101
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Shimizu Y, Shimizu T, Nara M, Kikumoto M, Kojima H, Morii H. Effects of the KIF2C neck peptide on microtubules: lateral disintegration of microtubules and β-structure formation. FEBS J 2013; 280:1681-92. [PMID: 23398918 DOI: 10.1111/febs.12182] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2012] [Revised: 01/23/2013] [Accepted: 02/07/2013] [Indexed: 11/29/2022]
Abstract
Members of the kinesin-13 sub-family, including KIF2C, depolymerize microtubules. The positive charge-rich 'neck' region extending from the N-terminus of the catalytic head is considered to be important in the depolymerization activity. Chemically synthesized peptides, covering the basic region (A182-E200), induced a sigmoidal increase in the turbidity of a microtubule suspension. The increase was suppressed by salt addition or by reduction of basicity by amino acid substitutions. Electron microscopic observations revealed ring structures surrounding the microtubules at high peptide concentrations. Using the peptide A182-D218, we also detected free thin straight filaments, probably protofilaments disintegrated from microtubules. Therefore, the neck region, even without the catalytic head domain, may induce lateral disintegration of microtubules. With microtubules lacking anion-rich C-termini as a result of subtilisin treatment, addition of the peptide induced only a moderate increase in turbidity, and rings and protofilaments were rarely detected, while aggregations, also thought to be caused by lateral disintegration, were often observed in electron micrographs. Thus, the C-termini are not crucial for the action of the peptides in lateral disintegration but contribute to structural stabilization of the protofilaments. Previous structural studies indicated that the neck region of KIF2C is flexible, but our IR analysis suggests that the cation-rich region (K190-A204) forms β-structure in the presence of microtubules, which may be of significance with regard to the action of the neck region. Therefore, the neck region of KIF2C is sufficient to cause disintegration of microtubules into protofilaments, and this may contribute to the ability of KIF2C to cause depolymerization of microtubules.
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Affiliation(s)
- Youské Shimizu
- National Institute of Information and Communications Technology (NICT), Advanced ICT Research Institute, Hyogo, Japan
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102
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Goulet A, Moores C. New insights into the mechanism of force generation by kinesin-5 molecular motors. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2013; 304:419-66. [PMID: 23809441 DOI: 10.1016/b978-0-12-407696-9.00008-7] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Kinesin-5 motors are members of a superfamily of microtubule-dependent ATPases and are widely conserved among eukaryotes. Kinesin-5s typically form homotetramers with pairs of motor domains located at either end of a dumbbell-shaped molecule. This quaternary structure enables cross-linking and ATP-driven sliding of pairs of microtubules, although the exact molecular mechanism of this activity is still unclear. Kinesin-5 function has been characterized in greatest detail in cell division, although a number of interphase roles have also been defined. The kinesin-5 ATPase is tuned for slow microtubule sliding rather than cellular transport and-in vertebrates-can be inhibited specifically by allosteric small molecules currently in cancer clinical trials. The biophysical and structural basis of kinesin-5 mechanochemistry is being elucidated and has provided further insight into kinesin-5 activities. However, it is likely that the precise mechanism of these important motors has evolved according to functional context and regulation in individual organisms.
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Affiliation(s)
- Adeline Goulet
- Institute of Structural and Molecular Biology, Birkbeck College, London, United Kingdom
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103
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Welburn JPI, Cheeseman IM. The microtubule-binding protein Cep170 promotes the targeting of the kinesin-13 depolymerase Kif2b to the mitotic spindle. Mol Biol Cell 2012; 23:4786-95. [PMID: 23087211 PMCID: PMC3521686 DOI: 10.1091/mbc.e12-03-0214] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
The N-terminus of the kinesin-13 family (Kif2a, Kif2b, Kif2c) is the primary localization determinant. However, the C-terminus of Kif2b associates with Cep170 and Cep170R to create targeting specificity. Cep170 has microtubule-binding properties in vitro and provides a second microtubule-binding site to Kif2b to target it to the spindle. Microtubule dynamics are essential throughout mitosis to ensure correct chromosome segregation. Microtubule depolymerization is controlled in part by microtubule depolymerases, including the kinesin-13 family of proteins. In humans, there are three closely related kinesin-13 isoforms (Kif2a, Kif2b, and Kif2c/MCAK), which are highly conserved in their primary sequences but display distinct localization and nonoverlapping functions. Here we demonstrate that the N-terminus is a primary determinant of kinesin-13 localization. However, we also find that differences in the C-terminus alter the properties of kinesin-13, in part by facilitating unique protein–protein interactions. We identify the spindle-localized proteins Cep170 and Cep170R (KIAA0284) as specifically associating with Kif2b. Cep170 binds to microtubules in vitro and provides Kif2b with a second microtubule-binding site to target it to the spindle. Thus the intrinsic properties of kinesin-13s and extrinsic factors such as their associated proteins result in the diversity and specificity within the kinesin-13 depolymerase family.
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Affiliation(s)
- Julie P I Welburn
- Whitehead Institute for Biomedical Research and Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02142, USA.
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104
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Portran D, Gaillard J, Vantard M, Thery M. Quantification of MAP and molecular motor activities on geometrically controlled microtubule networks. Cytoskeleton (Hoboken) 2012; 70:12-23. [DOI: 10.1002/cm.21081] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2012] [Accepted: 09/17/2012] [Indexed: 11/08/2022]
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105
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Talapatra SK, Schüttelkopf AW, Kozielski F. The structure of the ternary Eg5-ADP-ispinesib complex. ACTA CRYSTALLOGRAPHICA. SECTION D, BIOLOGICAL CRYSTALLOGRAPHY 2012; 68:1311-9. [PMID: 22993085 PMCID: PMC3447400 DOI: 10.1107/s0907444912027965] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/31/2012] [Accepted: 06/20/2012] [Indexed: 11/17/2022]
Abstract
The human kinesin Eg5 is responsible for bipolar spindle formation during early mitosis. Inhibition of Eg5 triggers the formation of monoastral spindles, leading to mitotic arrest that eventually causes apoptosis. There is increasing evidence that Eg5 constitutes a potential drug target for the development of cancer chemotherapeutics. The most advanced Eg5-targeting agent is ispinesib, which exhibits potent antitumour activity and is currently in multiple phase II clinical trials. In this study, the crystal structure of the Eg5 motor domain in complex with ispinesib, supported by kinetic and thermodynamic binding data, is reported. Ispinesib occupies the same induced-fit pocket in Eg5 as other allosteric inhibitors, making extensive hydrophobic interactions with the protein. The data for the Eg5-ADP-ispinesib complex suffered from pseudo-merohedral twinning and revealed translational noncrystallographic symmetry, leading to challenges in data processing, space-group assignment and structure solution as well as in refinement. These complications may explain the lack of available structural information for this important agent and its analogues. The present structure represents the best interpretation of these data based on extensive data-reduction, structure-solution and refinement trials.
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Affiliation(s)
- S. K. Talapatra
- Molecular Motor Laboratory, The Beatson Institute for Cancer Research, Garscube Estate, Switchback Road, Bearsden, Glasgow G61 1BD, Scotland, UK
| | - A. W. Schüttelkopf
- Molecular Motor Laboratory, The Beatson Institute for Cancer Research, Garscube Estate, Switchback Road, Bearsden, Glasgow G61 1BD, Scotland, UK
| | - F. Kozielski
- Molecular Motor Laboratory, The Beatson Institute for Cancer Research, Garscube Estate, Switchback Road, Bearsden, Glasgow G61 1BD, Scotland, UK
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106
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Kleylein-Sohn J, Pöllinger B, Ohmer M, Hofmann F, Nigg EA, Hemmings BA, Wartmann M. Acentrosomal spindle organization renders cancer cells dependent on the kinesin HSET. J Cell Sci 2012; 125:5391-402. [PMID: 22946058 DOI: 10.1242/jcs.107474] [Citation(s) in RCA: 74] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Centrosomes represent the major microtubule organizing centers (MTOCs) of animal somatic cells and orchestrate bipolar spindle assembly during mitotic cell division. In meiotic cells, the kinesin HSET compensates for the lack of centrosomes by focusing acentrosomal MTOCs into two spindle poles. By clustering multiple centrosomes into two spindle poles, HSET also mediates bipolar mitosis in cancer cells with supernumerary centrosomes. However, although dispensable in non-transformed human cells, the role of HSET in cancer cells with two centrosomes has remained elusive. In this study, we demonstrate that HSET is required for proper spindle assembly, stable pole-focusing and survival of cancer cells irrespective of normal or supernumerary centrosome number. Strikingly, we detected pronounced acentrosomal MTOC structures in untreated mitotic cancer cells. While in most cancer cells these acentrosomal MTOCs were rapidly incorporated into the assembling bipolar spindle, some cells eventually established bipolar spindles with acentrosomal poles and free centrosomes. These observations demonstrate that acentrosomal MTOCs were functional and that both centrosomal and acentrosomal mechanisms were required for bipolar spindle organization. Our study shows that HSET is critical for clustering acentrosomal and centrosomal MTOCs during spindle formation in human cancer cells with two bona fide centrosomes. Furthermore, we show that in checkpoint-defective cancer cells, acentrosomal spindle formation and HSET-dependence are partially mediated by a constitutive activation of the DNA damage response. In summary, we propose that acentrosomal spindle assembly mechanisms are hyperactive in cancer cells and promote HSET, a key driver of acentrosomal spindle organization, as an attractive target for cancer therapy.
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107
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Abstract
Kinesins are a family of molecular motors that travel unidirectionally along microtubule tracks to fulfil their many roles in intracellular transport or cell division. Over the past few years kinesins that are involved in mitosis have emerged as potential targets for cancer drug development. Several compounds that inhibit two mitotic kinesins (EG5 (also known as KIF11) and centromere-associated protein E (CENPE)) have entered Phase I and II clinical trials either as monotherapies or in combination with other drugs. Additional mitotic kinesins are currently being validated as drug targets, raising the possibility that the range of kinesin-based drug targets may expand in the future.
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Affiliation(s)
- Oliver Rath
- The Beatson Institute for Cancer Research, Garscube Estate, Switchback Road, Bearsden, Glasgow G61 1BD, Scotland, UK
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108
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Abstract
In this essay I describe my personal journey from reductionist to systems cell biology and describe how this in turn led to a 3-year sea voyage to explore complex ocean communities. In describing this journey, I hope to convey some important principles that I gleaned along the way. I realized that cellular functions emerge from multiple molecular interactions and that new approaches borrowed from statistical physics are required to understand the emergence of such complex systems. Then I wondered how such interaction networks developed during evolution. Because life first evolved in the oceans, it became a natural thing to start looking at the small organisms that compose the plankton in the world's oceans, of which 98% are … individual cells—hence the Tara Oceans voyage, which finished on 31 March 2012 in Lorient, France, after a 60,000-mile around-the-world journey that collected more than 30,000 samples from 153 sampling stations.
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Affiliation(s)
- Eric Karsenti
- European Molecular Biology Laboratory, D69117 Heidelberg, Germany.
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109
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Hu H, Hu L, Yu Z, Chasse AE, Chu F, Li Z. An orphan kinesin in trypanosomes cooperates with a kinetoplastid-specific kinesin to maintain cell morphology by regulating subpellicular microtubules. J Cell Sci 2012; 125:4126-36. [PMID: 22623724 DOI: 10.1242/jcs.106534] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Microtubules are a vital part of the cytoskeleton of eukaryotic cells and are involved in various cellular processes. The cytoskeleton of Trypanosoma brucei is characterized by an array of subpellicular microtubules and is essential for maintenance of cell shape and polarity, but little is known about the regulation of the assembly and organization of the subpellicular microtubule corset. Here, we report that the orphan kinesin TbKIN-D regulates the organization of subpellicular microtubules and is required for maintaining cell morphology. TbKIN-D possesses in vitro ATPase activity, associates with cytoskeletal microtubules and is distributed throughout the cytoskeleton at all cell cycle stages. RNAi of TbKIN-D disrupts the organization of the subpellicular microtubule corset and distorts cell morphology, resulting in round cells with an elongated posterior filled with newly assembled microtubules. Depletion of TbKIN-D also abolishes the segregation of organelles and cytoskeletal structures, suggesting that cellular morphogenesis is essential for proper organelle segregation. Moreover, TbKIN-D deficiency impairs the attachment of the new flagellum without compromising the formation of the flagellum attachment zone. Finally, we identified TbKIN-C, a kinetoplastid-specific kinesin known to regulate subpellicular microtubules and cell morphogenesis in T. brucei, as a partner of TbKIN-D. Further, we demonstrate that interaction between TbKIN-C and TbKIN-D requires the coiled-coil motifs in the C-termini of both proteins. Altogether, our results suggest that TbKIN-D cooperates with TbKIN-C to maintain cell morphology by regulating the organization of the subpellicular microtubule corset.
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Affiliation(s)
- Huiqing Hu
- Department of Microbiology and Molecular Genetics, University of Texas Medical School, Houston, TX 77030, USA
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110
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Telikicherla D, Maharudraiah J, Pawar H, Marimuthu A, Kashyap MK, Ramachandra YL, Roa JC, Pandey A. Overexpression of Kinesin Associated Protein 3 (KIFAP3) in Breast Cancer. JOURNAL OF PROTEOMICS & BIOINFORMATICS 2012; 5:122-126. [PMID: 26843789 PMCID: PMC4734396 DOI: 10.4172/jpb.1000223] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Gene expression profiling studies on breast cancer have generated catalogs of differentially expressed genes. However, many of these genes have not been investigated for their expression at the protein level. It is possible to systematically evaluate such genes in a high-throughput fashion for their overexpression at the protein level using breast cancer tissue microarrays. Our strategy involved integration of information from publicly available repositories of gene expression to prepare a list of genes upregulated at the mRNA level in breast cancer followed by curation of the published literature to identify those genes that were not tested for overexpression at the protein level. We identified Kinesin Associated Protein 3 (KIFAP3) as one such molecule for further validation at the protein level. Immunohistochemical labeling of KIFAP3 using breast cancer tissue microarrays revealed overexpression of KIFAP3 protein in 84% (240/285) of breast cancers indicating the utility of our integrated approach of combining computational analysis with experimental biology.
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Affiliation(s)
- Deepthi Telikicherla
- Institute of Bioinformatics, International Tech Park, Bangalore-560 066, India
- Department of Biotechnology, Kuvempu University, Shankaraghatta-577451, India
| | - Jagadeesha Maharudraiah
- Institute of Bioinformatics, International Tech Park, Bangalore-560 066, India
- Department of Pathology, Raja Rajeshwari Medical College and Hospital, Bangalore-560074, India
- Manipal University, Madhav Nagar, Manipal-576104, India
| | - Harsh Pawar
- Institute of Bioinformatics, International Tech Park, Bangalore-560 066, India
- Rajiv Gandhi University of Health Sciences, Bangalore-560041, India
- Department of Pathology, Kidwai Memorial Institute of Oncology, Bangalore-560029, India
| | | | - Manoj Kumar Kashyap
- Institute of Bioinformatics, International Tech Park, Bangalore-560 066, India
| | - Y. L. Ramachandra
- Department of Biotechnology, Kuvempu University, Shankaraghatta-577451, India
| | - Juan Carlos Roa
- Department of Pathology, Universidad de La Frontera, Temuco, Chile
| | - Akhilesh Pandey
- McKusick-Nathans Institute of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
- Departments of Biological Chemistry, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
- Department of Pathology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
- Department of Oncology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
- Corresponding author: Akhilesh Pandey M.D., Ph.D., McKusick-Nathans Institute of Genetic Medicine, 733 N. Broadway, BRB 527, Johns Hopkins University, Baltimore, MD 21205, USA, Tel: 410-502-6662; Fax: 410-502-7544;
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111
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Muresan V, Muresan Z. Unconventional functions of microtubule motors. Arch Biochem Biophys 2012; 520:17-29. [PMID: 22306515 PMCID: PMC3307959 DOI: 10.1016/j.abb.2011.12.029] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2011] [Revised: 12/21/2011] [Accepted: 12/23/2011] [Indexed: 11/21/2022]
Abstract
With the functional characterization of proteins advancing at fast pace, the notion that one protein performs different functions - often with no relation to each other - emerges as a novel principle of how cells work. Molecular motors are no exception to this new development. Here, we provide an account on recent findings revealing that microtubule motors are multifunctional proteins that regulate many cellular processes, in addition to their main function in transport. Some of these functions rely on their motor activity, but others are independent of it. Of the first category, we focus on the role of microtubule motors in organelle biogenesis, and in the remodeling of the cytoskeleton, especially through the regulation of microtubule dynamics. Of the second category, we discuss the function of microtubule motors as static anchors of the cargo at the destination, and their participation in regulating signaling cascades by modulating interactions between signaling proteins, including transcription factors. We also review atypical forms of transport, such as the cytoplasmic streaming in the oocyte, and the movement of cargo by microtubule fluctuations. Our goal is to provide an overview of these unexpected functions of microtubule motors, and to incite future research in this expanding field.
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Affiliation(s)
- Virgil Muresan
- Department of Pharmacology and Physiology, University of Medicine and Dentistry of New Jersey, New Jersey Medical School, Newark, New Jersey 07103, U.S.A
| | - Zoia Muresan
- Department of Pharmacology and Physiology, University of Medicine and Dentistry of New Jersey, New Jersey Medical School, Newark, New Jersey 07103, U.S.A
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112
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Abstract
Cell cycle deregulation is a common feature of human cancer. Tumor cells accumulate mutations that result in unscheduled proliferation, genomic instability and chromosomal instability. Several therapeutic strategies have been proposed for targeting the cell division cycle in cancer. Whereas inhibiting the initial phases of the cell cycle is likely to generate viable quiescent cells, targeting mitosis offers several possibilities for killing cancer cells. Microtubule poisons have proved efficacy in the clinic against a broad range of malignancies, and novel targeted strategies are now evaluating the inhibition of critical activities, such as cyclin-dependent kinase 1, Aurora or Polo kinases or spindle kinesins. Abrogation of the mitotic checkpoint or targeting the energetic or proteotoxic stress of aneuploid or chromosomally instable cells may also provide further benefits by inducing lethal levels of instability. Although cancer cells may display different responses to these treatments, recent data suggest that targeting mitotic exit by inhibiting the anaphase-promoting complex generates metaphase cells that invariably die in mitosis. As the efficacy of cell-cycle targeting approaches has been limited so far, further understanding of the molecular pathways modulating mitotic cell death will be required to move forward these new proposals to the clinic.
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113
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Chromokinesins: localization-dependent functions and regulation during cell division. Biochem Soc Trans 2011; 39:1154-60. [DOI: 10.1042/bst0391154] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The bipolar spindle is a highly dynamic structure that assembles transiently around the chromosomes and provides the mechanical support and the forces required for chromosome segregation. Spindle assembly and chromosome movements rely on the regulation of microtubule dynamics and a fine balance of forces exerted by various molecular motors. Chromosomes are themselves central players in spindle assembly. They generate a RanGTP gradient that triggers microtubule nucleation and stabilization locally and they interact dynamically with the microtubules through motors targeted to the chromatin. We have previously identified and characterized two of these so-called chromokinesins: Xkid (kinesin 10) and Xklp1 (kinesin 4). More recently, we found that Hklp2/kif15 (kinesin 12) is targeted to the chromosomes through an interaction with Ki-67 in human cells and is therefore a novel chromokinesin. Hklp2 also associates with the microtubules specifically during mitosis, in a TPX2 (targeting protein for Xklp2)-dependent manner. We have shown that Hklp2 participates in spindle pole separation and in the maintenance of spindle bipolarity in metaphase. To better understand the function of Hklp2, we have performed a detailed domain analysis. Interestingly, from its positioning on the chromosome arms, Hklp2 seems to restrict spindle pole separation. In the present review, we summarize the current knowledge of the function and regulation of the different kinesins associated with chromosome arms during cell division, including Hklp2 as a novel member of this so-called chromokinesin family.
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114
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Abstract
Long-distance transport in eukaryotic cells is driven by molecular motors that move along microtubule tracks. Molecular motors of the kinesin superfamily contain a kinesin motor domain attached to family-specific sequences for cargo binding, regulation, and oligomerization. The biochemical and biophysical properties of the kinesin motor domain have been widely studied, yet little is known about how kinesin motors work in the complex cellular environment. We discuss recent studies on the three major families involved in intracellular transport (kinesin-1, kinesin-2, and kinesin-3) that have begun to bridge the gap in knowledge between the in vitro and in vivo behaviors of kinesin motors. These studies have increased our understanding of how kinesin subunits assemble to produce a functional motor, how kinesin motors are affected by biochemical cues and obstacles present on cellular microtubules, and how multiple motors on a cargo surface can work collectively for increased force production and travel distance.
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Affiliation(s)
- Kristen J Verhey
- Department of Cell and Developmental Biology, University of Michigan, Ann Arbor, MI 48109, USA.
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115
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Bonner MK, Poole DS, Xu T, Sarkeshik A, Yates JR, Skop AR. Mitotic spindle proteomics in Chinese hamster ovary cells. PLoS One 2011; 6:e20489. [PMID: 21647379 PMCID: PMC3103581 DOI: 10.1371/journal.pone.0020489] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2011] [Accepted: 04/27/2011] [Indexed: 12/11/2022] Open
Abstract
Mitosis is a fundamental process in the development of all organisms. The mitotic spindle guides the cell through mitosis as it mediates the segregation of chromosomes, the orientation of the cleavage furrow, and the progression of cell division. Birth defects and tissue-specific cancers often result from abnormalities in mitotic events. Here, we report a proteomic study of the mitotic spindle from Chinese Hamster Ovary (CHO) cells. Four different isolations of metaphase spindles were subjected to Multi-dimensional Protein Identification Technology (MudPIT) analysis and tandem mass spectrometry. We identified 1155 proteins and used Gene Ontology (GO) analysis to categorize proteins into cellular component groups. We then compared our data to the previously published CHO midbody proteome and identified proteins that are unique to the CHO spindle. Our data represent the first mitotic spindle proteome in CHO cells, which augments the list of mitotic spindle components from mammalian cells.
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Affiliation(s)
- Mary Kate Bonner
- Department of Genetics, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
| | - Daniel S. Poole
- Department of Genetics, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
| | - Tao Xu
- Department of Chemical Physiology, The Scripps Research Institute, La Jolla, California, United States of America
| | - Ali Sarkeshik
- Department of Chemical Physiology, The Scripps Research Institute, La Jolla, California, United States of America
| | - John R. Yates
- Department of Chemical Physiology, The Scripps Research Institute, La Jolla, California, United States of America
| | - Ahna R. Skop
- Department of Genetics, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
- * E-mail:
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116
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Affiliation(s)
- Sharyn A Endow
- Department of Cell Biology, Duke University Medical Center, Durham, NC 27710, USA.
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117
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Chan KY, Matthews KR, Ersfeld K. Functional characterisation and drug target validation of a mitotic kinesin-13 in Trypanosoma brucei. PLoS Pathog 2010; 6:e1001050. [PMID: 20808899 PMCID: PMC2924347 DOI: 10.1371/journal.ppat.1001050] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2010] [Accepted: 07/19/2010] [Indexed: 12/31/2022] Open
Abstract
Mitotic kinesins are essential for faithful chromosome segregation and cell proliferation. Therefore, in humans, kinesin motor proteins have been identified as anti-cancer drug targets and small molecule inhibitors are now tested in clinical studies. Phylogenetic analyses have assigned five of the approximately fifty kinesin motor proteins coded by Trypanosoma brucei genome to the Kinesin-13 family. Kinesins of this family have unusual biochemical properties because they do not transport cargo along microtubules but are able to depolymerise microtubules at their ends, therefore contributing to the regulation of microtubule length. In other eukaryotic genomes sequenced to date, only between one and three Kinesin-13s are present. We have used immunolocalisation, RNAi-mediated protein depletion, biochemical in vitro assays and a mouse model of infection to study the single mitotic Kinesin-13 in T. brucei. Subcellular localisation of all five T. brucei Kinesin-13s revealed distinct distributions, indicating that the expansion of this kinesin family in kinetoplastids is accompanied by functional diversification. Only a single kinesin (TbKif13-1) has a nuclear localisation. Using active, recombinant TbKif13-1 in in vitro assays we experimentally confirm the depolymerising properties of this kinesin. We analyse the biological function of TbKif13-1 by RNAi-mediated protein depletion and show its central role in regulating spindle assembly during mitosis. Absence of the protein leads to abnormally long and bent mitotic spindles, causing chromosome mis-segregation and cell death. RNAi-depletion in a mouse model of infection completely prevents infection with the parasite. Given its essential role in mitosis, proliferation and survival of the parasite and the availability of a simple in vitro activity assay, TbKif13-1 has been identified as an excellent potential drug target.
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Affiliation(s)
- Kuan Yoow Chan
- Department of Biological Sciences, University of Hull, Hull, United Kingdom
| | - Keith R. Matthews
- Centre for Immunity, Infection and Evolution, Institute for Immunology and Infection Research, School of Biological Sciences, University of Edinburgh, Edinburgh, United Kingdom
| | - Klaus Ersfeld
- Department of Biological Sciences, University of Hull, Hull, United Kingdom
- Hull York Medical School, University of Hull, Hull, United Kingdom
- * E-mail:
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118
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Wacker SA, Kapoor TM. Targeting a kinetochore-associated motor protein to kill cancer cells. Proc Natl Acad Sci U S A 2010; 107:5699-700. [PMID: 20308538 PMCID: PMC2851886 DOI: 10.1073/pnas.1001277107] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Affiliation(s)
- Sarah A. Wacker
- Laboratory of Chemistry and Cell Biology, The Rockefeller University, New York, NY 10065
| | - Tarun M. Kapoor
- Laboratory of Chemistry and Cell Biology, The Rockefeller University, New York, NY 10065
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