REGULATION AND FUNCTION OF KIBRA IN THE HIPPO SIGNALING PATHWAY

这个子项目是利用资源的许多研究子项目之一。 由NIH/NCRR资助的中心拨款提供。对子项目的主要支持 子项目的首席调查员可能是由其他来源提供的， 包括美国国立卫生研究院的其他来源。为子项目列出的总成本可能 表示该子项目使用的中心基础设施的估计数量， 不是由NCRR赠款提供给次级项目或次级项目工作人员的直接资金。 Kibra是果蝇河马信号通路的新成员。Kibra影响河马信号转导的机制以及Kibra在哺乳动物细胞中的功能尚不清楚。 我们证明Kibra与Lats1和Lats2关联并激活它们。此外，我们还发现，Kibra特异性RNAi的表达减少，Kibra的过度表达增加了作为Lats1/2激酶下游底物/靶点的磷酸化YAP的细胞水平。有趣的是，我们发现Kibra通过抑制Lats2的泛素化来稳定Lats2。Kibra延长了Lats2的半衰期。Kibra本身是河马信号通路的转录目标，在小鼠和人类细胞中都是如此。 Kibra促进Lats2上S83的磷酸化，这依赖于Aur-A激酶。过表达Kibra强烈刺激Aur-A自身磷酸化水平(p-T288)显示的Aur-A激酶活性。此外，当Aur-A和Kibra蛋白在293T细胞中共转染时，我们能够检测到两者之间的相互作用。我们发现Kibra是一种磷酸化蛋白，Kibra的磷酸化水平出现在G2/M期。Kibra的RNAi敲除破坏了微管结构，影响了Aurora-A和Lats2的定位。Kibra还控制中心体成熟和染色体比对。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. KIBRA is a new component of the Hippo signaling pathway in Drosophila. Mechanisms by which KIBRA affects Hippo signaling and the function of KIBRA in mammalian cells are not clear. We demonstrated that KIBRA associates with and activates Lats1and Lats2. In addition, we showed that transfection of RNAi specific for KIBRA decreases and over-expression of KIBRA increases the cellular level of phosphorylated YAP, which is the downstream substrate/target of the Lats1/2 kinases. Interestingly, we found that KIBRA stabilizes Lats2 by inhibiting the ubiquitylation of Lats2. KIBRA prolongs the half-life of Lats2. KIBRA itself is a transcriptional target of the Hippo signaling pathway both in mouse and human cells. KIBRA promotes phosphorylation of S83 on Lats2, which is dependent on Aur-A kinase. Over-expression of KIBRA strongly stimulates Aur-A kinase activity revealed by Aur-A auto-phosphorylation level (p-T288). Furthermore, we were able to detect the interaction between Aur-A and KIBRA when these two proteins were co-transfected in 293T cells. We found that KIBRA is a phospho-protein, the phospho-level of KIBRA peaks at the G2/M phase. RNAi-knockdown of KIBRA disrupts the microtubule structure and affects the Aurora-A and Lats2 localization. KIBRA also controls centrosome maturation and chromosome alignment.