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

1993 ◽  
Vol 105 (4) ◽  
pp. 993-1000 ◽  
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.

scholarly journals 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.

1996 ◽  
Vol 134 (5) ◽  
pp. 1283-1300 ◽  
Author(s):  
S Orsulic ◽  
M Peifer
Keyword(s):  
Structure Function ◽  
Cellular Localization ◽  
Adherens Junctions ◽  
Adherens Junction ◽  
Beta Catenin ◽  
Function Study ◽  
Adherens Junction Protein ◽  
Junction Protein ◽  
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.

scholarly journals Abelson kinase regulates epithelial morphogenesis in Drosophila

2001 ◽  
Vol 155 (7) ◽  
pp. 1185-1198 ◽  
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.

scholarly journals The vertebrate adhesive junction proteins beta-catenin and plakoglobin and the Drosophila segment polarity gene armadillo form a multigene family with similar properties.

1992 ◽  
Vol 118 (3) ◽  
pp. 681-691 ◽  
Author(s):  
M Peifer ◽  
P D McCrea ◽  
K J Green ◽  
E Wieschaus ◽  
B M Gumbiner
Keyword(s):  
Sequence Similarity ◽  
Intracellular Localization ◽  
Amino Acid Sequence Similarity ◽  
Beta Catenin ◽  
Cell Adhesive ◽  
Segment Polarity ◽  
Segment Polarity Gene ◽  
Polarity Gene ◽  
E Cadherin ◽  
Cell Cell

Three proteins identified by quite different criteria in three different systems, the Drosophila segment polarity gene armadillo, the human desmosomal protein plakoglobin, and the Xenopus E-cadherin-associated protein beta-catenin, share amino acid sequence similarity. These findings raise questions about the relationship among the three molecules and their roles in different cell-cell adhesive junctions. We have found that antibodies against the Drosophila segment polarity gene armadillo cross react with a conserved vertebrate protein. This protein is membrane associated, probably via its interaction with a cadherin-like molecule. This cross-reacting protein is the cadherin-associated protein beta-catenin. Using anti-armadillo and antiplakoglobin antibodies, it was shown that beta-catenin and plakoglobin are distinct molecules, which can coexist in the same cell type. Plakoglobin interacts with the desmosomal glycoprotein desmoglein I, and weakly with E-cadherin. Although beta-catenin interacts tightly with E-cadherin, it does not seem to be associated with either desmoglein I or with isolated desmosomes. Anti-armadillo antibodies have been further used to determine the intracellular localization of beta-catenin, and to examine its tissue distribution. The implications of these results for the structure and function of different cell-cell adhesive junctions are discussed.

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

2000 ◽  
Vol 278 (3) ◽  
pp. G486-G491 ◽  
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.

A role for the Drosophila segment polarity gene armadillo in cell adhesion and cytoskeletal integrity during oogenesis

Development ◽  
1993 ◽  
Vol 118 (4) ◽  
pp. 1191-1207 ◽  
Author(s):  
M. Peifer ◽  
S. Orsulic ◽  
D. Sweeton ◽  
E. Wieschaus
Keyword(s):  
Cell Adhesion ◽  
Germ Line ◽  
Adherens Junctions ◽  
Beta Catenin ◽  
Cell Adhesive ◽  
Segment Polarity ◽  
Drosophila Ovary ◽  
Segment Polarity Gene ◽  
Polarity Gene ◽  
Cell Cell

The epithelial sheet is a structural unit common to many tissues. Its organization appears to depend on the function of the multi-protein complexes that form adherens junctions. Elegant cell biological experiments have provided support for hypotheses explaining the function of adherens junctions and of their components. These systems, however, lack the ability to test function within an entire organism during development. The realization that the product of the Drosophila segment polarity gene armadillo is related to the vertebrate adhesive junction components plakoglobin and beta-catenin led to the suggestion that armadillo might provide a genetic handle to study adhesive junction structure and function. An examination of the potential function of Armadillo in cell-cell adhesive junctions was initiated using the Drosophila ovary as the model system. We examined the distribution of Armadillo in the Drosophila ovary and demonstrated that this localization often parallels the location of cell-cell adhesive junctions. The consequences of removing armadillo function from the germ-line cells of the ovary were also examined. Germ-line armadillo mutations appear to disrupt processes requiring cell adhesion and integrity of the actin cytoskeleton, consistent with a role for Armadillo in cell-cell adhesive junctions. We have also used armadillo mutations to examine the effects on ovarian development of altering the stereotyped cell arrangements of the ovary. The implications of these results for the role of adhesive junctions during development are discussed.

scholarly journals Mechanisms involved in AMPK-mediated deposition of tight junction components to the plasma membrane

2020 ◽  
Vol 318 (3) ◽  
pp. C486-C501
Author(s):  
Jingshing Wu ◽  
Pascal Rowart ◽  
Francois Jouret ◽  
Brandon M. Gassaway ◽  
Vanathy Rajendran ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Tight Junction ◽  
Adherens Junction ◽  
Bound State ◽  
Ampk Activation ◽  
Zonula Occludens ◽  
Adherens Junction Protein ◽  
Junction Protein ◽  
Associated Proteins ◽  
Amp Activated Protein Kinase

AMP-activated protein kinase (AMPK) activation promotes early stages of epithelial junction assembly. AMPK activation in MDCK renal epithelial cells facilitates localization of the junction-associated proteins aPKCζ and Par3 to the plasma membrane and promotes conversion of Cdc42, a key regulator of epithelial polarization and junction assembly, to its active GTP bound state. Furthermore, Par3 is an important regulator of AMPK-mediated aPKCζ localization. Both aPKCζ and Par3 serve as intermediates in AMPK-mediated junction assembly, with inhibition of aPKCζ activity or Par3 knockdown disrupting AMPK’s ability to facilitate zonula occludens (ZO-1) localization. AMPK phosphorylates the adherens junction protein afadin and regulates its interaction with the tight-junction protein zonula occludens-1. Afadin is phosphorylated at two critical sites, S228 (residing within an aPKCζ consensus site) and S1102 (residing within an AMPK consensus site), that are differentially regulated during junction assembly and that exert different effects on the process. Expression of phospho-defective mutants (S228A and S1102A) perturbed ZO-1 localization to the plasma membrane during AMPK-induced junction assembly. Expression of S228A increased the ZO-1/afadin interaction, while S1102A reduced this interaction during extracellular calcium-induced junction assembly. Inhibition of aPKCζ activity also increased the ZO-1/afadin interaction. Taken together, these data suggest that aPKCζ phosphorylation of afadin terminates the ZO-1/afadin interaction and thus permits the later stages of junction assembly.

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