scholarly journals Functional characterization and localization of a gill-specific claudin isoform in Atlantic salmon

2012 ◽  
Vol 302 (2) ◽  
pp. R300-R311 ◽  
Author(s):  
M. B. Engelund ◽  
A. S. L. Yu ◽  
J. Li ◽  
S. S. Madsen ◽  
N. J. Færgeman ◽  
...  

Claudins are the major determinants of paracellular epithelial permeability in multicellular organisms. In Atlantic salmon ( Salmo salar L.), we previously found that mRNA expression of the abundant gill-specific claudin 30 decreases during seawater (SW) acclimation, suggesting that this claudin is associated with remodeling of the epithelium during salinity change. This study investigated localization, protein expression, and function of claudin 30. Confocal microscopy showed that claudin 30 protein was located at cell-cell interfaces in the gill filament in SW- and fresh water (FW)-acclimated salmon, with the same distribution, overall, as the tight junction protein ZO-1. Claudin 30 was located at the apical tight junction interface and in cell membranes deeper in the epithelia. Colocalization with the α-subunit of the Na+-K+-ATPase was negligible, suggesting limited association with mitochondria-rich cells. Immunoblotting of gill samples showed lower claudin 30 protein expression in SW than FW fish. Retroviral transduction of claudin 30 into Madin-Darby canine kidney cells resulted in a decreased conductance of 19%. The decreased conductance correlated with a decreased permeability of the cell monolayer to monovalent cations, whereas permeability to chloride was unaffected. Confocal microscopy revealed that claudin 30 was expressed in the lateral membrane, as well as in tight junctions of Madin-Darby canine kidney cells, thereby paralleling the findings in the native gill. This study suggests that claudin 30 functions as a cation barrier between pavement cells in the gill and also has a general role in cell-cell adhesion in deeper layers of the epithelium.

1989 ◽  
Vol 263 (2) ◽  
pp. 597-599 ◽  
Author(s):  
B R Stevenson ◽  
J M Anderson ◽  
I D Braun ◽  
M S Mooseker

A comparison was made of the phosphate content of the tight-junction-specific protein ZO-1 in two strains of Madin-Darby canine kidney cells which differ in transepithelial resistance, a parameter reflective of tight-junctional permeability. Analysis revealed that the ZO-1 from the low-resistance strain contained approximately twice as much phosphate as that from the high-resistance strain.


2003 ◽  
Vol 14 (5) ◽  
pp. 1757-1768 ◽  
Author(s):  
Erika S. Wittchen ◽  
Julie Haskins ◽  
Bruce R. Stevenson

We previously demonstrated that exogenous expression of a truncated form of the tight junction protein ZO-3 affected junctional complex assembly and function. Current results indicate that this ZO-3 construct influences actin cytoskeleton dynamics more globally. We show that expression of the amino-terminal half of ZO-3 (NZO-3) in Madin-Darby canine kidney cells results in a decreased number of stress fibers and focal adhesions and causes an increased rate of cell migration in a wound healing assay. We also demonstrate that RhoA activity is reduced in NZO-3–expressing cells. We determined that ZO-3 interacts with p120 catenin and AF-6, proteins localized to the junctional complex and implicated in signaling pathways important for cytoskeleton regulation and cell motility. We also provide evidence that NZO-3 interacts directly with the C terminus of ZO-3, and we propose a model where altered interactions between ZO-3 and p120 catenin in NZO-3–expressing cells affect RhoA GTPase activity. This study reveals a potential link between ZO-3 and RhoA-related signaling events.


2013 ◽  
Vol 24 (18) ◽  
pp. 2820-2833 ◽  
Author(s):  
Hiroshi Tokuo ◽  
Lynne M. Coluccio

Cooperation between cadherins and the actin cytoskeleton controls the formation and maintenance of cell–cell adhesions in epithelia. We find that the molecular motor protein myosin-1c (Myo1c) regulates the dynamic stability of E-cadherin–based cell–cell contacts. In Myo1c-depleted Madin–Darby canine kidney cells, E-cadherin localization was dis­organized and lateral membranes appeared less vertical with convoluted edges versus control cells. In polarized monolayers, Myo1c-knockdown (KD) cells were more sensitive to reduced calcium concentration. Myo1c separated in the same plasma membrane fractions as E-cadherin, and Myo1c KD caused a significant reduction in the amount of E-cadherin recovered in one peak fraction. Expression of green fluorescent protein (GFP)–Myo1c mutants revealed that the phosphatidylinositol-4,5-bisphosphate–binding site is necessary for its localization to cell–cell adhesions, and fluorescence recovery after photobleaching assays with GFP-Myo1c mutants revealed that motor function was important for Myo1c dynamics at these sites. At 18°C, which inhibits vesicle recycling, Myo1c-KD cells accumulated more E-cadherin–positive vesicles in their cytoplasm, suggesting that Myo1c affects E-cadherin endocytosis. Studies with photoactivatable GFP–E-cadherin showed that Myo1c KD reduced the stability of E-cadherin at cell–cell adhesions. We conclude that Myo1c stabilizes E-cadherin at adherens junctions in polarized epithelial cells and that the motor function and ability of Myo1c to bind membrane are critical.


2001 ◽  
Vol 12 (8) ◽  
pp. 2257-2274 ◽  
Author(s):  
Raul Rojas ◽  
Wily G. Ruiz ◽  
Som-Ming Leung ◽  
Tzuu-Shuh Jou ◽  
Gerard Apodaca

Polarized epithelial cells maintain the asymmetric composition of their apical and basolateral membrane domains by at least two different processes. These include the regulated trafficking of macromolecules from the biosynthetic and endocytic pathway to the appropriate membrane domain and the ability of the tight junction to prevent free mixing of membrane domain-specific proteins and lipids. Cdc42, a Rho family GTPase, is known to govern cellular polarity and membrane traffic in several cell types. We examined whether this protein regulated tight junction function in Madin-Darby canine kidney cells and pathways that direct proteins to the apical and basolateral surface of these cells. We used Madin-Darby canine kidney cells that expressed dominant-active or dominant-negative mutants of Cdc42 under the control of a tetracycline-repressible system. Here we report that expression of dominant-active Cdc42V12 or dominant-negative Cdc42N17 altered tight junction function. Expression of Cdc42V12 slowed endocytic and biosynthetic traffic, and expression of Cdc42N17 slowed apical endocytosis and basolateral to apical transcytosis but stimulated biosynthetic traffic. These results indicate that Cdc42 may modulate multiple cellular pathways required for the maintenance of epithelial cell polarity.


2000 ◽  
Vol 11 (3) ◽  
pp. 849-862 ◽  
Author(s):  
Yan-hua Chen ◽  
Qun Lu ◽  
Eveline E. Schneeberger ◽  
Daniel A. Goodenough

In the Madin-Darby canine kidney epithelial cell line, the proteins occludin and ZO-1 are structural components of the tight junctions that seal the paracellular spaces between the cells and contribute to the epithelial barrier function. In Ras-transformed Madin-Darby canine kidney cells, occludin, claudin-1, and ZO-1 were absent from cell–cell contacts but were present in the cytoplasm, and the adherens junction protein E-cadherin was weakly expressed. After treatment of the Ras-transformed cells with the mitogen-activated protein kinase kinase (MEK1) inhibitor PD98059, which blocks the activation of mitogen-activated protein kinase (MAPK), occludin, claudin-1, and ZO-1 were recruited to the cell membrane, tight junctions were assembled, and E-cadherin protein expression was induced. Although it is generally believed that E-cadherin–mediated cell–cell adhesion is required for tight junction assembly, the recruitment of occludin to the cell–cell contact area and the restoration of epithelial cell morphology preceded the appearance of E-cadherin at cell–cell contacts. Both electron microscopy and a fourfold increase in the transepithelial electrical resistance indicated the formation of functional tight junctions after MEK1 inhibition. Moreover, inhibition of MAPK activity stabilized occludin and ZO-1 by differentially increasing their half-lives. We also found that during the process of tight junction assembly after MEK1 inhibition, tyrosine phosphorylation of occludin and ZO-1, but not claudin-1, increased significantly. Our study demonstrates that down-regulation of the MAPK signaling pathway causes the restoration of epithelial cell morphology and the assembly of tight junctions in Ras-transformed epithelial cells and that tyrosine phosphorylation of occludin and ZO-1 may play a role in some aspects of tight junction formation.


2016 ◽  
Vol 105 (2) ◽  
pp. 630-638 ◽  
Author(s):  
Mathias Kaiser ◽  
Sudharani Chalapala ◽  
Christian Gorzelanny ◽  
Ramu Sridhar Perali ◽  
Francisco Martin Goycoolea

2007 ◽  
Vol 292 (3) ◽  
pp. C1094-C1102 ◽  
Author(s):  
Shobha Gopalakrishnan ◽  
Mark A. Hallett ◽  
Simon J. Atkinson ◽  
James A. Marrs

Renal ischemia and in vitro ATP depletion result in disruption of the epithelial tight junction barrier, which is accompanied by breakdown of plasma membrane polarity. Tight junction formation is regulated by evolutionarily conserved complexes, including that of atypical protein kinase C (aPKC), Par3, and Par6. The aPKC signaling complex is activated by Rac and regulated by protein phosphorylation and associations with other tight junction regulatory proteins, for example, mLgl. In this study, we examined the role of aPKC signaling complex during ATP depletion and recovery in Madin-Darby canine kidney cells. ATP depletion reduced Rac GTPase activity and induced Par3, aPKCζ, and mLgl-1 redistribution from sites of cell-cell contact, which was restored following recovery from ATP depletion. Zonula occludens (ZO)-1 and Par3 phosphorylation was reduced and association of aPKCζ with its substrates Par3 and mLgl-1 was stabilized in ATP-depleted Madin-Darby canine kidney cells. ATP depletion also induced a stable association of Par3 with Tiam-1, a Rac GTPase exchange factor, which explains how aPKCζ and Rac activities were suppressed. Experimental inhibition of aPKCζ during recovery from ATP depletion interfered with reassembly of ZO-1 and Par3 at cell junctions. These data indicate that aPKC signaling is impaired during ATP depletion, participates in tight junction disassembly during cell injury and is important for tight junction reassembly during recovery.


Oncogene ◽  
2003 ◽  
Vol 22 (14) ◽  
pp. 2097-2109 ◽  
Author(s):  
Tatsuo Katata ◽  
Kenji Irie ◽  
Atsunori Fukuhara ◽  
Tomomi Kawakatsu ◽  
Akio Yamada ◽  
...  

2021 ◽  
Author(s):  
Chia-hsuan Lu ◽  
Fu-lai Wen ◽  
Shawn Ching-Chung Hsueh ◽  
Wen-hsiu Wu ◽  
Yu-Fang Lin ◽  
...  

The tight junction outlines the apicolateral border of epithelial cells like a belt, sealing the paracellular space when cells form contacts with each other. The permeability and morphology of tight junction are regulated by actomyosin contractility, which has been conventionally thought from the purse-string-like circumferential actomyosin belt along tight junction. Spatially, the tight junction is close to the apical actin network, which exerts inward contractions orthogonal to the tight junction. To test the contributions from apical actin network, we laser-ablated spots on the apical surface of polarized Madin-Darby Canine Kidney (MDCK) epithelial cells. Laser ablation severed the apical cytoskeleton network, decreased in-plane tension, increased the apical surface area, and rendered the tight junction less tortuous in shape. Consistent with these observations, changes in MDCK cell sheet morphology due to cell proliferation, or perturbation with the ROCK inhibitor Y27632 increased the density of the apical actin network and decreased tight junction tortuosity. The morphological analysis revealed scutoids in flat MDCK cell sheets, contrary to predictions from a previous model that only considered cell-cell interactions as line tension. Additional cell-cell interactions from apical in-plane tension provides probable cause for the occurrence of scutoids on flat geometry. Taken together, our findings identify the importance of the apical actin network exerting in-plane apical tension to regulate tight-junction mechanobiology and epithelial cell shape.


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