NAT10 regulates mitotic cell fate by acetylating Eg5 to control bipolar spindle assembly and chromosome segregation.

Abstract

Cell fate of mitotic cell is controlled by spindle assembly. Deficient spindle assembly results in mitotic catastrophe leading to cell death to maintain cellular homeostasis. Therefore, inducing mitotic catastrophe provides a strategy for tumor therapy. Nucleolar acetyltransferase NAT10 has been found to regulate various cellular processes to maintain cell homeostasis. Here we report that NAT10 regulates mitotic cell fate by acetylating Eg5. NAT10 depletion results in multinuclear giant cells, which is the hallmark of mitotic catastrophe. Live-cell imaging showed that knockdown of NAT10 dramatically prolongs the mitotic time and induces defective chromosome segregation including chromosome misalignment, bridge and lagging. NAT10 binds and co-localizes with Eg5 in the centrosome during mitosis. Depletion of NAT10 reduces the centrosome loading of Eg5 and impairs the poleward movement of centrosome, leading to monopolar and asymmetrical spindle formation. Furthermore, NAT10 stabilizes Eg5 through its acetyltransferase function. NAT10 acetylates Eg5 at K771 to control Eg5 stabilization. We generated K771-Ac specific antibody and showed that Eg5 K771-Ac specifically localizes in the centrosome during mitosis. Additionally, K771 acetylation is required for the motor function of Eg5. The hyper-acetylation mimic Flag-Eg5 K771Q but not Flag-Eg5 rescued the NAT10 depletion-induced defective spindle formation and mitotic catastrophe, demonstrating that NAT10 controls mitosis through acetylating Eg5 K771. Collectively, we identify Eg5 as an important substrate of NAT10 in the control of mitosis and provide K771 as an essential acetylation site in the stabilization and motor function of Eg5. Our findings reveal that targeting the NAT10-mediated Eg5 K771 acetylation provides a potential strategy for tumor therapy.