scholarly journals Diverse cell junctions with unique molecular composition in tissues of a sponge (Porifera)

EvoDevo ◽  
2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Jennyfer M. Mitchell ◽  
Scott A. Nichols
Keyword(s):  
Extracellular Matrix ◽  
Focal Adhesion ◽  
Adherens Junction ◽  
Focal Adhesions ◽  
Molecular Composition ◽  
Cell Junctions ◽  
Adhesion Proteins ◽  
Focal Adhesion Proteins ◽  
Junction Protein ◽  
Cell Cell

Abstract The integrity and organization of animal tissues depend upon specialized protein complexes that mediate adhesion between cells with each other (cadherin-based adherens junctions), and with the extracellular matrix (integrin-based focal adhesions). Reconstructing how and when these cell junctions evolved is central to understanding early tissue evolution in animals. We examined focal adhesion protein homologs in tissues of the freshwater sponge, Ephydatia muelleri (phylum Porifera; class Demospongiae). Our principal findings are that (1) sponge focal adhesion homologs (integrin, talin, focal adhesion kinase, etc.) co-precipitate as a complex, separate from adherens junction proteins; (2) that actin-based structures resembling focal adhesions form at the cell–substrate interface, and their abundance is dynamically regulated in response to fluid shear; (3) focal adhesion proteins localize to both cell–cell and cell–extracellular matrix adhesions, and; (4) the adherens junction protein β-catenin is co-distributed with focal adhesion proteins at cell–cell junctions everywhere except the choanoderm, and at novel junctions between cells with spicules, and between cells with environmental bacteria. These results clarify the diversity, distribution and molecular composition of cell junctions in tissues of E. muelleri, but raise new questions about their functional properties and ancestry.

scholarly journals Diverse cell junctions with unique molecular composition in tissues of a sponge (Porifera)

2019 ◽  
Author(s):  
Jennyfer M. Mitchell ◽  
Scott A. Nichols
Keyword(s):  
Extracellular Matrix ◽  
Focal Adhesion ◽  
Protein Complexes ◽  
Adherens Junction ◽  
Focal Adhesions ◽  
Molecular Composition ◽  
Cell Junctions ◽  
Adhesion Proteins ◽  
Focal Adhesion Proteins ◽  
Junction Protein

AbstractThe integrity and organization of animal tissues depends upon specialized protein complexes that mediate adhesion between cells with each other (cadherin-based adherens junctions), and with the extracellular matrix (integrin-based focal adhesions). Reconstructing how and when these cell junctions evolved is central to understanding early tissue evolution in animals. We examined focal adhesion protein homologs in tissues of the freshwater sponge, Ephydatia muelleri (phylum Porifera). We found that sponge homologs of focal adhesion proteins co-precipitate as a complex and localize to cell junctions in sponge tissues. These data support that the adhesion roles of these proteins evolved early, prior to the divergence of sponges and other animals. However, in contrast to the spatially partitioned distribution of cell junctions in epithelia of other animals, focal adhesion proteins were found to be co-distributed with the adherens junction protein Emβ-catenin in sponge tissues; both at certain cell-cell and cell-extracellular matrix (ECM) adhesions. Sponge adhesion structures were found to be unique in other ways, too. The basopinacoderm (substrate-attachment epithelium) lacks typical polarity in that cell-ECM adhesions form on both basal and apical surfaces, and compositionally unique cell junctions form at the interface between cells with spicules (siliceous skeletal elements) and between cells and environmental bacteria. These results clarify the diversity, distribution and molecular composition of cell junctions in tissues of E. muelleri, but raise new questions about their function and homology with cell junctions in other animals.

scholarly journals A model system for cell adhesion and signal transduction in Drosophila

Development ◽  
1993 ◽  
Vol 119 (Supplement) ◽  
pp. 163-176 ◽  
Author(s):  
Mark Peifer ◽  
Sandra Orsulic ◽  
Li-Mei Pai ◽  
Joseph Loureiro
Keyword(s):  
Cell Adhesion ◽  
Function Analysis ◽  
Cell Communication ◽  
Adherens Junction ◽  
Cell Junctions ◽  
Direct Role ◽  
Junction Protein ◽  
Wingless Signaling ◽  
Segment Polarity ◽  
Cell Cell

Cells must cooperate and communicate to form a multicellular animal. Information about the molecules required for these processes have come from a variety of sources; the convergence between the studies of particular molecules by vertebrate cell biologists and the genes identified by scientists investigating development in Drosophila has been especially fruitful. We are interested in the connection between cadherin proteins that regulate cell-cell adhesion and the wingless/wnt-1 cell-cell signaling molecules controlling pattern formation during development. The Drosophila segment polarity gene armadillo, homolog of the vertebrate adherens junction protein-catenin, is required for both cell adhesion and wg signaling. We review what is known about wingless signaling in Drosophila, and discuss the role of cell-cell junctions in both cell adhesion and cell communication. We then describe the results of our preliminary structure-function analysis of Armadillo protein in both cell adhesion and wingless signaling. Finally, we discuss evidence supporting a direct role for Armadillo and adherens junction in transduction of wingless signal.

scholarly journals A Novel Role for Integrin-linked Kinase in Epithelial Sheet Morphogenesis

2005 ◽  
Vol 16 (9) ◽  
pp. 4084-4095 ◽  
Author(s):  
Alisa Vespa ◽  
Sudhir J.A. D'Souza ◽  
Lina Dagnino
Keyword(s):  
Cell Membrane ◽  
Adherens Junction ◽  
Focal Adhesions ◽  
Cell Junctions ◽  
Keratinocyte Differentiation ◽  
Epidermal Keratinocytes ◽  
Cell Periphery ◽  
Integrin Linked Kinase ◽  
E Cadherin ◽  
Cell Cell

Integrin-linked kinase (ILK) is a multidomain protein involved in cell motility and cell-extracellular matrix interactions. ILK is found in integrin-containing focal adhesions in undifferentiated primary epidermal keratinocytes. Induction of keratinocyte differentiation by treatment with Ca2+ triggers formation of cell–cell junctions, loss of focal adhesions, and ILK distribution to cell borders. We now show that Ca2+ treatment of keratinocytes induces rapid (≤1 h) translocation to the cell membrane of the adherens junction (AJ) proteins E-cadherin and β-catenin. This is followed by slower (>6 h) localization of tight junction (TJ) proteins. The kinetics of ILK movement toward the cell periphery mimics that of AJ components, suggesting that ILK plays a role in the early formation of cell–cell contacts. Whereas the N terminus in ILK mediates localization to cell borders, expression of an ILK deletion mutant incapable of localizing to the cell membrane (ILK 191-452) interferes with translocation of E-cadherin/β-catenin to cell borders, precluding Ca2+-induced AJ formation. Cells expressing ILK 191-452 also fail to form TJ and sealed cell–cell borders and do not form epithelial sheets. Thus, we have uncovered a novel role for ILK in epithelial cell–cell adhesion, independent of its well-established role in integrin-mediated adhesion and migration.

scholarly journals Requirements for localization of p130cas to focal adhesions.

1997 ◽  
Vol 17 (7) ◽  
pp. 3884-3897 ◽  
Author(s):  
T Nakamoto ◽  
R Sakai ◽  
H Honda ◽  
S Ogawa ◽  
H Ueno ◽  
...  
Keyword(s):  
Focal Adhesion ◽  
Src Kinase ◽  
Focal Adhesions ◽  
Sh3 Domain ◽  
Transformed Cells ◽  
Binding Motifs ◽  
Adhesion Proteins ◽  
C Terminus ◽  
Focal Adhesion Proteins ◽  
Tyrosine Phosphorylated Protein

p130cas (Cas) is an adapter protein that has an SH3 domain followed by multiple SH2 binding motifs in the substrate domain. It also contains a tyrosine residue and a proline-rich sequence near the C terminus, which are the binding sites for the SH2 and SH3 domains of Src kinase, respectively. Cas was originally identified as a major tyrosine-phosphorylated protein in v-Crk- and v-Src-transformed cells. Subsequently, Cas was shown to be inducibly tyrosine phosphorylated upon integrin stimulation; it is therefore regarded as one of the focal adhesion proteins. Using an immunofluorescence study, we examined the subcellular localization of Cas and determined the regions required for its localization to focal adhesions. In nontransformed cells, Cas was localized predominantly to the cytoplasm and partially to focal adhesions. However, in 527F-c-Src-transformed cells, Cas was localized mainly to podosomes, where the focal adhesion proteins are assembled. The localization of Cas to focal adhesions was also observed in cells expressing the kinase-negative 527F/295M-c-Src. A series of analyses with deletion mutants expressed in various cells revealed that the SH3 domain of Cas is necessary for its localization to focal adhesions in nontransformed cells while both the SH3 domain and the C-terminal Src binding domain of Cas are required in 527F-c-Src-transformed cells and fibronectin-stimulated cells. In addition, the localization of Cas to focal adhesions was abolished in Src-negative cells. These results demonstrate that the SH3 domain of Cas and the association of Cas with Src kinase play a pivotal role in the localization of Cas to focal adhesions.

scholarly journals Retrograde Fluxes of Focal Adhesion Proteins in Response to Cell Migration and Mechanical Signals

2007 ◽  
Vol 18 (11) ◽  
pp. 4519-4527 ◽  
Author(s):  
Wei-hui Guo ◽  
Yu-li Wang
Keyword(s):  
Cell Migration ◽  
Focal Adhesion ◽  
Mechanical Load ◽  
Focal Adhesions ◽  
Force Production ◽  
Retrograde Transport ◽  
Mechanical Stimuli ◽  
Adhesion Proteins ◽  
Mechanical Signals ◽  
Focal Adhesion Proteins

Recent studies suggest that mechanical signals mediated by the extracellular matrix play an essential role in various physiological and pathological processes; yet, how cells respond to mechanical stimuli remains elusive. Using live cell fluorescence imaging, we found that actin filaments, in association with a number of focal adhesion proteins, including zyxin and vasodilator-stimulated phosphoprotein, undergo retrograde fluxes at focal adhesions in the lamella region. This flux is inversely related to cell migration, such that it is amplified in fibroblasts immobilized on micropatterned islands. In addition, the flux is regulated by mechanical signals, including stretching forces applied to flexible substrates and substrate stiffness. Conditions favoring the flux share the common feature of causing large retrograde displacements of the interior actin cytoskeleton relative to the substrate anchorage site, which may function as a switch translating mechanical input into chemical signals, such as tyrosine phosphorylation. In turn, the stimulation of actin flux at focal adhesions may function as part of a feedback mechanism, regulating structural assembly and force production in relation to cell migration and mechanical load. The retrograde transport of associated focal adhesion proteins may play additional roles in delivering signals from focal adhesions to the interior of the cell.

scholarly journals Migration regulates cellular mechanical states

2019 ◽  
Vol 30 (26) ◽  
pp. 3104-3111 ◽  
Author(s):  
Stephanie S. Chang ◽  
Andrew D. Rape ◽  
Stephanie A. Wong ◽  
Wei-hui Guo ◽  
Yu-li Wang
Keyword(s):  
Cell Migration ◽  
Focal Adhesion ◽  
Focal Adhesions ◽  
Traction Forces ◽  
Adhesion Proteins ◽  
Focal Adhesion Proteins

Cell migration has a profound effect on the generation of traction forces and the phosphorylation of focal adhesion proteins. The mechanism may involve the dynamic turnover of focal adhesions during cell migration and mechanical interactions between nascent and preexisting focal adhesions.

scholarly journals Vinculin Is Part of the Cadherin–Catenin Junctional Complex: Complex Formation between α-Catenin and Vinculin

1998 ◽  
Vol 141 (3) ◽  
pp. 755-764 ◽  
Author(s):  
Elisabeth E. Weiss ◽  
Martina Kroemker ◽  
Angelika-H. Rüdiger ◽  
Brigitte M. Jockusch ◽  
Manfred Rüdiger
Keyword(s):  
Complex Formation ◽  
Transmembrane Protein ◽  
Adherens Junction ◽  
Focal Adhesions ◽  
Junctional Complex ◽  
Cell Contacts ◽  
Junction Protein ◽  
Cell Cell

In epithelial cells, α-, β-, and γ-catenin are involved in linking the peripheral microfilament belt to the transmembrane protein E-cadherin. α-Catenin exhibits sequence homologies over three regions to vinculin, another adherens junction protein. While vinculin is found in cell–matrix and cell–cell contacts, α-catenin is restricted to the latter. To elucidate, whether vinculin is part of the cell–cell junctional complex, we investigated complex formation and intracellular targeting of vinculin and α-catenin. We show that α-catenin colocalizes at cell–cell contacts with endogenous vinculin and also with the transfected vinculin head domain forming immunoprecipitable complexes. In vitro, the vinculin NH2-terminal head binds to α-catenin, as seen by immunoprecipitation, dot overlay, cosedimentation, and surface plasmon resonance measurements. The Kd of the complex was determined to 2–4 × 10−7 M. As seen by overlays and affinity mass spectrometry, the COOH-terminal region of α-catenin is involved in this interaction. Complex formation of vinculin and α-catenin was challenged in transfected cells. In PtK2 cells, intact α-catenin and α-catenin1-670, harboring the β-catenin– binding site, were directed to cell–cell contacts. In contrast, α-catenin697–906 fragments were recruited to cell–cell contacts, focal adhesions, and stress fibers. Our results imply that in vivo α-catenin, like vinculin, is tightly regulated in its ligand binding activity.

scholarly journals Transition of responsive mechanosensitive elements from focal adhesions to adherens junctions on epithelial differentiation

2018 ◽  
Vol 29 (19) ◽  
pp. 2317-2325 ◽  
Author(s):  
Barbara Noethel ◽  
Lena Ramms ◽  
Georg Dreissen ◽  
Marco Hoffmann ◽  
Ronald Springer ◽  
...  
Keyword(s):  
Mechanical Stress ◽  
Adherens Junctions ◽  
Adhesion Formation ◽  
Focal Adhesions ◽  
Intercellular Junctions ◽  
Cell Junctions ◽  
Epithelial Tissue ◽  
Cell Matrix ◽  
Junction Protein ◽  
Cell Cell

The skin’s epidermis is a multilayered epithelial tissue and the first line of defense against mechanical stress. Its barrier function depends on an integrated assembly and reorganization of cell–matrix and cell–cell junctions in the basal layer and on different intercellular junctions in suprabasal layers. However, how mechanical stress is recognized and which adhesive and cytoskeletal components are involved are poorly understood. Here, we subjected keratinocytes to cyclic stress in the presence or absence of intercellular junctions. Both states not only recognized but also responded to strain by reorienting actin filaments perpendicular to the applied force. Using different keratinocyte mutant strains that altered the mechanical link of the actin cytoskeleton to either cell–matrix or cell–cell junctions, we show that not only focal adhesions but also adherens junctions function as mechanosensitive elements in response to cyclic strain. Loss of paxillin or talin impaired focal adhesion formation and only affected mechanosensitivity in the absence but not presence of intercellular junctions. Further analysis revealed the adherens junction protein α-catenin as a main mechanosensor, with greatest sensitivity conferred on binding to vinculin. Our data reveal a mechanosensitive transition from cell–matrix to cell–cell adhesions on formation of keratinocyte monolayers with vinculin and α-catenin as vital players.

scholarly journals Integrin regulation of cell-cell adhesion during epithelial tubule formation

2001 ◽  
Vol 114 (5) ◽  
pp. 941-952 ◽  
Author(s):  
G.K. Ojakian ◽  
D.R. Ratcliffe ◽  
R. Schwimmer
Keyword(s):  
Extracellular Matrix ◽  
Adherens Junction ◽  
Cell Junctions ◽  
Junctional Complex ◽  
Tubule Formation ◽  
Epithelial Remodeling ◽  
Adherens Junction Proteins ◽  
Junction Proteins ◽  
E Cadherin ◽  
Cell Cell

The extracellular matrix plays an important role in regulation of epithelial development and organization. To determine more precisely the function of extracellular matrix in this process, the initial steps in collagen-mediated formation of epithelial tubules were studied using a model cell culture system. Previous studies have demonstrated that incubation of Madin-Darby canine kidney (MDCK) epithelial cells with a collagen gel overlay induces (beta)1 integrin-regulated epithelial remodeling accompanied by extensive cell rearrangements and formation of epithelial tubules. During epithelial remodeling there was extensive disruption of the epithelial junctional complex. Progressive opening of tight junctions was observed over 8 hours using transepithelial resistance measurements and immunofluorescence microscopy demonstrated that tight and adherens junction proteins were dispersed throughout the apical and basolateral membranes. Junction complex disruption allowed the formation of apical cell extensions and subsequent migration of selected cell sheets from the epithelial monolayer. Confocal microscopy demonstrated the presence of adherens junction (E-cadherin, (alpha)-catenin, (beta)-catenin, plakoglobin) and desmosomal (desmoplakin-1/2, plakoglobin) proteins on, and within, cell extensions demonstrating that cell junctions had undergone considerable disassembly. However, groups of cell extensions appeared to be associated by E-cadherin/catenin-mediated interactions. Association of E-cadherin/catenin complexes with the epithelial cytoskeleton was analyzed by differential detergent extraction. SDS-PAGE and immunoblot analysis demonstrated that adherens junction proteins were primarily cytoskeleton-associated in control cells. During integrin-regulated remodeling, there was a progressive reduction in the interaction of adherens junction proteins with the cytoskeleton suggesting that they play an important role in the maintenance of epithelial integrity. Since loss of transepithelial electrical resistance and disruption of junctional complexes were inhibited by an antifunctional integrin antibody, we propose that activation of integrin signaling pathways regulate junctional complex stability, cell-cell interactions and cell migration. These observations provide evidence that integrin-regulated MDCK epithelial tubule formation can serve as a model system for studying rearrangements of epithelial sheets which occur during development.

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