Pathogenic mutations in the chromokinesin KIF22 disrupt anaphase chromosome segregation
- University of Vermont, United States
- Mayo Clinic, United States
Abstract
The chromokinesin KIF22 generates forces that contribute to mitotic chromosome congression and alignment. Mutations in the a2 helix of the motor domain of KIF22 have been identified in patients with abnormal skeletal development, and we report the identification of a patient with a novel mutation in the KIF22 tail. We demonstrate that pathogenic mutations do not result in a loss of KIF22's functions in early mitosis. Instead, mutations disrupt chromosome segregation in anaphase, resulting in reduced proliferation, abnormal daughter cell nuclear morphology, and, in a subset of cells, cytokinesis failure. This phenotype could be explained by a failure of KIF22 to inactivate in anaphase. Consistent with this model, constitutive activation of the motor via a known site of phosphoregulation in the tail phenocopied the effects of pathogenic mutations. These results suggest the motor domain a2 helix may be an important site for regulation of KIF22 activity at the metaphase to anaphase transition. In support of this conclusion, mimicking phosphorylation of a2 helix residue T158 also prevents inactivation of KIF22 in anaphase. These findings demonstrate the importance of both the head and tail of the motor in regulating the activity of KIF22 and offer insight into the cellular consequences of preventing KIF22 inactivation and disrupting force balance in anaphase.
Data availability
All data generated or analyzed during this study are included in the manuscript and supporting files. Source Data files have been provided for Figure 2, Figure 2- Figure Supplement 1, Figure 3, Figure 4, Figure 4- Figure Supplement 1, Figure 5, Figure 6, Figure 6- Figure Supplement 1, Figure 7, Figure 8, Figure 8- Figure Supplement 1, Figure 9, Figure 9- Figure Supplement 1, Figure 9- Figure Supplement 2, and Figure 9- Figure Supplement 3.
Article and author information
Author details
Patrick R Blackburn
Funding
National Institutes of Health (F31AR074887)
- Alex F Thompson
National Institutes of Health (R01GM130556)
- Jason Stumpff
National Institutes of Health (R01GM121491)
- Jason Stumpff
National Institutes of Health (R35GM144133)
- Jason Stumpff
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
Copyright
© 2022, Thompson et al.
This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.
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Pathogenic mutations in the chromokinesin KIF22 disrupt anaphase chromosome segregation
eLife 11:e78653.
https://doi.org/10.7554/eLife.78653
Further reading
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- Cell Biology
Mitotic anaphase onset is a key cellular process tightly regulated by multiple kinases. The involvement of mitogen-activated protein kinases (MAPKs) in this process has been established in Xenopus egg extracts. However, the detailed regulatory cascade remains elusive, and it is also unknown whether the MAPK-dependent mitotic regulation is evolutionarily conserved in the single-cell eukaryotic organisms such as fission yeast (Schizosaccharomyces pombe). Here, we show that two MAPKs in S. pombe indeed act in concert to restrain anaphase-promoting complex/cyclosome (APC/C) activity upon activation of the spindle assembly checkpoint (SAC). One MAPK, Pmk1, binds to and phosphorylates Slp1Cdc20, the co-activator of APC/C. Phosphorylation of Slp1Cdc20 by Pmk1, but not by Cdk1, promotes its subsequent ubiquitylation and degradation. Intriguingly, Pmk1-mediated phosphorylation event is also required to sustain SAC under environmental stress. Thus, our study establishes a new underlying molecular mechanism of negative regulation of APC/C by MAPK upon stress stimuli, and provides a previously unappreciated framework for regulation of anaphase entry in eukaryotic cells.
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