UCD School of Biomolecular and Biomedical Science, Conway Institute of Biomolecular and Biomedical Research, University College Dublin, Belfield, Dublin 4, Ireland.
Cell Death Dis. 2013 Jan 24;4(1):e468. doi: 10.1038/cddis.2012.208.
Mitotic cell death following prolonged arrest is an important death mechanism that is not completely understood. This study shows that Protein Tyrosine Phosphatase 1B (PTP1B) undergoes phosphorylation during mitotic arrest induced by microtubule-targeting agents (MTAs) in chronic myeloid leukaemia cells. Inhibition of cyclin-dependent kinase 1 (Cdk1) or polo-like kinase 1 (Plk1) during mitosis prevents PTP1B phosphorylation, implicating these kinases in PTP1B phosphorylation. In support of this, Cdk1 and Plk1 co-immunoprecipitate with endogenous PTP1B from mitotic cells. In addition, active recombinant Cdk1-cyclin B1 directly phosphorylates PTP1B at serine 386 in a kinase assay. Recombinant Plk1 phosphorylates PTP1B on serine 286 and 393 in vitro, however, it requires a priming phosphorylation by Cdk1 at serine 386 highlighting a novel co-operation between Cdk1 and Plk1 in the regulation of PTP1B. Furthermore, overexpression of wild-type PTP1B induced mitotic cell death, which is potentiated by MTAs. Moreover, mutation of serine 286 abrogates the cell death induced by PTP1B, whereas mutation of serine 393 does not, highlighting the importance of serine 286 phosphorylation in the execution of mitotic cell death. Finally, phosphorylation on serine 286 enhanced PTP1B phosphatase activity. Collectively, these data reveal that PTP1B activity promotes mitotic cell death and is regulated by the co-operative action of Cdk1 and Plk1 during mitotic arrest.
有丝分裂细胞死亡是一种重要的死亡机制，但目前还不完全清楚。本研究表明，蛋白酪氨酸磷酸酶 1B（PTP1B）在慢性髓系白血病细胞中微管靶向药物（MTAs）诱导的有丝分裂阻滞期间发生磷酸化。在有丝分裂期间抑制周期蛋白依赖性激酶 1（Cdk1）或 Polo 样激酶 1（Plk1）可防止 PTP1B 磷酸化，表明这些激酶参与 PTP1B 磷酸化。支持这一观点的是，Cdk1 和 Plk1 从有丝分裂细胞中与内源性 PTP1B 共免疫沉淀。此外，活性重组 Cdk1-细胞周期蛋白 B1 在激酶测定中直接在丝氨酸 386 处磷酸化 PTP1B。重组 Plk1 在体外磷酸化 PTP1B 的丝氨酸 286 和 393，但需要 Cdk1 在丝氨酸 386 处的初始磷酸化，突出了 Cdk1 和 Plk1 在 PTP1B 调节中的新的合作关系。此外，野生型 PTP1B 的过表达诱导有丝分裂细胞死亡，而 MTAs 则增强了这种死亡。此外，丝氨酸 286 突变消除了 PTP1B 诱导的细胞死亡，而丝氨酸 393 突变则没有，这突出了丝氨酸 286 磷酸化在有丝分裂细胞死亡中的重要性。最后，丝氨酸 286 的磷酸化增强了 PTP1B 的磷酸酶活性。总之，这些数据表明 PTP1B 活性促进有丝分裂细胞死亡，并在有丝分裂阻滞期间由 Cdk1 和 Plk1 的协同作用调节。
