Abstract

In this study, indirect immunofluorescence labeling was used to examine the cellular dynamic distribution of Thr11 phosphorylated H3 at mitosis in MCF-7 cells. The Thr11 phosphorylation was observed beginning at prophase at centromeres. Upon progression of mitosis, fluorescence signal was enhanced in the central region of the metaphase plate and maintained till anaphase at centromeres. During telophase, the fluorescent signal of Thr11 phosphorylated H3 disappears from centromeres, but the signal appears again at the midbody during cytokinesis, which suggests that the modified histones may take part in the formation of the midbody and play a crucial role in cytokinesis. Chromatin immunoprecipitation (ChIP) was used to confirm that Thr11 phosphorylated H3 is specifically associated with centromere DNA at prophase to metaphase, which is coincident with the results observed by immunofluorescence. In conclusion, there was a precise spatial and temporal correlation between H3 phosphorylation of Thr11 and stages of chromatin condensation. The timing of Thr11 phosphorylation and dephosphorylation in mitosis were similar to that reported for Ser10 phosphorylation of H3. The Thr11 phosphorylated H3 localized at centromeres during mitosis, which was different from the Ser10 phosphorylated H3 localized at telomere regions and Thr3 phosphorylated H3 localized along the chromosome arms. The results suggest that the Thr11 phosphorylation of histone H3 may play a specific role which was different from Ser10 and Thr3 phosphorylation in mitosis.