WDR62 localizes katanin at spindle poles to ensure synchronous chromosome segregation

Abstract

Mutations in the WDR62 gene cause primary microcephaly, a pathological condition often associated with defective cell division that results in severe brain developmental defects. The precise function and localization of WDR62 within the mitotic spindle is, however, still under debate, as it has been proposed to act either at centrosomes or on the mitotic spindle. Here we explored the cellular functions of WDR62 in human epithelial cell lines using both short-term siRNA protein depletions and long-term CRISPR/Cas9 gene knockouts. We demonstrate that WDR62 localizes at spindle poles, promoting the recruitment of the microtubule-severing enzyme katanin. Depletion or loss of WDR62 stabilizes spindle microtubules due to insufficient microtubule minus-end depolymerization but does not affect plus-end microtubule dynamics. During chromosome segregation, WDR62 and katanin promote efficient poleward microtubule flux and favor the synchronicity of poleward movements in anaphase to prevent lagging chromosomes. We speculate that these lagging chromosomes might be linked to developmental defects in primary microcephaly.

WDR62 regulates spindle dynamics as an adaptor protein between TPX2/Aurora A and katanin

“…By contrast, in the current study, knockout of WDR62 dramatically reduced the spindle pole localization of p80 by ∼90%, suggesting that WDR62 might be the major recruiting factor of katanin in our system. In agreement with our results, an accompanying study from the Meraldi laboratory also demonstrated that WDR62 can localize katanin at spindle poles to ensure efficient minus-end depolymerization ( Guerreiro et al, 2021 ). Although our studies revealed two pathways (ASPM and WDR62) for recruiting katanin to the spindle pole in HeLa cells, how they work together needs further investigation.…”

Centrosome age breaks spindle size symmetry even in “symmetrically” dividing cells

“…The list of investigated proteins included centrobin, a daughter centriole-specific protein (Zou et al, 2005; Jeffery et al, 2010); the mitotic kinase Plk1 and Aurora-A (specifically the activated phosphorylated form of Aurora-A) and their centrosomal activator CEP192, which have been implicated in the regulation of spindle microtubule dynamics (Joukov et al, 2014; Barr and Gergely, 2007; Asteriti et al, 2015); pericentrosomal proteins required for microtubule nucleation such as pericentrin, Cdk5Rap2 and γ-tubulin that have been implicated in spindle size regulation (Fong et al, 2008; Choi et al, 2010; Greenan et al, 2010; Ren and Weisblat, 2006; Watanabe et al, 2020); and microtubule dynamics regulators at spindle poles such as the microtubule depolymerases Kif2A and MCAK (Ganem and Compton, 2004; Jang et al, 2009; Domnitz et al, 2012), the microtubule-severing enzyme Katanin (Loughlin et al, 2011; Huang et al, 2021; Guerreiro et al, 2021), as well as the microtubule-associated proteins TPX2 (Bird and Hyman, 2008; Sobajima et al, 2023), TACC3 (Cassimeris and Morabito, 2004; Gergely et al, 2003) and EB1 (Dema et al, 2022).…”

Microcephaly-associated WDR62 mutations hamper Golgi apparatus-to-spindle pole shuttling in human neural progenitors

“…Given previously described functions of WDR62 in regulating mitotic spindle stability and mitotic spindle angle (Bogoyevitch et al, 2012; Guerreiro et al, 2021; Miyamoto et al, 2017), and primary cilium assembly/disassembly (Shohayeb et al, 2020; Zhang et al, 2019), we evaluated inter-centrosomal distance (ICD) and spindle pole angle, two indicators of mitotic spindle formation and integrity. ICD, measured as edge-to-edge pericentrin (PCTN) signal, which localizes in close proximity to the centrosome, was not altered in WDR62 iPS-NES cells (Figure 2D).…”