LRRK2 and Neurodegeneration

描述（由申请人提供）：LRRK2突变是帕金森病（PD）的常见遗传原因。与LRRK2相关的疾病与α -突触核蛋白病理和tau病理相关。LRRK2与多种病理类型的关联表明，LRRK2的生物学特性可以为我们理解神经退行性疾病的机制提供特殊的见解。我们的研究表明，LRRK2可以改变细胞对压力的反应。表达野生型LRRK2赋予秀丽隐杆线虫对与增加的蛋白质错误折叠和保护线粒体毒素（如鱼藤酮和百草枯）相关的应激的惊人敏感性。LRRK2的线虫同系物lrk-1的敲低具有相反的作用，使线虫不易受到蛋白酶体抑制，更容易受到鱼藤酮的影响。表达pd相关LRRK2突变体的秀丽隐杆线虫比野生型LRRK2表现出更大的毒性。这些观察结果得到了人类细胞系蛋白质结合研究的支持，并表明LRRK2的作用需要蛋白质折叠机制和应激激酶级联。敲除和结合研究表明，与CHIP、MKK3、6和7、JIP2和4等几种结合蛋白的鉴定存在功能和物理相互作用，以及与hsp60和70的功能联系。LRRK2和MKK6之间的相互作用似乎在PD的病理生理中特别重要，因为LRRK2的PD相关突变显示出对MKK6选择性结合的增加。许多这些结合蛋白都有一个共同的功能，即它们介导细胞应激反应的不同元素。我们假设LRRK2通过与蛋白质错误折叠途径和应激激酶级联反应相关的蛋白质相互作用来协调细胞应激反应。该假说的第二个要素是，与PD相关的LRRK2突变通过应激激酶级联反应增加信号传导，从而增强细胞死亡和神经退行性变。第一个目标是研究LRRK2如何改变对细胞损伤的反应。该目的还将研究LRRK2结合蛋白的敲低如何改变秀丽隐杆线虫系和LRRK2诱导的人类细胞系中LRRK2的作用。第二个目标是确定LRRK2与其结合蛋白相互作用的结构机制。第三个目的是研究野生型、G2019S和R1441C LRRK2的表达如何改变秀丽隐杆线虫中PD （α -突触核蛋白和tau）相关遗传变化引起的毒性和包涵体形成。该目的将阐明野生型LRRK2是否正常保护PD相关的病理生理变化，以及LRRK2的PD相关突变是否增强了这些变化。

DESCRIPTION (provided by applicant): Mutations in LRRK2 are a common genetic cause of Parkinson's disease (PD). Diseases associated with LRRK2 are associated with both alpha-synuclein pathology and with tau pathology. The association of LRRK2 with multiple types of pathologies suggests that the biology of LRRK2 could provide particular insight to our understanding of mechanisms of neurodegeneration. Our studies suggest that LRRK2 modifies cellular responses to stress. Expressing wild type LRRK2 confers to C. elegans striking sensitization to stresses associated with increased protein misfolding and protection against mitochondrial toxins, such as rotenone and paraquat. Knockdown of lrk-1, the C. elegans homologue of LRRK2, has the opposite effects and renders C. elegans less vulnerable to proteasomal inhibition and more vulnerable to rotenone. C. elegans expressing PD-associated LRRK2 mutants show more toxicity than seen with wild type LRRK2. These observations are supported by protein-binding studies in human cell lines and suggest that the action of LRRK2 requires the protein folding machinery and the stress kinase cascade. The knockdown and binding studies show evidence of functional and physical interactions with identification of several binding proteins including CHIP, MKK3, 6 and 7, and JIP2 & 4, as well as functional links to hsp60 and 70. The interaction between LRRK2 and MKK6 appears to be particularly important in the pathophysiology of PD because the PD-related mutations in LRRK2 show increased binding that is selective for MKK6. Many of these binding proteins share a common function in that they mediate different elements of the cellular stress response. We hypothesize that LRRK2 coordinates the cellular stress response through its interaction with proteins linked to the protein misfolding pathways and the stress kinase cascades. A secondary element of this hypothesis is that mutations in LRRK2 associated with PD enhance cell death and neurodegeneration by increasing signaling through the stress kinase cascades. The first aim will investigate how LRRK2 modifies the response to cell injury. This aim will also examine how knockdown of LRRK2 binding proteins modifies the actions of LRRK2 in C. elegans lines and LRRK2 inducible human cell lines. The second aim will determine the structural mechanisms by which LRRK2 interacts with its binding proteins. The third aim examines how expression of wild type, G2019S and R1441C LRRK2 modify toxicity and inclusion formation caused by genetic changes related to PD (alpha-synuclein and tau) in C. elegans. This aim will elucidate whether wild type LRRK2 normally protects against pathophysiological changes associated with PD, and whether PD-related mutations in LRRK2 enhance these changes.