Asynchronous entry into anaphase induced by okadaic acid: spindle microtubule organization and microtubule/kinetochore attachments

PROTOPLASMA ◽  
1993 ◽  
Vol 177 (1-2) ◽  
pp. 53-65 ◽  
Author(s):  
P. M. Larsen ◽  
S. M. Wolniak
Keyword(s):  
Okadaic Acid ◽  
Microtubule Organization ◽  
Spindle Microtubule

AtNUF2 modulates spindle microtubule organization and chromosome segregation during mitosis

2021 ◽  
Author(s):  
Jin Li ◽  
Yutao Wang ◽  
Wenxuan Zou ◽  
Liufang Jian ◽  
Ying Fu ◽  
...  
Keyword(s):  
Chromosome Segregation ◽  
Microtubule Organization ◽  
Spindle Microtubule

Quinacrine-induced changes in mitotic PtK1 spindle microtubule organization

1987 ◽  
Vol 7 (1) ◽  
pp. 10-19 ◽  
Author(s):  
Lydia Armstrong ◽  
Judith Armstrong Snyder
Keyword(s):  
Microtubule Organization ◽  
Spindle Microtubule ◽  
Induced Changes

Ultrastructural Features of Spindle Microtubule Organization During the Neclear Division of Encephalitozoon hellem

1997 ◽  
Vol 44 (s6) ◽  
pp. 80s-80s ◽  
Author(s):  
LUCIANO SACCHI ◽  
ELISA BIGLIARDI ◽  
PAOLO LANZARINI ◽  
SILVIA CORONA ◽  
SIMONETTA GATTI ◽  
...  
Keyword(s):  
Microtubule Organization ◽  
Spindle Microtubule

scholarly journals Tektin 2 is required for central spindle microtubule organization and the completion of cytokinesis

2008 ◽  
Vol 181 (4) ◽  
pp. 595-603 ◽  
Author(s):  
Thomas M. Durcan ◽  
Elizabeth S. Halpin ◽  
Trisha Rao ◽  
Nicholas S. Collins ◽  
Emily K. Tribble ◽  
...  
Keyword(s):  
Cell Formation ◽  
Binucleate Cell ◽  
Aurora B ◽  
Microtubule Organization ◽  
Spindle Microtubule ◽  
Central Spindle ◽  
Daughter Cells ◽  
Spindle Poles ◽  
Spindle Midzone ◽  
Interfering Rna

During anaphase, the nonkinetochore microtubules in the spindle midzone become compacted into the central spindle, a structure which is required to both initiate and complete cytokinesis. We show that Tektin 2 (Tek2) associates with the spindle poles throughout mitosis, organizes the spindle midzone microtubules during anaphase, and assembles into the midbody matrix surrounding the compacted midzone microtubules during cytokinesis. Tek2 small interfering RNA (siRNA) disrupts central spindle organization and proper localization of MKLP1, PRC1, and Aurora B to the midzone and prevents the formation of a midbody matrix. Video microscopy revealed that loss of Tek2 results in binucleate cell formation by aberrant fusion of daughter cells after cytokinesis. Although a myosin II inhibitor, blebbistatin, prevents actin-myosin contractility, the microtubules of the central spindle are compacted. Strikingly, Tek2 siRNA abolishes this actin-myosin–independent midzone microtubule compaction. Thus, Tek2-dependent organization of the central spindle during anaphase is essential for proper midbody formation and the segregation of daughter cells after cytokinesis.

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

2009 ◽  
Vol 20 (6) ◽  
pp. 1639-1651 ◽  
Author(s):  
Rania S. Rizk ◽  
Kevin P. Bohannon ◽  
Laura A. Wetzel ◽  
James Powers ◽  
Sidney L. Shaw ◽  
...  
Keyword(s):  
Fluorescence Intensity ◽  
Mitotic Spindle ◽  
Fluorescence Recovery After Photobleaching ◽  
Microtubule Dynamics ◽  
Microtubule Organization ◽  
Spindle Microtubule ◽  
Quantitative Immunofluorescence ◽  
Spindle Microtubules ◽  
Low Levels ◽  
Paclitaxel Treatment

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 t1/2 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 t1/2 of K-fibers but no change in the t1/2 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.

scholarly journals Cytoskeletal reorganization of human platelets induced by the protein phosphatase 1/2 A inhibitors okadaic acid and calyculin A

1995 ◽  
Vol 307 (2) ◽  
pp. 439-449 ◽  
Author(s):  
Y Yano ◽  
M Sakon ◽  
J Kambayashi ◽  
T Kawasaki ◽  
T Senda ◽  
...  
Keyword(s):  
Okadaic Acid ◽  
Actin Filaments ◽  
Actin Polymerization ◽  
Molecular Mechanisms ◽  
Human Platelets ◽  
Calyculin A ◽  
Cytoskeletal Reorganization ◽  
Microtubule Organization ◽  
Electron Microscopic ◽  
Activated Platelets

Okadaic acid (OA) and calyculin A (CLA), which are potent and specific inhibitors of serine/threonine protein phosphatases type 1 and 2A, have been shown to induce drastic changes in platelet morphology. The aim of this study was to analyse the molecular mechanisms of OA- or CLA-induced cytoskeletal reorganization, with a specific focus on microtubules and actin filaments. Confocal fluorescence microscopy revealed that OA or CLA altered the distribution of microtubules from marginal band arrangements to homogeneous patterns, consistent with the transmission-electron-microscopic finding that microtubules were fragmented and redistributed into pseudopod-like processes. In thrombin-activated platelets, OA or CLA induced extremely long pseudopods containing an array of microtubules and actin filaments, and a condensed mass of actin filaments in the centre of platelets. OA or CLA induced the constriction of actin filaments without an increase in filamentous (F)-actin, and also rather significantly inhibited actin polymerization in thrombin-activated platelets. Furthermore, neither OA or CLA enhanced phosphorylation of myosin light chain (MLC). By immunoprecipitation of platelet lysate with anti-alpha-tubulin antibody, a 90 kDa protein was co-precipitated with tubulin and was predominantly phosphorylated in the presence of OA. As the time-dependent phosphorylation of 90 kDa protein correlated well with the reorganization of microtubules, these data suggest that phosphorylation and dephosphorylation of this protein might play a role in the regulation of microtubule organization. These findings indicate that OA or CLA induces reorganization of microtubules and actin filaments via the phosphorylation of a microtubule-associated 90 kDa protein and an MLC-phosphorylation-independent mechanism. mechanism.

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