利用免疫荧光标记研究磷酸化组蛋白H3在乳腺癌细胞中的分布

在时间上与细胞周期相关并且在功能上又与染色质凝集偶联的一类组蛋白翻译后修饰就是组蛋白H3磷酸化。运用一个针对H3 Ser10磷酸化的特异性抗体 ,通过SDS PAGE、免疫印迹和免疫荧光标记检测了磷酸化H3在MCF 7细胞周期中的分布。共聚焦显微结果显示 :H3磷酸化在早前期细胞核膜附近以斑点状起始 ,之后扩展到整个凝集的染色质上 ,然后在早中期达到最高水平。H3去磷酸化开始于有丝分裂后期 ,很快在末期完成 ,而此时末期细胞凝集的染色质并未完全解凝集。H3磷酸化与染色质初期凝集之间存在着精确的时间和空间上的相关性。另外 ,对H3磷酸化可能的作用进行了讨论。

Studies of Distribution of Phosphorylated H3 in Human MCF-7 Cells by Immunofluroescence Labeling

One of the prominent cell cycle related modifications of histone proteins whose function is correlated with chromosome condensation is the phosphorylation of histone H3. In this work we used immunofluorescence labeling on human MCF 7 cells with the antibody that was specific for phosphorylated histone H3 at Ser10 to examine the celluar distribution of this protein.The acid soluble proteins from interphase and mitotic cells were separated by SDS PAGE and the transferred proteins were probed with the antibody. A strong H3 specific band was only detected in the acid soluble proteins from mitotic cells, demonstrating the correlation between H3 phosphorylation and mitosis. With confocal microscopy on whole cells, our results showed that mitotic phosphorylation of H3 initiated in discrete foci near the nuclear envelope in early prophase cells. Following initiation, H3 phosphorylation appeared to spread throughout the condensing chromatin and reached maximum in early metaphase cells. Dephosphorylation of H3 began in anaphase cells and was complete immediately prior to detectable chromosome decondensation in telophase cells. There was a precise spatial and temporal correlation between H3 phosphorylation and initial stages of chromatin condensation. The possible functions of the singular phosphorylation of the amino terminus of H3 were discussed.