The spindle: a dynamic assembly of microtubules and motors

Wittmann, Torsten; Hyman, Anthony; Desai, Arshad

doi:10.1038/35050669

Cited by 473 publications

(410 citation statements)

References 116 publications

Supporting

Mentioning

390

Contrasting

Unclassified

Order By: Relevance

“…Interestingly, the reaction cycles of these proteins are tightly coupled to their diffusion 21 . More specifically, we investigate the Ran/RCC1 signalling network, which regulates microtubule self-assembly during mitosis [22][23][24][25][26] . To spatially control microtubule assembly, we first conjugate superparamagnetic nanoparticles to RanGTP (Ran-NPs) and RCC1 (RCC1-NPs) proteins and demonstrate the efficiency of the magnetic modulation of signalling pathways in cell extracts.…”

mentioning

confidence: 99%

Spatiotemporal control of microtubule nucleation and assembly using magnetic nanoparticles

et al. 2013

View full text Add to dashboard Cite

Decisions on the fate of cells and their functions are dictated by the spatiotemporal dynamics of molecular signalling networks. However, techniques to examine the dynamics of these intracellular processes remain limited. Here, we show that magnetic nanoparticles conjugated with key regulatory proteins can artificially control, in time and space, the Ran/RCC1 signalling pathway that regulates the cell cytoskeleton. In the presence of a magnetic field, RanGTP proteins conjugated to superparamagnetic nanoparticles can induce microtubule fibres to assemble into asymmetric arrays of polarized fibres in Xenopus laevis egg extracts. The orientation of the fibres is dictated by the direction of the magnetic force. When we locally concentrated nanoparticles conjugated with the upstream guanine nucleotide exchange factor RCC1, the assembly of microtubule fibres could be induced over a greater range of distances than RanGTP particles. The method shows how bioactive nanoparticles can be used to engineer signalling networks and spatial self-organization inside a cell environment.

show abstract

mentioning

confidence: 99%

Spatiotemporal control of microtubule nucleation and assembly using magnetic nanoparticles

et al. 2013

View full text Add to dashboard Cite

show abstract

“…A major question be- comes: to what extent can specific cellular factors influence the spatial and temporal coordination of MT dynamics? Several families of proteins alter MT turnover in cells, including both MT-stabilizing and MT-destabilizing proteins (Wittmann et al, 2001;Scholey et al, 2003). Of particular interest are members of the kinesin superfamily that regulate the polymerization dynamics of MTs (Wordeman, 2005;Moores and Milligan, 2006;Howard and Hyman, 2007).…”

Section: Introductionmentioning

confidence: 99%

MCAK and Paclitaxel Have Differential Effects on Spindle Microtubule Organization and Dynamics

Rizk

Bohannon

Wetzel

et al. 2009

MBoC

View full text Add to dashboard Cite

Within the mitotic spindle, there are multiple populations of microtubules with different turnover dynamics, but how these different dynamics are maintained is not fully understood. MCAK is a member of the kinesin-13 family of microtubule-destabilizing enzymes that is required for proper establishment and maintenance of the spindle. Using quantitative immunofluorescence and fluorescence recovery after photobleaching, we compared the differences in spindle organization caused by global suppression of microtubule dynamics, by treating cells with low levels of paclitaxel, versus specific perturbation of spindle microtubule subsets by MCAK inhibition. Paclitaxel treatment caused a disruption in spindle microtubule organization marked by a significant increase in microtubules near the poles and a reduction in K-fiber fluorescence intensity. This was correlated with a faster t 1/2 of both spindle and K-fiber microtubules. In contrast, MCAK inhibition caused a dramatic reorganization of spindle microtubules with a significant increase in astral microtubules and reduction in K-fiber fluorescence intensity, which correlated with a slower t 1/2 of K-fibers but no change in the t 1/2 of spindle microtubules. Our data support the model that MCAK perturbs spindle organization by acting preferentially on a subset of microtubules, and they support the overall hypothesis that microtubule dynamics is differentially regulated in the spindle. INTRODUCTIONThe cytoskeleton must undergo dramatic reorganization as cells transition from interphase to mitosis to assemble the mitotic spindle. The spindle is a macromolecular structure composed of a dynamic array of microtubules (MTs) and their associated proteins that is necessary for proper chromosome segregation (Compton, 2000;Walczak and Heald, 2008). At the onset of mitosis, there is an increase in MT turnover that allows for breakdown of the interphase array and assembly of the mitotic spindle (Saxton et al., 1984;. This change is correlated with an increased catastrophe frequency (transition from growth to shrinkage) and a decreased rescue frequency (transition from shrinkage to growth) (Belmont et al., 1990;Gliksman et al., 1992;Verde et al., 1992;Rusan et al., 2001). The changes in MT dynamics are also correlated with a change in MT polymer levels during mitosis (Zhai et al., 1996). At nuclear envelope breakdown, there is a dramatic decrease in MT polymer levels, which may allow the cell to rapidly assemble a mitotic spindle because the released tubulin dimers can polymerize into new spindle MTs. As the cell progresses from mitosis to the next interphase, there is no change in the levels of MT polymer (Zhai et al., 1996), suggesting that MT polymer gets reorganized to reform the interphase MT cytoskeleton, without a significant change in the dynamics of the MTs. These studies highlight the need for the cell to possess a mechanism to temporally regulate MT dynamics.In addition to the temporal changes in dynamics throughout the cell cycle, the dynamics of MTs within mitosis are also...

show abstract

“…Dynamic microtubules are essential because they serve several critical mitotic functions including, for example, generating and positioning the spindle, searching for and docking with kinetochores, congressing and segregating chromosomes, and performing a central role in the spindle checkpoint (Wittmann et al, 2001;Kline-Smith and Walczak, 2004). A particularly dramatic manifestation of spindle dynamics is poleward flux: the minus-end-directed flow of tubulin subunits through spindle microtubules, driven by the disassembly of microtubules at their minus ends (oriented toward the spindle poles) and assembly at their plus ends (oriented toward the spindle equator; Rogers et al, 2004;Mitchison, 2005).…”

Section: Introductionmentioning

confidence: 99%

Poleward Tubulin Flux in Spindles: Regulation and Function in Mitotic Cells

Buster

Zhang

Sharp

2007

MBoC

View full text Add to dashboard Cite

The poleward flux of tubulin subunits through spindle microtubules is a striking and conserved phenomenon whose function and molecular components remain poorly understood. To screen for novel components of the flux machinery, we utilized RNA interference to deplete regulators of microtubule dynamics, individually and in various combinations, from S2 cells and examined the resulting impact on flux rate. This led to the identification of two previously unknown flux inhibitors, KLP59C and KLP67A, and a flux promoter, Mini-spindles. Furthermore, we find that flux rate is regulated by functional antagonism among microtubule stabilizers and destabilizers specifically at plus ends. Finally, by examining mitosis on spindles in which flux has been up-or down-regulated or restored after the codepletion of antagonistic flux regulators, we show that flux is an integral contributor to anaphase A but is not responsible for chromosome congression, interkinetochore tension, or the establishment of normal spindle length during prometaphase/metaphase.

show abstract

The spindle: a dynamic assembly of microtubules and motors

Cited by 473 publications

References 116 publications

Spatiotemporal control of microtubule nucleation and assembly using magnetic nanoparticles

Spatiotemporal control of microtubule nucleation and assembly using magnetic nanoparticles

MCAK and Paclitaxel Have Differential Effects on Spindle Microtubule Organization and Dynamics

Poleward Tubulin Flux in Spindles: Regulation and Function in Mitotic Cells

Contact Info

Product

Resources

About