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Current Opinion in Cell Biology Oct 2011The adherens junction (AJ) is a major cell-cell junction that mediates cell recognition, adhesion, morphogenesis, and tissue integrity. Although AJs transmit forces... (Review)
Review
The adherens junction (AJ) is a major cell-cell junction that mediates cell recognition, adhesion, morphogenesis, and tissue integrity. Although AJs transmit forces generated by actomyosin from one cell to another, AJs have long been considered as an area where signal transduction from cadherin ligation takes place through cell adhesion. Through the efforts to understand embryonic or cellular morphogenesis, dynamic interactions between the AJ and actin filaments have become crucial issues to be addressed since actin association is essential for AJ development, remodeling and function. Here, I provide an overview of cadherin-actin interaction from morphological aspects and of possible molecular mechanisms revealed by recent studies.
Topics: Actins; Actomyosin; Adherens Junctions; Animals; Cadherins; Cell Adhesion; Cell Adhesion Molecules; Cell Communication; Cytoskeleton; Humans; Intercellular Junctions; Morphogenesis
PubMed: 21807490
DOI: 10.1016/j.ceb.2011.07.001 -
Cell Reports Aug 2020Entosis is a cell-in-cell (CIC)-mediated death program. Contractile actomyosin (CA) and the adherens junction (AJ) are two core elements essential for entotic CIC...
Entosis is a cell-in-cell (CIC)-mediated death program. Contractile actomyosin (CA) and the adherens junction (AJ) are two core elements essential for entotic CIC formation, but the molecular structures interfacing them remain poorly understood. Here, we report the characterization of a ring-like structure interfacing between the peripheries of invading and engulfing cells. The ring-like structure is a multi-molecular complex consisting of adhesive and cytoskeletal proteins, in which the mechanical sensor vinculin is highly enriched. The vinculin-enriched structure senses mechanical force imposed on cells, as indicated by fluorescence resonance energy transfer (FRET) analysis, and is thus termed the mechanical ring (MR). The MR actively interacts with CA and the AJ to help establish and maintain polarized actomyosin that drives cell internalization. Vinculin depletion leads to compromised MR formation, CA depolarization, and subsequent CIC failure. In summary, we suggest that the vinculin-enriched MR, in addition to CA and AJ, is another core element essential for entosis.
Topics: Actomyosin; Adherens Junctions; Cell Death; Cell-in-Cell Formation; Entosis; Humans
PubMed: 32846129
DOI: 10.1016/j.celrep.2020.108071 -
Cell Adhesion & Migration 2015The disproportional enlargement of the neocortex through evolution has been instrumental in the success of vertebrates, in particular mammals. The neocortex is a... (Review)
Review
The disproportional enlargement of the neocortex through evolution has been instrumental in the success of vertebrates, in particular mammals. The neocortex is a multilayered sheet of neurons generated from a simple proliferative neuroepithelium through a myriad of mechanisms with substantial evolutionary conservation. This developing neuroepithelium is populated by progenitors that can generate additional progenitors as well as post-mitotic neurons. Subtle alterations in the production of progenitors vs. differentiated cells during development can result in dramatic differences in neocortical size. This review article will examine how cadherin adhesion proteins, in particular α-catenin and N-cadherin, function in regulating the neural progenitor microenvironment, cell proliferation, and differentiation in cortical development.
Topics: Adherens Junctions; Animals; Cadherins; Cell Differentiation; Cell Proliferation; Cellular Microenvironment; Humans; Mice; Neocortex; Neurons; Signal Transduction; alpha Catenin; beta Catenin
PubMed: 25914082
DOI: 10.1080/19336918.2015.1027478 -
Trends in Cell Biology Jan 2007Adherens junctions and their core molecular components, classic cadherins, make major contributions to animal morphogenesis. Although the significance of cadherins in... (Review)
Review
Adherens junctions and their core molecular components, classic cadherins, make major contributions to animal morphogenesis. Although the significance of cadherins in development is generally accepted, the mechanisms regulating adherens junction function during morphogenesis remain a subject of intense research. Adherens junctions are involved in the organization of simple cellular patterns, and more complex cell shape changes and cell movements that depend on the dynamic modulation of adherens junctions.
Topics: Actins; Adherens Junctions; Animals; Cadherins; Catenins; Cell Adhesion; Drosophila; Immunoglobulins; Metamorphosis, Biological; Models, Biological; Morphogenesis; Photoreceptor Cells, Invertebrate; Pigmentation; Retina
PubMed: 17134901
DOI: 10.1016/j.tcb.2006.11.006 -
Advances in Experimental Medicine and... 2018The formation of solid tissues is not a simple aggregation of individual cells but rather an ordered assembly of cells connected by junctions. These junctions provide a... (Review)
Review
The formation of solid tissues is not a simple aggregation of individual cells but rather an ordered assembly of cells connected by junctions. These junctions provide a diffusion barrier as well as mechanical support and a conduit for signalling changes in the environment to the cells. Cell junctions are functionally categorized as occluding (e.g. tight junctions, TJs), anchoring (e.g. adherens junctions, AJs) and communicating junctions (e.g. gap junctions). Each type of the cell junction is formed by protein complexes with extracellular domains and/or intracellular domains, which bind partners that provide scaffolding and signalling components. Cell junctions are ubiquitously expressed in multiple tissues and organs, including the retina. In the retina, their biological impact is not limited to regulating tissue growth and development. Disruption of the complexes mediates both congenital and postnatal pathogenesis. In this review, we will focus on cell junctions, specifically AJs and TJs in the external limiting membrane, in order to articulate their influence on pathophysiology of the retina.
Topics: Adherens Junctions; Cell Communication; Eye Proteins; Gap Junctions; Humans; Membrane Proteins; Nerve Tissue Proteins; Retina; Retinal Diseases; Tight Junctions; Tomography, Optical Coherence
PubMed: 29721986
DOI: 10.1007/978-3-319-75402-4_66 -
The Journal of Cell Biology Jul 2018Tight junctions (TJs) are essential cell adhesion structures that act as a barrier to separate the internal milieu from the external environment in multicellular...
Tight junctions (TJs) are essential cell adhesion structures that act as a barrier to separate the internal milieu from the external environment in multicellular organisms. Although their major constituents have been identified, it is unknown how the formation of TJs is regulated. TJ formation depends on the preceding formation of adherens junctions (AJs) in epithelial cells; however, the underlying mechanism remains to be elucidated. In this study, loss of AJs in α-catenin-knockout (KO) EpH4 epithelial cells altered the lipid composition of the plasma membrane (PM) and led to endocytosis of claudins, a major component of TJs. Sphingomyelin with long-chain fatty acids and cholesterol were enriched in the TJ-containing PM fraction. Depletion of cholesterol abolished the formation of TJs. Conversely, addition of cholesterol restored TJ formation in α-catenin-KO cells. Collectively, we propose that AJs mediate the formation of TJs by increasing the level of cholesterol in the PM.
Topics: Adherens Junctions; Cell Adhesion; Cell Line; Cholesterol; Endocytosis; Epithelial Cells; Gene Knockout Techniques; Humans; Membrane Lipids; Sphingomyelins; Tight Junctions; alpha Catenin
PubMed: 29720382
DOI: 10.1083/jcb.201711042 -
Sub-cellular Biochemistry 2012The specification, maintenance, division and differentiation of stem cells are integral to the development and homeostasis of many tissues. These stem cells often live... (Review)
Review
The specification, maintenance, division and differentiation of stem cells are integral to the development and homeostasis of many tissues. These stem cells often live in specialized anatomical areas, called niches. While niches can be complex, most involve cell-cell interactions that are mediated by adherens junctions. A diverse array of functions have been attributed to adherens junctions in stem cell biology. These include physical anchoring to the niche, control of proliferation and division orientation, regulation of signaling cascades and of differentiation. In this review, a number of model stem cell systems that highlight various functions of adherens junctions are discussed. In addition, a summary of the current understanding of adherens junction function in mammalian tissues and embryonic and induced pluripotent stem cells is provided. This analysis demonstrates that the roles of adherens junctions are surprisingly varied and integrated with both the anatomy and the physiology of the tissue.
Topics: Adherens Junctions; Animals; Cell Differentiation; Humans; Signal Transduction; Stem Cells
PubMed: 22674079
DOI: 10.1007/978-94-007-4186-7_15 -
Biochemical and Biophysical Research... Aug 2015Adherens junctions are known for their role in mediating cell-cell adhesion. DE-cadherin and Echinoid are the principle adhesion molecules of adherens junctions in...
Adherens junctions are known for their role in mediating cell-cell adhesion. DE-cadherin and Echinoid are the principle adhesion molecules of adherens junctions in Drosophila epithelia. Here, using live imaging to trace the movement of endocytosed Echinoid vesicles in the epithelial cells of Drosophila embryos, we demonstrate that Echinoid vesicles co-localize and move with Rab5-or Rab11-positive endosomes. Surprisingly, these Echinoid-containing endosomes undergo directional cell-to-cell movement, through adherens junctions. Consistent with this, cell-to-cell movement of Echinoid vesicles requires the presence of DE-cadherin at adherens junctions. Live imaging further revealed that Echinoid vesicles move along adherens junction-associated microtubules into adjacent cells, a process requiring a kinesin motor. Importantly, DE-cadherin- and EGFR-containing vesicles also exhibit intercellular movement. Together, our results unveil a transport function of adherens junctions. Furthermore, this adherens junctions-based intercellular transport provides a platform for the exchange of junctional proteins and signaling receptors between neighboring cells.
Topics: Adherens Junctions; Animals; Biological Transport; Cadherins; Drosophila; Endosomes; ErbB Receptors; Green Fluorescent Proteins
PubMed: 26047695
DOI: 10.1016/j.bbrc.2015.05.125 -
Current Topics in Developmental Biology 2009Morphogenesis of epithelial tissues involves various forms of reshaping of cell layers, such as invagination or bending, convergent extension, and epithelial-mesenchymal... (Review)
Review
Morphogenesis of epithelial tissues involves various forms of reshaping of cell layers, such as invagination or bending, convergent extension, and epithelial-mesenchymal transition. At the cellular level, these processes include changes in the shape, position, and assembly pattern of cells. During such morphogenetic processes, epithelial sheets in general maintain their multicellular architecture, implying that they must engage the mechanisms to change the spatial relationship with their neighbors without disrupting the junctions. A major junctional structure in epithelial tissues is the "adherens junction," which is composed of cadherin adhesion receptors and associated proteins including F-actin. The adherens junctions are required for the firm associations between cells, as disruption of them causes disorganization of the epithelial architecture. The adherens junctions, however, appear to be a dynamic entity, allowing the rearrangement of cells within cell sheets. This dynamic nature of the adherens junctions seems to be supported by various mechanisms, such as the interactions of cadherins with actin cytoskeleton, endocytosis and recycling of cadherins, and the cooperation of cadherins with other adhesion receptors. In this chapter, we provide an overview of these mechanisms analyzed in vitro and in vivo.
Topics: Adherens Junctions; Animals; Cadherins; Cell Adhesion Molecules; Endocytosis; Humans; Monomeric GTP-Binding Proteins; Morphogenesis; Nectins
PubMed: 19737641
DOI: 10.1016/S0070-2153(09)89002-9 -
Human Reproduction Update 2004The seminiferous tubule of the mammalian testis is largely composed of Sertoli and germ cells, which coordinate with Leydig cells in the interstitium and perform two... (Review)
Review
The seminiferous tubule of the mammalian testis is largely composed of Sertoli and germ cells, which coordinate with Leydig cells in the interstitium and perform two major physiological functions, namely spermatogenesis and steroidogenesis respectively. Each tubule is morphologically divided into (i) the seminiferous epithelium composing Sertoli and germ cells, and (ii) the basement membrane (a modified form of extracellular matrix); underneath this lies the collagen fibril network, the myoid cell layer, and the lymphatic vessel, which collectively constitute the tunica propia. In the seminiferous epithelium, of rodent testes each type A1 spermatogonium (diploid, 2n) differentiates into 256 elongated spermatids (haploid, 1n) during spermatogenesis. Additionally, developing germ cells must migrate progressively from the basal to the luminal edge of the adluminal compartment so that fully developed spermatids can be released into the lumen at spermiation. Without this timely event of cell movement, spermatogenesis cannot reach completion and infertility will result. Yet developing round elongating/elongated spermatids must remain attached to the epithelium via a specialized Sertoli-germ cell actin-based adherens junction (AJ) type known as ectoplasmic specialization (ES), which is crucial not only for cell attachment but also for spermatid movement and orientation in the epithelium. However, the biochemical composition and molecular architecture of the protein complexes that constitute the ES have only recently been studied. Furthermore, the signalling pathways that regulate ES dynamics are virtually unknown. This review highlights recent advances in these two areas of research. It is expected that, if adequately expanded, these studies should yield new insights into the development of novel contraceptives targeted to perturb ES function in the testis. The potential to specifically target the ES may also mean that contraceptive action could be achieved without perturbing the hypothalamic-pituitary-testicular axis.
Topics: Actins; Adherens Junctions; Animals; Cell Communication; Cell Movement; Contraceptive Agents, Male; Humans; Hydrazines; Indazoles; Intracellular Signaling Peptides and Proteins; Male; Muscle Proteins; Rats; Seminiferous Epithelium; Spermatogenesis
PubMed: 15192055
DOI: 10.1093/humupd/dmh026