Direct kinetochore–spindle pole connections are not required for chromosome segregation

Sikirzhytski, Vitali; Magidson, Valentin; Steinman, Jonathan B.; He, Jie; Berre, Maël Le; Tikhonenko, Irina; Ault, Jeffrey G.; McEwen, Bruce F.; Chen, James; Sui, Haixin; Piel, Matthieu; Kapoor, Tarun M.; Khodjakov, Alexey

doi:10.1083/jcb.201401090

Cited by 107 publications

(159 citation statements)

References 52 publications

(86 reference statements)

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“…NuMA is required for dynein activity and dynactin localization at minusends If NuMA does target dynein-dynactin to minus-ends, localizing force there, we would expect NuMA to be required for dynein to transport minus-ends created by k-fiber ablation (Elting et al, 2014; Sikirzhytski et al, 2014). To test this hypothesis, we made inducible CRISPR/Cas9 RPE1 cell lines to knock out NuMA (Figure 3-figure supplement 1) (McKinley et al, 2015;Wang et al, 2015).…”

Section: Numa Localizes To Minus-ends Independently Of Dyneinmentioning

confidence: 99%

“…In computational models, localizing a minus-end-directed motor at microtubule ends permits microtubule clustering into asters or poles (Foster et al, 2015;Goshima et al, 2005;Nedelec and Surrey, 2001;Surrey et al, 2001) and the emergence of a robust steady-state spindle length (Burbank et al, 2007). More recently, experimental work has shown that dynein-dynactin and NuMA do indeed selectively localize to spindle minus-ends, with dynein pulling on them after kinetochore-fiber (k-fiber) ablation in mammalian spindles (Elting et al, 2014;Sikirzhytski et al, 2014). This is consistent with suggestions that dynein and NuMA capture and pull on distal k-fiber minus-ends in monopolar spindles (Khodjakov et al, 2003).…”

Section: Introductionmentioning

confidence: 99%

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NuMA Recruits Dynein Activity to Microtubule Minus-Ends at Mitosis

Hueschen

Kenny

et al. 2018

Biophysical Journal

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To build the spindle at mitosis, motors exert spatially regulated forces on microtubules. We know that dynein pulls on mammalian spindle microtubule minus-ends, and this localized activity at ends is predicted to allow dynein to cluster microtubules into poles. How dynein becomes enriched at minus-ends is not known. Here, we use quantitative imaging and laser ablation to show that NuMA targets dynactin to minus-ends, localizing dynein activity there. NuMA is recruited to new minus-ends independently of dynein and more quickly than dynactin; both NuMA and dynactin display specific, steady-state binding at minus-ends. NuMA localization to minus-ends involves a C-terminal region outside NuMA's canonical microtubule-binding domain and is independent of minus-end binders g-TuRC, CAMSAP1, and KANSL1/3. Both NuMA's minus-endbinding and dynein-dynactin-binding modules are required to rescue focused, bipolar spindle organization. Thus, NuMA may serve as a mitosis-specific minus-end cargo adaptor, targeting dynein activity to minus-ends to cluster spindle microtubules into poles.

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Section: Numa Localizes To Minus-ends Independently Of Dyneinmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

NuMA Recruits Dynein Activity to Microtubule Minus-Ends at Mitosis

Hueschen

Kenny

et al. 2018

Biophysical Journal

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“…Nicklas assumed this load was shared by a subset of 15 kinetochore-attached microtubules that extended all the way to spindle pole (out of a total of ~40 kinetochore-attached microtubules), leading to an often-cited estimate of 50 pN per microtubule [59]. This might be an overestimate, with the true value falling closer to 12 pN per microtubule, given the recent work indicating that all kinetochoreattached microtubules, even those that do not extend all the way to a pole, are anchored within the spindle [60,61]. But in either case the forces during a normal, unperturbed anaphase are probably much, much lower still.…”

Section: Anaphase Spindle Generates More Force Than Needed For Anaphamentioning

confidence: 83%

“…Questions also remain about how depolymerase activity is engaged when the motors and minus ends reach the pole. [60,61]. (a) Ablation of a k-fiber (yellow lightning bolt) during anaphase.…”

Section: Potential Biophysical Mechanisms For Kinetochore-microtubulementioning

confidence: 99%

Anaphase A: Melting Microtubules Move Chromosomes toward Spindle Poles

Cl¹

2017

Preprint

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Abstract:The separation of sister chromatids during anaphase is the culmination of mitosis and one of the most strikingly beautiful examples of cellular movement. It consists of two distinct processes: Anaphase A, the movement of chromosomes toward spindle poles via shortening of the connecting fibers, and anaphase B, separation of the two poles from one another via spindle elongation. I focus here on anaphase A chromosome-to-pole movement. The chapter begins by summarizing classical observations of chromosome movements, which support the current understanding of anaphase mechanisms. Live cell fluorescence microscopy studies showed that poleward chromosome movement is associated with disassembly, or 'melting' of the kinetochore-attached microtubule fibers that link chromosomes to poles. Microtubule-marking techniques established that kinetochore-fiber disassembly often occurs through a 'pac-man' mechanism, where tubulin subunits are lost from kinetochore-attached plus ends and the kinetochore appears to consume its microtubule track as it moves poleward. In addition, kinetochore-fiber disassembly in many cells occurs partly through 'flux', where the microtubules flow continuously toward the poles and tubulin subunits are lost from minus ends. Molecular mechanistic models for how load-bearing attachments are maintained to disassembling microtubule ends, and how the forces are generated to drive pac-man and flux-based movements, are discussed.

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“…Aurora B phosphorylation of Ndc80 reduces its microtubule-binding affinity, which prevents erroneous attachment of kinetochores to microtubules DeLuca et al 2006;Liu et al 2009;Alushin et al 2010;Lampson and Cheeseman 2011;Zaytsev et al 2015). Ndc80 phosphorylation is finely controlled until proper bi-orientation is established under tension during prometaphase (Magidson et al 2011;Sikirzhytski et al 2014). These stable attachments between kinetochores and microtubules are mediated by a feedback mechanism, which balances phosphorylation of Ndc80 by Aurora B and its dephosphorylation by B56-PP2A or PP1 phosphatases (Foley et al 2011;Suijkerbuijk et al 2012).…”

Section: Regulation Of Outer Kinetochore Dynamicsmentioning

confidence: 99%

Kinetochore assembly and function through the cell cycle

Nagpal

Fukagawa

2016

Chromosoma

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The kinetochore is an essential structure for the chromosome segregation machinery in eukaryotes; it serves as a bridge between the spindle microtubules and chromosomes. The kinetochore consists of multiple interconnecting components on the centromere; therefore, understanding its formation, molecular function, and regulation has remained an ongoing challenge. Recent studies have provided new insights into centromere identity, kinetochore assembly, and function. In this review, we discuss recent advances in our understanding of the function and regulation of key kinetochore components. We highlight the reciprocal localization dependencies of the different sub-complexes of the kinetochore and describe their regulation during the cell cycle.

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Direct kinetochore–spindle pole connections are not required for chromosome segregation

Abstract: In the absence of continuous K-fiber attachment between each kinetochore and the spindle pole, one or more additional mechanisms dependent on dynein-mediated kinetochore transport exist to ensure proper chromosome segregation during mitosis.

Cited by 107 publications

References 52 publications

NuMA Recruits Dynein Activity to Microtubule Minus-Ends at Mitosis

NuMA Recruits Dynein Activity to Microtubule Minus-Ends at Mitosis

Anaphase A: Melting Microtubules Move Chromosomes toward Spindle Poles

Kinetochore assembly and function through the cell cycle

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