Dynein motor regulation stabilizes interphase microtubule arrays and determines centrosome position

Koonce, Michael P.

doi:10.1093/emboj/18.23.6786

Cited by 114 publications

(113 citation statements)

References 48 publications

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“…2D). Similar bundled rings have been observed after overexpression of other MAPs in mammalian culture cells (13,15,16). When ASAP-⌬Cter was overexpressed, the fiber-like distribution of ASAP was lost in interphase.…”

Section: Molecular Characterization Of Asapsupporting

confidence: 76%

ASAP, a human microtubule-associated protein required for bipolar spindle assembly and cytokinesis

Saffin

Venoux

Prigent

et al. 2005

Proc. Natl. Acad. Sci. U.S.A.

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We have identified a unique human microtubule-associated protein (MAP) named ASAP for ASter-Associated Protein. ASAP localizes to microtubules in interphase, associates with the mitotic spindle during mitosis, localizes to the central body during cytokinesis and directly binds to purified microtubules by its COOHterminal domain. Overexpression of ASAP induces profound bundling of cytoplasmic microtubules in interphase cells and aberrant monopolar spindles in mitosis. Depletion of ASAP by RNA interference results in severe mitotic defects: it provokes aberrant mitotic spindle, delays mitotic progression, and leads to defective cytokinesis or cell death. These results suggest a crucial role for ASAP in the organization of the bipolar mitotic spindle, mitosis progression, and cytokinesis and define ASAP as a key factor for proper spindle assembly. mitosis D ivision of the cell requires coordination between chromosome segregation by a bipolar microtubule (MT)-based structure, the mitotic spindle, and cleavage of the cell by the cytokinetic apparatus. The transition from interphase to mitosis or meiosis is accompanied by a dramatic reorganization of the MT cytoskeleton. The assembly of bipolar spindles is preceded by the movement of centrosomes toward opposite poles of the cell, where these structures function as nucleation sites for MT polymerization (1-3). Spindle assembly and chromosome segregation require MT motor proteins including kinesin-like proteins and cytoplasmic dynein, nonmotor MT-associated proteins (MAPs) required for the regulation of MT dynamics and other molecules, including the small GTPase Ran involved in MT polymerization during mitosis (2, 3). Proper assembly and function of the bipolar spindle is essential for genomic stability (1), and identification of key factors involved in this process as well as knowledge of their regulation are crucial.To ensure high-fidelity DNA transmission during cell division, both chromosome segregation and cytokinesis must be tightly coordinated. Cytokinesis is accomplished by the contraction of an acto-myosin ring that leads to daughter cell separation at the midbody (4). A number of studies have suggested that the temporal and spatial organization of the cytokinetic machine is under the control of the mitotic spindle (5). The spindle midzone composed of highly bundled MTs, originating from the opposite poles, plays an essential role in the initiation and completion of cell cleavage, and is the binding site for a number of proteins that play a part in cytokinesis (6). Among these proteins are passenger proteins (7-9), protein kinases (10), MT motor proteins (11, 12), and MAPs (13). However, the mechanism of central spindle assembly, the molecular basis for maintenance of the midzone MT bundle and the functional roles of these midzone-associated proteins are still largely unknown. Thus, identification of previously undescribed factors involved in both mitosis and cytokinesis may shed light on these different mechanisms.In this paper, we report the identification of...

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Section: Molecular Characterization Of Asapsupporting

confidence: 76%

ASAP, a human microtubule-associated protein required for bipolar spindle assembly and cytokinesis

Saffin

Venoux

Prigent

et al. 2005

Proc. Natl. Acad. Sci. U.S.A.

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“…Tensions in the microtubule plus end coupled to the actin cortex can be generated by three possible mechanisms: first, by coupling of MT associated motor proteins such as dynactin [45] to the actin cortex (Fig. 7); second, by activation of actin/myosin micro-muscles located at the surface of the actin cortex; third, by spontaneous local growth of domain-like actin meshworks.…”

Section: How the Viscoplastic Cytoplasmic Space Can Generate And Resimentioning

confidence: 99%

Active mechanical stabilization of the viscoplastic intracellular space of Dictyostelia cells by microtubule–actin crosstalk

Heinrich

Sackmann²

2006

Acta Biomaterialia

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The micro-viscoelasticity of the intracellular space of Dictyostelium discoideum cells is studied by evaluating the intracellular transport of magnetic force probes and their viscoelastic responses to force pulses of 20-700 pN. The role of the actin cortex, the microtubule (MT) aster and their crosstalk is explored by comparing the behaviour of wild-type cells, myosin II null mutants, latrunculin A and benomyl treated cells. The MT coupled beads perform irregular local and long range directed motions which are characterized by measuring their velocity distributions (P(v)). The correlated motion of the MT and the centrosome are evaluated by microfluorescence of GFP-labelled MTs. P(v) can be represented by log-normal distributions with long tails and it is determined by random sweeping motions (v $ 0.5 lm/s) of the MTs (caused by tangential forces on the filament ends coupled to the actin cortex) and by intermittent bead transports parallel to the MTs (v max $ 1.5 lm/s). The tails are due to spontaneous filament deflections (with speeds up to 10 lm/s) attributed to pre-stressing of the MT by local cortical tensions, generated by dynactin motors generating plus-end directed forces in the MTs. The viscoelastic responses are strongly non-linear and are mostly directed opposite or perpendicular to the force, showing that the cytoplasm behaves as an active viscoplastic body with time and force dependent drag coefficients. Nano-Newton loads exerted on the soft MT are balanced by traction forces arising at the MT ends coupled to the actin cortex and the centrosome, respectively. The mechanical coupling between the soft microtubules and the viscoelastic actin cortex provides cells with high mechanical stability despite the softness of the cytoplasm.

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“…It is driven by movement of the nucleus through a long anterior process previously extended from the cell body and has been described as underlying the movement of adenocarcinoma cells, cultured neurons, and blastomeres of C. elegans; nucleokinesis is also possibly defective in lissencephaly (Morris et al, 1998;Morris, 2000). Finally, in some specialized animal cells, such as Schwann cells (Bunge et al, 1989), as well as in interphase cells of Dictyostelium (Koonce et al, 1999) and multinucleate cells of Nitella (Allen and Allen, 1978), various uncategorized forms of nuclear movement, such as rotations and circumnavigation around the cellular periphery, have been Figure 7. Movie 6.…”

Section: Movie 4/figure 4: Aggregation Of Subnuclear Structures Withimentioning

confidence: 99%

Nuclear Dynamics inArabidopsis thaliana

Chytilová

Macas

Śliwińska

et al. 2000

MBoC

118

108

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The nucleus is a definitive feature of eukaryotic cells, comprising twin bilamellar membranes, the inner and outer nuclear membranes, which separate the nucleoplasmic and cytoplasmic compartments. Nuclear pores, complex macromolecular assemblies that connect the two membranes, mediate communication between these compartments. To explore the morphology, topology, and dynamics of nuclei within living plant cells, we have developed a novel method of confocal laser scanning fluorescence microscopy under time-lapse conditions. This is used for the examination of the transgenic expression in Arabidopsis thaliana of a chimeric protein, comprising the GFP (Green-Fluorescent Protein of Aequorea victoria) translationally fused to an effective nuclear localization signal (NLS) and to ␤-glucuronidase (GUS) from E. coli. This large protein is targeted to the nucleus and accumulates exclusively within the nucleoplasm.This article provides online access to movies that illustrate the remarkable and unusual properties displayed by the nuclei, including polymorphic shape changes and rapid, longdistance, intracellular movement. Movement is mediated by actin but not by tubulin; it therefore appears distinct from mechanisms of nuclear positioning and migration that have been reported for eukaryotes. The GFP-based assay is simple and of general applicability. It will be interesting to establish whether the novel type of dynamic behavior reported here, for higher plants, is observed in other eukaryotic organisms. INTRODUCTIONA definitive feature of eukaryotic cells is the nucleus, first described in stamen cells of Tradescantia by Robert Brown in 1831, which is found in all cell types at some stage of their development. The nucleus comprises twin bilamellar membranes, the inner and outer nuclear membranes, which serve to separate the nuclear contents, the nucleoplasm, from the cytoplasm. Communication between these compartments is mediated by nuclear pores, complex macromolecular assemblies that connect the two membranes.All of our information concerning nuclear morphology, topology, and dynamics comes from the use of various forms of microscopy. The major components of the nucleoplasm, including proteins, RNA, and DNA, do not absorb in the visible part of the spectrum. Thus, nuclei are nearly translucent and nonfluorescent. This impedes the observation of nuclei within living cells with standard bright-field or fluorescence microscopy. Although other forms of light microscopy can be used to examine nuclei, particularly phase contrast and differential interference contrast microscopy, which rely on optical properties other than absorbance and fluorescence, this is practical only in nonpigmented cells and in tissues having simple three-dimensional organization.We have developed an alternative method for observation of nuclei in living plant cells that uses confocal laser scanning fluorescence microscopy (Chytilova et al., 1999). Based on the transgenic expression of the Green Fluorescent Protein (GFP) of Aequorea victoria, it involves ...

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Dynein motor regulation stabilizes interphase microtubule arrays and determines centrosome position

Cited by 114 publications

References 48 publications

ASAP, a human microtubule-associated protein required for bipolar spindle assembly and cytokinesis

ASAP, a human microtubule-associated protein required for bipolar spindle assembly and cytokinesis

Active mechanical stabilization of the viscoplastic intracellular space of Dictyostelia cells by microtubule–actin crosstalk

Nuclear Dynamics inArabidopsis thaliana

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