title: Excess F-actin mechanically impedes mitosis leading to cytokinesis failure in X-linked neutropenia by exceeding Aurora B kinase error correction capacity.
abstract: The constitutively active mutant of the Wiskott-Aldrich Syndrome protein (CA-WASp) is the cause of X-linked neutropenia and is linked with genomic instability and myelodysplasia. CA-WASp generates abnormally high levels of cytoplasmic F-actin through dysregulated activation of the Arp2/3 complex leading to defects in cell division. As WASp has no reported role in cell division, we hypothesized that alteration of cell mechanics because of increased F-actin may indirectly disrupt dynamic events during mitosis. Inhibition of the Arp2/3 complex revealed that excess cytoplasmic F-actin caused increased cellular viscosity, slowed all phases of mitosis, and perturbed mitotic mechanics. Comparison of chromosome velocity to the cytoplasmic viscosity revealed that cells compensated for increased viscosity by up-regulating force applied to chromosomes and increased the density of microtubules at kinetochores. Mitotic abnormalities were because of overload of the aurora signaling pathway as subcritical inhibition of Aurora in CA-WASp cells caused increased cytokinesis failure, while overexpression reduced defects. These findings demonstrate that changes in cell mechanics can cause significant mitotic abnormalities leading to genomic instability, and highlight the importance of mechanical sensors such as Aurora B in maintaining the fidelity of hematopoietic cell division.
authors.affiliation: Molecular Immunology Unit and Centre for Immunodeficiency, UCL Institute of Child Health, University College London, London, United Kingdom.
authors.forename: Dale A
authors.initials: DA
authors.lastname: Moulding
authors.forename: Emad
authors.initials: E
authors.lastname: Moeendarbary
authors.forename: Leo
authors.initials: L
authors.lastname: Valon
authors.forename: Julien
authors.initials: J
authors.lastname: Record
authors.forename: Guillaume T
authors.initials: GT
authors.lastname: Charras
authors.forename: Adrian J
authors.initials: AJ
authors.lastname: Thrasher
mesh_terms: D000199:Actins / Q000378:metabolism*; D064107:Aurora Kinase B; D064127:Aurora Kinases; D045744:Cell Line, Tumor; D043171:Chromosomal Instability / Q000235:genetics; D048749:Cytokinesis / Q000502:physiology*; D004260:DNA Repair / Q000502:physiology; D040181:Genetic Diseases, X-Linked / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D008938:Mitosis / Q000502:physiology*; D009154:Mutation; D009503:Neutropenia / Q000151:congenital* / Q000235:genetics / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D014161:Transduction, Genetic; D051316:Wiskott-Aldrich Syndrome Protein / Q000235:genetics / Q000378:metabolism
chemical_list: D000199:Actins; D051316:Wiskott-Aldrich Syndrome Protein; C576921:AURKB protein, human; D064107:Aurora Kinase B; D064127:Aurora Kinases; D017346:Protein Serine-Threonine Kinases