hTPX2 Is Required for Normal Spindle Morphology and Centrosome Integrity during Vertebrate Cell Division

Garrett, Sarah; Auer, Kristi; Compton, Duane A.; Kapoor, Tarun M.

doi:10.1016/s0960-9822(02)01277-0

Cited by 132 publications

(137 citation statements)

References 19 publications

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“…Eliminating RANBP1 facilitates RAN-GTP stabilization: in our experiments, RANBP1 downregulation by 80% increased the intracellular RAN-GTP concentration by around two-or three-fold. We have found that this does not affect the dissociation of classical import complexes such as those containing TPX2: neither TPX2 nor Aurora-A or TOGp were mis-localized in RANBP1-depleted mitoses, nor did TPX2 appear to be any less active than in control mitoses, taking spindle pole integrity Garrett et al, 2002) and Aurora-A localization to MTs as diagnostic features.…”

Section: Discussionmentioning

confidence: 78%

RANBP1 localizes a subset of mitotic regulatory factors on spindle microtubules and regulates chromosome segregation in human cells

Tedeschi

Ciciarello

Mangiacasale

et al. 2007

Journal of Cell Science

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The GTPase RAN has an established role in spindle assembly and in mitotic progression, although not all mechanisms are fully understood in somatic cells. Here, we have downregulated RAN-binding protein 1 (RANBP1), a RAN partner that has highest abundance in G2 and mitosis, in human cells. RANBP1-depleted cells underwent prolonged prometaphase delay often followed by apoptosis. Cells that remained viable assembled morphologically normal spindles; these spindles, however, were hyperstable and failed to recruit cyclin B1 or to restrict the localization of HURP (DLG7), a microtubule-stabilizing factor, to plus-ends. RANBP1 depletion did not increase the frequency of unattached chromosomes; however, RANBP1-depleted cells frequently showed lagging chromosomes in anaphase, suggesting that merotelic attachments form and are not efficiently resolved. These data indicate that RANBP1 activity is required for the proper localization of specific factors that regulate microtubule function; loss of this activity contributes to the generation of aneuploidy in a microtubule-dependent manner.

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Section: Discussionmentioning

confidence: 78%

RANBP1 localizes a subset of mitotic regulatory factors on spindle microtubules and regulates chromosome segregation in human cells

Tedeschi

Ciciarello

Mangiacasale

et al. 2007

Journal of Cell Science

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“…A number of proteins such as CPAP, GAK and TPX2 are known to be required for centrosome integrity (Garrett et al, 2002;Shimizu et al, 2009;Tang et al, 2009). However, depletion of these proteins results in a multipolar spindle phenotype.…”

Section: Discussionmentioning

confidence: 99%

Centrobin regulates the assembly of functional mitotic spindles

et al. 2010

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The proper function of the spindle is crucial to the high fidelity of chromosome segregation and is indispensable for tumor suppression in humans. Centrobin is a recently identified centrosomal protein that has a role in stabilizing the microtubule structure. Here we functionally characterize the defects in centrosome integrity and spindle assembly in Centrobin-depleted cells. Centrobin-depleted cells show a range of spindle abnormalities including unfocused poles that are not associated with centrosomes, S-shaped spindles and mini spindles. These cells undergo mitotic arrest and subsequently often die by apoptosis, as determined by live cell imaging. Co-depletion of Mad2 relieves the mitotic arrest, indicating that cells arrest due to a failure to silence the spindle checkpoint in metaphase. Consistent with this, Centrobin-depleted metaphase cells stained positive for BubR1 and BubR1 S676. Staining with a panel of centrosome markers showed a loss of centrosome anchoring to the mitotic spindle. Furthermore, these cells show less cold-stable microtubules and a shorter distance between kinetochore pairs. These results show a requirement of Centrobin in maintaining centrosome integrity, which in turn promotes anchoring of mitotic spindle to the centrosomes. Furthermore, this anchoring is required for the stability of microtubulekinetochore attachments and biogenesis of tension-ridden and properly functioning mitotic spindle.

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“…However, their ability to directly anchor components of the ␥ TuRC and thus serve as molecular scaffolds for tethering these complexes to centrosomes has not been demonstrated. These include the centrosome proteins Asp (do Carmo Avides and Glover, 1999), NuMA (Merdes et al, 1996), TPX-2 (Wittmann et al, 2000;Garrett et al, 2002), SPD-5 (Hamill et al, 2002), PCM-1 (Dammermann and Merdes, 2002), Sas-4 (Kirkham et al, 2003) centrosomin (Megraw et al, 1999;Terada et al, 2003), and several regulatory molecules, including Aurora A (Hannak et al, 2001;Giet et al, 2002), Polo (Lane and Nigg, 1996;Barbosa et al, 2000), PP1 (Katayama et al, 2001), and PP4 (Sumiyoshi et al, 2002).…”

Section: Other Proteins Involved In Centrosomal ␥ Turc Anchoring and mentioning

confidence: 99%

Mitosis-specific Anchoring of γ Tubulin Complexes by Pericentrin Controls Spindle Organization and Mitotic Entry

Zimmerman

Sillibourne

Rosa

et al. 2004

MBoC

270

258

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Microtubule nucleation is the best known function of centrosomes. Centrosomal microtubule nucleation is mediated primarily by ␥ tubulin ring complexes (␥ TuRCs). However, little is known about the molecules that anchor these complexes to centrosomes. In this study, we show that the centrosomal coiled-coil protein pericentrin anchors ␥ TuRCs at spindle poles through an interaction with ␥ tubulin complex proteins 2 and 3 (GCP2/3). Pericentrin silencing by small interfering RNAs in somatic cells disrupted ␥ tubulin localization and spindle organization in mitosis but had no effect on ␥ tubulin localization or microtubule organization in interphase cells. Similarly, overexpression of the GCP2/3 binding domain of pericentrin disrupted the endogenous pericentrin-␥ TuRC interaction and perturbed astral microtubules and spindle bipolarity. When added to Xenopus mitotic extracts, this domain uncoupled ␥ TuRCs from centrosomes, inhibited microtubule aster assembly, and induced rapid disassembly of preassembled asters. All phenotypes were significantly reduced in a pericentrin mutant with diminished GCP2/3 binding and were specific for mitotic centrosomal asters as we observed little effect on interphase asters or on asters assembled by the Ran-mediated centrosome-independent pathway. Additionally, pericentrin silencing or overexpression induced G2/antephase arrest followed by apoptosis in many but not all cell types. We conclude that pericentrin anchoring of ␥ tubulin complexes at centrosomes in mitotic cells is required for proper spindle organization and that loss of this anchoring mechanism elicits a checkpoint response that prevents mitotic entry and triggers apoptotic cell death. INTRODUCTIONThe centrosome is the primary microtubule-organizing center in animal cells. At the centrosome core is a pair of barrel-shaped microtubule assemblies, the centrioles (Doxsey, 2001). Centrioles are capable of self-assembly (Marshall et al., 2001;Khodjakov et al., 2002) and can serve as templates for recruitment and organization of the surrounding pericentriolar matrix (Bobinnec et al., 1998;Kirkham et al., 2003). The pericentriolar material or centrosome matrix contains a high proportion of coiled coil proteins and is the site of microtubule nucleation. Within the matrix are large protein complexes of ␥ tubulin and associated proteins that have a ring-like structure and mediate the nucleation of microtubules called ␥ tubulin ring complexes or ␥ TuRCs (Moritz et al., 1995a;Zheng et al., 1995). Other proteins may share the ability to nucleate microtubules because centrosomes can organize microtubules in the absence of functional ␥ tubulin (Sampaio et al., 2001;Strome et al., 2001;Hannak et al., 2002).During cell cycle progression, centrosomes "mature" by recruiting additional ␥ TuRCs and several other proteins, resulting in an increase in the nucleation capacity of the centrosome (reviewed in Blagden and Glover, 2003). However, we still know very little about proteins that directly anchor ␥ TuRCs to centrosomes in vertebrate cells. ...

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hTPX2 Is Required for Normal Spindle Morphology and Centrosome Integrity during Vertebrate Cell Division

Cited by 132 publications

References 19 publications

RANBP1 localizes a subset of mitotic regulatory factors on spindle microtubules and regulates chromosome segregation in human cells

RANBP1 localizes a subset of mitotic regulatory factors on spindle microtubules and regulates chromosome segregation in human cells

Centrobin regulates the assembly of functional mitotic spindles

Mitosis-specific Anchoring of γ Tubulin Complexes by Pericentrin Controls Spindle Organization and Mitotic Entry

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