Endolysosomal Function in Neuronal Maintenance

描述（由申请方提供）：溶酶体降解中的许多缺陷先于其他器官影响神经系统，表明神经元对内膜降解的需求增加或特化。我已经产生了第一个空突变体的普遍存在的内溶酶体rab GTcirab 7在果蝇。rab 7的部分或完全缺失导致感觉神经元先于其他细胞类型出现神经病样表型。此外，人rab 7中的四个点突变通过部分功能丧失机制引起常染色体显性感觉神经病Charcot-Marie-Tooth 2B型（CMT 2B）。果蝇rab 7无效突变体和人类CMT 2B疾病都突出了神经元对内溶酶体降解能力缺陷的敏感性。根据我的初步研究结果，我假设神经元对内溶酶体降解有专门或增加的要求。我将通过结合果蝇遗传学和新的活体成像方法来测试这一假设，以定量测量与细胞体和其他细胞类型相比，rab 7依赖性神经元突触降解的货物特异性和动力学。接下来，我将使用遗传相互作用实验，结合成像和电生理读数，研究rab 7功能的细胞机制，在无处不在的自噬和神经元特异性内溶酶体降解机制的背景下。最后，我将与我的共同赞助商一起，在小鼠神经元培养中表征rab 7功能，以测试我在果蝇模型中发现的一般性。总之，我的研究结果将阐明rab 7依赖性降解的细胞机制及其在神经元维持和长寿中的作用，并在建立方法以操纵受内溶酶体功能障碍影响的神经元的降解能力方面具有潜在的治疗应用。

DESCRIPTION (provided by applicant): Many defects in lysosomal degradation affect the nervous system before other organs, suggesting an increased or specialized neuronal demand for endomembrane degradation. I have generated the first null mutant for the ubiquitous endolysosomal rab GTPase rab7 in Drosophila. Partial or complete loss of rab7 causes neuropathy-like phenotypes in sensory neurons before other cell types. Moreover, four point mutations in human rab7 cause the autosomal dominant sensory neuropathy Charcot-Marie-Tooth type 2B (CMT 2B) through a partial loss-of-function mechanism. Both the Drosophila rab7 null mutant and the CMT 2B disease in human highlight the neuronal sensitivity to defects in endolysosomal degradative capacity. Based on my preliminary findings, I hypothesize that neurons have a specialized or increased requirement for endolysosomal degradation. I will test this hypothesis by combining fly genetics and novel live imaging approaches to quantitatively measure cargo-specificity and dynamics of rab7-dependent degradation at neuronal synapses compared to cell bodies and other cell types. Next, I will use genetic interaction experiments combined with imaging and electrophysiological read-outs to investigate the cellular mechanism of rab7 function in the context of ubiquitous autophagy and neuron-specific endolysosomal degradation mechanism. Finally, together with my Co-Sponsor, I will characterize rab7 function in mouse neuronal culture to test the generality of my findings from the Drosophila model. Together, my findings will elucidate the cellular mechanism of rab7-dependent degradation and its role in neuronal maintenance and longevity, with a potential therapeutic application in the establishment of methods to manipulate the degradative capacity of neurons affected by endolysosomal dysfunction.