Unraveling the Mechanisms of Neurodegeneration in TBCK Encephaloneuronopathy

揭示 TBCK 脑神经病神经变性的机制

基本信息

批准号：
10700602
负责人：
XILMA R ORTIZ-GONZALEZ
金额：
$ 66.93万
依托单位：
CHILDREN'S HOSP OF PHILADELPHIA
依托单位国家：
美国
项目类别：
财政年份：
2023
资助国家：
美国
起止时间：
2023-09-18 至 2028-06-30
项目状态：
未结题

来源：
https://reporter.nih.gov/project-details/10700602
关键词：
Address Affect Age Amyotrophic Lateral Sclerosis Award Axon Bioenergetics Biological Assay Cell Death Cell Nucleus Cessation of life Child Childhood Complex DNA Sequence Alteration Data Defect Developmental Delay Disorders Disease Distal Distant Early Endosome Encephalopathies Endosomes Environment Fibroblasts Functional disorder Genetic Diseases Goals Homeostasis Human Impairment Induced pluripotent stem cell derived neurons Institution Intellectual functioning disability Knowledge Lead Link Lysosomes Mediating Membrane Potentials Messenger RNA Microfluidics Mitochondria Mitochondrial Proteins Modeling Morphology Mutation NADP Nerve Degeneration Neurodegenerative Disorders Neurologic Neurons Oxygen Consumption Patients Peptide Synthesis Phenotype Physicians Physiological Play Population Predisposition Production Protein Biosynthesis Protein Import Proteins Proteome Proteomics Proxy Public Health Puerto Rican Quality Control RNA RNA Transport Reporter Reporting Research Ribosomes Role Scientist Seizures Severities Stress Testing Transcript Translations Visualization Work autosome confocal imaging differential expression effective therapy experimental study indexing induced pluripotent stem cell insight late endosome mRNA Translation mitochondrial dysfunction mitochondrial membrane neurodegenerative phenotype neuronal cell body new therapeutic target novel novel therapeutics null mutation polypeptide premature programs progressive neurodegeneration protein complex rare genetic disorder respiratory single molecule stem superoxide dismutase 1 trafficking transcriptome transcriptome sequencing

项目摘要

PROJECT SUMMARY Neurodegenerative disorders remain a public health burden and lack effective treatments. Rare genetic disorders can cause neurodegeneration in children, which is particularly devastating. Regardless of whether rare or common, the mechanisms underlying neurodegeneration remain incompletely understood. For instance, why neurons may be more susceptible to cell death when a genetic mutation is present throughout the body? Such is the case in TBCK encephalopathy (TBCKE), a rare autosomal recessive disorder that causes developmental delay and neurodegeneration in children. We previously characterized the neurologic phenotype of Puerto Rican children with a homozygous null mutation (p.R126X) in TBCK, and later found mitochondrial respiratory defects and evidence for abnormal mitochondrial quality control (i.e. mitophagy) in patient-derived fibroblasts. Nevertheless, the (1) physiologic role of TBCK and (2) how TBCK-deficiency leads to mitochondrial dysfunction and neurodegeneration, remain unclear. Our data support that Tbck protein may be part of a novel mRNA transport complex (Five-subunit Endosomal Rab5 and RNA/ribosome intermediary- FERRY). This complex may attach to early endosomes to deliver RNA transcripts, and therefore contribute to newly synthesized proteins, to cellular compartments distant from the nucleus, such as axons. Deficits in RNA transport and local protein translation, particularly to distant axonal mitochondria, have been recently proposed as a novel mechanism underlying a common neurodegenerative disorder (ALS, amyotrophic lateral sclerosis). Hence, our central hypothesis is that neuronal vulnerability in TBCK-deficiency stems from impaired transport of mRNA and/or local protein translation disrupting mitochondrial function. We predict this leads to compartment-specific mitochondrial deficits, with distal axonal mitochondria being more susceptible to TBCK- deficiency than those in the neuronal soma. In Aim 1 we will test how TBCK-deficiency impacts mitochondrial function and mitophagy, using human iPSC-derived neurons (iNeu). Then in Aim 2, we will test how TBCK- deficiency may affect the function of the FERRY complex, by examining effects in the RNA transcriptome in a compartment-specific fashion (neuronal soma vs axons). We will also directly assay local protein synthesis to test if TBCK is leading to mitochondrial dysfunction because of impaired protein translation in axonal compartments. These experiments will address a gap in knowledge regarding the role of neuronal RNA transport defects in mediating neurodegeneration, how these defects may particularly impact mitochondria and the role that Tbck protein may play in the novel FERRY complex. Support from this R01 award will be instrumental in growing my independent research program as a physician-scientist in a superb institutional environment. It will also contribute to my long-term goal of untangling disease mechanisms of pediatric neurodegenerative disorders linked to mitochondrial dysfunction; in order to, ultimately, identify novel therapeutic targets.

项目概要神经退行性疾病仍然是公共卫生负担，并且缺乏有效的治疗方法。稀有遗传疾病会导致儿童神经变性，这尤其具有破坏性。无论是否无论罕见还是常见，神经退行性疾病的潜在机制仍不完全清楚。为了例如，为什么当整个过程中存在基因突变时，神经元可能更容易受到细胞死亡的影响身体？ TBCK 脑病 (TBCKE) 就是这种情况，这是一种罕见的常染色体隐性遗传病，导致儿童发育迟缓和神经变性。我们之前描述了神经系统 TBCK 中具有纯合无效突变 (p.R126X) 的波多黎各儿童的表型，后来发现线粒体呼吸缺陷和线粒体质量控制异常（即线粒体自噬）的证据患者来源的成纤维细胞。尽管如此，(1) TBCK 的生理作用和 (2) TBCK 缺乏如何导致线粒体功能障碍和神经变性的影响仍不清楚。我们的数据支持 Tbck 蛋白可能是新型 mRNA 转运复合物（五亚基内体 Rab5 和 RNA/核糖体中间体）的一部分渡船）。该复合物可能附着在早期内体上以传递 RNA 转录本，因此有助于新合成的蛋白质，到远离细胞核的细胞区室，例如轴突。 RNA 缺陷最近提出了运输和局部蛋白质翻译，特别是远距离轴突线粒体作为常见神经退行性疾病（ALS，肌萎缩侧索硬化症）的一种新机制。因此，我们的中心假设是 TBCK 缺乏的神经元脆弱性源于运输受损 mRNA 和/或局部蛋白质翻译破坏线粒体功能。我们预测这会导致区室特异性线粒体缺陷，远端轴突线粒体更容易受到 TBCK- 比神经元体中的缺乏。在目标 1 中，我们将测试 TBCK 缺乏如何影响线粒体使用人类 iPSC 衍生神经元 (iNeu) 进行功能和线粒体自噬。然后在目标 2 中，我们将测试 TBCK- 通过检查 RNA 转录组的影响，缺陷可能会影响 FERRY 复合体的功能隔室特异性时尚（神经元胞体与轴突）。我们还将直接测定局部蛋白质合成测试 TBCK 是否因轴突蛋白质翻译受损而导致线粒体功能障碍隔间。这些实验将解决有关神经元 RNA 作用的知识空白介导神经变性的运输缺陷，这些缺陷如何特别影响线粒体和 Tbck 蛋白在新型 FERRY 复合物中可能发挥的作用。此 R01 奖项的支持将是作为一名优秀的机构中的医师科学家，这对我的独立研究项目的发展起到了重要作用环境。它还将有助于我阐明儿科疾病机制的长期目标与线粒体功能障碍相关的神经退行性疾病；为了最终确定新颖的治疗目标。