scholarly journals Comparative analysis of Synthetic Physical Interactions with the yeast centrosome

2019 ◽  
Author(s):  
Rowan S M Howell ◽  
Attila Csikász-Nagy ◽  
Peter H Thorpe
Keyword(s):  
Data Analysis ◽  
Comparative Analysis ◽  
Chromosome Segregation ◽  
Nuclear Membrane ◽  
Spindle Pole Body ◽  
Spindle Pole ◽  
Growth Defects ◽  
Pole Body ◽  
Physical Interactions ◽  
Spindle Microtubules

1AbstractThe yeast centrosome or Spindle Pole Body (SPB) is situated in the nuclear membrane, where it nucleates spindle microtubules and acts as a signalling hub. Previously, we used Synthetic Physical Interactions to map the regions of the cell that are sensitive to forced relocalization of proteins across the proteome [Berry et al., 2016]. Here, we expand on this work to show that the SPB, in particular, is sensitive to the relocalization of many proteins. This work inspired a new data analysis approach that indicates that relocalization screens may produce more growth defects than previously reported. A set of associations with the SPB result in elevated SPB number and since hyper-proliferation of centrosomes is a hallmark of cancer cells, these associations point the way for the use of yeast models in the study of spindle formation and chromosome segregation in cancer.

Ultrastructure of mitosis and the spindle pole body cycle in the smut fungus, Tilletia foetida

1985 ◽  
Vol 63 (1) ◽  
pp. 86-96 ◽  
Author(s):  
James A. Hoffmann ◽  
Blair J. Goates
Keyword(s):  
Nuclear Membrane ◽  
Spindle Pole Body ◽  
Spindle Pole ◽  
Dense Layer ◽  
Double Structure ◽  
Pole Body ◽  
Cytoplasmic Microtubules ◽  
Spindle Microtubules ◽  
Dense Chromatin ◽  
Tilletia Foetida

The interphase nucleus in secondary sporidia of Tilletia foetida consists of mostly diffuse chromatin, one or two nucleoli, and an area of heterochromatin located opposite an electron-dense, extranuclear spindle pole body (SPB). The interphase SPB is an oval- to bar-shaped, double-structured disc that has a crystallinelike substructure. During nuclear migration into nascent sporidia, SPBs and nucleoli are randomly oriented. At the onset of division, chromatin begins to condense and the SPB becomes located on a nuclear protuberance. Cytoplasmic microtubules terminate at the SPBs and multivesicular bodies surround the SPBs from the early stages of SPB division to early postdivision. SPB discs become spheroid and each develops a medial, dense layer. Then, a basal, dense layer develops and elongates as the SPBs separate and become positioned on opposite sides of the nuclear protuberance. The nuclear membrane opens opposite the SPB during SPB division. The nucleolus is extruded into a nuclear bleb and degenerates. SPBs migrate to opposing sides of the nucleus and become diffuse as a microtubular spindle develops between them. Some spindle microtubules terminate at dense chromatin patches that are contiguous with the major mass of chromatin surrounding the spindle. During late division stages, spindle microtubules often appear to be closely juxtaposed. Except for polar openings adjacent to the SPBs, the nuclear membrane is entire until late division when it degenerates in the midregion of the nucleus. During early postdivision, the SPB condenses into a small, dense sphere as the chromatin and heterochromatin opposite the SPB become diffuse. The SPB then elongates into a dense bar and SPB material increases, except at the midportion, reforming the double structure of interphase.

scholarly journals A microtubule polymerase cooperates with the kinesin-6 motor and a microtubule cross-linker to promote bipolar spindle assembly in the absence of kinesin-5 and kinesin-14 in fission yeast

2017 ◽  
Vol 28 (25) ◽  
pp. 3647-3659 ◽  
Author(s):  
Masashi Yukawa ◽  
Tomoki Kawakami ◽  
Masaki Okazaki ◽  
Kazunori Kume ◽  
Ngang Heok Tang ◽  
...  
Keyword(s):  
Fission Yeast ◽  
Chromosome Segregation ◽  
Spindle Pole Body ◽  
Spindle Assembly ◽  
Spindle Pole ◽  
Temperature Sensitive ◽  
Bipolar Spindle ◽  
Pole Body ◽  
Cross Linker ◽  
Spindle Elongation

Accurate chromosome segregation relies on the bipolar mitotic spindle. In many eukaryotes, spindle formation is driven by the plus-end–directed motor kinesin-5 that generates outward force to establish spindle bipolarity. Its inhibition leads to the emergence of monopolar spindles with mitotic arrest. Intriguingly, simultaneous inactivation of the minus-end–directed motor kinesin-14 restores spindle bipolarity in many systems. Here we show that in fission yeast, three independent pathways contribute to spindle bipolarity in the absence of kinesin-5/Cut7 and kinesin-14/Pkl1. One is kinesin-6/Klp9 that engages with spindle elongation once short bipolar spindles assemble. Klp9 also ensures the medial positioning of anaphase spindles to prevent unequal chromosome segregation. Another is the Alp7/TACC-Alp14/TOG microtubule polymerase complex. Temperature-sensitive alp7cut7pkl1 mutants are arrested with either monopolar or very short spindles. Forced targeting of Alp14 to the spindle pole body is sufficient to render alp7cut7pkl1 triply deleted cells viable and promote spindle assembly, indicating that Alp14-mediated microtubule polymerization from the nuclear face of the spindle pole body could generate outward force in place of Cut7 during early mitosis. The third pathway involves the Ase1/PRC1 microtubule cross-linker that stabilizes antiparallel microtubules. Our study, therefore, unveils multifaceted interplay among kinesin-dependent and -independent pathways leading to mitotic bipolar spindle assembly.

The influence of the microtubule inhibitor, methyl benzimidazol-2-yl-carbamate (MBC) on nuclear division and the cell cycle in Saccharomyces cerevisiae

1980 ◽  
Vol 46 (1) ◽  
pp. 341-352
Author(s):  
R.A. Quinlan ◽  
C.I. Pogson ◽  
K. Gull
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Cell Cycle ◽  
Spindle Pole Body ◽  
Spindle Pole ◽  
Ultrastructural Examination ◽  
Microtubule Inhibitor ◽  
Microtubule Polymerization ◽  
Pole Body ◽  
Outer Component ◽  
Spindle Microtubules

Methyl benzimidazol-2-yl-carbamate (MBC), at a concentration of 100 microM, has a pronounced effect on the growth of Saccharomyces cerevisiae, resulting in the accumulation of cells as large doublets. We have determined a specific execution point for the effect of MBC on the yeast cell cycle, and have shown that this execution point is between the cycle events of spindle pole body duplication and spindle pole body separation. An ultrastructural examination of the MBC-treated cells revealed the absence of cytoplasmic and spindle microtubules. MBC treatment also produced an altered spindle pole body morphology, causing the disappearance of the outer component. Nuclear size was also markedly increased in the MBC-induced doublet cells, although the septa were completely absent from these doublet cells. It is proposed that MBC inhibits microtubule polymerization, rather than causing the depolymerization of stable microtubules.

scholarly journals Requirement of the spindle pole body for targeting and/or tethering proteins to the inner nuclear membrane

Nucleus ◽  
2014 ◽  
Vol 5 (4) ◽  
pp. 352-366 ◽  
Author(s):  
Greetchen Diaz-Muñoz ◽  
Terri A Harchar ◽  
Tsung-Po Lai ◽  
Kuo-Fang Shen ◽  
Anita K Hopper
Keyword(s):  
Nuclear Membrane ◽  
Spindle Pole Body ◽  
Spindle Pole ◽  
Inner Nuclear Membrane ◽  
Pole Body

Ultrastructure of somatic mitosis in a diploid strain of the plant pathogenic fungus Cochliobolus sativus

1975 ◽  
Vol 53 (4) ◽  
pp. 403-414 ◽  
Author(s):  
H. C. Huang ◽  
R. D. Tinline ◽  
L. C. Fowke
Keyword(s):  
Nuclear Envelope ◽  
Ultrastructural Study ◽  
Pathogenic Fungus ◽  
Spindle Pole Body ◽  
Spindle Pole ◽  
Cochliobolus Sativus ◽  
Diploid Strain ◽  
Interphase Nuclei ◽  
Pole Body ◽  
Spindle Microtubules

An ultrastructural study of mitosis in a diploid strain of Cochliobolus sativus showed the event to be intranuclear. Two nucleoli occasionally were present in interphase nuclei. During division the spindle pole body peripheral to the nuclear envelope divided; spindle microtubules radiated into the nucleoplasm from the amorphous granular region abutting the nuclear envelope beneath the bodies; chromosomes condensed at prophase, approached the equatorial plane at metaphase, and moved asynchronously at anaphase; single microtubules appeared attached to kinetochore-like structures. At telophase, nuclei exhibited maximal elongation; fissures of the nuclear envelope appeared in the interzonal region; the nucleolus dispersed. The polar nuclear areas became new daughter nuclei with nucleoli.

scholarly journals Targeting of Nbp1 to the inner nuclear membrane is essential for spindle pole body duplication

2011 ◽  
Vol 30 (16) ◽  
pp. 3337-3352 ◽  
Author(s):  
Thomas Kupke ◽  
Leontina Di Cecco ◽  
Hans-Michael Müller ◽  
Annett Neuner ◽  
Frank Adolf ◽  
...  
Keyword(s):  
Nuclear Membrane ◽  
Spindle Pole Body ◽  
Spindle Pole ◽  
Inner Nuclear Membrane ◽  
Pole Body

Somatic nuclear division in the sporidia of Ustilago violacea. IV. Microtubules and the spindle-pole body

1976 ◽  
Vol 22 (4) ◽  
pp. 507-522 ◽  
Author(s):  
N. H. Poon ◽  
A. W. Day
Keyword(s):  
Nuclear Membrane ◽  
Spindle Pole Body ◽  
Spindle Pole ◽  
Control Center ◽  
Ustilago Violacea ◽  
Membrane Breakdown ◽  
Pole Body ◽  
Free Region ◽  
Nuclear Rotation ◽  
Anther Smut

In unbudded cells of the anther smut fungus Ustilago violacea there is a dome-shaped spindle-pole body (SPB) consisting of a core 0.1 μm in diameter surrounded by a ribosome-free region 0.3–0.4 μm in diameter lying in a pocket of the nuclear membrane. After budding the nucleus moves towards the bud and begins to rotate rapidly. At about this stage the SPB divides into two parallel bars each about 0.1–0.15 μm in diameter and 0.3 μm long, separated by a distance of about 0.3 μm. Microtubules associated with the nuclear membrane but not with the SPB are present at the time of nuclear rotation. These microtubules disappear when rotation stops. Microtubules attached to the SPB are found during migration of the chromatinic portion of the nucleus into the bud cell. These microtubules disappear when migration stops and the nuclear membrane begins to break down. The twin SPB bars appear to move into the nucleus through a break in the membrane and begin to move apart forming a spindle about 1 μm long. Chromosomal microtubules (one per kinetochore) were found in several serial sections, and in addition there appeared to be several continuous microtubules present. The separation of the two chromatinic masses appeared to result from elongation of the continuous microtubules to about 3 μm long. Cytoplasmic microtubules and spindle microtubules were both found attached to the SPB as it elongated and one nucleus returned to the mother cell.The paper concludes with a discussion of the SPB as a multifunctional control center affecting nuclear migration, spindle formation, membrane breakdown and synthesis, karyogamy, conjugation, budding, chromosomal movement, replication, and disjunction.

scholarly journals Spc24 interacts with Mps2 and is required for chromosome segregation, but is not implicated in spindle pole body duplication

2002 ◽  
Vol 43 (6) ◽  
pp. 1431-1443 ◽  
Author(s):  
Ivan Le Masson ◽  
Cosmin Saveanu ◽  
Anne Chevalier ◽  
Abdelkader Namane ◽  
Renee Gobin ◽  
...  
Keyword(s):  
Chromosome Segregation ◽  
Spindle Pole Body ◽  
Spindle Pole ◽  
Pole Body

scholarly journals The half-bridge component Kar1 promotes centrosome separation and duplication during budding yeast meiosis

2018 ◽  
Vol 29 (15) ◽  
pp. 1798-1810
Author(s):  
Meenakshi Agarwal ◽  
Hui Jin ◽  
Melainia McClain ◽  
Jinbo Fan ◽  
Bailey A. Koch ◽  
...  
Keyword(s):  
Chromosome Segregation ◽  
Budding Yeast ◽  
Spindle Pole Body ◽  
Spindle Pole ◽  
Pole Body ◽  
Centrosome Separation ◽  
Chromatid Segregation ◽  
Yeast Meiosis ◽  
Unique Mechanism

The budding yeast centrosome, often called the spindle pole body (SPB), nucleates microtubules for chromosome segregation during cell division. An appendage, called the half bridge, attaches to one side of the SPB and regulates SPB duplication and separation. Like DNA, the SPB is duplicated only once per cell cycle. During meiosis, however, after one round of DNA replication, two rounds of SPB duplication and separation are coupled with homologue segregation in meiosis I and sister-chromatid segregation in meiosis II. How SPB duplication and separation are regulated during meiosis remains to be elucidated, and whether regulation in meiosis differs from that in mitosis is unclear. Here we show that overproduction of the half-bridge component Kar1 leads to premature SPB separation during meiosis. Furthermore, excessive Kar1 induces SPB overduplication to form supernumerary SPBs, leading to chromosome missegregation and erroneous ascospore formation. Kar1-­mediated SPB duplication bypasses the requirement of dephosphorylation of Sfi1, another half-bridge component previously identified as a licensing factor. Our results therefore reveal an unexpected role of Kar1 in licensing meiotic SPB duplication and suggest a unique mechanism of SPB regulation during budding yeast meiosis.

scholarly journals Relief of the Dma1-mediated checkpoint requires Dma1 autoubiquitination and dynamic localization

2018 ◽  
Vol 29 (18) ◽  
pp. 2176-2189 ◽  
Author(s):  
Christine M. Jones ◽  
Jun-Song Chen ◽  
Alyssa E. Johnson ◽  
Zachary C. Elmore ◽  
Sierra N. Cullati ◽  
...  
Keyword(s):  
Cell Division ◽  
Chromosome Segregation ◽  
Ubiquitin Ligase ◽  
Spindle Pole Body ◽  
Mitotic Checkpoint ◽  
Spindle Pole ◽  
Checkpoint Activation ◽  
Pole Body ◽  
Septation Initiation Network ◽  
Anaphase B

Chromosome segregation and cell division are coupled to prevent aneuploidy and cell death. In the fission yeast Schizosaccharomyces pombe, the septation initiation network (SIN) promotes cytokinesis, but upon mitotic checkpoint activation, the SIN is actively inhibited to prevent cytokinesis from occurring before chromosomes have safely segregated. SIN inhibition during the mitotic checkpoint is mediated by the E3 ubiquitin ligase Dma1. Dma1 binds to the CK1-phosphorylated SIN scaffold protein Sid4 at the spindle pole body (SPB), and ubiquitinates it. Sid4 ubiquitination antagonizes the SPB localization of the Pololike kinase Plo1, the major SIN activator, so that SIN signaling is delayed. How this checkpoint is silenced once spindle defects are resolved has not been clear. Here we establish that Dma1 transiently leaves SPBs during anaphase B due to extensive autoubiquitination. The SIN is required for Dma1 to return to SPBs later in anaphase. Blocking Dma1 removal from SPBs by permanently tethering it to Sid4 prevents SIN activation and cytokinesis. Therefore, controlling Dma1’s SPB dynamics in anaphase is an essential step in S. pombe cell division and the silencing of the Dma1-dependent mitotic checkpoint.

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