Armadillo is required for adherens junction assembly, cell polarity, and morphogenesis during Drosophila embryogenesis.

Morphological and biochemical analyses have identified a set of proteins which together form a structure known as the adherens junction. Elegant experiments in tissue culture support the idea that adherens junctions play a key role in cell-cell adhesion and in organizing cells into epithelia. During normal embryonic development, cells quickly organize epithelia; these epithelial cells participate in many of the key morphogenetic movements of gastrulation. This prompted the hypothesis that adherens junctions ought to be critical for normal embryonic development. Drosophila Armadillo, the homologue of vertebrate beta-catenin, is a core component of the adherens junction protein complex and has been hypothesized to be essential for adherens junction function in vivo. We have used an intermediate mutant allele of armadillo, armadilloXP33, to test these hypotheses in Drosophila embryos. Adherens junctions cannot assemble in the absence of Armadillo, leading to dramatic defects in cell-cell adhesion. The epithelial cells of the embryo lose adhesion to each other, round up, and apparently become mesenchymal. Mutant cells also lose their normal cell polarity. These disruptions in the integrity of epithelia block the appropriate morphogenetic movements of gastrulation. These results provide the first demonstration of the effect of loss of adherens junctions on Drosophila embryonic development.

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Abelson kinase regulates epithelial morphogenesis in Drosophila

The Journal of Cell Biology ◽

10.1083/jcb.200105102 ◽

2001 ◽

Vol 155 (7) ◽

pp. 1185-1198 ◽

Cited By ~ 88

Author(s):

Elizabeth E. Grevengoed ◽

Joseph J. Loureiro ◽

Traci L. Jesse ◽

Mark Peifer

Keyword(s):

Epithelial Cells ◽

Adherens Junctions ◽

Adherens Junction ◽

Epithelial Morphogenesis ◽

Actin Dynamics ◽

Nonreceptor Tyrosine Kinase ◽

Abelson Kinase ◽

Adherens Junction Protein ◽

Junction Protein ◽

Guidance Receptors

Activation of the nonreceptor tyrosine kinase Abelson (Abl) contributes to the development of leukemia, but the complex roles of Abl in normal development are not fully understood. Drosophila Abl links neural axon guidance receptors to the cytoskeleton. Here we report a novel role for Drosophila Abl in epithelial cells, where it is critical for morphogenesis. Embryos completely lacking both maternal and zygotic Abl die with defects in several morphogenetic processes requiring cell shape changes and cell migration. We describe the cellular defects that underlie these problems, focusing on dorsal closure as an example. Further, we show that the Abl target Enabled (Ena), a modulator of actin dynamics, is involved with Abl in morphogenesis. We find that Ena localizes to adherens junctions of most epithelial cells, and that it genetically interacts with the adherens junction protein Armadillo (Arm) during morphogenesis. The defects of abl mutants are strongly enhanced by heterozygosity for shotgun, which encodes DE-cadherin. Finally, loss of Abl reduces Arm and α-catenin accumulation in adherens junctions, while having little or no effect on other components of the cytoskeleton or cell polarity machinery. We discuss possible models for Abl function during epithelial morphogenesis in light of these data.

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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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A model system for cell adhesion and signal transduction in Drosophila

Development ◽

10.1242/dev.119.supplement.163 ◽

1993 ◽

Vol 119 (Supplement) ◽

pp. 163-176 ◽

Cited By ~ 5

Author(s):

Mark Peifer ◽

Sandra Orsulic ◽

Li-Mei Pai ◽

Joseph Loureiro

Keyword(s):

Cell Adhesion ◽

Function Analysis ◽

Cell Communication ◽

Adherens Junction ◽

Cell Junctions ◽

Direct Role ◽

Junction Protein ◽

Wingless Signaling ◽

Segment Polarity ◽

Cell Cell

Cells must cooperate and communicate to form a multicellular animal. Information about the molecules required for these processes have come from a variety of sources; the convergence between the studies of particular molecules by vertebrate cell biologists and the genes identified by scientists investigating development in Drosophila has been especially fruitful. We are interested in the connection between cadherin proteins that regulate cell-cell adhesion and the wingless/wnt-1 cell-cell signaling molecules controlling pattern formation during development. The Drosophila segment polarity gene armadillo, homolog of the vertebrate adherens junction protein-catenin, is required for both cell adhesion and wg signaling. We review what is known about wingless signaling in Drosophila, and discuss the role of cell-cell junctions in both cell adhesion and cell communication. We then describe the results of our preliminary structure-function analysis of Armadillo protein in both cell adhesion and wingless signaling. Finally, we discuss evidence supporting a direct role for Armadillo and adherens junction in transduction of wingless signal.

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Adherens junction serves to generate cryptic lamellipodia required for collective migration of epithelial cells

10.1101/2020.04.20.052118 ◽

2020 ◽

Cited By ~ 1

Author(s):

Masayuki Ozawa ◽

Sylvain Hiver ◽

Takaki Yamamoto ◽

Tatsuo Shibata ◽

Srigokul Upadhyayula ◽

...

Keyword(s):

Epithelial Cells ◽

Adherens Junctions ◽

Myosin Ii ◽

Adherens Junction ◽

Cancer Invasion ◽

Biological Processes ◽

Collective Migration ◽

Epithelial Sheets ◽

Lamellipodia Formation ◽

Cell Cell

AbstractCollective migration of epithelial cells plays crucial roles in various biological processes such as cancer invasion. In migrating epithelial sheets, leader cells form lamellipodia to advance, and follower cells also form similar motile apparatus at cell-cell boundaries, which are called cryptic lamellipodia (c-lamellipodia). Using adenocarcinoma-derived epithelial cells, we investigated how c-lamellipodia are generated, and found that they sporadically grew from Ecadherin-based adherens junctions (AJs). WAVE and Arp2/3 complexes were localized along the AJs, and silencing them not only interfered with c-lamellipodia formation but also prevented follower cells from trailing the leaders. Disruption of AJs by removing αE-catenin resulted in uncontrolled c-lamellipodia growth, and this was brought about by myosin II activation and the resultant contraction of AJ-associated actomyosin cables. Additional observations indicated that c-lamellipodia tended to grow at mechanically weak sites of the junction. We conclude that AJs not only tie cells together but also generate c-lamellipodia by recruiting actin regulators, enabling epithelial cells to undergo ordered collective migration.

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The Protein Tyrosine Phosphatase Pez Is a Major Phosphatase of Adherens Junctions and Dephosphorylates β-Catenin

Molecular Biology of the Cell ◽

10.1091/mbc.e02-09-0577 ◽

2003 ◽

Vol 14 (6) ◽

pp. 2520-2529 ◽

Cited By ~ 71

Author(s):

Carol Wadham ◽

Jennifer R Gamble ◽

Mathew A Vadas ◽

Yeesim Khew-Goodall

Keyword(s):

Cell Adhesion ◽

Tyrosine Phosphorylation ◽

Adherens Junctions ◽

Tyrosine Phosphatase ◽

Adherens Junction ◽

Dominant Negative ◽

Dominant Negative Mutant ◽

Adherens Junction Proteins ◽

Cell Cell

Cell-cell adhesion regulates processes important in embryonal development, normal physiology, and cancer progression. It is regulated by various mechanisms including tyrosine phosphorylation. We have previously shown that the protein tyrosine phosphatase Pez is concentrated at intercellular junctions in confluent, quiescent monolayers but is nuclear in cells lacking cell-cell contacts. We show here with an epithelial cell model that Pez localizes to the adherens junctions in confluent monolayers. A truncation mutant lacking the catalytic domain acts as a dominant negative mutant to upregulate tyrosine phosphorylation at adherens junctions. We identified β-catenin, a component of adherens junctions, as a substrate of Pez by a “substrate trapping” approach and by in vitro dephosphorylation with recombinant Pez. Consistent with this, ectopic expression of the dominant negative mutant caused an increase in tyrosine phosphorylation of β-catenin, demonstrating that Pez regulates the level of tyrosine phosphorylation of adherens junction proteins, including β-catenin. Increased tyrosine phosphorylation of adherens junction proteins has been shown to decrease cell-cell adhesion, promoting cell migration as a result. Accordingly, the dominant negative Pez mutant enhanced cell motility in an in vitro “wound” assay. This suggests that Pez is also a regulator of cell motility, most likely through its action on cell-cell adhesion.

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Mechanosensitive EPLIN-dependent remodeling of adherens junctions regulates epithelial reshaping

The Journal of Cell Biology ◽

10.1083/jcb.201104124 ◽

2011 ◽

Vol 194 (4) ◽

pp. 643-656 ◽

Cited By ~ 96

Author(s):

Katsutoshi Taguchi ◽

Takashi Ishiuchi ◽

Masatoshi Takeichi

Keyword(s):

Epithelial Cell ◽

Epithelial Cells ◽

Adherens Junctions ◽

Adherens Junction ◽

Mechanical Forces ◽

Cell Adhesions ◽

Cell Cell

The zonula adherens (ZA), a type of adherens junction (AJ), plays a major role in epithelial cell–cell adhesions. It remains unknown how the ZA is remodeled during epithelial reorganization. Here we found that the ZA was converted to another type of AJ with punctate morphology (pAJ) at the margins of epithelial colonies. The F-actin–stabilizing protein EPLIN (epithelial protein lost in neoplasm), which functions to maintain the ZA via its association with αE-catenin, was lost in the pAJs. Consistently, a fusion of αE-catenin and EPLIN contributed to the formation of ZA but not pAJs. We show that junctional tension was important for retaining EPLIN at AJs, and another force derived from actin fibers laterally attached to the pAJs inhibited EPLIN–AJ association. Vinculin was required for general AJ formation, and it cooperated with EPLIN to maintain the ZA. These findings suggest that epithelial cells remodel their junctional architecture by responding to mechanical forces, and the αE-catenin–bound EPLIN acts as a mechanosensitive regulator for this process.

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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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Downregulation of Rap1GAP in Human Tumor Cells Alters Cell/Matrix and Cell/Cell Adhesion

Molecular and Cellular Biology ◽

10.1128/mcb.01345-09 ◽

2010 ◽

Vol 30 (13) ◽

pp. 3262-3274 ◽

Cited By ~ 29

Author(s):

Oxana M. Tsygankova ◽

Changqing Ma ◽

Waixing Tang ◽

Christopher Korch ◽

Michael D. Feldman ◽

...

Keyword(s):

Cell Adhesion ◽

Tumor Cells ◽

Adherens Junction ◽

Protein Distribution ◽

P120 Catenin ◽

Cell Contacts ◽

Cell Matrix ◽

Junction Protein ◽

E Cadherin ◽

Cell Cell

ABSTRACT Rap1GAP expression is decreased in human tumors. The significance of its downregulation is unknown. We show that Rap1GAP expression is decreased in primary colorectal carcinomas. To elucidate the advantages conferred on tumor cells by loss of Rap1GAP, Rap1GAP expression was silenced in human colon carcinoma cells. Suppressing Rap1GAP induced profound alterations in cell adhesion. Rap1GAP-depleted cells exhibited defects in cell/cell adhesion that included an aberrant distribution of adherens junction proteins. Depletion of Rap1GAP enhanced adhesion and spreading on collagen. Silencing of Rap expression normalized spreading and restored E-cadherin, β-catenin, and p120-catenin to cell/cell contacts, indicating that unrestrained Rap activity underlies the alterations in cell adhesion. The defects in adherens junction protein distribution required integrin signaling as E-cadherin and p120-catenin were restored at cell/cell contacts when cells were plated on poly-l-lysine. Unexpectedly, Src activity was increased in Rap1GAP-depleted cells. Inhibition of Src impaired spreading and restored E-cadherin at cell/cell contacts. These findings provide the first evidence that Rap1GAP contributes to cell/cell adhesion and highlight a role for Rap1GAP in regulating cell/matrix and cell/cell adhesion. The frequent downregulation of Rap1GAP in epithelial tumors where alterations in cell/cell and cell/matrix adhesion are early steps in tumor dissemination supports a role for Rap1GAP depletion in tumor progression.

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