scholarly journals Cell contacts orient some cell division axes in the Caenorhabditis elegans embryo.

1995 ◽  
Vol 129 (4) ◽  
pp. 1071-1080 ◽  
Author(s):  
B Goldstein
Keyword(s):  
Cell Division ◽  
Caenorhabditis Elegans ◽  
Mitotic Spindle ◽  
Spindle Orientation ◽  
Cell Contact ◽  
Specific Cell ◽  
Cell Contacts ◽  
Established Cell ◽  
A Site ◽  
Cell Cell

Cells of the early Caenorhabditis elegans embryo divide in an invariant pattern. Here I show that the division axes of some early cells (EMS and E) are controlled by specific cell-cell contacts (EMS-P2 or E-P3 contact). Altering the orientation of contact between these cells alters the axis along which the mitotic spindle is established, and hence the orientation of cell division. Contact-dependent mitotic spindle orientation appears to work by establishing a site of the type described by Hyman and White (1987. J. Cell Biol. 105:2123-2135) in the cortex of the responding cell: one centrosome moves toward the site of cell-cell contact during centrosome rotation in both intact embryos and reoriented cell pairs. The effect is especially apparent when two donor cells are placed on one side of the responding cell: both centrosomes are "captured," pulling the nucleus to one side of the cell. No centrosome rotation occurs in the absence of cell-cell contact, nor in nocodazole-treated cell pairs. The results suggest that some of the cortical sites described by Hyman and White are established cell autonomously (in P1, P2, and P3), and some are established by cell-cell contact (in EMS and E). Additional evidence presented here suggests that in the EMS cell, contact-dependent spindle orientation ensures a cleavage plane that will partition developmental information, received by induction, to one of EMS's daughter cells.

scholarly journals Cell-surface plasminogen activation causes a retraction of in vitro cultured human umbilical vein endothelial cell monolayer

Blood ◽  
1994 ◽  
Vol 83 (4) ◽  
pp. 994-1005
Author(s):  
G Conforti ◽  
C Dominguez-Jimenez ◽  
E Ronne ◽  
G Hoyer-Hansen ◽  
E Dejana
Keyword(s):  
Cell Surface ◽  
Umbilical Vein ◽  
Cell Monolayer ◽  
Cell Contact ◽  
Specific Cell ◽  
Human Umbilical Vein ◽  
Cell Contacts ◽  
Cell Matrix ◽  
Circulating Cells ◽  
Cell Cell

Vascular endothelium forms a dynamic interface between blood and underlying tissues. Endothelial monolayer integrity is required for controlled vascular permeability and to preclude exposure of subendothelial cell matrix to circulating cells. Recent studies have established that cultured human umbilical vein endothelial cells (ECs) express receptors for plasminogen (plg) and urokinase-like plasminogen activator (uPA). In the present study, we provide evidence that in EC, uPA receptor is present in focal contacts and at cell-cell contact sites. In these cells, addition of plg and uPA to confluent EC generates a retraction of the monolayer that is evidenced by loss of cell-cell contacts and increase in monolayer permeability. The phenomenon is reversible even after 6 hours of plg-uPA treatment. Inhibition of plg-uPA effect is obtained with plasmin inhibitors, as well as reagents that block binding of uPA or plg to the cell surface. The retractive effect of plg-uPA is concomitant to surface activation of plasminogen and to the loss of cell-cell activation of plg can induce EC retraction, possibly by causing proteolysis at specific cell-cell contacts and cell-matrix sites. This process may be important in mediating the passage of metastatic tumor cells through an intact EC monolayer as well as in regulating contacts between circulating cells and endothelium.

Cell-cell association directed mitotic spindle orientation in the early development of the marine shrimp Sicyonia ingentis

Development ◽  
1997 ◽  
Vol 124 (4) ◽  
pp. 773-780 ◽  
Author(s):  
S.W. Wang ◽  
F.J. Griffin ◽  
W.H. Clark
Keyword(s):  
Early Development ◽  
Mitotic Spindle ◽  
Laser Scanning ◽  
Cleavage Plane ◽  
Intrinsic Property ◽  
Laser Scanning Confocal Microscopy ◽  
Spindle Orientation ◽  
Cell Contact ◽  
Scanning Confocal Microscopy ◽  
Cell Cell

During early cleavages of Sicyonia ingentis embryos, mitotic spindle orientations differ between blastomeres and change in a predictable manner with each successive mitosis. From 2nd through 7th cleavages, spindles orient at a 90 degrees angle with respect to the spindle of the parent blastomere. Thus, spindle orientation is parallel to the cleavage plane that formed the blastomere. To determine if specific spindle orientations were intrinsic properties of individual blastomeres, we altered blastomere associations and asked how mitotic spindle orientation was affected in successive cleavages using laser scanning confocal microscopy. Linear embryos were constructed by dissociating 4-cell embryos and recombining the blastomeres in a linear array. The ensuing cleavage (3rd embryonic cleavage) of these linear embryos was parallel to the long axis of the embryo, resulting in four parallel pairs of blastomeres which lay in a common plane that was parallel to the substratum. The 4th cleavage produced a linear embryo with the 16 blastomeres arranged in four parallel quartets. Then, in preparation for 5th cleavage, spindles oriented at a 45 degrees angle (not parallel as in normal development) with respect to the previous cleavage plane. When 8-cell linear embryos were separated into linear half-embryos, subsequent spindle orientations were not like those observed for intact 8-cell linear embryos, but rather regressed to the orientation seen in 4-cell linear embryos. We suggest that the reorientation of mitotic spindles during early cleavage of S. ingentis is neither an intrinsic property nor age dependent, but rather is cell contact related. Further, these results in conjunction with observations of non-manipulated embryos suggest that spindle poles (centrosomes) avoid cytoplasmic regions adjacent to where there is cell-cell contact during early development.

scholarly journals Cell-surface plasminogen activation causes a retraction of in vitro cultured human umbilical vein endothelial cell monolayer

Blood ◽  
1994 ◽  
Vol 83 (4) ◽  
pp. 994-1005 ◽  
Author(s):  
G Conforti ◽  
C Dominguez-Jimenez ◽  
E Ronne ◽  
G Hoyer-Hansen ◽  
E Dejana
Keyword(s):  
Cell Surface ◽  
Umbilical Vein ◽  
Cell Monolayer ◽  
Cell Contact ◽  
Specific Cell ◽  
Human Umbilical Vein ◽  
Cell Contacts ◽  
Cell Matrix ◽  
Circulating Cells ◽  
Cell Cell

Abstract Vascular endothelium forms a dynamic interface between blood and underlying tissues. Endothelial monolayer integrity is required for controlled vascular permeability and to preclude exposure of subendothelial cell matrix to circulating cells. Recent studies have established that cultured human umbilical vein endothelial cells (ECs) express receptors for plasminogen (plg) and urokinase-like plasminogen activator (uPA). In the present study, we provide evidence that in EC, uPA receptor is present in focal contacts and at cell-cell contact sites. In these cells, addition of plg and uPA to confluent EC generates a retraction of the monolayer that is evidenced by loss of cell-cell contacts and increase in monolayer permeability. The phenomenon is reversible even after 6 hours of plg-uPA treatment. Inhibition of plg-uPA effect is obtained with plasmin inhibitors, as well as reagents that block binding of uPA or plg to the cell surface. The retractive effect of plg-uPA is concomitant to surface activation of plasminogen and to the loss of cell-cell activation of plg can induce EC retraction, possibly by causing proteolysis at specific cell-cell contacts and cell-matrix sites. This process may be important in mediating the passage of metastatic tumor cells through an intact EC monolayer as well as in regulating contacts between circulating cells and endothelium.

N-cadherin in adult rat cardiomyocytes in culture. II. Spatio-temporal appearance of proteins involved in cell-cell contact and communication. Formation of two distinct N-cadherin/catenin complexes

1996 ◽  
Vol 109 (1) ◽  
pp. 11-20 ◽  
Author(s):  
C.M. Hertig ◽  
S. Butz ◽  
S. Koch ◽  
M. Eppenberger-Eberhardt ◽  
R. Kemler ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Gap Junctions ◽  
Connexin 43 ◽  
Cell Contact ◽  
Beta Catenin ◽  
Rat Cardiomyocytes ◽  
Cell Contacts ◽  
Adult Rat ◽  
Spatio Temporal ◽  
Cell Cell

The spatio-temporal appearance and distribution of proteins forming the intercalated disc were investigated in adult rat cardiomyocytes (ARC). The ‘redifferentiation model’ of ARC involves extensive remodelling of the plasma membrane and of the myofibrillar apparatus. It represents a valuable system to elucidate the formation of cell-cell contact between cardiomyocytes and to assess the mechanisms by which different proteins involved in the cell-cell adhesion process are sorted in a precise manner to the sites of function. Appearance of N-cadherin, the catenins and connexin43 within newly formed adherens and gap junctions was studied. Here first evidence is provided for a formation of two distinct and separable N-cadherin/catenin complexes in cardiomyocytes. Both complexes are composed of N-cadherin and alpha-catenin which bind to either beta-catenin or plakoglobin in a mutually exclusive manner. The two N-cadherin/catenin complexes are assumed to be functionally involved in the formation of cell-cell contacts in ARC; however, the differential appearance and localization of the two types of complexes may also point to a specific role during ARC differentiation. The newly synthesized beta-catenin containing complex is more abundant during the first stages in culture after ARC isolation, while the newly synthesized plakoglobin containing complex progressively accumulates during the morphological changes of ARC. ARC formed a tissue-like pattern in culture whereby the new cell-cell contacts could be dissolved through Ca2+ depletion. Presence of cAMP and replenishment of Ca2+ content in the culture medium not only allowed reformation of cell-cell contacts but also affected the relative protein ratio between the two N-cadherin/catenin complexes, increasing the relative amount of newly synthesized beta-catenin over plakoglobin at a particular stage of ARC differentiation. The clustered N-cadherin/catenin complexes at the plasma membrane appear to be a prerequisite for the following gap junction formation; a temporal sequence of the appearance of adherens junction proteins and of gap junctions forming connexin-43 is suggested.

Robust T-cell signaling triggered on soft polydimethylsiloxane-supported lipid-bilayers

2020 ◽  
Author(s):  
Anna H. Lippert ◽  
Ivan B. Dimov ◽  
Alexander Winkel ◽  
James McColl ◽  
Jane Humphrey ◽  
...  
Keyword(s):  
T Cell ◽  
Lipid Bilayers ◽  
T Cell Activation ◽  
Cell Activation ◽  
Tyrosine Phosphatase ◽  
Supported Lipid Bilayers ◽  
Cell Contact ◽  
Mechanical Resistance ◽  
Cell Contacts ◽  
Cell Cell

AbstractThe T-cell receptor (TCR) is thought to be triggered either by mechano-transduction or local tyrosine phosphatase exclusion at cell-cell contacts. However, the effects of the mechanical properties of activating surfaces have only been tested for late-stage T-cell activation, and phosphatase segregation has mostly been studied on glass-supported lipid bilayers that favor imaging but are orders-of-magnitude stiffer than typical cells. We developed a method for attaching lipid bilayers to polydimethylsiloxane polymer supports, producing ‘soft bilayers’ with physiological levels of mechanical resistance (Young’s modulus of 4 kPa). Comparisons of T-cell behavior on soft and glass-supported bilayers revealed that early calcium signaling is unaffected by substrate rigidity, implying that early steps in TCR triggering are not mechanosensitive. Robust phosphatase exclusion was observed on the soft bilayers, however, suggesting it likely occurs at cell-cell contacts. This work sets the stage for an imaging-based exploration of receptor signaling under conditions closely mimicking physiological cell-cell contact.

scholarly journals ZO-1 mRNA and protein expression during tight junction assembly in Caco-2 cells.

1989 ◽  
Vol 109 (3) ◽  
pp. 1047-1056 ◽  
Author(s):  
J M Anderson ◽  
C M Van Itallie ◽  
M D Peterson ◽  
B R Stevenson ◽  
E A Carew ◽  
...  
Keyword(s):  
Tight Junction ◽  
Tight Junctions ◽  
Polyclonal Antibodies ◽  
Epithelial Cell Line ◽  
Cell Contact ◽  
Mrna Levels ◽  
Expression Library ◽  
Cell Contacts ◽  
Protein Levels ◽  
Cell Cell

We previously identified and characterized ZO-1 as a peripheral membrane protein specifically associated with the cytoplasmic surface of tight junctions. Here we describe the identification of partial cDNA sequences encoding rat and human ZO-1 and their use to study the assembly of tight junctions in the Caco-2 human intestinal epithelial cell line. A rat cDNA was isolated from a lambda-gtll expression library by screening with mAbs. Polyclonal antibodies were raised to cDNA-encoded fusion protein; several properties of these antibodies support this cDNA as encoding ZO-1. Expression of ZO-1 mRNA occurs in the rat and Caco-2 cells with a major transcript of approximately 7.5 kb. To disrupt tight junctions and study the subsequent process of assembly, Caco-2 cells were grown in suspension for 48 h in Ca++/Mg++-free spinner medium during which time they lose cell-cell contacts, become round, and by immunofluorescence microscopy show diffuse and speckled localization of ZO-1. Within hours of replating at confluent density in Ca++/Mg++-containing media, attached cells show discrete localization of ZO-1 at cell-cell contacts. Within 2 d, fully confluent monolayers form, and ZO-1 localizes in a continuous gasket-like fashion circumscribing all cells. ZO-1 mRNA levels are highest in cells in spinner culture, and upon replating rapidly fall and plateau at approximately 10% of initial levels after 2-3 wk in culture. ZO-1 protein levels are lowest in contact-free cells and rise five- to eightfold over the same period. In contrast, mRNA levels for sucrase-isomaltase, an apical membrane hydrolase, increase only after a confluent monolayer forms. Thus, in this model of contact-dependent assembly of the tight junction, there is both a rapid assembly beginning upon cell-cell contact, as well as a long-term modulation involving changes in expression of ZO-1 mRNA and protein levels.

scholarly journals N-Cadherin Association with Lipid Rafts Regulates Its Dynamic Assembly at Cell-Cell Junctions in C2C12 Myoblasts

2005 ◽  
Vol 16 (5) ◽  
pp. 2168-2180 ◽  
Author(s):  
Marie Causeret ◽  
Nicolas Taulet ◽  
Franck Comunale ◽  
Cyril Favard ◽  
Cécile Gauthier-Rouvière
Keyword(s):  
Plasma Membrane ◽  
Cell Adhesion ◽  
Lipid Rafts ◽  
Membrane Lipid ◽  
Cell Junctions ◽  
Cell Contact ◽  
C2c12 Myoblasts ◽  
Cell Contacts ◽  
Dynamic Assembly ◽  
Cell Cell

Cadherins are homophilic cell-cell adhesion molecules implicated in cell growth, differentiation, and organization into tissues during embryonic development. They accumulate at cell-cell contact sites and act as adhesion-activated signaling receptors. Here, we show that the dynamic assembly of N-cadherin at cell-cell contacts involves lipid rafts. In C2C12 myoblasts, immunofluorescence and biochemical experiments demonstrate that N-cadherin present at cell-cell contacts is colocalized with lipid rafts. Disruption of lipid rafts leads to the inhibition of cell-cell adhesion and disorganization of N-cadherin–dependent cell-cell contacts without modifying the association of N-cadherin with catenins and its availability at the plasma membrane. Fluorescent recovery after photobleaching experiments demonstrate that at the dorsal plasma membrane, lipid rafts are not directly involved in the diffusional mobility of N-cadherin. In contrast, at cell-cell junctions N-cadherin association with lipid rafts allows its stabilization enabling the formation of a functional adhesive complex. We show that lipid rafts, as homophilic interaction and F-actin association, stabilize cadherin-dependent adhesive complexes. Homophilic interactions and F-actin association of N-cadherin are both required for its association to lipid rafts. We thus identify lipid rafts as new regulators of cadherin-mediated cell adhesion.

scholarly journals Physical Description of Mitotic Spindle Orientation During Cell Division

2009 ◽  
Vol 96 (3) ◽  
pp. 195a-196a
Author(s):  
Andrea Jiménez-Dalmaroni ◽  
Manuel Théry ◽  
Victor Racine ◽  
Michel Bornens ◽  
Frank Jülicher
Keyword(s):  
Cell Division ◽  
Mitotic Spindle ◽  
Spindle Orientation ◽  
Physical Description

scholarly journals HIV corrupts the Cdc42-IQGAP1 axis of actin regulation to promote cell-cell viral spread

2019 ◽  
Author(s):  
Anupriya Aggarwal ◽  
Alberto Ospina Stella ◽  
Catherine Henry ◽  
Kedar Narayan ◽  
Stuart G. Turville
Keyword(s):  
Focused Ion Beam ◽  
Positive Curvature ◽  
Ion Beam ◽  
Membrane Curvature ◽  
Cell Contact ◽  
Cell Contacts ◽  
Viral Spread ◽  
Viral Release ◽  
Viral Mutagenesis ◽  
Cell Cell

AbstractF-Actin remodelling is important for the spread of HIV via cell-cell contacts, yet the mechanisms by which HIV corrupts the actin cytoskeleton are poorly understood. Through live cell imaging and focused ion beam scanning electron microscopy (FIB-SEM), we observed F-Actin structures that exhibit strong positive curvature to be enriched for HIV buds. Virion proteomics, gene silencing, and viral mutagenesis supported a Cdc42-IQGAP1-Arp2/3 pathway as the primary intersection of HIV budding, membrane curvature and F-Actin regulation. Whilst HIV egress activated the Cdc42-Arp2/3 filopodial pathway, this came at the expense of cell-free viral release. Importantly, release could be rescued by cell-cell contact, providing Cdc42 and IQGAP1 were present. From these observations we conclude that out-going HIV has corrupted a central F-Actin node that enables initial coupling of HIV buds to cortical F-Actin to place HIV at the leading cell edge. Whilst this initially prevents particle release, maturation of cell-cell contacts signals back to this F-Actin node to enable viral release & subsequent infection of the contacting cell.

scholarly journals Plk1 regulates spindle orientation by phosphorylating NuMA in human cells

2018 ◽  
Vol 1 (6) ◽  
pp. e201800223 ◽  
Author(s):  
Shrividya Sana ◽  
Riya Keshri ◽  
Ashwathi Rajeevan ◽  
Sukriti Kapoor ◽  
Sachin Kotak
Keyword(s):  
Cell Division ◽  
Mitotic Spindle ◽  
Molecular Mechanisms ◽  
Spindle Pole ◽  
Spindle Orientation ◽  
Cell Cortex ◽  
Division Plane ◽  
Evolutionarily Conserved ◽  
Cortical Localization ◽  
Proper Orientation

Proper orientation of the mitotic spindle defines the correct division plane and is essential for accurate cell division and development. In metazoans, an evolutionarily conserved complex comprising of NuMA/LGN/Gαi regulates proper orientation of the mitotic spindle by orchestrating cortical dynein levels during metaphase. However, the molecular mechanisms that modulate the spatiotemporal dynamics of this complex during mitosis remain elusive. Here, we report that acute inactivation of Polo-like kinase 1 (Plk1) during metaphase enriches cortical levels of dynein/NuMA/LGN and thus influences spindle orientation. We establish that this impact of Plk1 on cortical levels of dynein/NuMA/LGN is through NuMA, but not via dynein/LGN. Moreover, we reveal that Plk1 inhibition alters the dynamic behavior of NuMA at the cell cortex. We further show that Plk1 directly interacts and phosphorylates NuMA. Notably, NuMA-phosphorylation by Plk1 impacts its cortical localization, and this is needed for precise spindle orientation during metaphase. Overall, our finding connects spindle-pole pool of Plk1 with cortical NuMA and answers a long-standing puzzle about how spindle-pole Plk1 gradient dictates proper spindle orientation for error-free mitosis.

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