scholarly journals Drosophila PATJ supports adherens junction stability by modulating Myosin light chain activity

2012 ◽  
Vol 199 (4) ◽  
pp. 685-698 ◽  
Author(s):  
Arnab Sen ◽  
Zsanett Nagy-Zsvér-Vadas ◽  
Michael P. Krahn
Keyword(s):  
Epithelial Cells ◽  
Myosin Light Chain ◽  
Adherens Junction ◽  
Myosin Phosphatase ◽  
Junction Protein ◽  
Discs Large ◽  
Myosin Binding ◽  
The Stability ◽  
Key Events ◽  
Binding Subunit

The assembly and consolidation of the adherens junctions (AJs) are key events in the establishment of an intact epithelium. However, AJs are further modified to obtain flexibility for cell migration and morphogenetic movements. Intact AJs in turn are a prerequisite for the establishment and maintenance of apical–basal polarity in epithelial cells. In this study, we report that the conserved PDZ (PSD95, Discs large, ZO-1) domain–containing protein PATJ (Pals1-associated tight junction protein) was not per se crucial for the maintenance of apical–basal polarity in Drosophila melanogaster epithelial cells but rather regulated Myosin localization and phosphorylation. PATJ directly bound to the Myosin-binding subunit of Myosin phosphatase and decreased Myosin dephosphorylation, resulting in activated Myosin. Thereby, PATJ supports the stability of the Zonula Adherens. Notably, weakening of AJ in a PATJ mutant epithelium led first to a loss of Myosin from the AJ, subsequently to a disassembly of the AJ, and finally, to a loss of apical–basal polarity and disruption of the tissue.

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 Association of the Myosin-binding Subunit of Myosin Phosphatase and Moesin: Dual Regulation of Moesin Phosphorylation by Rho-associated Kinase and Myosin Phosphatase

1998 ◽  
Vol 141 (2) ◽  
pp. 409-418 ◽  
Author(s):  
Yuko Fukata ◽  
Kazushi Kimura ◽  
Noriko Oshiro ◽  
Hideyuki Saya ◽  
Yoshiharu Matsuura ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Phosphatase Activity ◽  
Mdck Cells ◽  
Rho Kinase ◽  
Small Gtpase ◽  
Myosin Phosphatase ◽  
Membrane Ruffling ◽  
Amino Terminal ◽  
Myosin Binding ◽  
Binding Subunit

The small GTPase Rho is believed to regulate the actin cytoskeleton and cell adhesion through its specific targets. We previously identified the Rho targets: protein kinase N, Rho-associated kinase (Rho- kinase), and the myosin-binding subunit (MBS) of myosin phosphatase. We found that in MDCK epithelial cells, MBS accumulated at the tetradecanoylphorbol-13-acetate (TPA)-induced membrane ruffling area, where moesin, a member of the ERM (ezrin, radixin, and moesin) family, was localized. Neither membrane ruffling nor an accumulation of moesin and MBS at the free-end plasma membrane was induced when MDCK cells were stimulated with TPA after the microinjection of C3, which ADP-ribosylates and inactivates Rho. MBS was colocalized with moesin at the cell–cell contact sites in MDCK cells. We also found that moesin was coimmunoprecipitated with MBS from MDCK cells. Recombinant MBS interacted with the amino-terminal domains of moesin and ezrin. Myosin phosphatase composed of the catalytic subunit and MBS showed phosphatase activity toward moesin, which was phosphorylated by Rho-kinase. The phosphatase activity was inhibited when MBS was phosphorylated by Rho-kinase. These results suggest that MBS is recruited with moesin to the plasma membrane and that myosin phosphatase and Rho-kinase regulate the phosphorylation state of moesin downstream of Rho.

scholarly journals Regulation of Myosin Phosphatase Through Phosphorylation of the Myosin-Binding Subunit in Platelet Activation

Blood ◽  
1997 ◽  
Vol 90 (10) ◽  
pp. 3936-3942 ◽  
Author(s):  
Keiji Nakai ◽  
Yoshinori Suzuki ◽  
Hisakazu Kihira ◽  
Hideo Wada ◽  
Masanori Fujioka ◽  
...  
Keyword(s):  
Protein Phosphatase ◽  
Rho Kinase ◽  
Human Platelets ◽  
Myosin Phosphatase ◽  
Phosphatase Treatment ◽  
Myosin Binding ◽  
Muscle Myosin ◽  
Protein Phosphatase Type ◽  
Putative Mechanism ◽  
Binding Subunit

Abstract Human platelets were found to contain myosin phosphatase consisting of a 38-kD catalytic subunit of protein phosphatase type 1δ, a 130-kD myosin-binding subunit (MBS) and a 20-kD subunit, all of which cross-reacted with antibodies against these subunits of smooth muscle myosin phosphatase. Anti-MBS antibody coimmunoprecipitated RhoA and Rho-kinase of human platelets. Platelets MBS is a substrate for Rho-kinase and phosphorylation of MBS decreases the activity of myosin phosphatase. Treatment of intact platelets with 9,11-epithio-11,12-methano-thromboxane A2 led to a dramatic increase in phosphorylation of MBS and a significant decrease in the activity of myosin phosphatase. These findings suggest a putative mechanism for agonist-induced regulation of myosin phosphatase activity in platelets.

scholarly journals Phosphorylation of the Myosin-binding Subunit of Myosin Phosphatase by Raf-1 and Inhibition of Phosphatase Activity

2001 ◽  
Vol 277 (4) ◽  
pp. 3053-3059 ◽  
Author(s):  
Constantinos G. Broustas ◽  
Nicholas Grammatikakis ◽  
Masumi Eto ◽  
Paul Dent ◽  
David L. Brautigan ◽  
...  
Keyword(s):  
Phosphatase Activity ◽  
Myosin Phosphatase ◽  
Myosin Binding ◽  
Binding Subunit

scholarly journals Tricellular junction proteins promote disentanglement of daughter and neighbour cells during epithelial cytokinesis

2018 ◽  
Author(s):  
Zhimin Wang ◽  
Floris Bosveld ◽  
Yohanns Bellaïche
Keyword(s):  
De Novo ◽  
Cell Structure ◽  
Adherens Junction ◽  
Septate Junction ◽  
Cell Junctions ◽  
Epithelial Tissue ◽  
Neighbouring Cell ◽  
Daughter Cells ◽  
Junction Protein ◽  
Discs Large

AbstractIn epithelial tissue, new cell-cell junctions are formed upon cytokinesis. To understand junction formation during cytokinesis, we explored in Drosophila epithelium, de novo formation of tricellular septate junctions (TCJs). We found that upon midbody formation, the membranes of the two daughter cells and of the neighbouring cells located below the adherens junction (AJ) remain entangled in a 4-cell structure apposed to the midbody. The septate junction protein Discs-Large and components of the TCJ, Gliotactin and Anakonda accumulate in this 4-cell structure. Subsequently, a basal movement of the midbody parallels the detachment of the neighbouring cell membranes from the midbody, the disengagement of the daughter cells from their neighbours and the reorganisation of TCJs between the two daughter cells and their neighbouring cells. While the movement of midbody is independent of the Alix and Shrub abscission regulators, the loss of Gliotactin or Anakonda function impedes both the resolution of the connection between the daughter-neighbour cells and midbody movement. TCJ proteins therefore control an additional step of cytokinesis necessary for the disentanglement of the daughter cells and their neighbours during cytokinesis.

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

1996 ◽  
Vol 134 (1) ◽  
pp. 133-148 ◽  
Author(s):  
R T Cox ◽  
C Kirkpatrick ◽  
M Peifer
Keyword(s):  
Cell Adhesion ◽  
Epithelial Cells ◽  
Embryonic Development ◽  
Cell Polarity ◽  
Adherens Junctions ◽  
Adherens Junction ◽  
Morphogenetic Movements ◽  
Junction Protein ◽  
Normal Embryonic Development ◽  
Cell Cell

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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