The Regulation of Microtubule Dynamics in <i>Saccharomyces cerevisiae</i> by Three Interacting Plus-End Tracking Proteins

Wolyniak, Michael J.; Blake-Hodek, Kristina; Kosco, Karena; Hwang, Eric; You, Liru; Huffaker, Tim C.

doi:10.1091/mbc.e05-09-0892

Cited by 74 publications

(108 citation statements)

References 40 publications

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“…The catastrophe rate was then calculated as v g /L, which, compared with wild type, increased about fourfold in the bik1 mutant and decreased about twofold in the kip3 mutant ( Figure 4B). The catastrophe rates for S. cerevisiae and A. gossypii cMTs are similar, but the growth and shrinkage speeds are threefold slower in S. cerevisiae ( Figure 4B) according to averaged published data (Tirnauer et al, 1999;Adames and Cooper, 2000;Kosco et al, 2001;Huang and Huffaker, 2006;Wolyniak et al, 2006;Caudron et al, 2008).…”

Section: Phenotypes Of Mutations Affecting Microtubule Dynamics Are Vsupporting

confidence: 61%

Mechanism of Nuclear Movements in a Multinucleated Cell

Gibeaux

Politi

Philippsen

et al. 2016

Preprint

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Multinucleated cells are important in many organisms, but the mechanisms governing the movements of nuclei sharing a common cytoplasm are not understood. In the hyphae of the plant pathogenic fungus Ashbya gossypii, nuclei move back and forth, occasionally bypassing each other, preventing the formation of nuclear clusters. This is essential for genetic stability. These movements depend on cytoplasmic microtubules emanating from the nuclei that are pulled by dynein motors anchored at the cortex. Using three-dimensional stochastic simulations with parameters constrained by the literature, we predict the cortical anchor density from the characteristics of nuclear movements. The model accounts for the complex nuclear movements seen in vivo, using a minimal set of experimentally determined ingredients. Of interest, these ingredients power the oscillations of the anaphase spindle in budding yeast, but in A. gossypii, this system is not restricted to a specific nuclear cycle stage, possibly as a result of adaptation to hyphal growth and multinuclearity. INTRODUCTIONPositioning of the nucleus and mitotic spindle appropriately within the cell is critical in eukaryotes during many processes, ranging from simple growth to tissue development (Morris, 2002;Dupin and Etienne-Manneville, 2011;Gundersen and Worman, 2013;Kiyomitsu, 2015). Accordingly, cells have evolved various strategies to place their nucleus or spindle in suitable locations. In most systems, this process is driven by dynein pulling on nuclei-associated cytoplasmic microtubules (cMTs). Dynein is a minus end-directed motor that can act primarily in two ways. End-on pulling occurs when cortex-anchored dynein captures a growing cMT plus end, thereby initiating its shrinkage while maintaining the attachment. Lateral or side-on pulling occurs when cortex-anchored dynein walks on cMTs toward the minus end using its motor activity. This mode of action is independent of cMT shrinkage and may result in cMT sliding parallel to the cortex (Kotak and Gönczy, 2013;McNally, 2013;Akhmanova and van den Heuvel, 2016).A detailed mechanistic view for directing nuclei during the cell cycle is known in the budding yeast Saccharomyces cerevisiae, as outlined in Figure 1 and references therein. In contrast to most eukaryotic cells, the site of the cleavage plane in S. cerevisiae is selected early in the cell cycle by generating a ring structure (future bud neck) at the mother cell cortex at which the daughter cell (bud) will emerge. In addition, in budding yeast the nuclear envelope does not disassemble during mitosis, and nuclei are always attached to the minus end of cMTs via spindle pole bodies (SPBs) embedded in the nuclear envelope. The two pathways elucidated in S. cerevisiae involve cortical pulling, but only the second pathway relies on dynein. During the Kar9-Bim1-Myo2 pathway, the nucleus is directed toward the bud neck by transporting cMT plus ends first along bud neck-emerging actin cables, followed by depolymerization of the transported cMT. In metaphase, cMTs ...

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Section: Phenotypes Of Mutations Affecting Microtubule Dynamics Are Vsupporting

confidence: 61%

Mechanism of Nuclear Movements in a Multinucleated Cell

Gibeaux

Politi

Philippsen

et al. 2016

Preprint

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“…Another possible Stu2⌬N rescue mechanism, which is not mutually exclusive with the previous mechanism, is that overexpression of STU2⌬N is titrating out a Stu2-interacting protein that is mediating spindle expansion in spc24-9 HU cells. Stu2 interacts with the CLIP-170 orthologue Bik1 at the C terminus of Stu2 (Wolyniak et al, 2006). We find that deletion of the Stu2-interacting protein Bik1 rescues the spc24-9 spindle expansion defects and HU lethality at 30°C and that the bik1 spc24-9 double mutant grows at a higher temperature than the spc24-9 mutant alone (Figure 4, C and E).…”

Section: Stu2 Activity Enables Spindle Expansion In Spc24-9 Hu-treatementioning

confidence: 72%

“…Although stu2-10 spc24-9 double mutants maintained a short spindle during HU treatment, they were lethal on HU plates at 30°C ( Figure 4B), suggesting that the defects in both Stu2 and Spc24 prevent cell cycle recovery after HU exposure. Stu2 interacts with two other MT plus-end tracking proteins, Bim1 and Bik1 (Chen et al, 1998;Lin et al, 2001;Wolyniak et al, 2006). Because we had previously shown that bim1 spc24 -9 mutants have a synthetic growth defect (Montpetit et al, 2005), we deleted BIK1 in spc24-9 cells and analyzed growth phenotypes.…”

Section: Hcs Rescue Occurs Through Restraining Spindle Expansionmentioning

confidence: 99%

Spc24 and Stu2 Promote Spindle Integrity When DNA Replication Is Stalled

McQueen

Cuschieri²,

Vogel

et al. 2007

MBoC

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The kinetochore, a protein complex that links chromosomes to microtubules (MTs), is required to prevent spindle expansion during S phase in budding yeast, but the mechanism of how the kinetochore maintains integrity of the bipolar spindle before mitosis is not well understood. Here, we demonstrate that a mutation of Spc24, a component of the conserved Ndc80 kinetochore complex, causes lethality when cells are exposed to the DNA replication inhibitor hydroxyurea (HU) due to premature spindle expansion and segregation of incompletely replicated DNA. Overexpression of Stu1, a CLASP-related MT-associated protein or a truncated form of the XMAP215 orthologue Stu2 rescues spc24-9 HU lethality and prevents spindle expansion. Truncated Stu2 likely acts in a dominant-negative manner, because overexpression of full-length STU2 does not rescue spc24-9 HU lethality, and spindle expansion in spc24-9 HU-treated cells requires active Stu2. Stu1 and Stu2 localize to the kinetochore early in the cell cycle and Stu2 kinetochore localization depends on Spc24. We propose that mislocalization of Stu2 results in premature spindle expansion in S phase stalled spc24-9 mutants. Identifying factors that restrain spindle expansion upon inhibition of DNA replication is likely applicable to the mechanism by which spindle elongation is regulated during a normal cell cycle. INTRODUCTIONPreserving the integrity of the genome is a fundamental requirement for eukaryotic cell viability. DNA replication must be completed before segregation of the chromosomes to prevent the transmission of partially replicated chromosomes to daughter cells. In the budding yeast Saccharomyces cerevisiae, cells undergo a closed mitosis and the microtubule (MT) organizing centers, or spindle pole bodies (SPBs), are imbedded in the nuclear envelope. SPB duplication begins at the end of anaphase and spindle formation begins during S phase when duplicated SPBs separate from each other (Adams and Kilmartin, 1999;Jaspersen and Winey, 2004). Because chromosomes remain attached to kinetochore MTs throughout the cell cycle, spindle expansion must be restrained until all 16 chromosomes have duplicated and kinetochores on sister chromatids have formed bipolar MT attachments. When DNA replication is stalled by hydroxyurea (HU) treatment, cells arrest with a large bud, an undivided nucleus positioned at the mother-bud neck and a short bipolar spindle (Allen et al., 1994). Maintaining a short spindle is crucial for cell survival during HU-induced arrest, which activates the DNA replication checkpoint effectors Mec1 and Rad53 (Kolodner et al., 2002). When mec1 and rad53 mutants are treated with HU, the DNA replication checkpoint is not activated, and, as a result, replication forks are not stabilized, the spindle expands, and unequal division of incompletely replicated nuclear material occurs-all of these events contribute to cell lethality (Allen et al., 1994;Weinert et al., 1994;Lopes et al., 2001).In human cells, stalled replication forks activate the ataxia telangiectasia mutat...

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“…According to the N-terminus acetylation model, Ber1 might aVect tubulin function via N-acetylation of regulators such as Bim1, Bik1 and/or Stu2 (Wolyniak et al 2006). Those proteins, are predicted to be acetylated at their N-termini (Csank et al 2002), and this might interfere with their stability or function and hence, with microtubule dynamics.…”

Section: Discussionmentioning

confidence: 99%

The evolutionary conserved BER1 gene is involved in microtubule stability in yeast

et al. 2007

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In yeast, microtubules are dynamic Wlaments necessary for spindle and nucleus positioning, as well as for proper chromosome segregation. We identify a function for the yeast gene BER1 (Benomyl REsistant 1) in microtubule stability. BER1 belongs to an evolutionary conserved gene family whose founding member Sensitivity to Red light Reduced is involved in red-light perception and circadian rhythms in Arabidopsis. Here, we present data showing that the ber1 mutant is aVected in microtubule stability, particularly in presence of microtubuledepolymerising drugs. The pattern of synthetic lethal interactions obtained with the ber1 mutant suggests that Ber1 may function in N-terminal protein acetylation. Our work thus suggests that microtubule stability might be regulated through this post-translational modiWcation on yetto-be determined proteins.

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The Regulation of Microtubule Dynamics in Saccharomyces cerevisiae by Three Interacting Plus-End Tracking Proteins

Cited by 74 publications

References 40 publications

Mechanism of Nuclear Movements in a Multinucleated Cell

Mechanism of Nuclear Movements in a Multinucleated Cell

Spc24 and Stu2 Promote Spindle Integrity When DNA Replication Is Stalled

The evolutionary conserved BER1 gene is involved in microtubule stability in yeast

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