Fission yeast Hrp1, a chromodomain ATPase, is required for proper chromosome segregation and its overexpression interferes with chromatin condensation

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.

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A role for the fission yeast Rqh1 helicase in chromosome segregation

Journal of Cell Science ◽

10.1242/jcs.02694 ◽

2005 ◽

Vol 118 (24) ◽

pp. 5777-5784 ◽

Cited By ~ 26

Author(s):

T. Z. Win

Keyword(s):

Fission Yeast ◽

Chromosome Segregation

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Immediate visualization of recombination events and chromosome segregation defects in fission yeast meiosis

Chromosoma ◽

10.1007/s00412-019-00691-y ◽

2019 ◽

Vol 128 (3) ◽

pp. 385-396 ◽

Cited By ~ 2

Author(s):

Dmitriy Li ◽

Marianne Roca ◽

Raif Yuecel ◽

Alexander Lorenz

Keyword(s):

Fission Yeast ◽

Chromosome Segregation ◽

Yeast Meiosis

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csi2p modulates microtubule dynamics and organizes the bipolar spindle for chromosome segregation

Molecular Biology of the Cell ◽

10.1091/mbc.e14-09-1370 ◽

2014 ◽

Vol 25 (24) ◽

pp. 3900-3908 ◽

Cited By ~ 10

Author(s):

Judite Costa ◽

Chuanhai Fu ◽

V. Mohini Khare ◽

Phong T. Tran

Keyword(s):

Fission Yeast ◽

Chromosome Segregation ◽

Spindle Assembly Checkpoint ◽

Microtubule Dynamics ◽

High Rate ◽

Spindle Formation ◽

Bipolar Spindle ◽

Eukaryotic Chromosome ◽

Relative Contribution ◽

Multiple Phenotypes

Proper chromosome segregation is of paramount importance for proper genetic inheritance. Defects in chromosome segregation can lead to aneuploidy, which is a hallmark of cancer cells. Eukaryotic chromosome segregation is accomplished by the bipolar spindle. Additional mechanisms, such as the spindle assembly checkpoint and centromere positioning, further help to ensure complete segregation fidelity. Here we present the fission yeast csi2+. csi2p localizes to the spindle poles, where it regulates mitotic microtubule dynamics, bipolar spindle formation, and subsequent chromosome segregation. csi2 deletion (csi2Δ) results in abnormally long mitotic microtubules, high rate of transient monopolar spindles, and subsequent high rate of chromosome segregation defects. Because csi2Δ has multiple phenotypes, it enables estimates of the relative contribution of the different mechanisms to the overall chromosome segregation process. Centromere positioning, microtubule dynamics, and bipolar spindle formation can all contribute to chromosome segregation. However, the major determinant of chromosome segregation defects in fission yeast may be microtubule dynamic defects.

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Inverted meiosis: an alternative way of chromosome segregation for reproduction

Acta Biochimica et Biophysica Sinica ◽

10.1093/abbs/gmaa054 ◽

2020 ◽

Vol 52 (7) ◽

pp. 702-707 ◽

Cited By ~ 1

Author(s):

Wenzhu Li ◽

Xiangwei He

Keyword(s):

Dna Replication ◽

Fission Yeast ◽

Chromosome Segregation ◽

Chromosome Structure ◽

Adaptive Strategy ◽

Homologous Chromosomes ◽

Working Model ◽

Sister Chromatids ◽

Holocentric Chromosome ◽

Inverted Order

Abstract Canonical meiosis is characterized by two sequential rounds of nuclear divisions following one round of DNA replication—reductional segregation of homologous chromosomes during the first division and equational segregation of sister chromatids during the second division. Meiosis in an inverted order of two nuclear divisions—inverted meiosis has been observed in several species with holocentromeres as an adaptive strategy to overcome the obstacle in executing a canonical meiosis due to the holocentric chromosome structure. Recent findings of co-existence of inverted and canonical meiosis in two monocentric organisms, human and fission yeast, suggested that inverted meiosis could be common and also lead to the puzzle regarding the mechanistic feasibility for executing two meiosis programs simultaneously. Here, we discuss apparent conflicts for concurrent canonical meiosis and inverted meiosis. Furthermore, we attempt to provide a working model that may be compatible for both forms of meiosis.

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The dhp1+ gene, encoding a putative nuclear 5'->3' exoribonuclease, is required for proper chromosome segregation in fission yeast

Nucleic Acids Research ◽

10.1093/nar/29.6.1326 ◽

2001 ◽

Vol 29 (6) ◽

pp. 1326-1333 ◽

Cited By ~ 25

Author(s):

T. Shobuike

Keyword(s):

Fission Yeast ◽

Chromosome Segregation ◽

Gene Encoding

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Spindle checkpoint activation at meiosis I advances anaphase II onset via meiosis-specific APC/C regulation

The Journal of Cell Biology ◽

10.1083/jcb.200802053 ◽

2008 ◽

Vol 182 (2) ◽

pp. 277-288 ◽

Cited By ~ 24

Author(s):

Ayumu Yamamoto ◽

Kenji Kitamura ◽

Daisuke Hihara ◽

Yukinobu Hirose ◽

Satoshi Katsuyama ◽

...

Keyword(s):

Protein Degradation ◽

Fission Yeast ◽

Chromosome Segregation ◽

Spindle Assembly Checkpoint ◽

Related Factor ◽

Anaphase Promoting Complex ◽

Checkpoint Activation ◽

Anaphase Onset ◽

Yeast Meiosis ◽

Meiosis I

During mitosis, the spindle assembly checkpoint (SAC) inhibits the Cdc20-activated anaphase-promoting complex/cyclosome (APC/CCdc20), which promotes protein degradation, and delays anaphase onset to ensure accurate chromosome segregation. However, the SAC function in meiotic anaphase regulation is poorly understood. Here, we examined the SAC function in fission yeast meiosis. As in mitosis, a SAC factor, Mad2, delayed anaphase onset via Slp1 (fission yeast Cdc20) when chromosomes attach to the spindle improperly. However, when the SAC delayed anaphase I, the interval between meiosis I and II shortened. Furthermore, anaphase onset was advanced and the SAC effect was reduced at meiosis II. The advancement of anaphase onset depended on a meiosis-specific, Cdc20-related factor, Fzr1/Mfr1, which contributed to anaphase cyclin decline and anaphase onset and was inefficiently inhibited by the SAC. Our findings show that impacts of SAC activation are not confined to a single division at meiosis due to meiosis-specific APC/C regulation, which has probably been evolved for execution of two meiotic divisions.

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Epigenetic dynamics across the cell cycle

Essays in Biochemistry ◽

10.1042/bse0480107 ◽

2010 ◽

Vol 48 ◽

pp. 107-120 ◽

Cited By ~ 19

Author(s):

Tony Bou Kheir ◽

Anders H. Lund

Keyword(s):

Cell Cycle ◽

Chromosome Segregation ◽

Cell Cycle Progression ◽

Current Knowledge ◽

Chromatin Condensation ◽

Chromatin Modifications ◽

Cycle Progression ◽

Daughter Cells ◽

Mammalian Cell Cycle ◽

Regulate Cell Cycle Progression

Progression of the mammalian cell cycle depends on correct timing and co-ordination of a series of events, which are managed by the cellular transcriptional machinery and epigenetic mechanisms governing genome accessibility. Epigenetic chromatin modifications are dynamic across the cell cycle, and are shown to influence and be influenced by cell-cycle progression. Chromatin modifiers regulate cell-cycle progression locally by controlling the expression of individual genes and globally by controlling chromatin condensation and chromosome segregation. The cell cycle, on the other hand, ensures a correct inheritance of epigenetic chromatin modifications to daughter cells. In this chapter, we summarize the current knowledge on the dynamics of epigenetic chromatin modifications during progression of the cell cycle.

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