scholarly journals Microtubules are the only structural constituent of the spindle apparatus required for induction of cell cleavage

2003 ◽  
Vol 162 (3) ◽  
pp. 383-390 ◽  
Author(s):  
G. Bradley Alsop ◽  
Dahong Zhang
Keyword(s):  
Cell Types ◽  
Cell Cortex ◽  
Cleavage Furrow ◽  
Central Spindle ◽  
Structural Constituent ◽  
Cell Cleavage ◽  
Spindle Apparatus

Structural constituents of the spindle apparatus essential for cleavage induction remain undefined. Findings from various cell types using different approaches suggest the importance of all structural constituents, including asters, the central spindle, and chromosomes. In this study, we systematically dissected the role of each constituent in cleavage induction in grasshopper spermatocytes and narrowed the essential one down to bundled microtubules. Using micromanipulation, we produced “cells” containing only asters, a truncated central spindle lacking both asters and chromosomes, or microtubules alone. We show that furrow induction occurs under all circumstances, so long as sufficient microtubules are present. Microtubules, as the only spindle structural constituent, undergo dramatic, stage-specific reorganizations, radiating toward cell cortex in “metaphase,” disassembling in “anaphase,” and bundling into arrays in “telophase.” Furrow induction usually occurs at multisites around microtubule bundles, but only those induced by sustained bundles ingress. We suggest that microtubules, regardless of source, are the only structural constituent of the spindle apparatus essential for cleavage furrow induction.

scholarly journals Delay of HeLa cell cleavage into interphase using dihydrocytochalasin B: retention of a postmitotic spindle and telophase disc correlates with synchronous cleavage recovery.

1995 ◽  
Vol 131 (1) ◽  
pp. 191-205 ◽  
Author(s):  
S N Martineau ◽  
P R Andreassen ◽  
R L Margolis
Keyword(s):  
Mammalian Cell ◽  
Mitotic Spindle ◽  
Cyclin B ◽  
Cell Cortex ◽  
Cleavage Furrow ◽  
Actin Assembly ◽  
Cell Cleavage ◽  
Integral Structure ◽  
G1 Cells ◽  
Molecular Signals

The molecular signals that determine the position and timing of the cleavage furrow during mammalian cell cytokinesis are presently unknown. We have studied in detail the effect of dihydrocytochalasin B (DCB), a drug that interferes with actin assembly, on specific late mitotic events in synchronous HeLa cells. When cleavage furrow formation is blocked at 10 microM DCB, cells return to interphase by the criteria of reformation of nuclei with lamin borders, degradation of the cyclin B component of p34cdc2 kinase, and loss of mitosis specific MPM-2 antigens. However, the machinery for cell cleavage is retained for up to one hour into G1 when cleavage cannot proceed. The components retained consist prominently of a "postmitotic" spindle and a telophase disc, a structure templated by the mitotic spindle in anaphase that may determine the position and timing of the cleavage furrow. Upon release from DCB block, G1 cells proceed through a rapid and synchronous cleavage. We conclude that the mitotic spindle is not inevitably destroyed at the end of mitosis, but persists as an integral structure with the telophase disc in the absence of cleavage. We also conclude that cell cleavage can occur in G1, and is therefore an event metabolically independent of mitosis. The retained telophase disc may indeed signal the position of furrow formation, as G1 cleavage occurs only in the position where the retained disc underlies the cell cortex. The protocol we describe should now enable development of a model system for the study of mammalian cell cleavage as a synchronous event independent of mitosis.

scholarly journals Protocadherin 7 localizes to the plasma membrane during mitosis and promotes cytokinesis by a palmitoylation-dependent mechanism

2020 ◽  
Author(s):  
Nazlı Ezgi Özkan-Küçük ◽  
Mohammad Haroon Qureshi ◽  
Berfu Nur Yiğit ◽  
Altuğ Kamacıoğlu ◽  
Nima Bavili ◽  
...  
Keyword(s):  
Cell Adhesion ◽  
Membrane Trafficking ◽  
Myosin Ii ◽  
Cell Types ◽  
Mitotic Cell ◽  
Cortical Reorganization ◽  
Cell Cortex ◽  
Cleavage Furrow ◽  
Cytoskeleton Organization ◽  
Dependent Mechanism

ABSTRACTSuccessful cell division requires dramatic reorganization of the cell cortex in coordination with actomyosin cytoskeleton organization, membrane trafficking and cell adhesion. Although the contractile actomyosin ring is considered as hallmark of cytokinesis, in some cell types cell adhesion systems have been shown to drive cytokinesis independently from actomyosin function. We previously reported that Protocadherin 7 (PCDH7) localizes to the mitotic cortex which is required for building up the full mitotic rounding pressure. Here, we show that PCDH7 localizes to the mitotic cell cortex and to the cleavage furrow by a palmitoylation-dependent mechanism. At the cleavage furrow, PCDH7 facilitates the activation of myosin II and successful cytokinesis. Strikingly, PCDH7 promotes cytokinesis even when the myosin II contractility and integrin mediated adhesion are blocked. This work describes a palmitoylation-dependent cortical reorganization which promotes cytokinesis under different conditions.

scholarly journals Ablation of PRC1 by Small Interfering RNA Demonstrates that Cytokinetic Abscission Requires a Central Spindle Bundle in Mammalian Cells, whereas Completion of Furrowing Does Not

2005 ◽  
Vol 16 (3) ◽  
pp. 1043-1055 ◽  
Author(s):  
Cristiana Mollinari ◽  
Jean-Philippe Kleman ◽  
Yasmina Saoudi ◽  
Sandra A. Jablonski ◽  
Julien Perard ◽  
...  
Keyword(s):  
Mammalian Cells ◽  
Time Lapse ◽  
Cell Cortex ◽  
Central Spindle ◽  
Spatial Regulation ◽  
Daughter Cells ◽  
Cell Cleavage ◽  
Temporal And Spatial ◽  
Interfering Rna ◽  
Passenger Proteins

The temporal and spatial regulation of cytokinesis requires an interaction between the anaphase mitotic spindle and the cell cortex. However, the relative roles of the spindle asters or the central spindle bundle are not clear in mammalian cells. The central spindle normally serves as a platform to localize key regulators of cell cleavage, including passenger proteins. Using time-lapse and immunofluorescence analysis, we have addressed the consequences of eliminating the central spindle by ablation of PRC1, a microtubule bundling protein that is critical to the formation of the central spindle. Without a central spindle, the asters guide the equatorial cortical accumulation of anillin and actin, and of the passenger proteins, which organize into a subcortical ring in anaphase. Furrowing goes to completion, but abscission to create two daughter cells fails. We conclude the central spindle bundle is required for abscission but not for furrowing in mammalian cells.

scholarly journals Role of Survivin in cytokinesis revealed by a separation-of-function allele

2011 ◽  
Vol 22 (20) ◽  
pp. 3779-3790 ◽  
Author(s):  
Edith Szafer-Glusman ◽  
Margaret T. Fuller ◽  
Maria Grazia Giansanti
Keyword(s):  
Myosin Ii ◽  
Cell Cortex ◽  
Direct Role ◽  
Central Spindle ◽  
Ring Assembly ◽  
Chromosomal Passenger ◽  
Missense Allele ◽  
Ring Analysis ◽  
And Function

The chromosomal passenger complex (CPC), containing Aurora B kinase, Inner Centromere Protein, Survivin, and Borealin, regulates chromosome condensation and interaction between kinetochores and microtubules at metaphase, then relocalizes to midzone microtubules at anaphase and regulates central spindle organization and cytokinesis. However, the precise role(s) played by the CPC in anaphase have been obscured by its prior functions in metaphase. Here we identify a missense allele of Drosophila Survivin that allows CPC localization and function during metaphase but not cytokinesis. Analysis of mutant cells showed that Survivin is essential to target the CPC and the mitotic kinesin-like protein 1 orthologue Pavarotti (Pav) to the central spindle and equatorial cell cortex during anaphase in both larval neuroblasts and spermatocytes. Survivin also enabled localization of Polo kinase and Rho at the equatorial cortex in spermatocytes, critical for contractile ring assembly. In neuroblasts, in contrast, Survivin function was not required for localization of Rho, Polo, or Myosin II to a broad equatorial cortical band but was required for Myosin II to transition to a compact, fully constricted ring. Analysis of this “separation-of-function” allele demonstrates the direct role of Survivin and the CPC in cytokinesis and highlights striking differences in regulation of cytokinesis in different cell systems.

scholarly journals THE CONTRACTILE RING

1972 ◽  
Vol 53 (2) ◽  
pp. 419-434 ◽  
Author(s):  
Thomas E. Schroeder
Keyword(s):  
Plasma Membrane ◽  
Sea Urchin ◽  
Cytochalasin B ◽  
Vital Role ◽  
Strict Sense ◽  
Cleavage Furrow ◽  
Contractile Ring ◽  
Cell Cleavage ◽  
Uniform Ring

The first cleavage furrow in eggs of Arbacia (sea urchin) is accompanied by a uniform ring of aligned microfilaments, called the contractile ring. Individual contractile ring filaments measure 35–60 A and occasionally appear "hollow." The contractile ring exists from about 20 sec after anaphase to the end of furrowing activity, i.e., 6–7 min at 20°C. It is closely associated with the plasma membrane at all times, and is probably assembled there. It is about 8 µ wide and 0.2 µ thick throughout cleavage. Its volume decreases, however, suggesting a contraction-related disassembly of contractile ring filaments, rather than a sliding-filament mechanism in the strict sense. Cytochalasin B (>10-6 M) arrests cleavage within 60 sec, by which time contractile ring filaments are no longer visible ultrastructurally. The furrow may be seen to recede within this time. Karyokinesis is unaffected. Simultaneous disruption of furrowing activity and of the contractile ring largely confirms the vital role of the contractile ring as the organelle of cell cleavage.

Effect of Calcium on the Growth and Differentiation of Cultured Rat Esophageal Epithelial Cells

1982 ◽  
Vol 40 ◽  
pp. 132-133
Author(s):  
W.T. Gunning ◽  
M.R. Marino ◽  
M.S. Babcock ◽  
G.D. Stoner
Keyword(s):  
Epithelial Cells ◽  
Cell Types ◽  
Replication Rate ◽  
Enzymatic Dissociation ◽  
Growth Assay ◽  
Epidermal Growth ◽  
Fetal Bovine ◽  
Esophageal Epithelial Cells ◽  
Cellular Replication

The role of calcium in modulating cellular replication and differentiation has been described for various cell types. In the present study, the effects of Ca++ on the growth and differentiation of cultured rat esophageal epithelial cells was investigated.Epithelial cells were isolated from esophagi taken from 8 week-old male CDF rats by the enzymatic dissociation method of Kaighn. The cells were cultured in PFMR-4 medium supplemented with 0.25 mg/ml dialyzed fetal bovine serum, 5 ng/ml epidermal growth factor, 10-6 M hydrocortisone 10-6 M phosphoethanolamine, 10-6 M ethanolamine, 5 pg/ml insulin, 5 ng/ml transferrin, 10 ng/ml cholera toxin and 50 ng/ml garamycin at 36.5°C in a humidified atmosphere of 3% CO2 in air. At weekly intervals, the cells were subcultured with a solution containing 1% polyvinylpyrrolidone, 0.01% EGTA, and 0.05% trypsin. After various passages, the replication rate of the cells in PFMR-4 medium containing from 10-6 M to 10-3 M Ca++ was determined using a clonal growth assay.

Role of PKC isozymes in water transport in toad urinary bladder

1991 ◽  
Vol 49 ◽  
pp. 302-303
Author(s):  
A.J. Mia ◽  
L.X. Oakford ◽  
T. Yorio
Keyword(s):  
Urinary Bladder ◽  
Apical Membrane ◽  
Membrane Surface ◽  
Protein A ◽  
Cell Types ◽  
Leukemic Cells ◽  
Toad Urinary Bladder ◽  
Pkc Isozymes ◽  
Antibody Labeling

Protein kinase C (PKC) isozymes, when activated, are translocated to particulate membrane fractions for transport to the apical membrane surface in a variety of cell types. Evidence of PKC translocation was demonstrated in human megakaryoblastic leukemic cells, and in cardiac myocytes and fibroblasts, using FTTC immunofluorescent antibody labeling techniques. Recently, we reported immunogold localizations of PKC subtypes I and II in toad urinary bladder epithelia, following 60 min stimulation with Mezerein (MZ), a PKC activator, or antidiuretic hormone (ADH). Localization of isozyme subtypes I and n was carried out in separate grids using specific monoclonal antibodies with subsequent labeling with 20nm protein A-gold probes. Each PKC subtype was found to be distributed singularly and in discrete isolated patches in the cytosol as well as in the apical membrane domains. To determine if the PKC isozymes co-localized within the cell, a double immunogold labeling technique using single grids was utilized.

Centrosome Aurora A gradient ensures single polarity axis in C. elegans embryos

2020 ◽  
Vol 48 (3) ◽  
pp. 1243-1253 ◽  
Author(s):  
Sukriti Kapoor ◽  
Sachin Kotak
Keyword(s):  
Symmetry Breaking ◽  
Cell Fate ◽  
Cell Cortex ◽  
Axis Formation ◽  
Aurora A Kinase ◽  
Aurora A ◽  
C Elegans ◽  
Cell Embryo ◽  
Polarity Establishment

Cellular asymmetries are vital for generating cell fate diversity during development and in stem cells. In the newly fertilized Caenorhabditis elegans embryo, centrosomes are responsible for polarity establishment, i.e. anterior–posterior body axis formation. The signal for polarity originates from the centrosomes and is transmitted to the cell cortex, where it disassembles the actomyosin network. This event leads to symmetry breaking and the establishment of distinct domains of evolutionarily conserved PAR proteins. However, the identity of an essential component that localizes to the centrosomes and promotes symmetry breaking was unknown. Recent work has uncovered that the loss of Aurora A kinase (AIR-1 in C. elegans and hereafter referred to as Aurora A) in the one-cell embryo disrupts stereotypical actomyosin-based cortical flows that occur at the time of polarity establishment. This misregulation of actomyosin flow dynamics results in the occurrence of two polarity axes. Notably, the role of Aurora A in ensuring a single polarity axis is independent of its well-established function in centrosome maturation. The mechanism by which Aurora A directs symmetry breaking is likely through direct regulation of Rho-dependent contractility. In this mini-review, we will discuss the unconventional role of Aurora A kinase in polarity establishment in C. elegans embryos and propose a refined model of centrosome-dependent symmetry breaking.

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