Novel mechanism of neural and muscular degeneration

神经和肌肉退化的新机制

基本信息

批准号：
10414131
负责人：
Xin Jie Chen
金额：
$ 42.51万
依托单位：
UPSTATE MEDICAL UNIVERSITY
依托单位国家：
美国
项目类别：
财政年份：
2020
资助国家：
美国
起止时间：
2020-09-01 至 2025-05-31
项目状态：
未结题

来源：
https://reporter.nih.gov/project-details/10414131
关键词：
Address Adenine Nucleotide Translocase Affect Aging Animals Area Autophagocytosis Behavioral Bioenergetics Cause of Death Cell Death Cells Charge Child Chronic progressive external ophthalmoplegia Clinical Cytosol Data Defect Degenerative Disorder Disease Equilibrium Experimental Models FRAP1 gene Functional disorder Future Gene Expression Profile Genes Genetic Transcription Goals Histologic Human Impairment Inner mitochondrial membrane Intervention Knock-in Mouse Late-Onset Disorder Lateral Maintenance Membrane Missense Mutation Mitochondria Mitochondrial DNA Mitochondrial Diseases Mitochondrial Proteins Modeling Molecular Mus Muscle Muscle Weakness Mutation Myocardium Myopathy Names Neuraxis Neuromuscular Diseases Neurons Nuclear Nucleotides Oxidative Phosphorylation Oxidative Stress Parkinson Disease Pathogenicity Pathology Pathway interactions Peripheral Phenotype Play Protein Import Protein Isoforms Proteins Research Respiration Role SLC25A4 gene Seizures Skeletal Muscle Spastic Paraplegia Spinocerebellar Ataxias Stress Suppressor-Effector T-Lymphocytes Surface Syndrome TOM translocase Testing Ubiquitination Validation Variant Yeasts aged cerebral atrophy frontotemporal lobar dementia-amyotrophic lateral sclerosis hearing impairment insight mitochondrial dysfunction mouse model muscle form mutant neuromechanism neuromuscular novel preference psychiatric symptom receptor relating to nervous system success tool translocase ubiquitin-protein ligase young adult

项目摘要

Ant1 is the muscle/heart/central nervous system (CNS) isoform of adenine nucleotide translocase that is primarily involved in ATP/ADP exchange across the inner mitochondrial membrane (IMM). An increasing number of missense mutations in Ant1 are found to cause dominant diseases that affect skeletal muscle and the central nervous system. These diseases are commonly manifested by fractional mtDNA deletions and mild bioenergetic defects. The mechanism of neuromuscular damage in the diseases is poorly understood. Interestingly, our recent studies in yeast and cultured human cells suggested that the mutant Ant1 is misfolded. This leads to cell death by a novel mechanism that we named mitochondrial Precursor Overaccumulation Stress (mPOS). mPOS is characterized by the toxic accumulation and aggregation of un-imported mitochondrial preproteins in the cytosol. These findings led to the central hypothesis that the mutant Ant1 primarily affects mitochondrial protein import. This results in mPOS in the cytosol, which plays an important role in inducing neural and muscular degeneration. Fractional mtDNA deletions occur independent of nucleotide transport activity, likely as a secondary damage collateral to reduced mitochondrial protein import. In this application, we propose to directly test this hypothesis in mouse models. We successfully generated knock-in (KI) mouse lines expressing misfolded variants of Ant1. Preliminary studies indicated that these mice develop phenotypes consistent with neural and muscular degeneration. In Specific Aim 1, we will use these unique experimental models to test the hypothesis that misfolded Ant1 induces neural and muscular degeneration and mtDNA instability independent of nucleotide transport. In Specific Aim 2, we will use various experimental tools that we developed in yeast, cultured human cells and the Ant1-KI mice to test the hypothesis that the misfolded Ant1 (or Aac2 in yeast) causes structural and functional damage to the mitochondrial protein import machinery and induces mPOS in the cytosol. In Specific Aim 3, we will determine the mechanisms that protect cells against Ant1-induced protein import stress and mPOS. Success of the project will establish a mouse model of protein import stress associated with mPOS. Particularly, validation of the mPOS model would help reconciling the mitochondrial and proteostatic pathways in many neural and muscular degenerative diseases. Finally, the results could have important implications for the understanding and therapy of Ant1-induced diseases, as well as many other clinical conditions that directly or indirectly affect mitochondrial protein import.

Ant1 是腺嘌呤核苷酸转位酶的肌肉/心脏/中枢神经系统 (CNS) 亚型，主要参与跨线粒体内膜 (IMM) 的 ATP/ADP 交换。越来越多的 Ant1 中的大量错义突变被发现会导致影响骨骼肌和骨骼肌的显性疾病中枢神经系统。这些疾病通常表现为线粒体 DNA 部分缺失和轻度生物能缺陷。这些疾病中神经肌肉损伤的机制尚不清楚。有趣的是，我们最近对酵母和培养的人类细胞的研究表明，突变体 Ant1 是错误折叠的。这通过一种我们称之为线粒体前体过度积累的新机制导致细胞死亡压力（mPOS）。 mPOS的特点是未输入的有毒物质积累和聚集细胞质中的线粒体前蛋白。这些发现引出了一个中心假设：突变体 Ant1 主要影响线粒体蛋白质的输入。这导致细胞质中产生 mPOS，它起着重要的作用诱导神经和肌肉变性的作用。部分 mtDNA 缺失的发生独立于核苷酸转运活性，可能是线粒体蛋白质输入减少的继发性损伤。在此应用中，我们建议在小鼠模型中直接检验这一假设。我们成功生成了表达 Ant1 错误折叠变体的敲入 (KI) 小鼠系。初步研究表明这些小鼠发展出与神经和肌肉退化一致的表型。在具体目标 1 中，我们将使用这些独特的实验模型来测试错误折叠的 Ant1 诱导神经和肌肉的假设与核苷酸运输无关的变性和 mtDNA 不稳定性。在具体目标 2 中，我们将使用各种我们在酵母、培养的人类细胞和 Ant1-KI 小鼠中开发的实验工具，用于测试假设错误折叠的 Ant1（或酵母中的 Aac2）会导致结构和功能损伤线粒体蛋白输入机器并在细胞质中诱导 mPOS。在具体目标 3 中，我们将确定保护细胞免受 Ant1 诱导的蛋白质输入应激和 mPOS 的机制。的成功项目将建立与 mPOS 相关的蛋白质输入应激小鼠模型。特别是，验证 mPOS 模型将有助于协调许多神经和蛋白质通路中的线粒体和蛋白质抑制途径。肌肉退行性疾病。最后，结果可能对理解具有重要意义 Ant1诱发的疾病以及许多其他直接或间接影响的临床病症的治疗和治疗线粒体蛋白输入。