Importin α and vNEBD Control Meiotic Spindle Disassembly in Fission Yeast

Flor-Parra, Ignacio; Iglesias-Romero, Ana Belén; Salas-Pino, Silvia; Lucena, Rafael; Jiménez, Juan; Daga, Rafael R.

doi:10.1016/j.celrep.2018.03.073

“…In line with this, when we used light microscopy to track transmembrane (Cut11; hereafter “transmembrane”) and nucleoplasmic ring (Nup60; hereafter “peripheral”) components of the nuclear pore complex (NPC) through mitosis (nucleoporins or “Nups”), we observed NPCs being depleted from stalk regions of the bridge where Les1 accumulated (Figure 3a). At the same time, the excluded NPCs became concentrated within the middle region of the bridge, as previously reported (18, 19), where Les1 levels appeared depleted (Figure 3a and 3b). Thus, Les1 and NPCs appear to have a mutually exclusive localisation.…”

Section: Resultssupporting

confidence: 87%

Closed mitosis requires local disassembly of the nuclear envelope

Dey

¹

,

Culley

²

,

Curran

³

et al. 2019

Preprint

2

1

0

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At the end of mitosis, eukaryotic cells must segregate both copies of their replicated genome into two new nuclear compartments (1). They do this either by first dismantling and later reassembling the nuclear envelope in a so called "open mitosis", or by reshaping an intact nucleus and then dividing into two in a "closed mitosis" (2, 3). However, while mitosis has been studied in a wide variety of eukaryotes for over a century (4), it is not known how the double membrane of the nuclear envelope is split into two at the end of a closed mitosis without compromising the impermeability of the nuclear compartment (5). In studying this problem in the fission yeast Schizosaccharomyces pombe, a classical model for closed mitosis (5), we use genetics, live cell imaging and electron tomography to show that nuclear fission is achieved via local disassembly of the nuclear envelope (NE) within the narrow bridge that links segregating daughter nuclei. In doing so, we identify a novel inner NE-localised protein Les1 that restricts the process of local NE breakdown (local NEB) to the bridge midzone and prevents the leakage of material from daughter nuclei. The mechanics of local NEB in a closed mitosis closely mirror those of NEB in open mitosis (3), revealing an unexpectedly deep conservation of nuclear remodelling mechanisms across diverse eukaryotes. closed mitosis | nuclear division | nuclear envelope | nuclear pore complex Correspondence: g.dey@ucl.ac.uk, b.baum@ucl.ac.uk Dey et al. | bioRχiv | September 23, 2019 | 1-9

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“…In line with this, when we used light microscopy to track transmembrane (Cut11; hereafter "transmembrane") and nucleoplasmic ring (Nup60; hereafter "peripheral") compo- nents of the nuclear pore complex (NPC) through mitosis (nucleoporins or "Nups"), we observed NPCs being depleted from stalk regions of the bridge where Les1 accumulated (Figure 3a). At the same time, the excluded NPCs became concentrated within the middle region of the bridge, as previously reported (18,19), where Les1 levels appeared depleted (Figure 3a and 3b). Thus, Les1 and NPCs appear to have a mutually exclusive localisation.…”

Section: Resultssupporting

confidence: 85%

Closed mitosis requires local disassembly of the nuclear envelope

Dey

¹

,

Culley

²

,

Curran

³

et al. 2020

Nature

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At the end of mitosis, eukaryotic cells must segregate both copies of their replicated genome into two new nuclear compartments (1). They do this either by first dismantling and later reassembling the nuclear envelope in a so called "open mitosis", or by reshaping an intact nucleus and then dividing into two in a "closed mitosis" (2, 3). However, while mitosis has been studied in a wide variety of eukaryotes for over a century (4), it is not known how the double membrane of the nuclear envelope is split into two at the end of a closed mitosis without compromising the impermeability of the nuclear compartment (5). In studying this problem in the fission yeast Schizosaccharomyces pombe, a classical model for closed mitosis (5), we use genetics, live cell imaging and electron tomography to show that nuclear fission is achieved via local disassembly of the nuclear envelope (NE) within the narrow bridge that links segregating daughter nuclei. In doing so, we identify a novel inner NE-localised protein Les1 that restricts the process of local NE breakdown (local NEB) to the bridge midzone and prevents the leakage of material from daughter nuclei. The mechanics of local NEB in a closed mitosis closely mirror those of NEB in open mitosis (3), revealing an unexpectedly deep conservation of nuclear remodelling mechanisms across diverse eukaryotes.

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“…7 F); however, in contrast to Klp6 deletion, Klp5 deletion also increased the maximum length of SPB-mediated spindles ( Fig. 7 F), as described previously ( Flor-Parra et al, 2018b ). Nonetheless, Klp5 deletion did not cause a significant improvement either in progression to MII in bqt1 Δ sad1.2 meiocytes ( Fig.…”

Section: Resultssupporting

confidence: 87%

Loss of kinesin-8 improves the robustness of the self-assembled spindle in Schizosaccharomyces pombe

Pineda-Santaella

¹

,

Fernández-Castillo

²

,

Jiménez-Martín

³

et al. 2021

Journal of Cell Science

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Chromosome segregation in female meiosis in many metazoans is mediated by acentrosomal spindles, the existence of which implies that microtubule spindles self-assemble without the participation of the centrosomes. Although it is thought that acentrosomal meiosis is not conserved in fungi, we recently reported the formation of self-assembled microtubule arrays, which were able to segregate chromosomes, in fission yeast mutants where the contribution of the spindle pole body (SPB, the centrosome equivalent in yeast) was specifically blocked during meiosis. Here, we demonstrate that this unexpected microtubule formation represents a bonafide type of acentrosomal spindle. Moreover, a comparative analysis of these self-assembled spindles and the canonical SPB-dependent spindle reveals similarities and differences: for example, both spindles have a similar polarity, but the location of the γ-tubulin complex differs. We also show that the robustness of self-assembled spindles can be reinforced by eliminating kinesin-8 family members, whereas kinesin-8 mutants have an adverse impact on SPB-dependent spindles. Hence, we consider that reinforced self-assembled spindles in yeast will help to clarify the molecular mechanisms behind acentrosomal meiosis, a crucial step towards better understanding gametogenesis.

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Importin α and vNEBD Control Meiotic Spindle Disassembly in Fission Yeast

Cited by 17 publications

References 39 publications

Closed mitosis requires local disassembly of the nuclear envelope

Closed mitosis requires local disassembly of the nuclear envelope

Closed mitosis requires local disassembly of the nuclear envelope

Loss of kinesin-8 improves the robustness of the self-assembled spindle in Schizosaccharomyces pombe

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