scholarly journals Peripheral microtubules ensure asymmetric furrow positioning in neural stem cells

2020 ◽  
Author(s):  
Alexandre Thomas ◽  
Emmanuel Gallaud ◽  
Aude Pascal ◽  
Laurence Serre ◽  
Isabelle Arnal ◽  
...  
Keyword(s):  
Stem Cells ◽  
Model Systems ◽  
Cell Cortex ◽  
Cleavage Furrow ◽  
Animal Cells ◽  
Daughter Cells ◽  
The Future ◽  
Spindle Midzone ◽  
Chromosome Passenger Complex ◽  
Size Asymmetry

AbstractNeuroblast (NB) cell division is characterized by a basal positioning of the cleavage furrow resulting in a large difference in size between the future daughter cells. In animal cells, furrow placement and assembly is governed by centralspindlin, a highly conserved complex that accumulates at the equatorial cell cortex of the future cleavage site and at the spindle midzone. In contrast to model systems studied so far, these two centralspindlin populations are spatially and temporally separated in NBs. A cortical leading pool is located at the basal cleavage furrow site and a second pool accumulates at the midzone before travelling to the site of the basal cleavage furrow during cytokinesis completion. By manipulating microtubule (MT) dynamics, we show that the cortical centralspindlin population requires peripheral astral microtubules and the Chromosome Passenger Complex (CPC) for efficient recruitment. Loss of this pool does not prevent cytokinesis but enhances centralspindlin levels at the midzone leading to furrow repositioning towards the equator and decreased size asymmetry between daughter cells. Together these data reveal that the asymmetrical furrow placement characteristic of NBs results from a competition between spatially and functionally separate centralspindlin pools in which the cortical pool is dominant and requires peripheral astral microtubules.

scholarly journals Localization of Pavarotti-KLP in Living Drosophila Embryos Suggests Roles in Reorganizing the Cortical Cytoskeleton during the Mitotic Cycle

2003 ◽  
Vol 14 (10) ◽  
pp. 4028-4038 ◽  
Author(s):  
Gianluca Minestrini ◽  
Alyssa S. Harley ◽  
David M. Glover
Keyword(s):  
Leading Edge ◽  
Spindle Pole ◽  
Equatorial Region ◽  
Cell Cortex ◽  
Cleavage Furrow ◽  
Daughter Cells ◽  
Spindle Midzone ◽  
Anaphase B ◽  
Actomyosin Cytoskeleton ◽  
Drosophila Embryos

Pav-KLP is the Drosophila member of the MKLP1 family essential for cytokinesis. In the syncytial blastoderm embryo, GFP-Pav-KLP cyclically associates with astral, spindle, and midzone microtubules and also to actomyosin pseudocleavage furrows. As the embryo cellularizes, GFP-Pav-KLP also localizes to the leading edge of the furrows that form cells. In mononucleate cells, nuclear localization of GFP-Pav-KLP is mediated through NLS elements in its C-terminal domain. Mutants in these elements that delocalize Pav-KLP to the cytoplasm in interphase do not affect cell division. In mitotic cells, one population of wild-type GFP-Pav-KLP associates with the spindle and concentrates in the midzone at anaphase B. A second is at the cell cortex on mitotic entry and later concentrates in the region of the cleavage furrow. An ATP binding mutant does not localize to the cortex and spindle midzone but accumulates on spindle pole microtubules to which actin is recruited. This leads either to failure of the cleavage furrow to form or later defects in which daughter cells remain connected by a microtubule bridge. Together, this suggests Pav-KLP transports elements of the actomyosin cytoskeleton to plus ends of astral microtubules in the equatorial region of the cell to permit cleavage ring formation.

scholarly journals Contractile Ring-independent Localization of DdINCENP, a Protein Important for Spindle Stability and Cytokinesis

2006 ◽  
Vol 17 (2) ◽  
pp. 779-788 ◽  
Author(s):  
Qian Chen ◽  
Hui Li ◽  
Arturo De Lozanne
Keyword(s):  
Myosin Ii ◽  
Cleavage Furrow ◽  
Contractile Ring ◽  
Subsequent Formation ◽  
Daughter Cells ◽  
Chromosomal Passenger ◽  
Spindle Midzone ◽  
Spindle Stability ◽  
Passenger Protein

Dictyostelium DdINCENP is a chromosomal passenger protein associated with centromeres, the spindle midzone, and poles during mitosis and the cleavage furrow during cytokinesis. Disruption of the single DdINCENP gene revealed important roles for this protein in mitosis and cytokinesis. DdINCENP null cells lack a robust spindle midzone and are hypersensitive to microtubule-depolymerizing drugs, suggesting that their spindles may not be stable. Furthermore DdCP224, a protein homologous to the microtubule-stabilizing protein TOGp/XMAP215, was absent from the spindle midzone of DdINCENP null cells. Overexpression of DdCP224 rescued the weak spindle midzone defect of DdINCENP null cells. Although not required for the localization of the myosin II contractile ring and subsequent formation of a cleavage furrow, DdINCENP is important for the abscission of daughter cells at the end of cytokinesis. Finally, we show that the localization of DdINCENP at the cleavage furrow is modulated by myosin II but it occurs by a mechanism different from that controlling the formation of the contractile ring.

scholarly journals Classical and Emerging Regulatory Mechanisms of Cytokinesis in Animal Cells

Biology ◽  
2019 ◽  
Vol 8 (3) ◽  
pp. 55 ◽  
Author(s):  
Vikash Verma ◽  
Alex Mogilner ◽  
Thomas J. Maresca
Keyword(s):  
Molecular Mechanisms ◽  
Myosin Ii ◽  
Dynamic Structure ◽  
Regulatory Proteins ◽  
Cleavage Furrow ◽  
Filamentous Actin ◽  
Animal Cells ◽  
Contractile Ring ◽  
Daughter Cells ◽  
Sister Chromatids

The primary goal of cytokinesis is to produce two daughter cells, each having a full set of chromosomes. To achieve this, cells assemble a dynamic structure between segregated sister chromatids called the contractile ring, which is made up of filamentous actin, myosin-II, and other regulatory proteins. Constriction of the actomyosin ring generates a cleavage furrow that divides the cytoplasm to produce two daughter cells. Decades of research have identified key regulators and underlying molecular mechanisms; however, many fundamental questions remain unanswered and are still being actively investigated. This review summarizes the key findings, computational modeling, and recent advances in understanding of the molecular mechanisms that control the formation of the cleavage furrow and cytokinesis.

scholarly journals Molecular Mechanism of Cytokinesis

2019 ◽  
Vol 88 (1) ◽  
pp. 661-689 ◽  
Author(s):  
Thomas D. Pollard ◽  
Ben O'Shaughnessy
Keyword(s):  
Cell Cycle ◽  
Computer Simulations ◽  
Actin Filaments ◽  
Myosin Ii ◽  
Cleavage Furrow ◽  
Animal Cells ◽  
Contractile Ring ◽  
Daughter Cells ◽  
Ancient Proteins ◽  
Biochemical Mechanisms

Division of amoebas, fungi, and animal cells into two daughter cells at the end of the cell cycle depends on a common set of ancient proteins, principally actin filaments and myosin-II motors. Anillin, formins, IQGAPs, and many other proteins regulate the assembly of the actin filaments into a contractile ring positioned between the daughter nuclei by different mechanisms in fungi and animal cells. Interactions of myosin-II with actin filaments produce force to assemble and then constrict the contractile ring to form a cleavage furrow. Contractile rings disassemble as they constrict. In some cases, knowledge about the numbers of participating proteins and their biochemical mechanisms has made it possible to formulate molecularly explicit mathematical models that reproduce the observed physical events during cytokinesis by computer simulations.

scholarly journals Chromosomal Proteins and Cytokinesis: Patterns of Cleavage Furrow Formation and Inner Centromere Protein Positioning in Mitotic Heterokaryons and Mid-anaphase Cells

1997 ◽  
Vol 136 (6) ◽  
pp. 1169-1183 ◽  
Author(s):  
D. Mark Eckley ◽  
Alexandra M. Ainsztein ◽  
Alastair M. Mackay ◽  
Ilya G. Goldberg ◽  
William C. Earnshaw
Keyword(s):  
Cultured Cells ◽  
Shape Change ◽  
Current Model ◽  
Metaphase Plate ◽  
Cleavage Furrow ◽  
Single Plane ◽  
Daughter Cells ◽  
Centromere Protein ◽  
Cell Position ◽  
Spindle Midzone

After the separation of sister chromatids in anaphase, it is essential that the cell position a cleavage furrow so that it partitions the chromatids into two daughter cells of roughly equal size. The mechanism by which cells position this cleavage furrow remains unknown, although the best current model is that furrows always assemble midway between asters. We used micromanipulation of human cultured cells to produce mitotic heterokaryons with two spindles fused in a V conformation. The majority (15/19) of these cells cleaved along a single plane that transected the two arms of the V at the position where the metaphase plate had been, a result at odds with current views of furrow positioning. However, four cells did form an additional ectopic furrow between the spindle poles at the open end of the V, consistent with the established view. To begin to address the mechanism of furrow assembly, we have begun a detailed study of the properties of the chromosome passenger inner centromere protein (INCENP) in anaphase and telophase cells. We found that INCENP is a very early component of the cleavage furrow, accumulating at the equatorial cortex before any noticeable cortical shape change and before any local accumulation of myosin heavy chain. In mitotic heterokaryons, INCENP was detected in association with spindle midzone microtubules beneath sites of furrowing and was not detected when furrows were absent. A functional role for INCENP in cytokinesis was suggested in experiments where a nearly full-length INCENP was tethered to the centromere. Many cells expressing the chimeric INCENP failed to complete cytokinesis and entered the next cell cycle with daughter cells connected by a large intercellular bridge with a prominent midbody. Together, these results suggest that INCENP has a role in either the assembly or function of the cleavage furrow.

scholarly journals Novel Myosin Heavy Chain Kinase Involved in Disassembly of Myosin II Filaments and Efficient Cleavage in MitoticDictyostelium Cells

2002 ◽  
Vol 13 (12) ◽  
pp. 4333-4342 ◽  
Author(s):  
Akira Nagasaki ◽  
Go Itoh ◽  
Shigehiko Yumura ◽  
Taro Q.P. Uyeda
Keyword(s):  
Myosin Heavy Chain ◽  
Heavy Chain ◽  
Myosin Ii ◽  
Kinase Domain ◽  
Cleavage Furrow ◽  
Wild Type ◽  
Daughter Cells ◽  
Cleavage Process ◽  
Interphase Cells ◽  
Myosin Heavy Chain Kinase

We have cloned a full-length cDNA encoding a novel myosin II heavy chain kinase (mhckC) from Dictyostelium. Like other members of the myosin heavy chain kinase family, themhckC gene product, MHCK C, has a kinase domain in its N-terminal half and six WD repeats in the C-terminal half. GFP-MHCK C fusion protein localized to the cortex of interphase cells, to the cleavage furrow of mitotic cells, and to the posterior of migrating cells. These distributions of GFP-MHCK C always corresponded with that of myosin II filaments and were not observed in myosin II-null cells, where GFP-MHCK C was diffusely distributed in the cytoplasm. Thus, localization of MHCK C seems to be myosin II-dependent. Cells lacking the mhckC gene exhibited excessive aggregation of myosin II filaments in the cleavage furrows and in the posteriors of the daughter cells once cleavage was complete. The cleavage process of these cells took longer than that of wild-type cells. Taken together, these findings suggest MHCK C drives the disassembly of myosin II filaments for efficient cytokinesis and recycling of myosin II that occurs during cytokinesis.

scholarly journals Mechanism of the formation of contractile ring in dividing cultured animal cells. II. Cortical movement of microinjected actin filaments.

1990 ◽  
Vol 111 (5) ◽  
pp. 1905-1911 ◽  
Author(s):  
L G Cao ◽  
Y L Wang
Keyword(s):  
Actin Filaments ◽  
Average Rate ◽  
Rat Kidney ◽  
Equatorial Region ◽  
Cell Cortex ◽  
Polar Regions ◽  
Cortical Actin ◽  
Animal Cells ◽  
Contractile Ring ◽  
Directional Movement

The contractile ring in dividing animal cells is formed primarily through the reorganization of existing actin filaments (Cao, L.-G., and Y.-L. Wang. 1990. J. Cell Biol. 110:1089-1096), but it is not clear whether the process involves a random recruitment of diffusible actin filaments from the cytoplasm, or a directional movement of cortically associated filaments toward the equator. We have studied this question by observing the distribution of actin filaments that have been labeled with fluorescent phalloidin and microinjected into dividing normal rat kidney (NRK) cells. The labeled filaments are present primarily in the cytoplasm during prometaphase and early metaphase, but become associated extensively with the cell cortex 10-15 min before the onset of anaphase. This process is manifested both as an increase in cortical fluorescence intensity and as movements of discrete aggregates of actin filaments toward the cortex. The concentration of actin fluorescence in the equatorial region, accompanied by a decrease of fluorescence in polar regions, is detected 2-3 min after the onset of anaphase. By directly tracing the distribution of aggregates of labeled actin filaments, we are able to detect, during anaphase and telophase, movements of cortical actin filaments toward the equator at an average rate of 1.0 micron/min. Our results, combined with previous observations, suggest that the organization of actin filaments during cytokinesis probably involves an association of cytoplasmic filaments with the cortex, a movement of cortical filaments toward the cleavage furrow, and a dissociation of filaments from the equatorial cortex.

scholarly journals Spindle-to-cortex communication in cleaving, polyspermic Xenopus eggs

2015 ◽  
Vol 26 (20) ◽  
pp. 3628-3640 ◽  
Author(s):  
Christine M. Field ◽  
Aaron C. Groen ◽  
Phuong A. Nguyen ◽  
Timothy J. Mitchison
Keyword(s):  
Positive Feedback ◽  
Natural Experiment ◽  
Cell Cortex ◽  
Lateral Growth ◽  
Mitotic Spindles ◽  
Microtubule Stabilization ◽  
Spindle Poles ◽  
Early Embryos ◽  
Position And Orientation ◽  
Chromosome Passenger Complex

Mitotic spindles specify cleavage planes in early embryos by communicating their position and orientation to the cell cortex using microtubule asters that grow out from the spindle poles during anaphase. Chromatin also plays a poorly understood role. Polyspermic fertilization provides a natural experiment in which aster pairs from the same spindle (sister asters) have chromatin between them, whereas asters pairs from different spindles (nonsisters) do not. In frogs, only sister aster pairs induce furrows. We found that only sister asters recruited two conserved furrow-inducing signaling complexes, chromosome passenger complex (CPC) and Centralspindlin, to a plane between them. This explains why only sister pairs induce furrows. We then investigated factors that influenced CPC recruitment to microtubule bundles in intact eggs and a cytokinesis extract system. We found that microtubule stabilization, optimal starting distance between asters, and proximity to chromatin all favored CPC recruitment. We propose a model in which proximity to chromatin biases initial CPC recruitment to microtubule bundles between asters from the same spindle. Next a positive feedback between CPC recruitment and microtubule stabilization promotes lateral growth of a plane of CPC-positive microtubule bundles out to the cortex to position the furrow.

scholarly journals Experimental Models to Study COVID-19 Effect in Stem Cells

Cells ◽  
2021 ◽  
Vol 10 (1) ◽  
pp. 91
Author(s):  
Rishi Man Chugh ◽  
Payel Bhanja ◽  
Andrew Norris ◽  
Subhrajit Saha
Keyword(s):  
Stem Cells ◽  
Ex Vivo ◽  
Drug Efficacy ◽  
Cell Loss ◽  
Experimental Models ◽  
Model Systems ◽  
Virus Infectivity ◽  
Ex Vivo Model ◽  
Global Pandemic ◽  
The Impact

The new strain of coronavirus (severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2)) emerged in 2019 and hence is often referred to as coronavirus disease 2019 (COVID-19). This disease causes hypoxic respiratory failure and acute respiratory distress syndrome (ARDS), and is considered as the cause of a global pandemic. Very limited reports in addition to ex vivo model systems are available to understand the mechanism of action of this virus, which can be used for testing of any drug efficacy against virus infectivity. COVID-19 induces tissue stem cell loss, resulting inhibition of epithelial repair followed by inflammatory fibrotic consequences. Development of clinically relevant models is important to examine the impact of the COVID-19 virus in tissue stem cells among different organs. In this review, we discuss ex vivo experimental models available to study the effect of COVID-19 on tissue stem cells.

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