Tossidou Irini, Dangers Marc, Koch Alexandra, Brandt Dominique T, Schiffer Mario, Kardinal Christian
Nephrologie, Medizinische Hochschule Hannover (MHH), Hannover, Germany.
Cell Cycle. 2008 Dec 15;7(24):3858-68. doi: 10.4161/cc.7.24.7260. Epub 2008 Dec 24.
Tyrosine phosphorylation of the cell cycle regulator p27(Kip1) plays a crucial role in its binding to cyclin dependent kinases and its subcellular localization. While Src and Bcr-Abl were shown to be responsible for tyrosine phosphorylation, no data are available on the dephosphorylation of p27(Kip1) and the phosphatase involved. Considering the associated dephosphorylation as a pivotal event in the regulation of cell cycle proteins, we focused on the tyrosine phosphatase SHP-2, which is regulated in promyelocytic leukemia cells on G-CSF stimulation. SHP-2 was thus found in association with p27(Kip1) and the G-CSF receptor, and we observed a nuclear translocation of SHP-2 on G-CSF stimulation. Using a catalytically inactive form of SHP-2 and siRNA directed against SHP-2, we could demonstrate the involvement of SHP-2 in tyrosine dephosphorylation of p27(Kip1). Moreover, SHP-2 was strongly activated on G-CSF stimulation and specifically dephosphorylated p27(Kip1) in vitro. Most importantly, we could illustrate that SHP-2 modulates p27(Kip1) stability and contributes to p27(Kip1)-mediated cell cycle progression. Taken together, our results demonstrate that SHP-2 is a key regulator of p27(Kip1) tyrosine phosphorylation.
细胞周期调节因子p27（Kip1）的酪氨酸磷酸化在其与细胞周期蛋白依赖性激酶的结合及其亚细胞定位中起着关键作用。虽然已证明Src和Bcr-Abl负责酪氨酸磷酸化，但关于p27（Kip1）的去磷酸化及相关磷酸酶尚无数据。鉴于相关去磷酸化是细胞周期蛋白调节中的关键事件，我们聚焦于酪氨酸磷酸酶SHP-2，其在粒细胞集落刺激因子（G-CSF）刺激下的早幼粒细胞白血病细胞中受到调节。因此发现SHP-2与p27（Kip1）和G-CSF受体相关，并且我们观察到在G-CSF刺激下SHP-2发生核转位。使用催化失活形式的SHP-2和针对SHP-2的小干扰RNA（siRNA），我们能够证明SHP-2参与p27（Kip1）的酪氨酸去磷酸化。此外，SHP-2在G-CSF刺激下被强烈激活，并在体外特异性地使p27（Kip1）去磷酸化。最重要的是，我们能够说明SHP-2调节p27（Kip1）的稳定性并促进p27（Kip1）介导的细胞周期进程。综上所述，我们的结果表明SHP-2是p27（Kip1）酪氨酸磷酸化的关键调节因子。
