Department of Biomedical Sciences, Florida State University, Tallahassee, Florida, United States of America.
Sci Rep. 2017 Aug 30;7(1):10084. doi: 10.1038/s41598-017-10935-5.
Successful execution of mitotic cell division requires the tight synchronisation of numerous biochemical pathways. The underlying mechanisms that govern chromosome segregation have been thoroughly investigated. However, the mechanisms that regulate transcription factors in coordination with mitotic progression remain poorly understood. In this report, we identify the transcription factor YY1 as a novel mitotic substrate for the Aurora A kinase, a key regulator of critical mitotic events, like centrosome maturation and spindle formation. Using in vitro kinase assays, we show that Aurora A directly phosphorylates YY1 at serine 365 in the DNA-binding domain. Using a new phospho-specific antibody, we show that YY1 phosphorylation at serine 365 occurs during mitosis, and that this phosphorylation is significantly reduced upon inhibition of Aurora A. Furthermore, we show, using electrophoretic mobility shift and chromatin immunoprecipitation assays, that phosphorylation of YY1 at this site abolishes its DNA binding activity in vitro and in vivo. In conformity with this loss of binding activity, phosphorylated YY1 also loses its transctivation ability as demonstrated by a luciferase reporter assay. These results uncover a novel mechanism that implicates Aurora A in the mitotic inactivation of transcription factors.
成功进行有丝分裂细胞分裂需要许多生化途径的紧密同步。调控染色体分离的基本机制已经得到了深入研究。然而，与有丝分裂进程协调调控转录因子的机制仍知之甚少。在本报告中，我们发现转录因子 YY1 是 Aurora A 激酶的一种新型有丝分裂底物，Aurora A 激酶是关键的有丝分裂事件（如中心体成熟和纺锤体形成）的关键调节剂。通过体外激酶测定，我们表明 Aurora A 可直接在 DNA 结合域中的丝氨酸 365 处磷酸化 YY1。通过使用新的磷酸特异性抗体，我们表明 YY1 在丝氨酸 365 处的磷酸化发生在有丝分裂过程中，并且在 Aurora A 抑制时，这种磷酸化显著降低。此外，我们通过电泳迁移率变动和染色质免疫沉淀测定表明，该位点的磷酸化在体外和体内均会破坏 YY1 的 DNA 结合活性。与这种结合活性丧失一致，磷酸化的 YY1 也会失去其转录激活能力，如荧光素酶报告基因测定所示。这些结果揭示了一种新的机制，表明 Aurora A 参与了转录因子的有丝分裂失活。
