Bqt2p is essential for initiating telomere clustering upon pheromone sensing in fission yeast

The telomere bouquet, i.e., telomere clustering on the nuclear envelope (NE) during meiotic prophase, is thought to promote homologous chromosome pairing. Using a visual screen, we identified bqt2/im295, a mutant that disrupts telomere clustering in fission yeast. Bqt2p is required for linking telomeres to the meiotic spindle pole body (SPB) but not for attachment of telomeres or the SPB to the NE. Bqt2p is expressed upon pheromone sensing and colocalizes thereafter to Sad1p, an SPB protein. This localization only depends on Bqt1p, not on other identified proteins required for telomere clustering. Upon pheromone sensing, generation of Sad1p foci next to telomeres depends on Bqt2p. However, depletion of Bqt2p from the SPB is dispensable for dissolving the telomere bouquet at the end of meiotic prophase. Therefore, telomere bouquet formation requires Bqt2p as a linking component and is finely regulated during meiotic progression.

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Faculty Opinions recommendation of Fission yeast Myo51 is a meiotic spindle pole body component with discrete roles during cell fusion and spore formation.

Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature ◽

10.3410/f.2137023.1737135 ◽

2010 ◽

Author(s):

Christopher McInerny

Keyword(s):

Fission Yeast ◽

Cell Fusion ◽

Spindle Pole Body ◽

Spindle Pole ◽

Spore Formation ◽

Meiotic Spindle ◽

Pole Body ◽

Body Component

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The Fission Yeast Homolog of the Human Transcription Factor EAP30 Blocks Meiotic Spindle Pole Body Amplification

Developmental Cell ◽

10.1016/j.devcel.2005.04.016 ◽

2005 ◽

Vol 9 (1) ◽

pp. 63-73 ◽

Cited By ~ 20

Author(s):

Ye Jin ◽

Joel J. Mancuso ◽

Satoru Uzawa ◽

Daniela Cronembold ◽

W. Zacheus Cande

Keyword(s):

Transcription Factor ◽

Fission Yeast ◽

Spindle Pole Body ◽

Spindle Pole ◽

Meiotic Spindle ◽

Pole Body ◽

Yeast Homolog ◽

Human Transcription Factor

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The Fission Yeast Homolog of the Human Transcription Factor EAP30 Blocks Meiotic Spindle Pole Body Amplification

Developmental Cell ◽

10.1016/j.devcel.2005.08.009 ◽

2005 ◽

Vol 9 (3) ◽

pp. 439

Author(s):

Ye Jin ◽

Joel J. Mancuso ◽

Satoru Uzawa ◽

Daniela Cronembold ◽

W. Zacheus Cande

Keyword(s):

Transcription Factor ◽

Fission Yeast ◽

Spindle Pole Body ◽

Spindle Pole ◽

Meiotic Spindle ◽

Pole Body ◽

Yeast Homolog ◽

Human Transcription Factor

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Faculty Opinions recommendation of The fission yeast homolog of the human transcription factor EAP30 blocks meiotic spindle pole body amplification.

Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature ◽

10.3410/f.1027252.327667 ◽

2005 ◽

Author(s):

Iain Hagan

Keyword(s):

Transcription Factor ◽

Fission Yeast ◽

Spindle Pole Body ◽

Spindle Pole ◽

Meiotic Spindle ◽

Pole Body ◽

Yeast Homolog ◽

Human Transcription Factor

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Spindle pole body components are reorganized during fission yeast meiosis

Molecular Biology of the Cell ◽

10.1091/mbc.e11-11-0951 ◽

2012 ◽

Vol 23 (10) ◽

pp. 1799-1811 ◽

Cited By ~ 24

Author(s):

Midori Ohta ◽

Masamitsu Sato ◽

Masayuki Yamamoto

Keyword(s):

Fission Yeast ◽

Meiotic Prophase ◽

Spindle Pole Body ◽

Mitotic Cell ◽

Spindle Pole ◽

Nuclear Movement ◽

Pole Body ◽

Proper Number ◽

Body Components ◽

Yeast Meiosis

During meiosis, the centrosome/spindle pole body (SPB) must be regulated in a manner distinct from that of mitosis to achieve a specialized cell division that will produce gametes. In this paper, we demonstrate that several SPB components are localized to SPBs in a meiosis-specific manner in the fission yeast Schizosaccharomyces pombe. SPB components, such as Cut12, Pcp1, and Spo15, which stay on the SPB during the mitotic cell cycle, disassociate from the SPB during meiotic prophase and then return to the SPB immediately before the onset of meiosis I. Interestingly, the polo kinase Plo1, which normally localizes to the SPB during mitosis, is excluded from them in meiotic prophase, when meiosis-specific, horse-tail nuclear movement occurs. We found that exclusion of Plo1 during this period was essential to properly remodel SPBs, because artificial targeting of Plo1 to SPBs resulted in an overduplication of SPBs. We also found that the centrin Cdc31 was required for meiotic SPB remodeling. Thus Plo1 and a centrin play central roles in the meiotic SPB remodeling, which is essential for generating the proper number of meiotic SPBs and, thereby provide unique characteristics to meiotic divisions.

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Dissociation of the Nuf2-Ndc80 Complex Releases Centromeres from the Spindle-Pole Body during Meiotic Prophase in Fission Yeast

Molecular Biology of the Cell ◽

10.1091/mbc.e04-11-0996 ◽

2005 ◽

Vol 16 (5) ◽

pp. 2325-2338 ◽

Cited By ~ 48

Author(s):

Haruhiko Asakawa ◽

Aki Hayashi ◽

Tokuko Haraguchi ◽

Yasushi Hiraoka

Keyword(s):

Fission Yeast ◽

Chromosome Segregation ◽

Meiotic Prophase ◽

Spindle Pole Body ◽

Spindle Pole ◽

Mating Pheromone ◽

Pole Body ◽

Pheromone Signaling ◽

Ndc80 Complex ◽

Mutant Cells

In the fission yeast Schizosaccharomyces pombe, centromeres remain clustered at the spindle-pole body (SPB) during mitotic interphase. In contrast, during meiotic prophase centromeres dissociate from the SPB. Here we examined the behavior of centromere proteins in living meiotic cells of S. pombe. We show that the Nuf2-Ndc80 complex proteins (Nuf2, Ndc80, Spc24, and Spc25) disappear from the centromere in meiotic prophase when the centromeres are separated from the SPB. The centromere protein Mis12 also dissociates during meiotic prophase; however, Mis6 remains throughout meiosis. When cells are induced to meiosis by inactivation of Pat1 kinase (a key negative regulator of meiosis), centromeres remain associated with the SPB during meiotic prophase. However, inactivation of Nuf2 by a mutation causes the release of centromeres from the SPB in pat1 mutant cells, suggesting that the Nuf2-Ndc80 complex connects centromeres to the SPB. We further found that removal of the Nuf2-Ndc80 complex from the centromere and centromere-SPB dissociation are caused by mating pheromone signaling. Because pat1 mutant cells also show aberrant chromosome segregation in the first meiotic division and this aberration is compensated by mating pheromone signaling, dissociation of the Nuf2-Ndc80 complex may be associated with remodeling of the kinetochore for meiotic chromosome segregation.

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Membrane proteins Bqt3 and -4 anchor telomeres to the nuclear envelope to ensure chromosomal bouquet formation

The Journal of Cell Biology ◽

10.1083/jcb.200902122 ◽

2009 ◽

Vol 187 (3) ◽

pp. 413-427 ◽

Cited By ~ 76

Author(s):

Yuji Chikashige ◽

Miho Yamane ◽

Kasumi Okamasa ◽

Chihiro Tsutsumi ◽

Tomoko Kojidani ◽

...

Keyword(s):

Nuclear Envelope ◽

Fission Yeast ◽

Nuclear Membrane ◽

Meiotic Prophase ◽

Spindle Pole Body ◽

Spindle Pole ◽

Null Mutant ◽

Vegetative Cells ◽

Nuclear Membranes ◽

Pole Body

In many organisms, telomeres cluster to form a bouquet arrangement of chromosomes during meiotic prophase. Previously, we reported that two meiotic proteins, Bqt1 and -2, are required for tethering telomeres to the spindle pole body (SPB) during meiotic prophase in fission yeast. This study has further identified two novel, ubiquitously expressed inner nuclear membrane (INM) proteins, Bqt3 and -4, which are required for bouquet formation. We found that in the absence of Bqt4, telomeres failed to associate with the nuclear membranes in vegetative cells and consequently failed to cluster to the SPB in meiotic prophase. In the absence of Bqt3, Bqt4 protein was degraded during meiosis, leading to a phenotype similar to that of the bqt4-null mutant. Collectively, these results show that Bqt4 anchors telomeres to the INM and that Bqt3 protects Bqt4 from protein degradation. Interestingly, the functional integrity of telomeres is maintained even when they are separated from the nuclear envelope in vegetative cells.

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Fission Yeast Mutants Affecting Telomere Clustering and Meiosis-Specific Spindle Pole Body Integrity

Genetics ◽

10.1093/genetics/160.3.861 ◽

2002 ◽

Vol 160 (3) ◽

pp. 861-876

Author(s):

Ye Jin ◽

Satoru Uzawa ◽

W Z Cande

Keyword(s):

Fission Yeast ◽

Spindle Pole Body ◽

Spindle Pole ◽

Specific Protein ◽

Spore Wall ◽

Isolation And Characterization ◽

Pole Body ◽

Homologous Chromosome Pairing ◽

Eukaryotic Organisms ◽

And Function

Abstract In meiotic prophase of many eukaryotic organisms, telomeres attach to the nuclear envelope and form a polarized configuration called the bouquet. Bouquet formation is hypothesized to facilitate homologous chromosome pairing. In fission yeast, bouquet formation and telomere clustering occurs in karyogamy and persists throughout the horsetail stage. Here we report the isolation and characterization of six mutants from our screen for meiotic mutants. These mutants show defective telomere clustering as demonstrated by mislocalization of Swi6::GFP, a heterochromatin-binding protein, and Taz1p::GFP, a telomere-specific protein. These mutants define four complementation groups and are named dot1 to dot4—defective organization of telomeres. dot3 and dot4 are allelic to mat1-Mm and mei4, respectively. Immunolocalization of Sad1, a protein associated with the spindle pole body (SPB), in dot mutants showed an elevated frequency of multiple Sad1-nuclei signals relative to wild type. Many of these Sad1 foci were colocalized with Taz1::GFP. Impaired SPB structure and function were further demonstrated by failure of spore wall formation in dot1, by multiple Pcp1::GFP signals (an SPB component) in dot2, and by abnormal microtubule organizations during meiosis in dot mutants. The coincidence of impaired SPB functions with defective telomere clustering suggests a link between the SPB and the telomere cluster.

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