Ser28磷酸化组蛋白H3在哺乳动物有丝分裂细胞中的动态分布

Dynatic Distribution of Phosporylated H3 Ser28 during Mitosis in Mammal Cells

利用特异性抗Ser28磷酸化组蛋白H3抗体,应用间接免疫荧光标记技术,标记人乳腺癌细胞 (MCF-7)和小鼠成纤维细胞(NIH 3T3),用激光共聚焦显微术研究这两种哺乳动物细胞中Ser28磷酸化组蛋白 H3在有丝分裂过程中的动态分布,以研究Ser28磷酸化组蛋白在细胞有丝分裂过程中的作用.结果表明,Ser28 的磷酸化作用是这两种细胞有丝分裂期的特有事件.组蛋白H3的Ser28磷酸化信号首先出现在早期的核外周, Ser28磷酸化在中期达到高峰,并扩展到染色体的所有部分,后期和末期逐渐减退,随着胞质分裂的完成而消失. 实验结果表明,组蛋白H3 Ser28的磷酸化与有丝分裂染色体的凝集和解凝集过程有着时间和空间上的相关性. Ser28磷酸化使得组蛋白H3氨基末端的正电荷数降低,这可能是导致染色质变构凝集的原因之一.有丝分裂期 间组蛋白H3在Ser28位置磷酸化过程与Ser10相比有明显的差异,因此在动物细胞中,组蛋白H3氨基末端这 两个不同丝氨酸残基的磷酸化可能有不同的生物学功能.

The post-translation modifications of the histories play crucial roles in DNA replication, recombination, transcription, gene expression and chromosome packaging. In present study, indirect immunofluorescence labeling and laser confocal microscopy were adopted to examine the dynamic distribution and functions of Ser28 phosphorylated H3 in breast cancer cell MCF-7 and mouse fibroblast NIH 3T3 during mitosis. The results showed that, histone H3 Ser28 phosphorylation is a special event in mitosis of the cells. The phosphorylation of histone H3 at Ser28 initiated at prophase of the cells, and then reached maximum at metaphase and spread out on whole chromosomes, finally the signal of Ser28 phosphorylation dispersed at anaphase and telophase, and disappeared along with cytokinesis. The results suggest that the histone H3 Ser28 phosphorylation correlated with mitotic chromosome condensation and decondensation in temporally and spatially. Histone H3 Ser28 phosphorylation might be a factor of inducing chromatin remolding and condensation by reducing positive charges of the H3 N-terminal. Compared to histone H3 Ser10 phosphorylation, the distribution of Ser28 phosphorylated histone H3 is different at metaphase, anaphase and telophase, especially during the cytokinesis. The evidence means that the Ser10 and Ser28 phosphorylations of histone H3 are distinctive mitotic events and have different functions.