ZO-1, in reassembling tight junction structure. Reassembly of the major adherens junction component E-cadherin was not affected by JAM specific mAbs. Our findings suggest that JAM plays an important role in the regulation of tight junction assembly in epithelia. Furthermore, these JAM-mediated effects may occur by either direct, or indirect interactions with occludin.

Polyamines are necessary for synthesis and stability of occludin protein in intestinal epithelial cells

2005 ◽  
Vol 288 (6) ◽  
pp. G1159-G1169 ◽  
Author(s):  
Xin Guo ◽  
Jaladanki N. Rao ◽  
Lan Liu ◽  
Tongtong Zou ◽  
Kaspar M. Keledjian ◽  
...  
Keyword(s):  
Epithelial Cells ◽  
Tight Junction ◽  
Barrier Function ◽  
Intestinal Epithelial Cells ◽  
Integral Membrane Protein ◽  
Epithelial Barrier ◽  
Intestinal Epithelial ◽  
Tight Junction Proteins ◽  
Epithelial Barrier Function ◽  
Junction Proteins

Occludin is an integral membrane protein that forms the sealing element of tight junctions and is critical for epithelial barrier function. Polyamines are implicated in multiple signaling pathways driving different biological functions of intestinal epithelial cells (IEC). The present study determined whether polyamines are involved in expression of occludin and play a role in intestinal epithelial barrier function. Studies were conducted in stable Cdx2-transfected IEC-6 cells (IEC-Cdx2L1) associated with a highly differentiated phenotype. Polyamine depletion by α-difluoromethylornithine (DFMO) decreased levels of occludin protein but failed to affect expression of its mRNA. Other tight junction proteins, zonula occludens (ZO)-1, ZO-2, claudin-2, and claudin-3, were also decreased in polyamine-deficient cells. Decreased levels of tight junction proteins in DFMO-treated cells were associated with dysfunction of the epithelial barrier, which was overcome by exogenous polyamine spermidine. Decreased levels of occludin in polyamine-deficient cells was not due to the reduction of intracellular-free Ca2+ concentration ([Ca2+]cyt), because either increased or decreased [Ca2+]cyt did not alter levels of occludin in the presence or absence of polyamines. The level of newly synthesized occludin protein was decreased by ∼70% following polyamine depletion, whereas its protein half-life was reduced from ∼120 min in control cells to ∼75 min in polyamine-deficient cells. These findings indicate that polyamines are necessary for the synthesis and stability of occludin protein and that polyamine depletion disrupts the epithelial barrier function, at least partially, by decreasing occludin.

scholarly journals Effects of HMGB1 on Tricellular Tight Junctions via TGF-β Signaling in Human Nasal Epithelial Cells

2021 ◽  
Vol 22 (16) ◽  
pp. 8390
Author(s):  
Kizuku Ohwada ◽  
Takumi Konno ◽  
Takayuki Kohno ◽  
Masaya Nakano ◽  
Tsuyoshi Ohkuni ◽  
...  
Keyword(s):  
Epithelial Cells ◽  
Tight Junctions ◽  
Chronic Rhinosinusitis ◽  
Kinase Inhibitor ◽  
High Mobility ◽  
Epithelial Barrier ◽  
Type I ◽  
Nasal Epithelial Cells ◽  
Human Nasal Epithelial Cells ◽  
Matrigel Culture

The airway epithelium of the human nasal mucosa acts as a physical barrier that protects against inhaled substances and pathogens via bicellular and tricellular tight junctions (bTJs and tTJs) including claudins, angulin-1/LSR and tricellulin. High mobility group box-1 (HMGB1) increased by TGF-β1 is involved in the induction of nasal inflammation and injury in patients with allergic rhinitis, chronic rhinosinusitis, and eosinophilic chronic rhinosinusitis. However, the detailed mechanisms by which this occurs remain unknown. In the present study, to investigate how HMGB1 affects the barrier of normal human nasal epithelial cells, 2D and 2.5D Matrigel culture of primary cultured human nasal epithelial cells were pretreated with TGF-β type I receptor kinase inhibitor EW-7197 before treatment with HMGB1. Knockdown of angulin-1/LSR downregulated the epithelial barrier. Treatment with EW-7197 decreased angulin-1/LSR and concentrated the expression at tTJs from bTJs and increased the epithelial barrier. Treatment with a binder to angulin-1/LSR angubindin-1 decreased angulin-1/LSR and the epithelial barrier. Treatment with HMGB1 decreased angulin-1/LSR and the epithelial barrier. In 2.5D Matrigel culture, treatment with HMGB1 induced permeability of FITC-dextran (FD-4) into the lumen. Pretreatment with EW-7197 prevented the effects of HMGB1. HMGB1 disrupted the angulin-1/LSR-dependent epithelial permeability barriers of HNECs via TGF-β signaling in HNECs.

scholarly journals Pilt, a Novel Peripheral Membrane Protein at Tight Junctions in Epithelial Cells

2001 ◽  
Vol 276 (51) ◽  
pp. 48350-48355 ◽  
Author(s):  
Hiroshi Kawabe ◽  
Hiroyuki Nakanishi ◽  
Masanori Asada ◽  
Atsunori Fukuhara ◽  
Koji Morimoto ◽  
...  
Keyword(s):  
Epithelial Cells ◽  
Membrane Protein ◽  
Tight Junctions ◽  
Peripheral Membrane Protein

scholarly journals Occludin is concentrated at tight junctions of mouse/rat but not human/guinea pig Sertoli cells in testes

1998 ◽  
Vol 274 (6) ◽  
pp. C1708-C1717 ◽  
Author(s):  
Seiji Moroi ◽  
Mitinori Saitou ◽  
Kazushi Fujimoto ◽  
Akira Sakakibara ◽  
Mikio Furuse ◽  
...  
Keyword(s):  
Membrane Protein ◽  
Guinea Pig ◽  
Tight Junctions ◽  
Sertoli Cells ◽  
Banding Pattern ◽  
Adult Mouse ◽  
Immunofluorescence Microscopy ◽  
Integral Membrane Protein ◽  
Integral Membrane Proteins ◽  
Mouse Testis

Occludin is the only integral membrane protein identified to date as a component of tight junctions (TJs). Here, we examined the distribution and expression of occludin in murine testis bearing well-developed TJ. In the adult mouse testis, occludin was concentrated at TJ strands, which are located at the most basal regions of lateral membranes of Sertoli cells. In immunoblotting, occludin showed a characteristic multiple banding pattern, suggesting that occludin is highly phosphorylated in the testis. In 1-wk-old mouse testis, occludin was distributed diffusely at the lateral membranes of Sertoli cells, and even at this stage, highly phosphorylated occludin was detected. With development, occludin gradually became concentrated at the most basal regions of Sertoli cells. The same results were obtained in rat, but unexpectedly occludin was not detected in human or guinea pig Sertoli cells by immunofluorescence microscopy as well as by immunoblotting. Inasmuch as TJs are also well developed in Sertoli cells of these species, we concluded that, at least in the testes of these species, there are some Sertoli cell-specific isoforms of occludin or other TJ-associated integral membrane proteins that differ from occludin.

scholarly journals Polyhexamethylene Guanidine Phosphate Damages Tight Junctions and the F-Actin Architecture by Activating Calpain-1 via the P2RX7/Ca2+ Signaling Pathway

Cells ◽  
2019 ◽  
Vol 9 (1) ◽  
pp. 59 ◽  
Author(s):  
Sun Woo Jin ◽  
Gi Ho Lee ◽  
Hoa Thi Pham ◽  
Jae Ho Choi ◽  
Hye Gwang Jeong
Keyword(s):  
Epithelial Cells ◽  
Tight Junctions ◽  
Bronchial Epithelium ◽  
Extracellular Atp ◽  
Bronchial Epithelial Cells ◽  
Epithelial Barrier ◽  
Bronchial Epithelial ◽  
Calcium Dependent ◽  
Polyhexamethylene Guanidine ◽  
Guanidine Phosphate

Polyhexamethylene guanidine phosphate (PHMG-p), a member of the polymeric guanidine family, has strong antimicrobial activity and may increase the risk of inflammation-associated pulmonary fibrosis. However, the effect of PHMG-p on the barrier function of the bronchial epithelium is unknown. Epithelial barrier functioning is maintained by tight junctions (TJs); damage to these TJs is the major cause of epithelial barrier breakdown during lung inflammation. The present study showed that, in BEAS-2B human bronchial epithelial cells, exposure to PHMG-p reduced the number of TJs and the E-cadherin level and impaired the integrity of the F-actin architecture. Furthermore, exposure to PHMG-p stimulated the calcium-dependent protease calpain-1, which breaks down TJs. However, treatment with the calpain-1 inhibitor, ALLN, reversed the PHMG-p-mediated impairment of TJs and the F-actin architecture. Furthermore, exposure to PHMG-p increased the intracellular Ca2+ level via P2X purinoreceptor 7 (P2RX7) and inhibition of P2RX7 abolished the PHMG-p-induced calpain-1 activity and protein degradation and increased the intracellular Ca2+ level. Although exposure to PHMG-p increased the extracellular ATP level, hydrolysis of extracellular ATP by apyrase did not influence its detrimental effect on bronchial epithelial cells. These results implicate the impairment of TJs and the F-actin architecture in the pathogenesis of pulmonary diseases.

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