P90 RSK arranges Chk1 in the nucleus for monitoring of genomic integrity during cell proliferation.
P90 RSK arranges Chk1 in the nucleus for monitoring of genomic integrity during cell proliferation.
复制标题
DOI：
10.1091/mbc.e11-10-0883
复制
发表时间：
2012-04
影响因子：
3.3
通讯作者：
Inagaki M
中科院分区：
文献类型：
--
作者：
Li P;Goto H;Kasahara K;Matsuyama M;Wang Z;Yatabe Y;Kiyono T;Inagaki M
P90 RSK，而不是Akt/PKB，通过Chk 1-Ser-280磷酸化促进Chk 1在细胞核内的滞留。UV照射后Chk 1-Ser-280磷酸化也以p90 RSK依赖性方式升高，并加速UV照射后Chk 1活化过程（Chk 1上的Ser-345和Ser-296磷酸化）。共济失调毛细血管扩张症突变和rad 3相关激酶（ATR）/Chk 1通路是细胞周期进程的哨兵。另一方面，Ras/促分裂原活化蛋白激酶/90-kDa核糖体S6激酶（p90 RSK）途径是生长因子下游细胞信号传导的中心节点。这些途径在细胞增殖中密切相关，但它们的相互作用在很大程度上是未知的。在这里，我们表明，Chk 1磷酸化主要是在Ser-280和易位从细胞质到细胞核中的血清刺激。非磷酸化的Chk 1-Ser-280突变减弱了Chk 1在细胞核内的积累，而拟磷酸化的突变对Chk 1的定位有相反的作用。用p90 RSK抑制剂处理损害Chk 1在Ser-280的磷酸化和血清刺激后在细胞核的积累，而这两种现象是由血清饥饿细胞中p90 RSK的组成型活性突变体的表达诱导的。体外分析表明，p90 RSK化学计量磷酸化Chk 1上的Ser-280。与Chk 1通过ATR在Ser-345处的磷酸化及其在Ser-296处的自磷酸化一起，这对于检查点信号传导至关重要，Chk 1-Ser-280磷酸化在UV照射后以p90 RSK依赖性方式升高。此外，通过用p90 RSK抑制剂处理或通过Ser-280突变为Ala，UV照射后Ser-345和Ser-296处的Chk 1磷酸化也减弱。这些结果表明，p90 RSK通过Chk 1-Ser-280磷酸化促进核Chk 1积累，并且该途径在制备用于监测细胞增殖期间的遗传稳定性中起重要作用。
P90 RSK, but not Akt/PKB, facilitates nuclear retention of Chk1 through Chk1–Ser-280 phosphorylation in response to serum stimulation. Chk1–Ser-280 phosphorylation is also elevated in a p90 RSK–dependent manner after UV irradiation and accelerates the Chk1 activation process (Ser-345 and Ser-296 phosphorylation on Chk1) after UV irradiation. The ataxia telangiectasia mutated- and rad3-related kinase (ATR)/Chk1 pathway is a sentinel of cell cycle progression. On the other hand, the Ras/mitogen-activated protein kinase/90-kDa ribosomal S6 kinase (p90 RSK) pathway is a central node in cell signaling downstream of growth factors. These pathways are closely correlated in cell proliferation, but their interaction is largely unknown. Here we show that Chk1 is phosphorylated predominantly at Ser-280 and translocated from cytoplasm to nucleus in response to serum stimulation. Nonphosphorylated Chk1–Ser-280 mutation attenuates nuclear Chk1 accumulation, whereas the phosphomimic mutation has a reverse effect on the localization. Treatment with p90 RSK inhibitor impairs Chk1 phosphorylation at Ser-280 and accumulation at the nucleus after serum stimulation, whereas these two phenomena are induced by the expression of the constitutively active mutant of p90 RSK in serum-starved cells. In vitro analyses indicate that p90 RSK stoichiometrically phosphorylates Ser-280 on Chk1. Together with Chk1 phosphorylation at Ser-345 by ATR and its autophosphorylation at Ser-296, which are critical for checkpoint signaling, Chk1–Ser-280 phosphorylation is elevated in a p90 RSK–dependent manner after UV irradiation. In addition, Chk1 phosphorylation at Ser-345 and Ser-296 after UV irradiation is also attenuated by the treatment with p90 RSK inhibitor or by Ser-280 mutation to Ala. These results suggest that p90 RSK facilitates nuclear Chk1 accumulation through Chk1–Ser-280 phosphorylation and that this pathway plays an important role in the preparation for monitoring genetic stability during cell proliferation.