The p42/p44 mitogen-activated protein kinase activation triggers p27Kip1 degradation independently of CDK2/cyclin E in NIH 3T3 cells
The p42/p44 mitogen-activated protein kinase activation triggers p27Kip1 degradation independently of CDK2/cyclin E in NIH 3T3 cells
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DOI：
10.1074/jbc.m101714200
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发表时间：
2001-09-14
影响因子：
4.8
通讯作者：
Darbon, JM
中科院分区：
文献类型：
--
作者：
Delmas, C;Manenti, S;Darbon, JM
p42/p44丝裂原活化蛋白（mitogen-activated protein，MAP）激酶受多种促有丝分裂刺激物的刺激，其持续激活是细胞周期G（1）进程和G（1）/S转换所必需的。G（1）进展和G（1）/S转换也依赖于连续的细胞周期蛋白依赖性激酶（CDK）激活。在这里，我们证明，MAP激酶抑制导致积累的CDK抑制剂P27（Kip 1）在NIH 3 T3细胞。阻断p27（Kip 1）的蛋白酶体依赖性降解损害了这种积累，表明MAP激酶不作用于p271（Kip 1）蛋白合成。在细胞外信号（生长因子或细胞粘附）的情况下，MAP激酶的遗传激活降低了P27（Kip 1）的表达，通过共转染实验和免疫荧光检测评估。重要的是，MAP激酶激活还降低了p27（Kip 1）突变体的表达，该突变体不能被CDK 2磷酸化，这表明MAP激酶依赖性p27（Kip 1）调节是不依赖于CDK 2的。因此，显性阴性CDK 2的表达并不损害MAP激酶激活诱导的p27（Kip 1）下调。这些数据表明，MAP激酶途径调节p27（Kip 1）在成纤维细胞中的表达基本上通过降解机制，独立于p27（Kip 1）磷酸化的CDK 2。这加强了这种CDK抑制剂作为G（1）生长停滞的关键效应物的作用，其表达可以通过细胞外刺激依赖性信号通路控制。
The p42/p44 mitogen-activated protein (MAP) kinase is stimulated by various mitogenic stimuli, and its sustained activation is necessary for cell cycle G(1) progression and G(1)/S transition. G(1) progression and G(1)/S transition also depend on sequential cyclin-dependent kinase (CDK) activation. Here, we demonstrate that MAP kinase inhibition leads to accumulation of the CDK inhibitor P27(Kip1) in NIH 3T3 cells. Blocking the proteasome-dependent degradation of p27(Kip1) impaired this accumulation, suggesting that MAP kinase does not act on p271(Kip1) protein synthesis. In the absence of extracellular signals (growth factors or cell adhesion), genetic activation of MAP kinase decreased the expression of P27(Kip1) as assessed by cotransfection experiments and by immunofluorescence detection. Importantly, MAP kinase activation also decreased the expression of a p27(Kip1) mutant, which cannot be phosphorylated by CDK2, suggesting that MAP kinase-dependent p27(Kip1) regulation is CDK2-independent. Accordingly, expression of dominant-negative CDK2 did not impair the down-regulation of p27(Kip1) induced by MAP kinase activation. These data demonstrate that the MAP kinase pathway regulates p27(Kip1) expression in fibroblasts essentially through a degradation mechanism, independently of p27(Kip1) phosphorylation by CDK2. This strengthens the role of this CDK inhibitor as a key effector of G(1) growth arrest, whose expression can be controlled by extracellular stimuli-dependent signaling pathways.