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SARM1 functional polymorphisms and their contribution to ALS risk

SARM1 功能多态性及其对 ALS 风险的影响

基本信息

批准号：
10320381
负责人：
ADAM JOSEPH BLOOM
金额：
$ 62.01万
依托单位：
WASHINGTON UNIVERSITY
依托单位国家：
美国
项目类别：
财政年份：
2021
资助国家：
美国
起止时间：
2021-01-01 至 2025-12-31
项目状态：
未结题

来源：
https://reporter.nih.gov/project-details/10320381
关键词：
ALS pathology ALS patients Affect Alleles Amino Acids Amyotrophic Lateral Sclerosis Attenuated Axon Biological Assay Categories Cell Death Cessation of life Chemicals Clustered Regularly Interspaced Short Palindromic Repeats Complex Data Development Disease Disease model Dominant-Negative Mutation Enzymes Etiology Face Foundations Functional disorder General Population Genes Genetic Polymorphism Genetic Variation Genetic study Human Human Genetics Injury Investigation Knock-in Knock-in Mouse Knockout Mice Link Longevity Maintenance Mediating Messenger RNA Metabolic Methods Modeling Molecular Motor Motor Neurons Mus Muscle Mutate Mutation NAD+ Nucleosidase Nerve Degeneration Nervous system structure Neurons Neuropathy Paralysed Pathogenesis Pathogenicity Pathology Pathway interactions Phenotype Process Proteins Risk Role Route Spinal Cord Structure Symptoms TDP-43 aggregation Testing Therapeutic Trauma Variant Viral axon injury axonal degeneration base cohort disorder risk druggable target enzyme activity experimental study falls gain of function gain of function mutation gene therapy genetic risk factor genetic variant genome wide association study genotyped patients induced pluripotent stem cell inhibitor therapy innovation loss of function member motor disorder mouse model neurodegenerative phenotype neuron loss novel overexpression programs protein TDP-43 small molecule inhibitor superoxide dismutase 1

项目摘要

Motor axon loss is a cardinal symptom of amyotrophic lateral sclerosis (ALS). Axon loss can be driven by a genetically encoded program in which the axon survival factors NMNAT2 and STMN2 inhibit the activity of the axon destruction factor SARM1. Recent data suggest that this program of axon self-destruction may contribute to pathology in ALS. First, aggregation of TDP-43, a hallmark of most ALS cases, results in the selective loss of mRNA encoding functional STMN2, a key axon survival factor. Second, loss of SARM1 suppresses some neurodegenerative phenotypes in a mouse ALS model that expresses pathogenic human TDP-43. Here we investigate the contribution of this axon degeneration pathway to ALS. We have defined the mechanism of action of SARM1, demonstrating that it is the founding member of a new class of NAD-cleaving enzymes. SARM1 enzyme activity is normally held in check via an autoinhibitory domain. Injury- or disease- induced loss of NMNAT2 and STMN2 disinhibits SARM1, leading to rapid NAD+ depletion, metabolic catastrophe, and axon fragmentation. Our structure-function studies of the SARM1 protein have identified mutations with a range of consequences, from constitutively active variants that promote cell death and axon loss, to dominant negative variants that are neuroprotective. These findings imply that human variants may exist that either promote or protect against neurodegeneration, and that understanding the phenotypic consequences of genetic variation requires functional studies of enzyme activity. In support of this hypothesis, we have identified several rare SARM1 variants in ALS patients, but not in controls, that have constitutive NADase activity and promote neuron death and axon loss. These variants also cause motor dysfunction and paralysis when expressed in the mouse CNS, suggesting that activating SARM1 mutations may contribute to ALS pathogenesis. Here we propose to define the function of SARM1 variants from ALS patients, controls, and the general population. These studies will allow us to categorize SARM1 variants as putatively pro-degenerative, neuroprotective, or neutral. In parallel, we will dissect the contribution of variation in components of the programmed axon destruction pathway to ALS phenotypes, alone and in combination with known ALS genetic risk-factors, in motor neurons differentiated from human induced pluripotent stem cells (iPSCs). Finally, we will investigate neurodegeneration in a mouse knock-in model carrying a Sarm1 allele equivalent to a pro- degenerative allele found in ALS patients, alone and in combination with a SOD1 model, based on a specific patient genotype that we identified. We will attempt to suppress ALS phenotypes with SARM1 inhibition via a proven gene therapy approach and with experimental small molecule inhibitors. Results of these studies will establish the relationship between the SARM1-mediated axon destruction program and ALS, and build the foundation to develop axoprotective therapeutics to treat this devastating disease.

运动轴突丧失是肌萎缩性侧索硬化症（ALS）的主要症状。轴突损失可以被驱动