Dimerization and Cytoplasmic Localization Regulate Hippo Kinase Signaling Activity in Organ Size Control
Dimerization and Cytoplasmic Localization Regulate Hippo Kinase Signaling Activity in Organ Size Control
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二聚化和细胞质定位调节器官大小控制中的河马激酶信号活性
DOI：
10.1074/jbc.m111.310334
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发表时间：
2012-02-17
影响因子：
4.8
通讯作者：
Zhang, Lei
中科院分区：
文献类型：
--
作者：
Jin, Yunyun;Dong, Liang;Zhang, Lei
Hippo（Hpo）信号通路通过调节细胞增殖和凋亡之间的平衡来控制器官大小。虽然Hpo的功能是保守的，很少有人知道它的激酶活性是如何调节的机制。基于结构信息，我们进行了突变功能分析，并提供了体外和体内的证据表明，Hpo激活需要适当的二聚化的N-末端激酶结构域以及C-末端SARAH结构域。携带点突变M242 E的Hpo仍然可以二聚化，但分子间激酶结构域之间形成的二聚体在构象上发生了改变。结果，Hpo在Thr-195的自磷酸化被阻断，其激酶活性被消除。相反，携带I634 D的Hpo，在Hpo C-末端SARAH结构域中引入的单一突变，破坏了SARAH结构域的二聚化，导致Hippo活性降低。我们还发现，Hpo的C-末端一半包含两个核输出信号，促进细胞质定位和活性的Hpo。两者合计，我们的研究结果表明，二聚化和核质易位的HPO是至关重要的，其生物学功能，并表明，一个适当的二聚体构象的激酶结构域是必不可少的HPO自磷酸化和激酶活性。
The Hippo (Hpo) signaling pathway controls organ size by regulating the balance between cell proliferation and apoptosis. Although the Hpo function is conserved, little is known about the mechanism of how its kinase activity is regulated. Based on structural information, we performed mutation-function analysis and provided in vitro and in vivo evidence that Hpo activation requires proper dimerization of its N-terminal kinase domain as well as the C-terminal SARAH domain. Hpo carrying point mutation M242E can still dimerize, yet the dimers formed between intermolecular kinase domains were altered in conformation. As a result, autophosphorylation of Hpo at Thr-195 was blocked, and its kinase activity was abolished. In contrast, Hpo carrying I634D, a single mutation introduced in the Hpo C-terminal SARAH domain, disrupted the dimerization of the SARAH domain, leading to reduced Hippo activity. We also find that the Hpo C-terminal half contains two nuclear export signals that promote cytoplasmic localization and activity of Hpo. Taken together, our results suggest that dimerization and nucleocytoplasmic translocation of Hpo are crucial for its biological function and indicate that a proper dimer conformation of the kinase domain is essential for Hpo autophosphorylation and kinase activity.