KSP Mitotic Spindle Motor Protein

The Drosophila microtubule motor protein, nonclaret disjunctional (ncd), is required for proper chromosome distribution in meiosis and mitosis. We have examined the meiotic and mitotic divisions in wild-type Drosophila oocytes and early embryos, and the effects of three ncd mutants (cand, ncd and ncdD) on spindle structure and chromosome movement. The ncd mutants cause abnormalities in spindle structure early in meiosis I, and abnormal chromosome configurations throughout meiosis I and II. Defective divisions continue in early embryos of the motor null mutant, cand, with abnormal early mitotic spindles. The effects of mutants on spindle structure suggest that ncd is required for proper meiotic spindle assembly, and may play a role in forming or maintaining spindle poles in meiosis. The disruption of normal meiotic and mitotic chromosome distribution by ncd mutants can be attributed to its role as a spindle motor, although a role for ncd as a chromosome-associated motor protein is not excluded. The ncd motor protein functions not only in meiosis, but also performs an active role in the early mitotic divisions of the embryo.

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Use of GFP Fusions to a Microtubule Motor Protein to Analyze Spindle Dynamics in Live Oocytes and Embryos of Drosophila

Microscopy and Microanalysis ◽

10.1017/s1431927600007522 ◽

1997 ◽

Vol 3 (S2) ◽

pp. 127-128

Author(s):

S. A. Endow ◽

D. J. Komma

Keyword(s):

Fusion Proteins ◽

Motor Protein ◽

Spindle Motor ◽

Gene Fusions ◽

Mitotic Spindles ◽

Wild Type ◽

Early Embryos ◽

Microtubule Motor ◽

Microtubule Motor Protein ◽

Spindle Fibers

Ncd is a kinesin-related microtubule motor protein of Drosophila that plays essential roles in spindle assembly and function during meiosis in oocytes and mitosis in early embryos. Antibody staining experiments have localized the Ned motor protein to spindle fibers and spindle poles throughout the meiotic and early mitotic divisions, demonstrating that Ncd is a spindle motor.We have made ncd-gfp gene fusions with wild-type and S65T gfp and expressed the chimaeric genes in Drosophila to target GFP to the spindle. Transgenic Drosophila carrying the ncd-gfp gene fusions in an ncd null mutant background are wild type with respect to chromosome segregation, indicating that the Ncd-GFP fusion proteins can replace the function of wild-type Ncd. The Ncd-GFP fusion proteins in transgenic Drosophila are expressed under the regulation of the native ncd promoter.Analysis of live Drosophila oocytes and early embryos shows green fluorescent spindles, demonstrating association of Ncd-GFP with meiotic and mitotic spindles. In mitotic spindles, Ncd-GFP localizes to centrosomes (Fig. 1a) and spindle fibers (Fig. 1b).

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Mitotic Kinesin-Like Protein 2 Binds and Colocalizes with Papillomavirus E2 during Mitosis

Journal of Virology ◽

10.1128/jvi.01638-06 ◽

2006 ◽

Vol 81 (4) ◽

pp. 1736-1745 ◽

Cited By ~ 17

Author(s):

Ting Yu ◽

Yu-Cai Peng ◽

Elliot J. Androphy

Keyword(s):

Cell Cycle ◽

Mitotic Spindle ◽

Chromatin Immunoprecipitation ◽

Viral Genome ◽

Motor Protein ◽

Dna Binding Protein ◽

E2 Protein ◽

Viral Genomes ◽

Daughter Cells ◽

Transcription And Replication

ABSTRACT MKlp2 is a kinesin-like motor protein of the central mitotic spindle required for completion of cytokinesis. Papillomavirus E2 is a sequence specific DNA binding protein that regulates viral transcription and replication and is responsible for partitioning viral episomes into daughter cells during cell division. We demonstrate that MKlp2 specifically associates with the E2 protein during mitosis. Using chromatin immunoprecipitation, we show viral genomes are in complex with MKlp2 only within this stage of cell cycle. By immunofluorescence, a subpopulation of papillomavirus E2 colocalizes with MKlp2 in the midbody/midplate during late mitosis. We conclude that during specific stages of mitosis, the papillomavirus E2 protein binds to MKlp2, and infer that association with this motor protein ensures viral genome partitioning during cytokinesis.

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Expression of a minus-end-directed motor protein induces Sf9 cells to form axon-like processes with uniform microtubule polarity orientation

Journal of Cell Science ◽

10.1242/jcs.110.19.2373 ◽

1997 ◽

Vol 110 (19) ◽

pp. 2373-2380

Author(s):

D.J. Sharp ◽

R. Kuriyama ◽

R. Essner ◽

P.W. Baas

Keyword(s):

Molecular Motors ◽

Mitotic Spindle ◽

Morphological Characteristics ◽

Motor Protein ◽

Motor Domain ◽

Sf9 Cells ◽

Atp Binding Site ◽

Microtubule Polarity ◽

Process Formation ◽

Induce Process

Neurons extend two types of processes with distinct morphologies and patterns of microtubule polarity orientation. Axons are thin cylindrical processes containing microtubules that are uniformly oriented with their plus-ends-distal to the cell body while dendrites are stout tapering processes that contain nonuniformly oriented microtubules. We have proposed that these distinct microtubule patterns are established by molecular motors that transport microtubules into each type of process with the appropriate orientation. To test the feasibility of this proposal, we have embarked on a series of studies involving the expression of vertebrate motors in insect Sf9 cells. We previously focused on a kinesin-related protein termed CHO1/MKLP1, which localizes to the midzone of the mitotic spindle, and which has been shown to have the appropriate properties to transport microtubules of opposite orientation relative to one another. Expression of a fragment of CHO1/MKLP1 containing its motor domain induces Sf9 cells to extend processes with a stout tapering morphology and a nonuniform microtubule polarity pattern similar to dendrites. Here we focus on a minus-end-directed kinesin-related motor protein termed CHO2, which localizes to the non-overlapping regions of the mitotic spindle, and which has been shown to have the appropriate properties to transport microtubules with plus-ends-leading. Sf9 cells induced to express a fragment of CHO2 containing its motor domain extend processes with a long cylindrical morphology and a uniformly plus-end-distal microtubule polarity pattern similar to axons. These results show that motor proteins have the capacity to organize distinct patterns of microtubule polarity orientation during process outgrowth, and that these patterns are intimately related to the unique morphological characteristics of the processes. Moreover, mutation of three amino acids corresponding to the ATP binding site necessary for motor function suppresses the capacity of the CHO2 fragment to induce process formation and microtubule reorganization, indicating that at least in the case of CHO2, the transport properties of the motor are essential for it to elicit these effects.

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Kinesin-5 regulates the growth of the axon by acting as a brake on its microtubule array

The Journal of Cell Biology ◽

10.1083/jcb.200702074 ◽

2007 ◽

Vol 178 (6) ◽

pp. 1081-1091 ◽

Cited By ~ 106

Author(s):

Kenneth A. Myers ◽

Peter W. Baas

Keyword(s):

Growth Rates ◽

Mitotic Spindle ◽

Live Cell Imaging ◽

Cell Imaging ◽

Motor Protein ◽

Live Cell ◽

Cultured Neurons ◽

Wild Type ◽

Microtubule Array ◽

Inverse Effect

Kinesin-5 is a homotetrameric motor protein that interacts with adjacent microtubules in the mitotic spindle. Kinesin-5 is also highly expressed in developing postmitotic neurons. Axons of cultured neurons experimentally depleted of kinesin-5 grow up to five times longer than controls and display more branches. The faster growth rates are accompanied by a doubling of the frequency of transport of short microtubules, suggesting a major role for kinesin-5 in the balance of motor-driven forces on the axonal microtubule array. Live-cell imaging reveals that the effects on axonal length of kinesin-5 depletion are caused partly by a lower propensity of the axon and newly forming branches to undergo bouts of retraction. Overexpression of wild-type kinesin-5, but not a rigor mutant of kinesin-5, has the inverse effect on axonal length. These results indicate that kinesin-5 imposes restrictions on the growth of the axon and does so at least in part by generating forces on the axonal microtubule array.

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Effects of kinesin-5 inhibition on dendritic architecture and microtubule organization

Molecular Biology of the Cell ◽

10.1091/mbc.e14-08-1313 ◽

2015 ◽

Vol 26 (1) ◽

pp. 66-77 ◽

Cited By ~ 37

Author(s):

Olga I. Kahn ◽

Vandana Sharma ◽

Christian González-Billault ◽

Peter W. Baas

Keyword(s):

Growth Cone ◽

Mitotic Spindle ◽

Essential Role ◽

Additional Data ◽

Motor Protein ◽

Dendritic Morphology ◽

Primary Neurons ◽

Microtubule Organization ◽

Tyrosinated Tubulin

Kinesin-5 is a slow homotetrameric motor protein best known for its essential role in the mitotic spindle, where it limits the rate at which faster motors can move microtubules. In neurons, experimental suppression of kinesin-5 causes the axon to grow faster by increasing the mobility of microtubules in the axonal shaft and the invasion of microtubules into the growth cone. Does kinesin-5 act differently in dendrites, given that they have a population of minus end–distal microtubules not present in axons? Using rodent primary neurons in culture, we found that inhibition of kinesin-5 during various windows of time produces changes in dendritic morphology and microtubule organization. Specifically, dendrites became shorter and thinner and contained a greater proportion of minus end–distal microtubules, suggesting that kinesin-5 acting normally restrains the number of minus end–distal microtubules that are transported into dendrites. Additional data indicate that, in neurons, CDK5 is the kinase responsible for phosphorylating kinesin-5 at Thr-926, which is important for kinesin-5 to associate with microtubules. We also found that kinesin-5 associates preferentially with microtubules rich in tyrosinated tubulin. This is consistent with an observed accumulation of kinesin-5 on dendritic microtubules, as they are known to be less detyrosinated than axonal microtubules.

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