Torques within and outside the human spindle balance twist at anaphase

Lila Neahring; Yifei He; Nathan H Cho; Gaoxiang Liu; Jonathan Fernandes; Caleb J Rux; Konstantinos Nakos; Radhika Subramanian; Srigokul Upadhyayula; Ahmet Yildiz; Sophie Dumont

doi:10.1101/2023.12.10.570990

Torques within and outside the human spindle balance twist at anaphase

bioRxiv [Preprint]. 2023 Dec 10:2023.12.10.570990. doi: 10.1101/2023.12.10.570990.

Authors

Lila Neahring^{1

2}, Yifei He³, Nathan H Cho^{1

4}, Gaoxiang Liu⁵, Jonathan Fernandes³, Caleb J Rux^{1

6}, Konstantinos Nakos^{7

8}, Radhika Subramanian^{7

8}, Srigokul Upadhyayula^{5

9

10}, Ahmet Yildiz^{5

11}, Sophie Dumont^{1

2

4

6

10

12}

Affiliations

¹ Department of Bioengineering & Therapeutic Sciences, University of California San Francisco, San Francisco, CA, USA.
² Developmental & Stem Cell Biology Graduate Program, University of California San Francisco, San Francisco, CA, USA.
³ Department of Chemistry, University of California Berkeley, Berkeley, CA, USA.
⁴ Tetrad Graduate Program, University of California San Francisco, San Francisco, CA, USA.
⁵ Department of Molecular and Cell Biology, University of California Berkeley, Berkeley, CA, USA.
⁶ UC Berkeley/UC San Francisco Graduate Group in Bioengineering, Berkeley, CA, USA.
⁷ Department of Molecular Biology, Massachusetts General Hospital, Boston, MA, USA.
⁸ Department of Genetics, Harvard Medical School, Boston, MA, USA.
⁹ Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA.
¹⁰ Chan Zuckerberg Biohub, San Francisco, CA, USA.
¹¹ Physics Department, University of California Berkeley, Berkeley, CA, USA.
¹² Department of Biochemistry & Biophysics, University of California San Francisco, San Francisco, CA, USA.

Abstract

At each cell division, nanometer-scale motors and microtubules give rise to the micron-scale spindle. Many mitotic motors step helically around microtubules in vitro, and most are predicted to twist the spindle in a left-handed direction. However, the human spindle exhibits only slight global twist, raising the question of how these molecular torques are balanced. Here, using lattice light sheet microscopy, we find that anaphase spindles in the epithelial cell line MCF10A have a high baseline twist, and we identify factors that both increase and decrease this twist. The midzone motors KIF4A and MKLP1 are redundantly required for left-handed twist at anaphase, and we show that KIF4A generates left-handed torque in vitro. The actin cytoskeleton also contributes to left-handed twist, but dynein and its cortical recruitment factor LGN counteract it. Together, our work demonstrates that force generators regulate twist in opposite directions from both within and outside the spindle, preventing strong spindle twist during chromosome segregation.

Keywords: chirality; cortex; dynein; lattice light sheet microscopy; mitosis; motors; spindle; torque; twist.

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Preprint

Abstract

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