scholarly journals RanGTP induces an effector gradient of XCTK2 and importin α/β for spindle microtubule cross-linking

2019 ◽  
Author(s):  
Stephanie C. Ems-McClung ◽  
Mackenzie Emch ◽  
Stephanie Zhang ◽  
Serena Mahnoor ◽  
Lesley N. Weaver ◽  
...  
Keyword(s):  
Cancer Cells ◽  
Spindle Assembly ◽  
Cross Linking ◽  
Tail Domain ◽  
Inhibitory Effects ◽  
Cross Link ◽  
Spindle Microtubule ◽  
Spindle Poles ◽  
Importin Α ◽  
Combined Actions

AbstractHigh RanGTP around chromatin is important for governing spindle assembly during meiosis and mitosis by releasing the inhibitory effects of importin α/β. Here we examine how the Ran gradient regulates Kinesin-14 function to control spindle organization. We show that Xenopus Kinesin-14, XCTK2, and importin α/β form an effector gradient, which is highest at the poles that diminishes toward the chromatin and is inverse of the RanGTP gradient. Importin α/β preferentially inhibit XCTK2 anti-parallel microtubule cross-linking and sliding by decreasing the microtubule affinity of the XCTK2 tail domain. This change in microtubule affinity enables RanGTP to target endogenous XCTK2 to the spindle. We propose that these combined actions of the Ran pathway are critical to promote Kinesin-14 parallel microtubule cross-linking at the spindle poles to cluster centrosomes in cancer cells. Furthermore, our work illustrates that RanGTP regulation in the spindle is not simply a switch, but rather generates effector gradients where RanGTP gradually tunes the activities of spindle assembly factors.SummaryEms-McClung et al. visualize a RanGTP effector gradient of association between XCTK2 and importin α/β in the spindle. The importins preferentially inhibit XCTK2-mediate anti-parallel microtubule cross-linking and sliding, which allows XCTK2 to cross-link parallel microtubules and help focus spindle poles.

scholarly journals RanGTP induces an effector gradient of XCTK2 and importin α/β for spindle microtubule cross-linking

2020 ◽  
Vol 219 (2) ◽  
Author(s):  
Stephanie C. Ems-McClung ◽  
Mackenzie Emch ◽  
Stephanie Zhang ◽  
Serena Mahnoor ◽  
Lesley N. Weaver ◽  
...  
Keyword(s):  
Spindle Assembly ◽  
Cross Linking ◽  
Tail Domain ◽  
Inhibitory Effects ◽  
Spindle Microtubule ◽  
Bipolar Spindle ◽  
Spindle Poles ◽  
Assembly Factors ◽  
Importin Α ◽  
Combined Actions

High RanGTP around chromatin is important for governing spindle assembly during meiosis and mitosis by releasing the inhibitory effects of importin α/β. Here we examine how the Ran gradient regulates Kinesin-14 function to control spindle organization. We show that Xenopus Kinesin-14, XCTK2, and importin α/β form an effector gradient that is highest at the poles and diminishes toward the chromatin, which is opposite the RanGTP gradient. Importin α and β preferentially inhibit XCTK2 antiparallel microtubule cross-linking and sliding by decreasing the microtubule affinity of the XCTK2 tail domain. This change in microtubule affinity enables RanGTP to target endogenous XCTK2 to the spindle. We propose that these combined actions of the Ran pathway are critical to promote Kinesin-14 parallel microtubule cross-linking to help focus spindle poles for efficient bipolar spindle assembly. Furthermore, our work illustrates that RanGTP regulation in the spindle is not simply a switch, but rather generates effector gradients where importins α and β gradually tune the activities of spindle assembly factors.

scholarly journals Kinesin-14 Family Proteins HSET/XCTK2 Control Spindle Length by Cross-Linking and Sliding Microtubules

2009 ◽  
Vol 20 (5) ◽  
pp. 1348-1359 ◽  
Author(s):  
Shang Cai ◽  
Lesley N. Weaver ◽  
Stephanie C. Ems-McClung ◽  
Claire E. Walczak
Keyword(s):  
Atpase Activity ◽  
Nuclear Localization ◽  
Hela Cells ◽  
Nuclear Localization Signal ◽  
Spindle Assembly ◽  
Cross Linking ◽  
Wild Type ◽  
Cross Link ◽  
Importin Α ◽  
Localization Signal

Kinesin-14 family proteins are minus-end directed motors that cross-link microtubules and play key roles during spindle assembly. We showed previously that the Xenopus Kinesin-14 XCTK2 is regulated by Ran via the association of a bipartite NLS in the tail of XCTK2 with importin α/β, which regulates its ability to cross-link microtubules during spindle formation. Here we show that mutation of the nuclear localization signal (NLS) of human Kinesin-14 HSET caused an accumulation of HSET in the cytoplasm, which resulted in strong microtubule bundling. HSET overexpression in HeLa cells resulted in longer spindles, similar to what was seen with NLS mutants of XCTK2 in extracts, suggesting that Kinesin-14 proteins play similar roles in extracts and in somatic cells. Conversely, HSET knockdown by RNAi resulted in shorter spindles but did not affect pole formation. The change in spindle length was not dependent on K-fibers, as elimination of the K-fiber by Nuf2 RNAi resulted in an increase in spindle length that was partially rescued by co-RNAi of HSET. However, these changes in spindle length did require microtubule sliding, as overexpression of an HSET mutant that had its sliding activity uncoupled from its ATPase activity resulted in cells with spindle lengths shorter than cells overexpressing wild-type HSET. Our results are consistent with a model in which Ran regulates the association of Kinesin-14s with importin α/β to prevent aberrant cross-linking and bundling of microtubules by sequestering Kinesin-14s in the nucleus during interphase. Kinesin-14s act during mitosis to cross-link and slide between parallel microtubules to regulate spindle length.

scholarly journals Poleward transport of Eg5 by dynein–dynactin in Xenopus laevis egg extract spindles

2008 ◽  
Vol 182 (4) ◽  
pp. 715-726 ◽  
Author(s):  
Marianne Uteng ◽  
Christian Hentrich ◽  
Kota Miura ◽  
Peter Bieling ◽  
Thomas Surrey
Keyword(s):  
Cell Division ◽  
Xenopus Laevis ◽  
Molecular Motors ◽  
Motor Proteins ◽  
Motor Protein ◽  
Spindle Assembly ◽  
Cross Linking ◽  
Motor Movement ◽  
Spindle Poles ◽  
Egg Extract

Molecular motors are required for spindle assembly and maintenance during cell division. How motors move and interact inside spindles is unknown. Using photoactivation and photobleaching, we measure mitotic motor movement inside a dynamic spindle. We find that dynein–dynactin transports the essential motor Eg5 toward the spindle poles in Xenopus laevis egg extract spindles, revealing a direct interplay between two motors of opposite directionality. This transport occurs throughout the spindle except at the very spindle center and at the spindle poles, where Eg5 remains stationary. The variation of Eg5 dynamics with its position in the spindle is indicative of position-dependent functions of this motor protein. Our results suggest that Eg5 drives microtubule flux by antiparallel microtubule sliding in the spindle center, whereas the dynein-dependent concentration of Eg5 outside the spindle center could contribute to parallel microtubule cross-linking. These results emphasize the importance of spatially differentiated functions of motor proteins and contribute to our understanding of spindle organization.

scholarly journals The microtubule cross-linker Feo controls the midzone stability, motor composition, and elongation of the anaphase B spindle in Drosophila embryos

2015 ◽  
Vol 26 (8) ◽  
pp. 1452-1462 ◽  
Author(s):  
Haifeng Wang ◽  
Ingrid Brust-Mascher ◽  
Jonathan M. Scholey
Keyword(s):  
Chromosome Segregation ◽  
Cross Linking ◽  
Cross Link ◽  
Spindle Poles ◽  
Cross Linker ◽  
Spindle Elongation ◽  
Anaphase B ◽  
Drosophila Embryos ◽  
Poleward Flux

Chromosome segregation during anaphase depends on chromosome-to-pole motility and pole-to-pole separation. We propose that in Drosophila embryos, the latter process (anaphase B) depends on a persistent kinesin-5–generated interpolar (ip) microtubule (MT) sliding filament mechanism that “engages” to push apart the spindle poles when poleward flux is turned off. Here we investigated the contribution of the midzonal, antiparallel MT-cross-linking nonmotor MAP, Feo, to this “slide-and-flux-or-elongate” mechanism. Whereas Feo homologues in other systems enhance the midzone localization of the MT-MT cross-linking motors kinesin-4, -5 and -6, the midzone localization of these motors is respectively enhanced, reduced, and unaffected by Feo. Strikingly, kinesin-5 localizes all along ipMTs of the anaphase B spindle in the presence of Feo, including at the midzone, but the antibody-induced dissociation of Feo increases kinesin-5 association with the midzone, which becomes abnormally narrow, leading to impaired anaphase B and incomplete chromosome segregation. Thus, although Feo and kinesin-5 both preferentially cross-link MTs into antiparallel polarity patterns, kinesin-5 cannot substitute for loss of Feo function. We propose that Feo controls the organization, stability, and motor composition of antiparallel ipMTs at the midzone, thereby facilitating the kinesin-5–driven sliding filament mechanism underlying proper anaphase B spindle elongation and chromosome segregation.

scholarly journals SART1 localizes to spindle poles forming a SART1 cap and promotes centrosome and spindle assembly

2021 ◽  
Author(s):  
Hideki Yokoyama ◽  
Kaoru Takizawa ◽  
Jian Ma ◽  
Daniel Moreno-Andrés ◽  
Wolfram Antonin ◽  
...  
Keyword(s):  
Cancer Cells ◽  
Physiological Function ◽  
Spindle Assembly ◽  
Scaffold Protein ◽  
Human Cells ◽  
Dependent Manner ◽  
Normal Cells ◽  
Spindle Poles ◽  
Egg Extracts ◽  
Centrosomal Proteins

Abstract SART1 is overexpressed in various cancers. However, its physiological function and cancer relevance remains elusive. Here we identify SART1 as a mitotic-specific and Ran-regulated microtubule-associated protein. SART1 downregulation in human cells as well as its depletion from frog egg extracts disrupts spindle assembly. While SART1 is nuclear in interphase, it localizes during mitosis to spindle poles in a microtubule-dependent manner. SART1 accumulates close to centrosomes forming a half circle which we designate as SART1 cap. Immunoprecipitation of SART1 identifies the centrosome scaffold protein Cep192 as an interaction partner. Accordingly, Cep192 downregulation abolishes SART1 localization to spindle poles, and SART1 downregulation displaces centrosomal proteins like Ninein from centrosomes, but does not affect γ-tubulin localization. Furthermore, SART1 downregulation selectively kills cancer cells and prevents normal cells from oncogenic transformation. Our data unravel a novel function of SART1 for centrosome organization and spotlight SRAT1 as a potential target for anticancer therapies.

Inhibitory effects of Actinidia Chinensis planch root extracts (acRoots) on human lung cancer cells through retinoic acid receptor beta

2017 ◽  
Vol 5 (1) ◽  
Author(s):  
Lingyan Wang ◽  
Jiayun Hou ◽  
Minghuan Zheng ◽  
Lin Shi
Keyword(s):  
Lung Cancer ◽  
Cancer Cells ◽  
Human Lung ◽  
Retinoic Acid Receptor ◽  
Lung Cancer Cells ◽  
Human Lung Cancer ◽  
Inhibitory Effects ◽  
The Core ◽  
Human Lung Cancer Cells ◽  
Receptor Beta

Actinidia Chinensis Planch roots (acRoots) are used to treat many cancers, although the anti-tumor mechanism by which acRoots inhibit cancer cell growth remains unclear. The present study aims at investigating inhibitory effects of acRoots on human lung cancer cells and potential mechanisms. Our data demonstrate that the inhibitory effects of acRoots on lung cancer cells depend on genetic backgrounds and phenotypes of cells. We furthermore found the expression of metabolism-associated gene profiles varied between acRoots-hypersensitive (H460) or hyposensitive lung cancer cells (H1299) after screening lung cancer cells with different genetic backgrounds. We selected retinoic acid receptor beta (RARB) as the core target within metabolism-associated core gene networks and evaluated RARB changes and roles in cells treated with acRoots at different concentrations and timeframes. Hypersensitive cancer cells with the deletion of RARB expression did not response to the treatment with acRoots, while RARB deletion did not change effects of acRoots on hyposensitive cells. Thus, it seems that RARB as the core target within metabolism-associated networks plays important roles in the regulation of lung cancer cell sensitivity to acRoots.

Synthetic Naphthoflavonoids Showing Inhibitory Effects on Clonogenicity against Cisplatin-Resistant A2780/Cis Human Ovarian Cancer Cells

2015 ◽  
Vol 12 (8) ◽  
pp. 628-639
Author(s):  
Yearam Jung ◽  
Soon Young Shin ◽  
Yeonjoong Yong ◽  
Hyuk Yoon ◽  
Seunghyun Ahn ◽  
...  
Keyword(s):  
Ovarian Cancer ◽  
Cancer Cells ◽  
Ovarian Cancer Cells ◽  
Human Ovarian Cancer ◽  
Inhibitory Effects

scholarly journals Melatonin as an Adjuvant to Antiangiogenic Cancer Treatments

Cancers ◽  
2021 ◽  
Vol 13 (13) ◽  
pp. 3263
Author(s):  
Alicia González ◽  
Carolina Alonso-González ◽  
Alicia González-González ◽  
Javier Menéndez-Menéndez ◽  
Samuel Cos ◽  
...  
Keyword(s):  
Synergistic Effect ◽  
Protective Effect ◽  
Cancer Cells ◽  
Tumor Cells ◽  
Chemotherapeutic Agents ◽  
Inhibitory Effects ◽  
Anticancer Effect ◽  
Cancer Treatments ◽  
Melatonin Administration ◽  
Effects Of Radiation

Melatonin is a hormone with different functions, antitumor actions being one of the most studied. Among its antitumor mechanisms is its ability to inhibit angiogenesis. Melatonin shows antiangiogenic effects in several types of tumors. Combination of melatonin and chemotherapeutic agents have a synergistic effect inhibiting angiogenesis. One of the undesirable effects of chemotherapy is the induction of pro-angiogenic factors, whilst the addition of melatonin is able to overcome these undesirable effects. This protective effect of the pineal hormone against angiogenesis might be one of the mechanisms underlying its anticancer effect, explaining, at least in part, why melatonin administration increases the sensitivity of tumors to the inhibitory effects exerted by ordinary chemotherapeutic agents. Melatonin has the ability to turn cancer totally resistant to chemotherapeutic agents into a more sensitive chemotherapy state. Definitely, melatonin regulates the expression and/or activity of many factors involved in angiogenesis which levels are affected (either positively or negatively) by chemotherapeutic agents. In addition, the pineal hormone has been proposed as a radiosensitizer, increasing the oncostatic effects of radiation on tumor cells. This review serves as a synopsis of the interaction between melatonin and angiogenesis, and we will outline some antiangiogenic mechanisms through which melatonin sensitizes cancer cells to treatments, such as radiotherapy or chemotherapy.

scholarly journals Antagonizing the spindle assembly checkpoint silencing enhances paclitaxel and Navitoclax-mediated apoptosis with distinct mechanistic

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Ana C. Henriques ◽  
Patrícia M. A. Silva ◽  
Bruno Sarmento ◽  
Hassan Bousbaa
Keyword(s):  
Cell Death ◽  
Cancer Cells ◽  
Cell Fate ◽  
Spindle Assembly Checkpoint ◽  
Spindle Assembly ◽  
Time Lapse ◽  
Antimitotic Drugs ◽  
Mitotic Slippage ◽  
Mitotic Death ◽  
Chronic Activation

AbstractAntimitotic drugs arrest cells in mitosis through chronic activation of the spindle assembly checkpoint (SAC), leading to cell death. However, drug-treated cancer cells can escape death by undergoing mitotic slippage, due to premature mitotic exit. Therefore, overcoming slippage issue is a promising chemotherapeutic strategy to improve the effectiveness of antimitotics. Here, we antagonized SAC silencing by knocking down the MAD2-binding protein p31comet, to delay mitotic slippage, and tracked cancer cells treated with the antimitotic drug paclitaxel, over 3 days live-cell time-lapse analysis. We found that in the absence of p31comet, the duration of mitotic block was increased in cells challenged with nanomolar concentrations of paclitaxel, leading to an additive effects in terms of cell death which was predominantly anticipated during the first mitosis. As accumulation of an apoptotic signal was suggested to prevent mitotic slippage, when we challenged p31comet-depleted mitotic-arrested cells with the apoptosis potentiator Navitoclax (previously called ABT-263), cell fate was shifted to accelerated post-mitotic death. We conclude that inhibition of SAC silencing is critical for enhancing the lethality of antimitotic drugs as well as that of therapeutic apoptosis-inducing small molecules, with distinct mechanisms. The study highlights the potential of p31comet as a target for antimitotic therapies.

Sign in / Sign up

Export Citation Format

Share Document