Aurora-A promotes the establishment of spindle assembly checkpoint by priming the Haspin-Aurora-B feedback loop in late G2 phase

Abstract

Aurora-A kinase functions mainly in centrosome maturation, separation and spindle formation. It has also been found to be amplified or overexpressed in a range of solid tumors, which is linked with tumor progression and poor prognosis. Importantly, Aurora-A inhibitors are being studied in a number of ongoing clinical trials. However, whether and how Aurora-A has a role in the regulation of the mitotic checkpoint is controversial. Additionally, the function of nuclear-accumulated Aurora-A in late G2 phase is not clear. Here we show that knockout, inhibition or blockade of the nuclear entry of Aurora-A severely decreased the centromere localization of Aurora-B and the phosphorylation of histone H3 threonine 3 (H3T3-ph) mediated by the kinase Haspin in late G2 phase. We further reveal that nuclear-accumulated Aurora-A phosphorylates Haspin at multiple sites at its N-terminus and that this promotes H3T3-ph and the rapid recruitment to the centromere of the chromosomal passenger complex. In addition, Aurora-A facilitates the association of Aurora-B with their common substrates: Haspin and Plk1. Notably, these functions of Aurora-A are mostly independent of Plk1. Thus we demonstrate that, in late G2 and prophase, Aurora-A phosphorylates Haspin to trigger the Haspin-H3T3-ph-Aurora-B positive feedback loop that supports the timely establishment of the chromosomal passenger complex and the mitotic checkpoint before spindle assembly.

Selective targeting of non-centrosomal AURKA functions through use of a targeted protein degradation tool

“…The effect of PROTAC-D in promoting mitotic exit could potentially be explained by a number of studies showing a role for AURKA in the SAC [35][36][37] , but could also occur through 'mitotic slippage', should there be any non-specific targeting of Cyclin B1 by PROTAC-D in the presence of an active SAC 38 . We tested this possibility using a RPE1-cyclin B1-Venus KI line 39 .…”

Chromosome biorientation and APC activity remain uncoupled in oocytes with reduced volume

“…This enriches the mitotic checkpoint complex (MCC) in the half-oocyte containing the nucleus, because it is generated at nuclear pores ( Rodriguez-Bravo et al, 2014 ; Kyogoku and Kitajima, 2017 ). In addition, other checkpoint kinases are known to have roles in G2 that influence SAC efficacy in mitosis ( Yu et al, 2017 ) and so may also be enriched by halving before NEB. In our study, the reduction in volume was performed after NEB, and thus is more likely to reflect the ability of kinetochores to prevent anaphase with unperturbed concentrations of cytoplasmic APC inhibitors.…”

Aurora A kinase activity is required to maintain an active spindle assembly checkpoint during prometaphase

“…Although Aurora A has never been directly involved in kinetochore functions, it phosphorylates CENP-A in prophase to allow Aurora B localisation at kinetochores (Kunitoku et al, 2003). Aurora A also phosphorylates Haspin in late G2, participating indirectly to the phosphorylation of threonine 3 of histone H3 and to the recruitment of Aurora B to kinetochores, and more directly to the localisation of CPC and SAC proteins at kinetochores (Yu et al, 2017). Aurora A was also recently reported to phosphorylate Ndc80 and to associate with the inner centromere Aurora B partner INCENP, when overexpressed, to localise at the mitotic chromosome kinetochore (DeLuca et al, 2018).…”