[Studies of dynamic distribution of Thr11-phosphorylated H3 in MCF-7 at mitosis]

The phosphorylations of histone H3 on Ser10, Ser28, Thrll and Thr3 of the amino terminal are the events that related to mitosis of the cell. To study the function of Thrll phosphorylation of histone H3,indirect immunofluorescence labeling and laser confocal were employed with the antibody that was specific for Thrll-phosphorylated histone H3. The celluar dynamic distribution of this protein was examined at mitosis in MCF-7 cell. Our results showed that Thrll- phosphorylation of H3 initiated at centromere at early prophase in MCF-7 cells. The fluorescence signal on Thr1l-phorphoslated histone H3 reached the strongest at early metaphase at the centromere punctated in the central of mitotic cell. The dephosphorylation of Thrll-phorphoslated histone H3 was completed in anaphase. The behavior of Thrll phosphorylation and dephosphorylation in mitotic cell of MCF-7 were different from that of Ser10 phorphorylation and dephosphorylation. The results suggest that the Thrll phosphorylation of histone H3 has a specific function in mitosis different from Ser10 phosphorylation. There was a precise spatial and temporal correlation between H3 phosphorylation of Thrll and initial stages of chromatin condensation. Thrll -phorphoslated histone H3 located on centromeres suggest that it maybe included in the active kinetochore during mitosis.