Characterization of a New γTuRC Subunit with WD Repeats

Gunawardane, Ruwanthi N.; Martin, Ona C.; Zheng, Yixian

doi:10.1091/mbc.e02-01-0034

Cited by 58 publications

(68 citation statements)

References 35 publications

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“…2; Table 1) (Choi et al, 2010;Gunawardane et al, 2003;Haren et al, 2006;Hutchins et al, 2010;Lüders et al, 2006;Teixido-Travesa et al, 2010). We define as 'cTuRC core components' all proteins that co-purify with cTuRCs at amounts that are similar to the GCP family members, co-fractionate with cTuRCs in sucrose gradients and colocalize with c-tubulin in cells.…”

Section: Molecular Composition Of Cturcsmentioning

confidence: 99%

The where, when and how of microtubule nucleation – one ring to rule them all

Teixidó-Travesa¹,

Roig

Lüders³

2012

Journal of Cell Science

153

162

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SummaryThe function of microtubules depends on their arrangement into highly ordered arrays. Spatio-temporal control over the formation of new microtubules and regulation of their properties are central to the organization of these arrays. The nucleation of new microtubules requires c-tubulin, an essential protein that assembles into multi-subunit complexes and is found in all eukaryotic organisms. However, the way in which c-tubulin complexes are regulated and how this affects nucleation and, potentially, microtubule behavior, is poorly understood. c-tubulin has been found in complexes of various sizes but several lines of evidence suggest that only large, ring-shaped complexes function as efficient microtubule nucleators. Human c-tubulin ring complexes (cTuRCs) are composed of c-tubulin and the c-tubulin complex components (GCPs) 2, 3, 4, 5 and 6, which are members of a conserved protein family. Recent work has identified additional unrelated cTuRC subunits, as well as a large number of more transient cTuRC interactors. In this Commentary, we discuss the regulation of cTuRC-dependent microtubule nucleation as a key mechanism of microtubule organization. Specifically, we focus on the regulatory roles of the cTuRC subunits and interactors and present an overview of other mechanisms that regulate cTuRC-dependent microtubule nucleation and organization.

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Section: Molecular Composition Of Cturcsmentioning

confidence: 99%

The where, when and how of microtubule nucleation – one ring to rule them all

Teixidó-Travesa¹,

Roig

Lüders³

2012

Journal of Cell Science

153

162

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“…The molecular details of this process are still poorly understood (Oakley and Oakley, 1989;Oakley et al, 1990;Erickson and Stoffler, 1996;Gunawardane et al, 2003). In vitro, ␥-tubulin monomers enhance the assembly of ␣/␤ heterodimers and block the minus ends of microtubules (Li and Joshi, 1995;Leguy et al, 2000).…”

Section: Introductionmentioning

confidence: 99%

“…It is assumed that the ␥-TuRC results from the association of several ␥-TuSCs with at least four other proteins. Three of them show sequence homologies (grip motifs) with the two ␥-tubulin-associated proteins in the ␥-TuSC, whereas the fourth exhibits five WD repeats (Fava et al, 1999;Gunawardane et al, 2000;Moritz et al, 2000;Murphy et al, 2001;Gunawardane et al, 2003). The function of ␥-tubulin has been studied extensively in several organisms and in cultured cells using antibody microinjection, mutants or gene silencing (Oakley et al, 1990;Horio et al, 1991;Joshi et al, 1992;Sunkel et al, 1995;Marschall et al, 1996;Spang et al, 1996;Wilson and Borisy, 1998;Llamazares et al, 1999;Ruiz et al, 1999;Bobinnec et al, 2000;Sampaio et al, 2001;Raynaud-Messina et al, 2004).…”

Section: Introductionmentioning

confidence: 99%

TheDrosophilaγ-Tubulin Small Complex Subunit Dgrip84 Is Required for Structural and Functional Integrity of the Spindle Apparatus

Colombié

Vérollet

Sampaio

et al. 2006

MBoC

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␥-Tubulin, a protein critical for microtubule assembly, functions within multiprotein complexes. However, little is known about the respective role of ␥-tubulin partners in metazoans. For the first time in a multicellular organism, we have investigated the function of Dgrip84, the Drosophila orthologue of the Saccharomyces cerevisiae ␥-tubulin-associated protein Spc97p. Mutant analysis shows that Dgrip84 is essential for viability. Its depletion promotes a moderate increase in the mitotic index, correlated with the appearance of monopolar or unpolarized spindles, impairment of centrosome maturation, and increase of polyploid nuclei. This in vivo study is strengthened by an RNA interference approach in cultured S2 cells. Electron microscopy analysis suggests that monopolar spindles might result from a failure of centrosome separation and an unusual microtubule assembly pathway via centriolar triplets. Moreover, we point to an involvement of Dgrip84 in the spindle checkpoint regulation and in the maintenance of interphase microtubule dynamics. Dgrip84 also seems essential for male meiosis, ensuring spindle bipolarity and correct completion of cytokinesis. These data sustain that Dgrip84 is required in some aspects of microtubule dynamics and organization both in interphase and mitosis. The nature of a minimal ␥-tubulin complex necessary for proper microtubule organization in the metazoans is discussed. INTRODUCTIONThe mechanisms of microtubule nucleation remain unclear, although it has been demonstrated that ␥-tubulin, a universal component of the microtubule-organizing centers, plays an essential role in microtubule nucleation. The molecular details of this process are still poorly understood (Oakley and Oakley, 1989;Oakley et al., 1990;Erickson and Stoffler, 1996;Gunawardane et al., 2003). In vitro, ␥-tubulin monomers enhance the assembly of ␣/␤ heterodimers and block the minus ends of microtubules (Li and Joshi, 1995;Leguy et al., 2000). However, in vivo, ␥-tubulin does not seem to act as a monomer, but rather in a variety of protein complexes (Murphy et al., 1998;Oegema et al., 1999;Fujita et al., 2002). The simplest one called ␥-tubulin small complex (␥-TuSC) has been well characterized in Saccharomyces cerevisiae , Drosophila melanogaster (Oegema et al., 1999), and vertebrates (Murphy et al., 1998). It is formed by ␥-tubulin and two associated proteins in a 2:1:1 stoichiometry Oegema et al., 1999;Murphy et al., 2001). This small complex is recruited at the inner and outer spindle plaques of S. cerevisiae spindle pole bodies (SPB) where it is responsible for microtubule nucleation Schiebel, 1997, 1998;Pereira et al., 1998). Besides ␥-TuSC, other larger ␥-tubulin-containing complexes have been described (Zheng et al., 1995;Fujita et al., 2002). One termed ␥-tubulin ring complex (␥-TuRC) has been characterized in multicellular organisms such as D. melanogaster, Xenopus laevis, and Homo sapiens (Zheng et al., 1995;Oegema et al., 1999;Murphy et al., 2001). It is assumed that the ␥-TuRC results from the associa...

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“…Homologues in Drosophila and Xenopus are not required for this centrosomal g-tubulin recruitment. 12,13,28 It is interesting to note that this study has revealed that the depletion of zNEDD1 from zebrafish also causes a reduction in g-tubulin at the centrosome. Hence, zNEDD1 functions to recruit g-tubulin to the centrosome in zebrafish, and this is presumably important for correct mitotic progression and embryonic development.…”

Section: Discussionmentioning

confidence: 82%

“…In addition, NEDD1 homologues have been described in Drosophila, Xenopus and Arabidopsis. [12][13][14] Despite the consistent centrosomal localisation of NEDD1 in these species, its effect on g-tubulin recruitment appears to be species dependant. Hence, this study also aimed to compare the function of zebrafish NEDD1 (zNEDD1) to other homologues.…”

mentioning

confidence: 96%

An essential function for the centrosomal protein NEDD1 in zebrafish development

et al. 2010

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The centrosome is the primary microtubule organising centre of the cell. It is composed of many proteins, some of which make up the core of the centrosome, whereas others are used for specific functions. Although the cellular roles of many centrosomal proteins are well defined, much less is known about their functions and the role of the centrosome in development. In this study we investigated the function of NEDD1, a critical component of the centrosome essential for microtubule nucleation, in zebrafish (Danio rerio) development. The zebrafish homologue of NEDD1 (zNEDD1) was cloned and found to have a similar localisation and function to mammalian NEDD1. We show that zNEDD1 is essential for survival, as a high level of knockdown was embryonic lethal. Partial knockdown of zNEDD1 caused abnormalities including an increase in mitotic and apoptotic cells. Pronounced phenotypic defects were seen in the brain, with a lack of defined brain structures, incomplete neural tube formation and a disorganisation of neurons. In addition, we show that a reduction in zNEDD1 resulted in the loss of c-tubulin at the centrosome. Our data thus demonstrate that zNEDD1 is critical for the recruitment of c-tubulin to the centrosome, and is essential for the proper development of zebrafish. The centrosome is the major microtubule organising centre (MTOC) of cells and serves as a centralised location for controlling many cellular processes. The centrosomal protein neural precursor cell expressed developmentally downregulated gene 1 (NEDD1), 1 functions in the centrosomal and mitotic-spindle recruitment of the g-tubulin ring complex (g-TuRC). This complex is required for the nucleation of microtubules, correct formation of the mitotic spindle and hence progression of the cell cycle. 2,3 Because of this, depletion of NEDD1 from mammalian cells results in dispersion of the MTOC, impaired centrosomal and chromatin nucleation of microtubules, mitotic chaos and cell-cycle arrest. [2][3][4] Given the centrosomal localisation and function of NEDD1, and its dynamic expression during mouse embryogenesis, 5 it is expected that this protein has an important role during development. However, because of the early embryonic lethality of mouse knockouts of centrosomal proteins, including g-tubulin, it has not been possible to study the function of these proteins in later stages of development in this organism. 6,7 Zebrafish (Danio rerio) posses many benefits for developmental studies including the conservation of genes involved in cell growth and proliferation, 8 the rapid maturation of translucent embryos 9 and the ability to specifically deplete proteins of interest. 10 Although there has been much work analysing the cell cycle in zebrafish, 11 there has been limited analysis of the centrosome in this species. Therefore, this system was chosen as a model to study the role of NEDD1 during development. In addition, NEDD1 homologues have been described in Drosophila, Xenopus and Arabidopsis. [12][13][14] Despite the consistent centrosomal localisation o...

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Characterization of a New γTuRC Subunit with WD Repeats

Cited by 58 publications

References 35 publications

The where, when and how of microtubule nucleation – one ring to rule them all

The where, when and how of microtubule nucleation – one ring to rule them all

TheDrosophilaγ-Tubulin Small Complex Subunit Dgrip84 Is Required for Structural and Functional Integrity of the Spindle Apparatus

An essential function for the centrosomal protein NEDD1 in zebrafish development

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