Aurora A contributes to p150glued phosphorylation and function during mitosis

Aurora A is a spindle pole–associated protein kinase required for mitotic spindle assembly and chromosome segregation. In this study, we show that Drosophila melanogaster aurora A phosphorylates the dynactin subunit p150^glued on sites required for its association with the mitotic spindle. Dynactin strongly accumulates on microtubules during prophase but disappears as soon as the nuclear envelope breaks down, suggesting that its spindle localization is tightly regulated. If aurora A''s function is compromised, dynactin and dynein become enriched on mitotic spindle microtubules. Phosphorylation sites are localized within the conserved microtubule-binding domain (MBD) of the p150^glued. Although wild-type p150^glued binds weakly to spindle microtubules, a variant that can no longer be phosphorylated by aurora A remains associated with spindle microtubules and fails to rescue depletion of endogenous p150^glued. Our results suggest that aurora A kinase participates in vivo to the phosphoregulation of the p150^glued MBD to limit the microtubule binding of the dynein–dynactin complex and thus regulates spindle assembly.