An in vivo structure-function study of armadillo, the beta-catenin homologue, reveals both separate and overlapping regions of the protein required for cell adhesion and for wingless signaling.

Armadillo, the Drosophila homologue of vertebrate beta-catenin, plays a pivotal role both in Wingless signaling and in assembly of adherens junctions. We performed the first in vivo structure-function study of an adherens junction protein, by generating and examining a series of Armadillo mutants in the context of the entire animal. We tested each mutant by assaying its biological function, its ability to bind proteins that normally associate with Armadillo in adherens junctions, its cellular localization, and its pattern of phosphorylation. We mapped the binding sites for DE-cadherin and alpha-catenin. Although these bind to Armadillo independently of each other, binding of each is required for the function of adherens junctions. We identified two separate regions of Armadillo critical for Wingless signaling. We demonstrated that endogenous Armadillo accumulates in the nucleus and provide evidence that it may act there in transducing Wingless signal. We found that the Arm repeats, which make up the central two-thirds of Armadillo, differ among themselves in their functional importance in different processes. Finally, we demonstrated that Armadillo's roles in adherens junctions and Wingless signaling are independent. We discuss the potential biochemical role of Armadillo in each process.

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The product of the Drosophila segment polarity gene armadillo is part of a multi-protein complex resembling the vertebrate adherens junction

Journal of Cell Science ◽

10.1242/jcs.105.4.993 ◽

1993 ◽

Vol 105 (4) ◽

pp. 993-1000 ◽

Cited By ~ 28

Author(s):

M. Peifer

Keyword(s):

Sequence Similarity ◽

Adherens Junctions ◽

Adherens Junction ◽

Beta Catenin ◽

Adherens Junction Protein ◽

Junction Protein ◽

Drosophila Homolog ◽

Segment Polarity ◽

Associated Proteins ◽

Segment Polarity Gene

Sequence similarity between the Drosophila segment polarity protein Armadillo and the vertebrate adherens junction protein beta-catenin raised the possibility that adherens junctions function in transduction of intercellular signals like that mediated by Wingless/Wnt-1. To substantiate the sequence similarity, properties of Armadillo were evaluated for consistency with a junctional role. Armadillo is part of a membrane-associated complex. This complex includes Armadillo, a glycoprotein similar in size to vertebrate cadherins, and the Drosophila homolog of alpha-catenin. Armadillo co-localizes with junctions that resemble vertebrate adherens junctions in morphology and position. These results suggest that Drosophila and vertebrate adherens junctions are structurally similar, validating use of Armadillo and its associated proteins as a model for vertebrate adherens junctions.

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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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PLEKHA7, an apical adherens junction protein, suppresses inflammatory breast cancer in the context of high E-cadherin and p120-catenin expression.

10.21203/rs.3.rs-57687/v1 ◽

2020 ◽

Author(s):

Lindy J Pence ◽

Antonis Kourtidis ◽

Ryan W. Feathers ◽

Mary T. Haddad ◽

Sotiris Sotiriou ◽

...

Keyword(s):

Breast Cancer ◽

Cell Line ◽

Inflammatory Breast Cancer ◽

Adherens Junction ◽

Major Protein ◽

Breast Cancers ◽

Adherens Junction Protein ◽

Junction Protein ◽

E Cadherin

Abstract Background: Inflammatory breast cancer is a highly aggressive form of breast cancer that robustly forms clusters of tumor emboli in dermal lymphatics and readily metastasizes. Inflammatory breast cancers express high levels of E-cadherin, the major protein of adherens junctions, which may enhance the ability of tumor cells to form such clusters and contribute to metastasis. Seemingly contradictory, E-cadherin has both tumor-suppressing and tumor-promoting roles in cancer; previous studies suggest that this depends on the balance between apical and basolateral cadherin-catenin complexes. Methods: In the present study, we use immunohistochemistry of inflammatory breast cancer patient samples and biochemical analysis of cell lines to determine the expression of PLEKHA7, an apical adherens junction protein. We use viral transduction to ectopically express PLEKHA7 in the SUM149 inflammatory breast cancer cell line. The effect of PLEKHA7 on the aggressiveness of inflammatory breast cancer in 2D, 3D and in-vivo were examined. Results: We determined that PLEKHA7 was deregulated in inflammatory breast cancer, demonstrating improper localization or lost expression in a strong majority of patient samples and very low expression in cell line models. We found that re-expressing PLEKHA7 is sufficient to suppress proliferation, anchorage independent growth, spheroid viability, and tumor growth in-vivo. We also observed a negative-selection pressure within the xenograft tumors to lose PLEKHA7 function or expression.Conclusions: The data indicate that PLEKHA7 is frequently deregulated and acts as a suppressor of inflammatory breast cancer. They also suggest that the resulting imbalance between apical and basolateral cadherin-catenin complexes contributes to growth, survival and emboli-forming capacities of inflammatory breast cancer.

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Morphogenetic forces planar polarize LGN/Pins in the embryonic head during Drosophila gastrulation

10.1101/2022.01.07.475359 ◽

2022 ◽

Author(s):

Jaclyn M Camuglia ◽

Soline Chanet ◽

Adam C Martin

Keyword(s):

Planar Cell Polarity ◽

Adherens Junction ◽

Drosophila Embryo ◽

Spindle Orientation ◽

Planar Polarity ◽

Ventral Furrow ◽

Adherens Junction Protein ◽

Early Drosophila Embryo ◽

Junction Protein

Spindle orientation is often achieved by a complex of Pins/LGN, Mud/NuMa, Gαi, and Dynein, which interacts with astral microtubules to rotate the spindle. Cortical Pins/LGN recruitment serves as a critical step in this process. Here, we identify Pins-mediated planar cell polarized divisions in several of the mitotic domains of the early Drosophila embryo. We found that neither planar cell polarity pathways nor planar polarized myosin localization determined division orientation; instead, our findings strongly suggest that Pins planar polarity and force generated from mesoderm invagination are important. Disrupting Pins polarity via overexpression of a myristoylated version of Pins caused randomized division angles. We found that disrupting forces through chemical inhibitors, laser ablation, and depletion of an adherens junction protein disrupted Pins planar polarity and spindle orientation. Furthermore, snail depletion, which abrogates ventral furrow forces, disrupted Pins polarization and spindle orientation, suggesting that morphogenetic movements and resulting forces transmitted through the tissue can polarize Pins and orient division. Thus, morphogenetic forces associated with mesoderm invagination result in planar polarized Pins to mediate division orientation at a distant region of the embryo during morphogenesis. To our knowledge, this is the first in vivo example where mechanical force has been shown to polarize Pins to mediate division orientation.

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PLEKHA7, an Apical Adherens Junction Protein, Suppresses Inflammatory Breast Cancer in the Context of High E-Cadherin and p120-Catenin Expression

International Journal of Molecular Sciences ◽

10.3390/ijms22031275 ◽

2021 ◽

Vol 22 (3) ◽

pp. 1275

Author(s):

Lindy J. Pence ◽

Antonis Kourtidis ◽

Ryan W. Feathers ◽

Mary T. Haddad ◽

Sotiris Sotiriou ◽

...

Keyword(s):

Breast Cancer ◽

Cell Lines ◽

Inflammatory Breast Cancer ◽

Driving Forces ◽

Adherens Junction ◽

Adherens Junction Protein ◽

Junction Protein ◽

Tumor Emboli ◽

E Cadherin

Inflammatory breast cancer is a highly aggressive form of breast cancer that forms clusters of tumor emboli in dermal lymphatics and readily metastasizes. These cancers express high levels of E-cadherin, the major mediator of adherens junctions, which enhances formation of tumor emboli. Previous studies suggest that E-cadherin promotes cancer when the balance between apical and basolateral cadherin complexes is disrupted. Here, we used immunohistochemistry of inflammatory breast cancer patient samples and analysis of cell lines to determine the expression of PLEKHA7, an apical adherens junction protein. We used viral transduction to re-express PLEKHA7 in inflammatory breast cancer cells and examined their aggressiveness in 2D and 3D cultures and in vivo. We determined that PLEKHA7 was deregulated in inflammatory breast cancer, demonstrating improper localization or lost expression in most patient samples and very low expression in cell lines. Re-expressing PLEKHA7 suppressed proliferation, anchorage independent growth, spheroid viability, and tumor growth in vivo. The data indicate that PLEKHA7 is frequently deregulated and acts to suppress inflammatory breast cancer. The data also promote the need for future inquiry into the imbalance between apical and basolateral cadherin complexes as driving forces in inflammatory breast cancer.

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116. Contribution of claudin-11 to the inter-Sertoli cell tight junction, in vitro

Reproduction Fertility and Development ◽

10.1071/srb05abs116 ◽

2005 ◽

Vol 17 (9) ◽

pp. 72

Author(s):

M. J. McCabe ◽

P. G. Stanton

Keyword(s):

Tight Junction ◽

Mrna Expression ◽

Sertoli Cell ◽

Adhesion Molecule ◽

Sertoli Cells ◽

Adherens Junction ◽

Adherens Junction Protein ◽

Junction Protein

The inter-Sertoli cell tight junction (TJ) forms the blood testis barrier (BTB) between Sertoli cells and is composed of three major transmembrane proteins: claudin-11, occludin and junctional adhesion molecule. Formation of the BTB occurs during puberty associating with an increase in circulating gonadotrophins. Claudin-11 and occludin are hormonally regulated in vitro although their importance to the function of the TJ is unknown. The aim of this study was to investigate the contribution of claudin-11 to the inter-Sertoli cell TJ in vitro by blocking gene expression using RNA interference. Two claudin-11-specific siRNA fragments were designed for this purpose. Sertoli cells in primary culture formed stable TJs within 5 days as measured by transepithelial electrical resistance (TER). The addition of siRNA for 2 days resulted in a significant (P < 0.01) 55% (mean, SD, n = 4 cultures) decrease in TER along with a major reduction in claudin-11 localisation to the TJ as assessed by immunocytochemistry. The specificity of the siRNA was shown by the presence of extensive immunostaining of occludin and of the adherens junction protein β-catenin in the same treatments. Similarly, claudin-11 mRNA expression significantly (P < 0.01) decreased by 71% (mean, SD, n = 3 cultures) in response to both claudin-11 siRNA fragments. Occludin mRNA expression was not affected. It is concluded that claudin-11 contributes at least 55% to the function of the rat Sertoli cell TJ in vitro. It is hypothesised that the remaining 45% of TJ function can be attributed to other integral proteins, such as occludin and junctional adhesion molecule. It is expected that claudin-11 and other TJ proteins play a pivotal role in the function of the BTB in vivo with potential implications in fertility and contraception.

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Regulation of adherens junction protein p120ctnby 10 nM CCK precedes actin breakdown in rat pancreatic acini

AJP Gastrointestinal and Liver Physiology ◽

10.1152/ajpgi.2000.278.3.g486 ◽

2000 ◽

Vol 278 (3) ◽

pp. G486-G491 ◽

Cited By ~ 11

Author(s):

J. Leser ◽

M. F. Beil ◽

O. A. Musa ◽

G. Adler ◽

M. P. Lutz

Keyword(s):

Tyrosine Phosphorylation ◽

Actin Filament ◽

Adherens Junctions ◽

Adherens Junction ◽

Acinar Cells ◽

Pancreatic Acini ◽

Filament System ◽

Adherens Junction Protein ◽

Junction Protein ◽

E Cadherin

The initial pathophysiological events that characterize CCK-hyperstimulation pancreatitis include the breakdown of the actin filament system and disruption of cadherin-catenin protein complexes. Cadherins and catenins are part of adherens junctions, which may act as anchor for the cellular actin filament system. We examined the composition and regulation of adherens junctions during CCK-induced acinar cell damage. Freshly isolated CCK-stimulated rat pancreatic acini were examined for actin filaments and functional adherens junctions by immunocytology and laser confocal scanning microscopy or by coprecipitation and immunoblotting for E-cadherin, β- and α-catenin, p120ctn, and phosphotyrosine. In addition to E-cadherin and β-catenin, acinar cells express the cadherin-regulatory protein p120ctn and the attachment protein α-catenin. Both colocalize and coimmunoprecipitate with E-cadherin in one complex, and all colocalize with the terminal actin web. Supramaximal secretory CCK concentrations (10 nM) initiated tyrosine phosphorylation of p120ctn but not of β-catenin within 2 min, preceding the breakdown of the terminal actin web by several minutes. Under these conditions, the cadherin-catenin association within the adherens junction complex remained intact. We describe for the first time supramaximal CCK-dependent tyrosine phosphorylation of the adherens junction protein p120ctnand demonstrate the presence of an intact adherens junction protein complex in acinar cells. p120ctn may participate in the actin filament breakdown during experimental conditions mimicking pancreatitis.

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