Function of NF2/Merlin in regulation of the Hippo/Salvador/Warts growth control pathway

项目总结/摘要 2型神经纤维瘤病（NF 2）是一种以双侧前庭神经纤维瘤形成为特征的人类疾病， 神经鞘瘤（导致耳聋）和其他肿瘤，是由肿瘤抑制因子的丢失引起的 蛋白质梅林使用果蝇进行的研究，随后在哺乳动物系统中得到证实 表明Merlin是Hippo途径上游组分，Hippo途径是一种保守的信号转导途径， 调节组织生长的途径。Merlin和其他Hippo通路组分的突变是 据信是因为它们引起致癌蛋白Yorkie/雅普的活化， 促进生长基因的表达增加。识别特定蛋白质和信号转导 与Merlin相互作用的途径尤其重要，因为这些伴侣可能作为遗传因子， NF 2疾病表型的修饰剂，并为治疗剂提供潜在的靶点。 我们试图了解梅林和其他HSW组件是如何组织成一个信号 复杂的细胞皮层和如何控制这种复杂的活动。我们已经证明梅林 和它的结合伴侣Kibra在一个位点上形成信号复合物， 细胞间连接，因此这些蛋白质可以平行于另一个上游蛋白质发挥作用。 调节器，扩展。我们还表明，当这些蛋白质组装成信号复合物时， 招募E3-连接酶复合物，降解Kibra并抑制负反馈回路中的信号传导。 在下一个资助期内，我们建议通过机械张力促进Kibra降解， 这是张力控制组织生长的一种机制。我们还计划测试一个模型， 我建议，其中Kibra和Merlin被招募到交界皮层，处于不活动状态，由顶端 极性蛋白aPKC与促进中膜积累的中膜肌动球蛋白网络相反 和激活这些蛋白质。为了探索这些新的假设，我们开发了工具， 这些技术使我们能够检查Hippo通路蛋白的定位和动力学， 在活组织中以内源性水平表达。使用精致的基因工具， 果蝇，我们现在可以阐明每个通路组件在组装和激活 河马通道。这些实验有望提供对NF 2，肿瘤抑制， 一般，和肌动球蛋白动力学在调节信号传导过程中的作用。最后，这些研究 应该有助于研究细胞相互作用控制组织的机制， 生长并决定发育和再生过程中的细胞命运。

Project Summary/Abstract Neurofibromatosis type 2 (NF2), a human disease characterized by the formation of bilateral vestibular Schwannomas (resulting in deafness) and other tumors, is caused by loss of the tumor suppressor protein Merlin. Studies using the fruit fly Drosophila and subsequently confirmed in mammalian systems indicate that Merlin is an upstream component of the Hippo pathway, a conserved signal transduction pathway that regulates tissue growth. Mutations in Merlin and other Hippo pathway components are believed to cause tumors because they cause activation of an oncogenic protein Yorkie/YAP and increased expression of growth promoting genes. Identifying specific proteins and signal transduction pathways with which Merlin interacts is especially important because these partners may act as genetic modifiers of NF2 disease phenotypes and provide potential targets for therapeutic agents. We seek to understand how Merlin and the other HSW components are organized into a signaling complex at the cell cortex and how the activity of this complex is controlled. We have shown that Merlin and its binding partner Kibra nucleate formation of a signaling complex at a site separate from intercellular junctions, and thus that these proteins can function in parallel to another upstream regulator, Expanded. We also have shown that as these proteins assemble a signaling complex, they recruit an E3-ligase complex that degrades Kibra and represses signaling in a negative feedback loop. In the next funding period, we propose that Kibra degradation is promoted by mechanical tension and that this is one mechanism by which tension controls tissue growth. We also plan to test a model we propose in which Kibra and Merlin are recruited to the junctional cortex in an inactive state by the apical polarity protein aPKC in opposition to medial actomyosin networks which facilitate medial accumulation and activation of these proteins. To explore these novel hypotheses, we have developed tools and techniques that allow us to examine the localization and dynamics of Hippo pathway proteins expressed at endogenous levels in living tissues. Using with the exquisite genetic tools available in Drosophila, we can now elucidate the role of each pathway component in assembling and activating the Hippo pathway. These experiments are expected to provide insights into NF2, tumor suppression in general, and the role of actomyosin dynamics in regulating signaling processes. Finally, these studies should contribute to work on the mechanisms by which cellular interactions function to control tissue growth and determine cell fate during development and regeneration.