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Theses

Mechanisms of anaphase B spindle elongation & scaling in Schizosaccharomyzes pombe

Abstract : During cell division, a highly dynamic molecular machine, the mitotic spindle, separates the previously duplicated DNA into two identical sets. This is achieved by movement of sister-chromatids to opposite spindle poles (anaphase A) and separation of the spindle poles driven by elongation of the spindle (anaphase B). In most organisms, anaphase B spindle elongation is primarily driven by microtubule sliding forces generated by kinesin motors at the spindle midzone, the region of antiparallel overlapping microtubules at the spindle center. At the same time, the spindle microtubules have to grow in order to allow the spindle to elongate. In fact, microtubule sliding and microtubule growth have to be coordinated to ensure flawless spindle elongation.This work demonstrates that, in the model organism Schizosaccharomyces pombe, the homotetrameric kinesin-6 Klp9 is a crucial regulator of anaphase B spindle elongation. A combination of in vivo and in vitro experiments indicates that the motor holds a dual function: it can slide microtubules apart and regulate their growth velocity. Thus, the motor may inherently coordinate microtubule sliding and growth during anaphase.Accordingly, altering the number of motors present at the spindle midzone was sufficient to alter the speed of anaphase B spindle elongation. In fact, this is utilized by cells of different sizes to adjust the spindle elongation velocity to cell size. Increasing the Klp9 amount allows bigger cells, which form longer spindles, to elongate the spindle with higher speeds, as compared to smaller cells, which form shorter spindles. Scaling of the spindle elongation velocity eventually allows cells of different sizes with different spindle length to keep the process of sister-chromatid separation in a constant time frame, a potential advantage for cell viability.
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https://pastel.archives-ouvertes.fr/tel-03467854
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Submitted on : Monday, December 6, 2021 - 5:08:07 PM
Last modification on : Wednesday, January 12, 2022 - 12:18:02 PM
Long-term archiving on: : Monday, March 7, 2022 - 7:39:35 PM

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  • HAL Id : tel-03467854, version 1

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Lara Krüger. Mechanisms of anaphase B spindle elongation & scaling in Schizosaccharomyzes pombe. Other. Université Paris sciences et lettres, 2021. English. ⟨NNT : 2021UPSLS066⟩. ⟨tel-03467854⟩

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