DLG-1 Is a MAGUK Similar to SAP97 and Is Required for Adherens Junction Formation

Cellular junctions are critical for intercellular communication and for the assembly of cells into tissues. Cell junctions often consist of tight junctions, which form a permeability barrier and prevent the diffusion of lipids and proteins between cell compartments, and adherens junctions, which control the adhesion of cells and link cortical actin filaments to attachment sites on the plasma membrane. Proper tight junction formation and cell polarity require the function of membrane-associated guanylate kinases (MAGUKs) that contain the PDZ protein-protein interaction domain. In contrast, less is known about how adherens junctions are assembled. Here we describe how the PDZ-containing protein DLG-1 is required for the proper formation and function of adherens junctions in Caenorhabditis elegans. DLG-1 is a MAGUK protein that is most similar in sequence to mammalian SAP97, which is found at both synapses of the CNS, as well as at cell junctions of epithelia. DLG-1 is localized to adherens junctions, and DLG-1 localization is mediated by an amino-terminal domain shared with SAP97 but not found in other MAGUK family members. DLG-1 recruits other proteins and signaling molecules to adherens junctions, while embryos that lack DLG-1 fail to recruit the proteins AJM-1 and CPI-1 to adherens junctions. DLG-1 is required for the proper organization of the actin cytoskeleton and for the morphological elongation of embryos. In contrast to other proteins that have been observed to affect adherens junction assembly and function, DLG-1 is not required to maintain cell polarity. Our results suggest a new function for MAGUK proteins distinct from their role in cell polarity.

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A-CAM: a 135-kD receptor of intercellular adherens junctions. II. Antibody-mediated modulation of junction formation.

The Journal of Cell Biology ◽

10.1083/jcb.103.4.1451 ◽

1986 ◽

Vol 103 (4) ◽

pp. 1451-1464 ◽

Cited By ~ 84

Author(s):

T Volk ◽

B Geiger

Keyword(s):

Cell Adhesion ◽

Adherens Junctions ◽

Adherens Junction ◽

Recovery Phase ◽

Inhibitory Effect ◽

Cell Junctions ◽

Specific Cell ◽

Normal Medium ◽

Junction Formation ◽

Cell Cell

Intercellular adherens junctions between cultured lens epithelial cells are highly Ca2+-dependent and are readily dissociated upon chelation of extracellular Ca2+ ions. Addition of Ca2+ to EGTA-treated cells results in the recovery of cell-cell junctions including the reorganization of adherens junction-specific cell adhesion molecule (A-CAM), vinculin, and actin (Volk, T., and B. Geiger, 1986, J. Cell Biol., 103:000-000). Incubation of cells during the recovery phase with Fab' fragments of anti-A-CAM specifically inhibited the re-formation of cell-cell adherens junctions. This inhibition was accompanied by remarkable changes in microfilament organization manifested by an apparent deterioration of stress fibers and the appearance of fragmented actin bundles throughout the cytoplasm. Incubation of EGTA-dissociated cells with intact divalent anti-A-CAM antibodies in normal medium had no apparent inhibitory effect on junction formation and did not affect the assembly of actin microfilament bundles. Moreover, adherens junctions formed in the presence of the divalent antibodies became essentially Ca2+-independent, suggesting that cell-cell adhesion between them was primarily mediated by the antibodies. These studies suggest that A-CAM participates in intercellular adhesion in adherens-type junctions and point to its involvement in microfilament bundle assembly.

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Increased Expression of Adherens Junction Components in Mouse Liver following Bile Duct Ligation

Biomolecules ◽

10.3390/biom9100636 ◽

2019 ◽

Vol 9 (10) ◽

pp. 636 ◽

Cited By ~ 1

Author(s):

Van Campenhout ◽

Crespo Yanguas ◽

Cooreman ◽

Gijbels ◽

Leroy ◽

...

Keyword(s):

Bile Duct ◽

Mouse Liver ◽

Bile Duct Ligation ◽

Adherens Junctions ◽

Adherens Junction ◽

Cell Junctions ◽

Tissue Architecture ◽

Fibrotic Liver ◽

Protein Levels ◽

Duct Ligation

Adherens junctions, consisting of cadherins and catenins, are a group of cell-to-cell junctions that mediate mechanistic linkage between neighboring cells. By doing so, adherens junctions ensure direct intercellular contact and play an indispensable role in maintaining tissue architecture. Considering these critical functions, it is not surprising that adherens junctions are frequently involved in disease. In the present study, the effects of bile duct ligation—a surgical procedure to experimentally induce cholestatic and fibrotic liver pathology—on hepatic adherens junctions were investigated in mice. In essence, it was found that liver mRNA and protein levels of E-cadherin, β-catenin and γ-catenin drastically increase following bile duct ligation. These results could suggest a cytoprotective role for hepatic adherens junctions following bile duct ligation.

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Cell Polarity Development and Protein Trafficking in Hepatocytes Lacking E-Cadherin/β-Catenin–based Adherens Junctions

Molecular Biology of the Cell ◽

10.1091/mbc.e06-11-1040 ◽

2007 ◽

Vol 18 (6) ◽

pp. 2313-2321 ◽

Cited By ~ 48

Author(s):

Delphine Théard ◽

Magdalena Steiner ◽

Dharamdajal Kalicharan ◽

Dick Hoekstra ◽

Sven C.D. van IJzendoorn

Keyword(s):

Cell Polarity ◽

Membrane Trafficking ◽

Protein Trafficking ◽

Adherens Junctions ◽

Adherens Junction ◽

Dipeptidyl Peptidase ◽

Dipeptidyl Peptidase Iv ◽

Apical Surface ◽

Tight Junction Formation ◽

E Cadherin

Using a mutant hepatocyte cell line in which E-cadherin and β-catenin are completely depleted from the cell surface, and, consequently, fail to form adherens junctions, we have investigated adherens junction requirement for apical–basolateral polarity development and polarized membrane trafficking. It is shown that these hepatocytes retain the capacity to form functional tight junctions, develop full apical–basolateral cell polarity, and assemble a subapical cortical F-actin network, although with a noted delay and a defect in subsequent apical lumen remodeling. Interestingly, whereas hepatocytes typically target the plasma membrane protein dipeptidyl peptidase IV first to the basolateral surface, followed by its transcytosis to the apical domain, hepatocytes lacking E-cadherin–based adherens junctions target dipeptidyl peptidase IV directly to the apical surface. Basolateral surface-directed transport of other proteins or lipids tested was not visibly affected in hepatocytes lacking E-cadherin–based adherens junctions. Together, our data show that E-cadherin/β-catenin–based adherens junctions are dispensable for tight junction formation and apical lumen biogenesis but not for apical lumen remodeling. In addition, we suggest a possible requirement for E-cadherin/β-catenin–based adherens junctions with regard to the indirect apical trafficking of specific proteins in hepatocytes.

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Role of IQGAP1 in endothelial barrier enhancement caused by OxPAPC

AJP Lung Cellular and Molecular Physiology ◽

10.1152/ajplung.00095.2016 ◽

2016 ◽

Vol 311 (4) ◽

pp. L800-L809 ◽

Cited By ~ 6

Author(s):

Yufeng Tian ◽

Xinyong Tian ◽

Grzegorz Gawlak ◽

Nicolene Sarich ◽

David B. Sacks ◽

...

Keyword(s):

Actin Cytoskeleton ◽

Actin Polymerization ◽

Adherens Junctions ◽

Adherens Junction ◽

Cell Junctions ◽

Endothelial Barrier ◽

Cell Junction ◽

Protective Effects ◽

P120 Catenin

Oxidized 1-palmitoyl-2-arachidonoyl- sn-glycero-3-phosphatidylcholine (OxPAPC) attenuates agonist-induced endothelial cell (EC) permeability and increases pulmonary endothelial barrier function via enhancement of both the peripheral actin cytoskeleton and cell junctions mediated by Rac1 and Cdc42 GTPases. This study evaluated the role for the multifunctional Rac1/Cdc42 effector and regulator, IQ domain containing GTPase-activating protein (IQGAP1), as a molecular transducer of the OxPAPC-mediated EC barrier-enhancing signal. IQGAP1 knockdown in endothelial cells by gene-specific small-interfering RNA abolished OxPAPC-induced enlargement of VE-cadherin-positive adherens junctions, suppressed peripheral accumulation of actin polymerization regulators, namely cortactin, neural Wiskott-Aldrich syndrome protein (N-WASP), and actin-related protein 3, and attenuated remodeling of the peripheral actin cytoskeleton. Inhibition of OxPAPC-induced barrier enhancement by IQGAP1 knockdown was due to suppressed Rac1 and Cdc42 activation. Expression of an IQGAP1 truncated mutant showed that the GTPase regulatory domain of IQGAP1 was essential for the OxPAPC-induced membrane localization of cortactin, adherens junction proteins VE-cadherin and p120-catenin, as well as for EC permeability response. IQGAP1 knockdown attenuated the protective effect of OxPAPC against thrombin-induced cell contraction, cell junction disruption, and EC permeability. These results demonstrate for the first time the role of IQGAP1 as a critical transducer of OxPAPC-induced Rac1/Cdc42 signaling to the actin cytoskeleton and adherens junctions, which promotes cortical cytoskeletal remodeling and EC barrier-protective effects of oxidized phospholipids.

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Assembly of adherens junctions is required for sphingosine 1-phosphate-induced matriptase accumulation and activation at mammary epithelial cell-cell contacts

AJP Cell Physiology ◽

10.1152/ajpcell.00400.2003 ◽

2004 ◽

Vol 286 (5) ◽

pp. C1159-C1169 ◽

Cited By ~ 32

Author(s):

Ruei-Jiun Hung ◽

Ia-Wen J. Hsu ◽

Jennifer L. Dreiling ◽

Mon-Juan Lee ◽

Cicely A. Williams ◽

...

Keyword(s):

Epithelial Cells ◽

Mammary Epithelial Cells ◽

Adherens Junctions ◽

Adherens Junction ◽

Mammary Epithelial ◽

Cell Junctions ◽

Cell Contacts ◽

Cytoskeletal Rearrangement ◽

Sphingosine 1 Phosphate ◽

Cell Cell

Sphingosine 1-phosphate (S1P), a bioactive phospholipid, simultaneously induces actin cytoskeletal rearrangements and activation of matriptase, a membrane-associated serine protease in human mammary epithelial cells. In this study, we used a monoclonal antibody selective for activated, two-chain matriptase to examine the functional relationship between these two S1P-induced events. Ten minutes after exposure of 184 A1N4 mammary epithelial cells to S1P, matriptase was observed to accumulate at cell-cell contacts. Activated matriptase first began to appear as small spots at cell-cell contacts, and then its deposits elongated along cell-cell contacts. Concomitantly, S1P induced assembly of adherens junctions and subcortical actin belts. Matriptase localization was observed to be coincident with markers of adherens junctions at cell-cell contacts but likely not to be incorporated into the tightly bound adhesion plaque. Disruption of subcortical actin belt formation and prevention of adherens junction assembly led to prevention of accumulation and activation of the protease at cell-cell contacts. These data suggest that S1P-induced accumulation and activation of matriptase depend on the S1P-induced adherens junction assembly. Although MAb M32, directed against one of the low-density lipoprotein receptor class A domains of matriptase, blocked S1P-induced activation of the enzyme, the antibody had no effect on S1P-induced actin cytoskeletal rearrangement. Together, these data indicate that actin cytoskeletal rearrangement is necessary but not sufficient for S1P-induced activation of matriptase at cell-cell contacts. The coupling of matriptase activation to adherens junction assembly and actin cytoskeletal rearrangement may serve to ensure tight control of matriptase activity, restricted to cell-cell junctions of mammary epithelial cells.

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Control of dynamic cell behaviors during angiogenesis and anastomosis by Rasip 1

Development ◽

10.1242/dev.197509 ◽

2021 ◽

Author(s):

Minkyoung Lee ◽

Charles Betz ◽

Jianmin Yin ◽

Ilkka Paatero ◽

Niels Schellinx ◽

...

Keyword(s):

Cell Junctions ◽

Interacting Protein ◽

Cell Behaviors ◽

Sprouting Angiogenesis ◽

Junction Formation ◽

Phenotype Analysis ◽

Membrane Compartment ◽

Dynamic Cell ◽

Cellular Behaviors ◽

And Function

Organ morphogenesis is driven by a wealth of tightly orchestrated cellular behaviors, which ensure proper organ assembly and function. Many of these cell activities involve cell-cell interactions and remodeling of the F-actin cytoskeleton. Here, we analyze the requirement for Rasip1 (Ras-interacting protein 1), an endothelial-specific regulator of junctional dynamics, during blood vessel formation. Phenotype analysis of rasip1 mutants in zebrafish embryos reveal distinct functions of Rasip1 during sprouting angiogenesis, anastomosis and lumen formation. During angiogenic sprouting, loss of Rasip1 causes cell pairing defects due to a destabilization of tricellular junctions, indicating that stable tri-cellular junctions are essential to maintain multicellular organization within the sprout. During anastomosis, Rasip1 is required to establish a stable apical membrane compartment; rasip1 mutants display ectopic, reticulated junctions and the apical compartment is frequently collapsed. Loss of Ccm1 and Heg1 function mimics junctional defects of rasip1 mutants. Furthermore, downregulation of ccm1 and heg1 leads to a delocalization of Rasip1 at cell junctions, indicating that junctional tethering of Rasip1 is required for its function during junction formation and stabilization during sprouting angiogenesis.

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Quantitative cell polarity imaging defines leader-to-follower transitions during collective migration and the key role of microtubule-dependent adherens junction formation

Development ◽

10.1242/dev.101675 ◽

2014 ◽

Vol 141 (6) ◽

pp. 1282-1291 ◽

Cited By ~ 69

Author(s):

C. Revenu ◽

S. Streichan ◽

E. Dona ◽

V. Lecaudey ◽

L. Hufnagel ◽

...

Keyword(s):

Cell Polarity ◽

Adherens Junction ◽

Collective Migration ◽

Junction Formation

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FSH regulates the formation of adherens junctions and ectoplasmic specialisations between rat Sertoli cells in vitro and in vivo

Journal of Endocrinology ◽

10.1677/joe.1.06634 ◽

2006 ◽

Vol 189 (2) ◽

pp. 381-395 ◽

Cited By ~ 41

Author(s):

P Sluka ◽

L O’Donnell ◽

J R Bartles ◽

P G Stanton

Keyword(s):

Sertoli Cell ◽

Sertoli Cells ◽

Adherens Junctions ◽

Adherens Junction ◽

Cell Junctions ◽

Junctional Complex ◽

Intermediate Filament Protein ◽

Adult Rat

Spermatogenesis is dependent on the ability of Sertoli cells to form mature junctions that maintain a unique environment within the seminiferous epithelium. Adjacent Sertoli cells form a junctional complex that includes classical adherens junctions and testis-specific ectoplasmic specialisations (ES). The regulation of inter-Sertoli cell junctions by the two main endocrine regulators of spermatogenesis, FSH and testosterone, is unclear. This study aimed to investigate the effects of FSH and testosterone on inter-Sertoli cell adherens junctions (as determined by immunolocalisation of cadherin, catenin and actin) and ES junctions (as determined by immunolocalisation of espin, actin and vinculin) in cultured immature Sertoli cells and GnRH-immunised adult rat testes given FSH or testosterone replacement in vivo. When hormones were absent in vitro, adherens junctions formed as discrete puncta between interdigitating, finger-like projections of Sertoli cells, but ES junctions were not present. The adherens junction puncta included actin filaments that were oriented perpendicularly to the Sertoli cell plasma membrane, but were not associated with the intermediate filament protein vimentin. When FSH was added in vitro, ES junctions formed, and adjacent adherens junction puncta fused into extensive adherens junction belts. After hormone suppression in vivo, ES junctions were absent, while FSH replacement restored ES junctions, as confirmed by electron microscopy and confocal analysis of ES-associated proteins. Testosterone alone did not affect adherens junctions or ES in vitro or in vivo. We conclude that FSH can regulate the formation of ES junctions and stimulate the organisation and orientation of extensive adherens junctions in Sertoli cells.

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Excess centrosomes disrupt vascular lumenization and endothelial cell adherens junctions

Angiogenesis ◽

10.1007/s10456-020-09737-7 ◽

2020 ◽

Vol 23 (4) ◽

pp. 567-575

Author(s):

Danielle B. Buglak ◽

Erich J. Kushner ◽

Allison P. Marvin ◽

Katy L. Davis ◽

Victoria L. Bautch

Keyword(s):

Endothelial Cells ◽

Endothelial Cell ◽

Cell Polarity ◽

Adherens Junctions ◽

Cell Junctions ◽

Microtubule Organizing Center ◽

Sprouting Angiogenesis ◽

Organizing Center ◽

Important Regulator ◽

Cell Cell

Abstract Proper blood vessel formation requires coordinated changes in endothelial cell polarity and rearrangement of cell–cell junctions to form a functional lumen. One important regulator of cell polarity is the centrosome, which acts as a microtubule organizing center. Excess centrosomes perturb aspects of endothelial cell polarity linked to migration, but whether centrosome number influences apical–basal polarity and cell–cell junctions is unknown. Here, we show that excess centrosomes alter the apical–basal polarity of endothelial cells in angiogenic sprouts and disrupt endothelial cell–cell adherens junctions. Endothelial cells with excess centrosomes had narrower lumens in a 3D sprouting angiogenesis model, and zebrafish intersegmental vessels had reduced perfusion following centrosome overduplication. These results indicate that endothelial cell centrosome number regulates proper lumenization downstream of effects on apical–basal polarity and cell–cell junctions. Endothelial cells with excess centrosomes are prevalent in tumor vessels, suggesting how centrosomes may contribute to tumor vessel dysfunction.

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Activation of Both MAP Kinase and Phosphatidylinositide 3-Kinase by Ras Is Required for Hepatocyte Growth Factor/Scatter Factor–induced Adherens Junction Disassembly

Molecular Biology of the Cell ◽

10.1091/mbc.9.8.2185 ◽

1998 ◽

Vol 9 (8) ◽

pp. 2185-2200 ◽

Cited By ~ 233

Author(s):

Sandra Potempa ◽

Anne J. Ridley

Keyword(s):

Growth Factor ◽

Hepatocyte Growth Factor ◽

Map Kinase ◽

Adherens Junctions ◽

Adherens Junction ◽

Dominant Negative ◽

Cell Junctions ◽

Scatter Factor ◽

Cell Scattering ◽

Hepatocyte Growth

Hepatocyte growth factor/scatter factor (HGF/SF) stimulates the motility of epithelial cells, initially inducing centrifugal spreading of colonies followed by disruption of cell–cell junctions and subsequent cell scattering. In Madin–Darby canine kidney cells, HGF/SF-induced motility involves actin reorganization mediated by Ras, but whether Ras and downstream signals regulate the breakdown of intercellular adhesions has not been established. Both HGF/SF and V12Ras induced the loss of the adherens junction proteins E-cadherin and β-catenin from intercellular junctions during cell spreading, and the HGF/SF response was blocked by dominant-negative N17Ras. Desmosomes and tight junctions were regulated separately from adherens junctions, because they were not disrupted by V12Ras. MAP kinase, phosphatidylinositide 3-kinase (PI 3-kinase), and Rac were required downstream of Ras, because loss of adherens junctions was blocked by the inhibitors PD098059 and LY294002 or by dominant-inhibitory mutants of MAP kinase kinase 1 or Rac1. All of these inhibitors also prevented HGF/SF-induced cell scattering. Interestingly, activated Raf or the activated p110α subunit of PI 3-kinase alone did not induce disruption of adherens junctions. These results indicate that activation of both MAP kinase and PI 3-kinase by Ras is required for adherens junction disassembly and that this is essential for the motile response to HGF/SF.

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