scholarly journals Cytokinetic actomyosin ring formation and septation in fission yeast are dependent on the full recruitment of the polo-like kinase Plo1 to the spindle pole body and a functional spindle assembly checkpoint

2002 ◽  
Vol 115 (18) ◽  
pp. 3575-3586 ◽  
Author(s):  
D. P. Mulvihill
2017 ◽  
Vol 28 (25) ◽  
pp. 3647-3659 ◽  
Author(s):  
Masashi Yukawa ◽  
Tomoki Kawakami ◽  
Masaki Okazaki ◽  
Kazunori Kume ◽  
Ngang Heok Tang ◽  
...  

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.


FEBS Letters ◽  
2014 ◽  
Vol 588 (17) ◽  
pp. 2814-2821 ◽  
Author(s):  
Ngang Heok Tang ◽  
Naoyuki Okada ◽  
Chii Shyang Fong ◽  
Kunio Arai ◽  
Masamitsu Sato ◽  
...  

Chromosoma ◽  
2019 ◽  
Vol 128 (3) ◽  
pp. 267-277 ◽  
Author(s):  
Alberto Pineda-Santaella ◽  
Alfonso Fernández-Álvarez

1998 ◽  
Vol 9 (4) ◽  
pp. 759-774 ◽  
Author(s):  
Amy R. Schutz ◽  
Mark Winey

In Saccharomyces cerevisiae, the Mps1p protein kinase is critical for both spindle pole body (SPB) duplication and the mitotic spindle assembly checkpoint. The mps1–1mutation causes failure early in SPB duplication, and because the spindle assembly checkpoint is also compromised, mps1–1cells proceed with a monopolar mitosis and rapidly lose viability. Here we report the genetic and molecular characterization ofmps1–1 and five new temperature-sensitive alleles ofMPS1. Each of the six alleles contains a single point mutation in the region of the gene encoding the protein kinase domain. The mutations affect several residues conserved among protein kinases, most notably the invariant glutamate in subdomain III. In vivo and in vitro kinase activity of the six epitope-tagged mutant proteins varies widely. Only two display appreciable in vitro activity, and interestingly, this activity is not thermolabile under the assay conditions used. While five of the six alleles cause SPB duplication to fail early, yielding cells with a single SPB, mps1–737cells proceed into SPB duplication and assemble a second SPB that is structurally defective. This phenotype, together with the observation of intragenic complementation between this unique allele and two others, suggests that Mps1p is required for multiple events in SPB duplication.


Nature ◽  
1990 ◽  
Vol 347 (6294) ◽  
pp. 680-682 ◽  
Author(s):  
Caroline E. Alfa ◽  
Bernard Ducommun ◽  
David Beach ◽  
Jeremy S. Hyams

2005 ◽  
Vol 9 (1) ◽  
pp. 63-73 ◽  
Author(s):  
Ye Jin ◽  
Joel J. Mancuso ◽  
Satoru Uzawa ◽  
Daniela Cronembold ◽  
W. Zacheus Cande

2003 ◽  
Vol 270 (6) ◽  
pp. 449-461 ◽  
Author(s):  
F. Miki ◽  
A. Kurabayashi ◽  
Y. Tange ◽  
K. Okazaki ◽  
M. Shimanuki ◽  
...  

2016 ◽  
Vol 27 (11) ◽  
pp. 1753-1763 ◽  
Author(s):  
Hirohisa Masuda ◽  
Takashi Toda

In fission yeast, γ-tubulin ring complex (γTuRC)–specific components Gfh1GCP4, Mod21GCP5, and Alp16GCP6 are nonessential for cell growth. Of these deletion mutants, only alp16Δ shows synthetic lethality with temperature-sensitive mutants of Mzt1MOZART1, a component of the γTuRC required for recruitment of the complex to microtubule-organizing centers. γ-Tubulin small complex levels at mitotic spindle pole bodies (SPBs, the centrosome equivalent in fungi) and microtubule levels for preanaphase spindles are significantly reduced in alp16Δ cells but not in gfh1Δ or mod21Δ cells. Furthermore, alp16Δ cells often form monopolar spindles and frequently lose a minichromosome when the spindle assembly checkpoint is inactivated. Alp16GCP6 promotes Mzt1-dependent γTuRC recruitment to mitotic SPBs and enhances spindle microtubule assembly in a manner dependent on its expression levels. Gfh1GCP4 and Mod21GCP5 are not required for Alp16GCP6-dependent γTuRC recruitment. Mzt1 has an additional role in the activation of the γTuRC for spindle microtubule assembly. The ratio of Mzt1 to γTuRC levels for preanaphase spindles is higher than at other stages of the cell cycle. Mzt1 overproduction enhances spindle microtubule assembly without affecting γTuRC levels at mitotic SPBs. We propose that Alp16GCP6 and Mzt1 act synergistically for efficient bipolar spindle assembly to ensure faithful chromosome segregation.


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