REGULATION AND FUNCTION OF KIBRA IN THE HIPPO SIGNALING PATHWAY

这个子项目是许多研究子项目中的一个 由NIH/NCRR资助的中心赠款提供的资源。子项目和 研究者（PI）可能从另一个NIH来源获得了主要资金， 因此可以在其他CRISP条目中表示。所列机构为 中心，不一定是研究者的机构。 KIBRA是果蝇中Hippo信号通路的新组分。KIBRA影响Hippo信号传导的机制以及KIBRA在哺乳动物细胞中的功能尚不清楚。 我们证明了KIBRA与Lats 1和Lats 2相关并激活Lats 1和Lats 2。此外，我们发现KIBRA特异性RNAi的转染降低了磷酸化雅普的细胞水平，而KIBRA的过表达增加了磷酸化YAP的细胞水平，磷酸化YAP是Lats 1/2激酶的下游底物/靶标。有趣的是，我们发现KIBRA通过抑制Lats 2的泛素化来稳定Lats 2。KIBRA延长了Lats 2的半衰期。KIBRA本身是小鼠和人类细胞中Hippo信号通路的转录靶点。 KIBRA促进Lats 2上S83的磷酸化，这依赖于Aur-A激酶。KIBRA的过表达强烈刺激Aur-A激酶活性，其通过Aur-A自身磷酸化水平（p-T288）揭示。此外，我们能够检测到Aur-A和KIBRA之间的相互作用时，这两个蛋白质共转染293 T细胞。我们发现KIBRA是一种磷酸化蛋白，其磷酸化水平在G2/M期达到峰值。KIBRA的RNAi敲低破坏微管结构并影响Aurora-A和Lats 2定位。KIBRA还控制中心体成熟和染色体排列。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. 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.