The stress-activated protein kinases p38α and JNK1 stabilize p21Cip1 by phosphorylation
The stress-activated protein kinases p38α and JNK1 stabilize p21Cip1 by phosphorylation
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DOI：
10.1074/jbc.m201299200
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发表时间：
2002-08-16
影响因子：
4.8
通讯作者：
Friedman, E
中科院分区：
文献类型：
--
作者：
Kim, GY;Mercer, SE;Friedman, E
应激信号激活SAPK/JNK和p38 MAPK类蛋白激酶，其介导细胞应答，包括细胞凋亡和某些细胞类型成熟的步骤。我们现在发现，由转化生长因子β 1（TGF-β 1）启动的应激信号通过CDK抑制剂p21（Cip 1）的蛋白质稳定化诱导G（1）停滞。以前显示TGF-β 1增加p21蛋白水平，这又通过HD 3细胞中CDK 2-细胞周期蛋白E复合物的失活介导G（1）停滞（Yan，Z.，金，G.-是的，邓，X. Friedman，E.（2002）J.Biol.Chem.277，9870-9879）。我们现在证明p21丰度的增加是由转录后的SMAD独立机制引起的。TGF-β 1激活p38 α和JNK 1，启动p21的磷酸化。TGF-β 1治疗使p21的半衰期增加了3-4倍。在p38 a和JNK 1活化后检测到p21稳定性的增加，并且用p38抑制剂SB 203580处理细胞阻止了p21稳定性的这种增加。p38 a和JNK 1在体内磷酸化p21，并且p38 a和JNK 1在体外都磷酸化p21的Ser（130）。肽图谱显示，TGF-β 1和p38 a在体内均诱导p21在Ser（130）处的磷酸化，并且Ser（130）突变为丙氨酸使p21比野生型p21更不稳定。TGF-β 1增加野生型p21的稳定性，但不增加p21-S130 A突变体的稳定性。这些发现表明SAPKs可以通过p21的翻译后修饰介导细胞周期阻滞。
Stress signals activate the SAPK/JNK and p38 MAPK classes of protein kinases, which mediate cellular responses, including steps in apoptosis and the maturation of some cell types. We now show that stress signals initiated by transforming growth factor-beta1 (TGF-beta1) induce G(1) arrest through protein stabilization of the CDK inhibitor p21(Cip1). TGF-beta1 was previously shown to increase p21 protein levels, which in turn mediated G(1) arrest through inactivation of the CDK2-cyclin E complex in HD3 cells (Yan, Z., Kim, G.-Y., Deng, X., and Friedman, E. (2002) J. Biol. Chem. 277, 9870-9879). We now demonstrate that the increase in p21 abundance is caused by a post-transcriptional, SMAD-independent mechanism. TGF-beta1 activated p38alpha and JNK1, which initiated the phosphorylation of p21. TGF-beta1 treatment increased the half-life of p21 by 3-4-fold. The increase in p21 stability was detected following activation of p38a and JNK1, and treatment of cells with the p38 inhibitor SB203580 prevented this increase in p21 stability. p38a and JNK1 phosphorylated p21 in vivo, and both p38a and JNK1 phosphorylated p21 at Ser(130) in vitro. Peptide mapping demonstrated that both TGF-beta1 and p38a induced phosphorylation of p21 at Ser(130) in vivo, and mutation of Ser(130) to alanine rendered p21 less stable than wild-type p21. TGF-beta1 increased the stability of wildtype p21, but not the p21-S130A mutant. These findings demonstrate that SAPKs can mediate cell cycle arrest through post-translational modification of p21.