Polo-like Kinase1Triggers Histone H3Phosphorvlation By Haspin In Mitosis

Histone modifications coordinate the chromatin localization of key regulatory factors in mitosis. For example, mitotic phosphorylation of Histone H3threonine-3(H3T3ph) by Haspin creates a binding site for Survivin, a subunit of the Chromosomal Passenger Complex (CPC) and therefore modulates Aurora B function, particularly at centromeres to ensure the correct segregation of sister chromatids during mitosis.The mechanisms that exert spatiotemporal control over such modifications, however, have been unclear. Here we show that Plk1binds to Haspin in a-phosphorylation-dependent manner. Reducing Plk1activity decreases the phosphorylation of Haspin and inhibits H3T3ph, particularly in prophase, suggesting that Plkl is required for initial activation of Haspin in early mitosis. These studies reveal a positive role for Plkl in regulation of the CPC in mitosis.