scholarly journals Electrostatic plasma membrane targeting contributes to Dlg function in cell polarity and tumorigenesis

Development ◽  
2021 ◽  
pp. dev.196956
Author(s):  
Juan Lu ◽  
Wei Dong ◽  
Yan Tao ◽  
Yang Hong
Keyword(s):  
Plasma Membrane ◽  
Tumor Suppressor ◽  
Epithelial Cells ◽  
Cell Polarity ◽  
Significant Role ◽  
Discs Large ◽  
Cortical Localization ◽  
Polarity Proteins ◽  
Positively Charged

Discs large (Dlg) is an essential polarity protein and a tumor suppressor originally characterized in Drosophila but is also well conserved in vertebrates. Like the majority of polarity proteins, plasma membrane (PM)/cortical localization of Dlg is required for its function in polarity and tumorigenesis, but the exact mechanisms targeting Dlg to PM remain to be fully elucidated. Here we show that, similar to the recently discovered polybasic polarity proteins such as Lgl and aPKC, Dlg also contains a positively charged polybasic domain that electrostatically binds the PM phosphoinositides PI4P and PI(4,5)P2. Electrostatic targeting by the polybasic domain contributes significantly to the PM localization of Dlg in follicular and early embryonic epithelial cells, and is crucial for Dlg to regulate both polarity and tumorigenesis. The electrostatic PM targeting of Dlg is controlled by a potential phosphorylation-dependent allosteric regulation of its polybasic domain, and is specifically enhanced by the interactions between Dlg and another basolateral polarity protein and tumor suppressor Scrib. Our studies highlight an increasingly significant role of electrostatic PM targeting of polarity proteins in regulating cell polarity.

scholarly journals Electrostatic Plasma Membrane Targeting is Essential for Dlg Function in Cell Polarity and Tumorigenesis

2020 ◽  
Author(s):  
Juan Lu ◽  
Wei Dong ◽  
Yan Tao ◽  
Yang Hong
Keyword(s):  
Plasma Membrane ◽  
Tumor Suppressor ◽  
Epithelial Cells ◽  
Cell Polarity ◽  
Primary Mechanism ◽  
Discs Large ◽  
Cortical Localization ◽  
Polarity Proteins ◽  
Positively Charged

SUMMARYDiscs large (Dlg) is an essential polarity protein and a tumor suppressor originally characterized in Drosophila but is also well conserved in vertebrates. Like the majority of polarity proteins, plasma membrane (PM)/cortical localization of Dlg is required for its function in regulating apical-basal polarity and tumorigenesis, but the exact mechanisms targeting Dlg to PM remain to be unclear. Here we show that, similar to recently discovered polybasic polarity proteins such as Lgl and aPKC, Dlg also contains a positively charged polybasic domain that electrostatically binds the PM phosphoinositides PI4P and PI(4,5)P2. Electrostatic targeting by the polybasic domain acts as the primary mechanism localizing Dlg to the PM in follicular and early embryonic epithelial cells, and is crucial for Dlg to regulate both polarity and tumorigenesis. The electrostatic PM targeting of Dlg is controlled by a potential phosphorylation-dependent allosteric regulation of its polybasic domain, and is specifically enhanced by interactions between Dlg and another basolateral polarity protein and tumor suppressor Scrib. Our studies highlight an increasingly significant role of electrostatic PM targeting of polarity proteins in regulating cell polarity.

scholarly journals The Case of the Scribble Polarity Module in Asymmetric Neuroblast Division in Development and Tumorigenesis

2020 ◽  
Vol 21 (8) ◽  
pp. 2865
Author(s):  
Ana Carmena
Keyword(s):  
Epithelial Cell ◽  
Tumor Suppressor ◽  
Cell Polarity ◽  
Tumor Suppressor Genes ◽  
Asymmetric Division ◽  
Suppressor Genes ◽  
Epithelial Cell Polarity ◽  
Discs Large ◽  
Underlying Mechanisms

The Scribble polarity module is composed by Scribble (Scrib), Discs large 1 (Dlg1) and Lethal (2) giant larvae (L(2)gl), a group of highly conserved neoplastic tumor suppressor genes (TSGs) from flies to humans. Even though the Scribble module has been profusely studied in epithelial cell polarity, the number of tissues and processes in which it is involved is increasingly growing. Here we discuss the role of the Scribble module in the asymmetric division of Drosophila neuroblasts (NBs), as well as the underlying mechanisms by which those TSGs act in this process. Finally, we also describe what we know about the consequences of mutating these genes in impairing the process of asymmetric NB division and promoting tumor-like overgrowth.

The GTPase Rac1 selectively regulates Salmonella invasion at the apical plasma membrane of polarized epithelial cells

2001 ◽  
Vol 114 (7) ◽  
pp. 1331-1341 ◽  
Author(s):  
A.K. Criss ◽  
D.M. Ahlgren ◽  
T.S. Jou ◽  
B.A. McCormick ◽  
J.E. Casanova
Keyword(s):  
Plasma Membrane ◽  
Epithelial Cells ◽  
Mdck Cells ◽  
Bacterial Pathogen ◽  
Small Gtpases ◽  
Apical Plasma Membrane ◽  
Membrane Domains ◽  
Intestinal Epithelial ◽  
Actin Structure

The bacterial pathogen Salmonella typhimurium colonizes its animal hosts by inducing its internalization into intestinal epithelial cells. This process requires reorganization of the actin cytoskeleton of the apical plasma membrane into elaborate membrane ruffles that engulf the bacteria. Members of the Ρ family of small GTPases are critical regulators of actin structure, and in nonpolarized cells, the GTPase Cdc42 has been shown to modulate Salmonella entry. Because the actin architecture of epithelial cells is organized differently from that of nonpolarized cells, we examined the role of two ‘Rgr; family GTPases, Cdc42 and Rac1, in invasion of polarized monolayers of MDCK cells by S. typhimurium. Surprisingly, we found that endogenous Rac1, but not Cdc42, was activated during bacterial entry at the apical pole, and that this activation required the bacterial effector protein SopE. Furthermore, expression of dominant inhibitory Rac1 but not Cdc42 significantly inhibited apical internalization of Salmonella, indicating that Rac1 activation is integral to the bacterial entry process. In contrast, during basolateral internalization, both Cdc42 and Rac1 were activated; however, neither GTPase was required for entry. These findings, which differ significantly from previous observations in nonpolarized cells, indicate that the host cell signaling pathways activated by bacterial pathogens may vary with cell type, and in epithelial tissues may further differ between plasma membrane domains.

scholarly journals The cell polarity proteins Boi1p and Boi2p stimulate vesicle fusion at the plasma membrane of yeast cells

2017 ◽  
Vol 130 (18) ◽  
pp. 2996-3008 ◽  
Author(s):  
Jochen Kustermann ◽  
Yehui Wu ◽  
Lucia Rieger ◽  
Dirk Dedden ◽  
Tamara Phan ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Cell Polarity ◽  
Vesicle Fusion ◽  
Yeast Cells ◽  
Polarity Proteins

scholarly journals Neisseria gonorrhoeae Porin P1.B Induces Endosome Exocytosis and a Redistribution of Lamp1 to the Plasma Membrane

2002 ◽  
Vol 70 (11) ◽  
pp. 5965-5971 ◽  
Author(s):  
Patricia Ayala ◽  
Brandi Vasquez ◽  
Lee Wetzler ◽  
Magdalene So
Keyword(s):  
Plasma Membrane ◽  
Epithelial Cells ◽  
Cell Surface ◽  
Neisseria Gonorrhoeae ◽  
Bacterial Infection ◽  
Immunoglobulin A ◽  
Late Endosomes ◽  
A Cell ◽  
Iga Protease

ABSTRACT The immunoglobulin A (IgA) protease secreted by pathogenic Neisseria spp. cleaves Lamp1, thereby altering lysosomes in a cell and promoting bacterial intracellular survival. We sought to determine how the IgA protease gains access to cellular Lamp1 in order to better understand the role of this cleavage event in bacterial infection. In a previous report, we demonstrated that the pilus-induced Ca2+ transient triggers lysosome exocytosis in human epithelial cells. This, in turn, increases the level of Lamp1 at the plasma membrane, where it can be cleaved by IgA protease. Here, we show that porin also induces a Ca2+ flux in epithelial cells. This transient is similar in nature to that observed in phagocytes exposed to porin. In contrast to the pilus-induced Ca2+ transient, the porin-induced event does not trigger lysosome exocytosis. Instead, it stimulates exocytosis of early and late endosomes and increases Lamp1 on the cell surface. These results indicate that Neisseria pili and porin perturb Lamp1 trafficking in epithelial cells by triggering separate and distinct Ca2+-dependent exocytic events, bringing Lamp1 to the cell surface, where it can be cleaved by IgA protease.

scholarly journals The Interaction of JRAB/MICAL-L2 with Rab8 and Rab13 Coordinates the Assembly of Tight Junctions and Adherens Junctions

2008 ◽  
Vol 19 (3) ◽  
pp. 971-983 ◽  
Author(s):  
Rie Yamamura ◽  
Noriyuki Nishimura ◽  
Hiroyoshi Nakatsuji ◽  
Seiji Arase ◽  
Takuya Sasaki
Keyword(s):  
Plasma Membrane ◽  
Epithelial Cells ◽  
Tight Junctions ◽  
Binding Protein ◽  
Adherens Junctions ◽  
Binding Domain ◽  
Endocytic Recycling ◽  
E Cadherin

The assembly of tight junctions (TJs) and adherens junctions (AJs) is regulated by the transport of integral TJ and AJ proteins to and/or from the plasma membrane (PM) and it is tightly coordinated in epithelial cells. We previously reported that Rab13 and a junctional Rab13-binding protein (JRAB)/molecule interacting with CasL-like 2 (MICAL-L2) mediated the endocytic recycling of an integral TJ protein occludin and the formation of functional TJs. Here, we investigated the role of Rab13 and JRAB/MICAL-L2 in the transport of other integral TJ and AJ proteins claudin-1 and E-cadherin to the PM by using a Ca2+-switch model. Although knockdown of Rab13 specifically suppressed claudin-1 and occludin but not E-cadherin transport, knockdown of JRAB/MICAL-L2 and expression of its Rab13-binding domain (JRAB/MICAL-L2-C) inhibited claudin-1, occludin, and E-cadherin transport. We then identified Rab8 as another JRAB/MICAL-L2-C-binding protein. Knockdown of Rab8 inhibited the Rab13-independent transport of E-cadherin to the PM. Rab8 and Rab13 competed with each other for the binding to JRAB/MICAL-L2 and functionally associated with JRAB/MICAL-L2 at the perinuclear recycling/storage compartments and PM, respectively. These results suggest that the interaction of JRAB/MICAL-L2 with Rab8 and Rab13 coordinates the assembly of AJs and TJs.

scholarly journals Morphogenic Effects of Ezrin Require a Phosphorylation-Induced Transition from Oligomers to Monomers at the Plasma Membrane

2000 ◽  
Vol 150 (1) ◽  
pp. 193-204 ◽  
Author(s):  
Alexis Gautreau ◽  
Daniel Louvard ◽  
Monique Arpin
Keyword(s):  
Plasma Membrane ◽  
Epithelial Cells ◽  
Wild Type ◽  
Erm Proteins ◽  
Threonine Residue ◽  
Phosphorylation Event ◽  
Membrane Bound

ERM (ezrin, radixin, moesin) proteins act as linkers between the plasma membrane and the actin cytoskeleton. An interaction between their NH2- and COOH-terminal domains occurs intramolecularly in closed monomers and intermolecularly in head-to-tail oligomers. In vitro, phosphorylation of a conserved threonine residue (T567 in ezrin) in the COOH-terminal domain of ERM proteins disrupts this interaction. Here, we have analyzed the role of this phosphorylation event in vivo, by deriving stable clones producing wild-type, T567A, and T567D ezrin from LLC-PK1 epithelial cells. We found that T567A ezrin was poorly associated with the cytoskeleton, but was able to form oligomers. In contrast, T567D ezrin was associated with the cytoskeleton, but its distribution was shifted from oligomers to monomers at the membrane. Moreover, production of T567D ezrin induced the formation of lamellipodia, membrane ruffles, and tufts of microvilli. Both T567A and T567D ezrin affected the development of multicellular epithelial structures. Collectively, these results suggest that phosphorylation of ERM proteins on this conserved threonine regulates the transition from membrane-bound oligomers to active monomers, which induce and are part of actin-rich membrane projections.

Gap junctions and cell polarity: connexin32 and connexin43 expressed in polarized thyroid epithelial cells assemble into separate gap junctions, which are located in distinct regions of the lateral plasma membrane domain

1995 ◽  
Vol 108 (7) ◽  
pp. 2609-2617 ◽  
Author(s):  
A. Guerrier ◽  
P. Fonlupt ◽  
I. Morand ◽  
R. Rabilloud ◽  
C. Audebet ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Epithelial Cells ◽  
Gap Junctions ◽  
Cell Polarity ◽  
Laser Scanning ◽  
Thyroid Tissue ◽  
Thyroid Cell ◽  
Membrane Domain ◽  
Thyroid Cells ◽  
Connexin43 Gap Junctions

Epithelial cells of the thyroid gland present an uncommon connexin expression pattern, they coexpress connexin32 and connexin43. In the present work, we have analyzed the membrane distribution of these two connexins to determine: (i) whether they co-assemble in the same gap junctions or form separate gap junctions; and (ii) whether their location is somehow related to the thyroid cell polarity. Immunofluorescence analyses of the localization of the two connexins in thyroid tissue sections revealed that connexin32 and connexin43 are located in different regions of the plasma membrane. We further analyzed the location of each of the two connexins with regard to that of the tight junction-associated protein, ZO1. Laser scanning confocal microscope observations of connexin32 or connexin43 and ZO1 double-immunolabelled thyroid cells, gave evidence for a separate localization of gap junctions made of each of these two connexins. Connexin32 gap junctions appeared as fluorescent spots scattered over the lateral membrane domain, while connexin43 gap junctions formed a meshed network superimposable with that of tight junctions in the subapical region of the cells. Western blot analyses of the distribution of connexins in thyroid plasma membrane subfractions obtained by ultracentrifugation on a sucrose gradient led to the identification of membrane sub-populations enriched in either connexin32 gap junctions or connexin43 gap junctions. Connexin32 gap junctions and connexin43 gap junctions were found to differ in their resistance to solubilization by N-lauroylsarcosine. Increasing concentrations of this detergent from 0.12% to 0.42% caused a progressive solubilization of connexin43 while connexin32 remained membrane-bound.(ABSTRACT TRUNCATED AT 250 WORDS)

scholarly journals Cancer-associated fibroblasts suppress SOX2-induced dysplasia in a lung squamous cancer coculture

2018 ◽  
Vol 115 (50) ◽  
pp. E11671-E11680 ◽  
Author(s):  
Shuang Chen ◽  
Andreas Giannakou ◽  
Sarah Wyman ◽  
Janet Gruzas ◽  
Jonathon Golas ◽  
...  
Keyword(s):  
Epithelial Cells ◽  
Cell Polarity ◽  
Squamous Carcinoma ◽  
Phenotypic Switching ◽  
Cancer Associated Fibroblasts ◽  
Disease Phenotype ◽  
Tissue Architecture ◽  
Squamous Cancer ◽  
Lung Squamous Carcinoma

Tumorigenesis depends on intricate interactions between genetically altered tumor cells and their surrounding microenvironment. While oncogenic drivers in lung squamous carcinoma (LUSC) have been described, the role of stroma in modulating tissue architecture, particularly cell polarity, remains unclear. Here, we report the establishment of a 3D coculture system of LUSC epithelial cells with cancer-associated fibroblasts (CAFs) and extracellular matrix that together capture key components of the tumor microenvironment (TME). Single LUSC epithelial cells develop into acinar-like structures with 0.02% efficiency, and addition of CAFs provides proper tumor−stromal interactions within an appropriate 3D architectural context. Using this model, we recapitulate key pathological changes during tumorigenesis, from hyperplasia to dysplasia and eventually invasion, in malignant LUSC spheroids that undergo phenotypic switching in response to cell intrinsic and extrinsic changes. Overexpression of SOX2 is sufficient to mediate the transition from hyperplasia to dysplasia in LUSC spheroids, while the presence of CAFs makes them invasive. Unexpectedly, CAFs suppress the activity of high SOX2 levels, restore hyperplasia, and enhance the formation of acinar-like structures. Taken together, these observations suggest that stromal factors can override cell intrinsic oncogenic changes in determining the disease phenotype, thus providing fundamental evidence for the existence of dynamic reciprocity between the nucleus and the TME of LUSC.

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