Mitochondrial mechanisms and vulnerability to alpha-synuclein toxicity

线粒体机制和α-突触核蛋白毒性的脆弱性

基本信息

批准号：
9385532
负责人：
DAVID K. SIMON
金额：
$ 21.63万
依托单位：
BETH ISRAEL DEACONESS MEDICAL CENTER
依托单位国家：
美国
项目类别：
财政年份：
2017
资助国家：
美国
起止时间：
2017-07-01 至 2019-06-30
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/9385532
关键词：
Accounting Age Behavioral Bioenergetics Biogenesis Brain Cell Line Cells Cessation of life Complex Corpus striatum structure DNA-Directed DNA Polymerase Data Defect Dopamine Functional disorder Future Gene Dosage Gene Expression Goals Gray unit of radiation dose Hair Human Impairment Incidence Inherited Injection of therapeutic agent Lead Mediating Mitochondria Mitochondrial DNA Mus Mutation Nerve Degeneration Neurodegenerative Disorders Neurons Parkinson Disease Parkinsonian Disorders Pathologic Pathology Patients Phenotype Premature aging syndrome Proteins Role Substantia nigra structure Testing Therapeutic Toxic effect Tyrosine 3-Monooxygenase Viral Work age related age related neurodegeneration alpha synuclein alpha synuclein gene base brain cell dopaminergic neuron mitochondrial DNA mutation mitochondrial dysfunction mouse model mouse synuclein alpha mutant neuron loss normal aging novel novel therapeutics overexpression vector control

项目摘要

Acquired (somatic) mitochondrial DNA (mtDNA) mutations accumulate with age and reach high levels in dopaminergic neurons at early pathological stages in Parkinson's disease (PD). POLG “mutator” mice have an accelerated accumulation of somatic mtDNA mutations and develop a premature aging phenotype at levels of mutations comparable to levels found in neurons in PD patients, demonstrating that somatic mtDNA mutations can be functionally significant. Furthermore, some patients with POLG mutations develop parkinsonism associated with α-synuclein (αSyn) pathology and loss of dopaminergic neurons in the substantia nigra (SN). Based on these and other data, we hypothesize a “two-hit” hypothesis whereby somatic mtDNA mutations contribute to mitochondrial dysfunction, and thereby exacerbate vulnerability to αSyn. This may help to explain the dramatic rise with age in the incidence of PD. The overall goal of this proposal is to assess the relationship between somatic mtDNA mutations and vulnerability to αSyn toxicity. We will do this using 2 strategies. First, we we will assess the impact of increased levels of somatic mtDNA mutations on αSyn toxicity by assessing heterozygous and homozygous POLG mutator mice that overexpress double-mutant (A30P and A53T) αSyn in dopaminergic neurons. Double-mutant αSyn mice (dMutαSyn) develop a slowly progressive phenotype including striatal dopamine deficiency with behavioral deficits and loss of dopaminergic SN neurons. We predict earlier and more severe behavioral deficits, mitochondrial dysfunction, impaired mitophagy, more severe loss of striatal dopamine and dopaminergic terminals, and increased SN dopaminergic neuronal loss compared to αSyn overexpression in the SN of WT mice. Second, we will perform stereotaxic SN injections of AAV-αSyn (wild-type or A53T) or a control vector (GFP-degron) in wild-type and heterozygous and homozygous POLG mutator mice. We again predict that somatic mtDNA mutations will exacerbate the phenotype associated with increased αSyn expression, including the progressive death of neurons normally seen following AAV-αSyn injections, resulting in earlier and more severe deficits. These studies may yield the first experimental evidence that somatic mtDNA mutations, at levels relevant to early stages in PD, influence vulnerability to αSyn toxicity, a result that may in part explain the dramatic rise in the incidence of PD with age. These studies also will have characterized a novel mouse model of dopaminergic neuronal degeneration that combines two mechanisms of pathophysiological relevance to PD.

获得性（体细胞）线粒体 DNA (mtDNA) 突变随着年龄的增长而积累，并在帕金森病 (PD) 小鼠的早期病理阶段的多巴胺能神经元具有突变。加速体细胞 mtDNA 突变的积累并在突变与 PD 患者神经元中发现的水平相当，表明体细胞 mtDNA 突变此外，一些 POLG 突变患者会出现帕金森病。与 α-突触核蛋白 (αSyn) 病理学和黑质 (SN) 中多巴胺能神经元的丢失有关。基于这些和其他数据，我们得出了“二次打击”假设，即体细胞 mtDNA 突变导致线粒体功能障碍，并加剧对 αSyn 的脆弱性，这可能有助于解释。 PD 发病率随年龄急剧上升该提案的总体目标是评估这种关系。体细胞 mtDNA 突变和 αSyn 毒性的脆弱性之间的关系我们将使用两种策略来做到这一点。我们将通过评估体细胞 mtDNA 突变水平的增加对 αSyn 毒性的影响杂合子和纯合子 POLG 突变小鼠在体内过表达双突变体（A30P 和 A53T）αSyn 多巴胺能神经元双突变 αSyn 小鼠 (dMutαSyn) 形成缓慢进展的表型。包括纹状体多巴胺缺乏导致的行为缺陷和多巴胺能 SN 神经元的丧失。预测更早和更严重的行为缺陷、线粒体功能障碍、线粒体自噬受损等纹状体多巴胺和多巴胺能末梢严重缺失，SN 多巴胺能神经元缺失增加与 WT 小鼠 SN 中的 αSyn 过度表达相比，我们将进行立体定向 SN 注射。 AAV-αSyn（野生型或 A53T）或野生型和杂合子的对照载体（GFP-degron）我们再次预测体细胞 mtDNA 突变会使纯合 POLG 突变小鼠的病情恶化。与αSyn表达增加相关的表型，包括通常神经元的进行性死亡 AAV-αSyn 注射后出现，导致更早、更严重的缺陷。这些研究可能会产生这种结果。第一个实验证据表明，与 PD 早期阶段相关的体细胞 mtDNA 突变会影响易受 αSyn 毒性影响，这一结果可能部分解释了 PD 发病率随着年龄的增长而急剧上升。这些研究还将描述一种新的多巴胺能神经元变性小鼠模型，该模型结合了与 PD 病理生理学相关的两种机制。