-
Appropriate tension sensitivity of α-catenin ensures rounding morphogenesis of epithelial spheroids.Cell Structure and Function Jul 2022The adherens junction (AJ) is an actin filament-anchoring junction. It plays a central role in epithelial morphogenesis through cadherin-based recognition and adhesion...
The adherens junction (AJ) is an actin filament-anchoring junction. It plays a central role in epithelial morphogenesis through cadherin-based recognition and adhesion among cells. The stability and plasticity of AJs are required for the morphogenesis. An actin-binding α-catenin is an essential component of the cadherin-catenin complex and functions as a tension transducer that changes its conformation and induces AJ development in response to tension. Despite much progress in understanding molecular mechanisms of tension sensitivity of α-catenin, its significance on epithelial morphogenesis is still unknown. Here we show that the tension sensitivity of α-catenin is essential for epithelial cells to form round spheroids through proper multicellular rearrangement. Using a novel in vitro suspension culture model, we found that epithelial cells form round spheroids even from rectangular-shaped cell masses with high aspect ratios without using high tension and that increased tension sensitivity of α-catenin affected this morphogenesis. Analyses of AJ formation and cellular tracking during rounding morphogenesis showed cellular rearrangement, probably through AJ remodeling. The rearrangement occurs at the cell mass level, but not single-cell level. Hypersensitive α-catenin mutant-expressing cells did not show cellular rearrangement at the cell mass level, suggesting that the appropriate tension sensitivity of α-catenin is crucial for the coordinated round morphogenesis.Key words: α-catenin, vinculin, adherens junction, morphogenesis, mechanotransduction.
Topics: Adherens Junctions; Cadherins; Mechanotransduction, Cellular; Morphogenesis; alpha Catenin
PubMed: 35732428
DOI: 10.1247/csf.22014 -
Development (Cambridge, England) Nov 2019Apical-basal polarity is a fundamental property of animal tissues. embryos provide an outstanding model for defining mechanisms that initiate and maintain polarity....
Apical-basal polarity is a fundamental property of animal tissues. embryos provide an outstanding model for defining mechanisms that initiate and maintain polarity. Polarity is initiated during cellularization, when cell-cell adherens junctions are positioned at the future boundary of apical and basolateral domains. Polarity maintenance then involves complementary and antagonistic interplay between apical and basal polarity complexes. The Scribble/Dlg module is well-known for promoting basolateral identity during polarity maintenance. Here, we report a surprising role for Scribble/Dlg in polarity initiation, placing it near the top of the network-positioning adherens junctions. Scribble and Dlg are enriched in nascent adherens junctions, are essential for adherens junction positioning and supermolecular assembly, and also play a role in basal junction assembly. We test the hypotheses for the underlying mechanisms, exploring potential effects on protein trafficking, cytoskeletal polarity or Par-1 localization/function. Our data suggest that the Scribble/Dlg module plays multiple roles in polarity initiation. Different domains of Scribble contribute to these distinct roles. Together, these data reveal novel roles for Scribble/Dlg as master scaffolds regulating assembly of distinct junctional complexes at different times and places.
Topics: Adherens Junctions; Animals; Armadillo Domain Proteins; Biotinylation; Cell Polarity; Cytoskeleton; Dogs; Drosophila Proteins; Drosophila melanogaster; Ectoderm; Epithelial Cells; Female; Gastrula; Gene Expression Regulation, Developmental; Intracellular Signaling Peptides and Proteins; Madin Darby Canine Kidney Cells; Male; Membrane Proteins; Morphogenesis; Mutation; Phenotype; RNA Interference; Shelterin Complex; Signal Transduction; Telomere-Binding Proteins; Tight Junctions; Transcription Factors; Tumor Suppressor Proteins; rab5 GTP-Binding Proteins
PubMed: 31628110
DOI: 10.1242/dev.180976 -
Developmental Cell Oct 2015This Perspective considers how classical cadherin cell-cell adhesion receptors are organized at the nanoscale to generate lateral clusters. Recent advances in optical... (Review)
Review
This Perspective considers how classical cadherin cell-cell adhesion receptors are organized at the nanoscale to generate lateral clusters. Recent advances in optical microscopy reveal that clustering constitutes a general feature of cadherin organization, but one that takes diverse forms. Here we consider the molecular mechanisms responsible for cadherin clustering and their functional implications. We frame our discussion in light of what is known about how nanoscale organization is conferred upon the plasma membrane, through protein-protein interactions, regulation of the cortical actin cytoskeleton, and the lipid environment of the membrane.
Topics: Actin Cytoskeleton; Adherens Junctions; Cadherins; Cell Adhesion; Cell Membrane; Humans; Nanostructures
PubMed: 26460944
DOI: 10.1016/j.devcel.2015.09.012 -
FEBS Letters Jan 2022The apical junctional complex (AJC) is a membrane protein ultrastructure that regulates cell adhesion and homeostasis. The tight junction (TJ) and the adherens junction...
The apical junctional complex (AJC) is a membrane protein ultrastructure that regulates cell adhesion and homeostasis. The tight junction (TJ) and the adherens junction (AJ) are substructures of the AJC. The interplay between TJ and AJ membrane proteins to assemble the AJC remains unclear. We employed synthetic biology strategies to express the basic membrane elements of a simple AJC-the adhesive extracellular domains of junctional adhesion molecule A (JAM-A), epithelial cadherin, claudin 1, and occludin-to study their interactions. Our results suggest that calcium concentration fluctuations and JAM-A, acting as an interface molecule between the TJ and AJ, orchestrate their interplay. Calcium affects the secondary structure, oligomerization, and binding affinity of homotypic and heterotypic interactions of TJ and AJ components, thus acting as a molecular switch influencing AJC dynamics.
Topics: Adherens Junctions
PubMed: 34882783
DOI: 10.1002/1873-3468.14252 -
Cellular Physiology and Biochemistry :... 2019Ouabain, a well-known plant-derived toxin, is also a hormone found in mammals at nanomolar levels that binds to a site located in the a-subunit of Na⁺,K⁺-ATPase. Our...
BACKGROUND/AIMS
Ouabain, a well-known plant-derived toxin, is also a hormone found in mammals at nanomolar levels that binds to a site located in the a-subunit of Na⁺,K⁺-ATPase. Our main goal was to understand the physiological roles of ouabain. Previously, we found that ouabain increases the degree of tight junction sealing, GAP junction-mediated communication and ciliogenesis. Considering our previous results, we investigated the effect of ouabain on adherens junctions.
METHODS
We used immunofluorescence and immunoblot methods to measure the effect of 10 nM ouabain on the cellular and nuclear content of E-cadherin, β-catenin and γ-catenin in cultured monolayers of Marin Darby canine renal cells (MDCK). We also studied the effect of ouabain on adherens junction biogenesis through sequential Ca²⁺ removal and replenishment. Then, we investigated whether c-Src and ERK1/2 kinases are involved in these responses.
RESULTS
Ouabain enhanced the cellular content of the adherens junction proteins E-cadherin, β-catenin and γ-catenin and displaced β-catenin and γ-catenin from the plasma membrane into the nucleus. Ouabain also increased the expression levels of E-cadherin and β-catenin in the plasma membrane after Ca²⁺ replenishment. These effects on adherens junctions were sensitive to PP2 and PD98059, suggesting that they depend on c-Src and ERK1/2 signaling. The translocation of β-catenin and γ-catenin into the nucleus was specific because ouabain did not change the localization of the tight junction proteins ZO-1 and ZO-2. Moreover, in ouabain-resistant MDCK cells, which express a Na⁺,K⁺-ATPase α1-subunit with low affinity for ouabain, this hormone was unable to regulate adherens junctions, indicating that the ouabain receptor that regulates adherens junctions is Na⁺,K⁺-ATPase.
CONCLUSION
Ouabain (10 nM) upregulated adherens junctions. This novel result supports the proposition that one of the physiological roles of this hormone is the modulation of cell contacts.
Topics: Adherens Junctions; Animals; CSK Tyrosine-Protein Kinase; Cadherins; Calcium; Cell Nucleus; Dogs; Madin Darby Canine Kidney Cells; Microscopy, Fluorescence; Mitogen-Activated Protein Kinase 1; Mitogen-Activated Protein Kinase 3; Ouabain; Signal Transduction; Sodium-Potassium-Exchanging ATPase; beta Catenin; gamma Catenin; src-Family Kinases
PubMed: 31075189
DOI: 10.33594/000000097 -
Molecular Biology of the Cell May 2023Given the role of E-cadherin (E-cad) in holding epithelial cells together, an inverse relationship between E-cad levels and cell invasion during the...
Given the role of E-cadherin (E-cad) in holding epithelial cells together, an inverse relationship between E-cad levels and cell invasion during the epithelial-mesenchymal transition and cancer metastasis has been well recognized. Here we report that E-cad is necessary for the invasiveness of -transformed intestinal epithelial cells in . E-cad/β-catenin disassembles at adherens junctions and assembles at invasive protrusions--the actin- and cortactin-rich invadopodium-like protrusions associated with the breach of the extracellular matrix (ECM)--during dissemination of -transformed intestinal epithelial cells. Loss of E-cad impairs the elongation of invasive protrusions and attenuates the ability of -transformed cells to compromise the ECM. Notably, E-cad and cortactin affect each other's localization to invasive protrusions. Given the essential roles of cortactin in cell invasion, our observations indicate that E-cad plays a role in the invasiveness of -transformed intestinal epithelial cells by controlling cortactin localization to invasive protrusions. Thus our study demonstrates that E-cad is a component of invasive protrusions and provides molecular insights into the unconventional role of E-cad in cell dissemination in vivo.
Topics: Animals; Cortactin; Cadherins; Epithelial Cells; Actins; Adherens Junctions; Drosophila
PubMed: 36989029
DOI: 10.1091/mbc.E23-03-0087 -
Current Opinion in Cell Biology Oct 2018The adherens junction has been historically considered an essential structural component of epithelial tissues. Although primarily discussed as targets of signaling... (Review)
Review
The adherens junction has been historically considered an essential structural component of epithelial tissues. Although primarily discussed as targets of signaling pathways responsible for cell fate and tissue remodeling, they have also emerged as critical signaling regulators in developmental processes or in disease progression. The recent discovery of a functional localized RNA interference (RNAi) machinery at epithelial adherens junctions revealed a new layer of signaling regulation that is directly associated with the structure itself. This and other findings also indicate that our view of the subcellular localization of RNAi requires revisiting. A number of questions emerge regarding the physiological role and the modes of regulation of the junctional RNAi machinery, pointing towards new directions of investigation.
Topics: Adherens Junctions; Animals; Cell Differentiation; Humans; Models, Biological; RNA; RNA Interference
PubMed: 29587176
DOI: 10.1016/j.ceb.2018.03.001 -
Development (Cambridge, England) Oct 2021The Notch pathway mediates cell-to-cell communication in a variety of tissues, developmental stages and organisms. Pathway activation relies on the interaction between...
The Notch pathway mediates cell-to-cell communication in a variety of tissues, developmental stages and organisms. Pathway activation relies on the interaction between transmembrane ligands and receptors on adjacent cells. As such, pathway activity could be influenced by the size, composition or dynamics of contacts between membranes. The initiation of Notch signalling in the Drosophila embryo occurs during cellularization, when lateral cell membranes and adherens junctions are first being deposited, allowing us to investigate the importance of membrane architecture and specific junctional domains for signalling. By measuring Notch-dependent transcription in live embryos, we established that it initiates while lateral membranes are growing and that signalling onset correlates with a specific phase in their formation. However, the length of the lateral membranes per se was not limiting. Rather, the adherens junctions, which assemble concurrently with membrane deposition, contributed to the high levels of signalling required for transcription, as indicated by the consequences of α-Catenin depletion. Together, these results demonstrate that the establishment of lateral membrane contacts can be limiting for Notch trans-activation and suggest that adherens junctions play an important role in modulating Notch activity.
Topics: Adherens Junctions; Animals; Drosophila Proteins; Drosophila melanogaster; Embryo, Nonmammalian; Receptors, Notch; Signal Transduction; alpha Catenin
PubMed: 34486648
DOI: 10.1242/dev.199831 -
Cells Jun 2021The blood-brain barrier (BBB) is a highly selective cellular monolayer unique to the microvasculature of the central nervous system (CNS), and it mediates the... (Review)
Review
The blood-brain barrier (BBB) is a highly selective cellular monolayer unique to the microvasculature of the central nervous system (CNS), and it mediates the communication of the CNS with the rest of the body by regulating the passage of molecules into the CNS microenvironment. Limitation of passage of substances through the BBB is mainly due to tight junctions (TJ) and adherens junctions (AJ) between brain microvascular endothelial cells. The importance of actin filaments and microtubules in establishing and maintaining TJs and AJs has been indicated; however, recent studies have shown that intermediate filaments are also important in the formation and function of cell-cell junctions. The most common intermediate filament protein in endothelial cells is vimentin. Vimentin plays a role in blood-brain barrier permeability in both cell-cell and cell-matrix interactions by affecting the actin and microtubule reorganization and by binding directly to VE-cadherin or integrin proteins. The BBB permeability increases due to the formation of stress fibers and the disruption of VE-cadherin interactions between two neighboring cells in various diseases, disrupting the fiber network of intermediate filament vimentin in different ways. Intermediate filaments may be long ignored key targets in regulation of BBB permeability in health and disease.
Topics: Adherens Junctions; Animals; Blood-Brain Barrier; Brain Diseases; Endothelial Cells; Humans; Intermediate Filaments; Tight Junctions
PubMed: 34198868
DOI: 10.3390/cells10061400 -
The Journal of Cell Biology Jul 2022Epithelial cells often leave their tissue context and ingress to form new cell types or acquire migratory ability to move to distant sites during development and tumor...
Epithelial cells often leave their tissue context and ingress to form new cell types or acquire migratory ability to move to distant sites during development and tumor progression. Cells lose their apical membrane and epithelial adherens junctions during ingression. However, how factors that organize apical-basal polarity contribute to ingression is unknown. Here, we show that the dynamic regulation of the apical Crumbs polarity complex is crucial for normal neural stem cell ingression. Crumbs endocytosis and recycling allow ingression to occur in a normal timeframe. During early ingression, Crumbs and its complex partner the RhoGEF Cysts support myosin and apical constriction to ensure robust ingression dynamics. During late ingression, the E3-ubiquitin ligase Neuralized facilitates the disassembly of the Crumbs complex and the rapid endocytic removal of the apical cell domain. Our findings reveal a mechanism integrating cell fate, apical polarity, endocytosis, vesicle trafficking, and actomyosin contractility to promote cell ingression, a fundamental morphogenetic process observed in animal development and cancer.
Topics: Adherens Junctions; Animals; Cell Membrane; Cell Polarity; Drosophila Proteins; Drosophila melanogaster; Epithelial Cells; Membrane Proteins; Morphogenesis; Neural Stem Cells; Ubiquitin-Protein Ligases
PubMed: 35588693
DOI: 10.1083/jcb.202108076