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Developing an inducible mouse model for gene replacement therapy in Succinic Semialdehyde Dehydrogenase Deficiency (SSADHD)

开发用于琥珀半醛脱氢酶缺乏症 (SSADHD) 基因替代疗法的诱导小鼠模型

基本信息

批准号：
10544054
负责人：
Alexander Rotenberg
金额：
$ 26.55万
依托单位：
BOSTON CHILDREN'S HOSPITAL
依托单位国家：
美国
项目类别：
财政年份：
2022
资助国家：
美国
起止时间：
2022-01-01 至 2023-12-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/10544054
关键词：
Address Age Animal Model Ataxia Biology Blood Body Fluids Bolus Infusion Brain Brain Injuries Brain region Breeding Catabolism Cells Chlorides Clinical Clinical Research Depressed mood Development Developmental Delay Disorders Disease Dose Down-Regulation Doxycycline Elderly Encephalopathies Enterobacteria phage P1 Cre recombinase Enzymes Epilepsy Family member Frequencies Functional disorder Future GABA Receptor Genes Genetic Recombination Grant Growth Immunohistochemistry Injections Intellectual functioning disability Internal Ribosome Entry Site Interneurons Intraperitoneal Injections Introns Knockout Mice Lead Life Liver Measures Mediating Medical Metabolic Diseases Modeling Mouse Strains Mus Mutation Natural History Neurons Neurotransmitters Outcome Pathologic Patients Phenocopy Phenotype Preclinical Testing Predisposition Protocols documentation Readiness Receptor Down-Regulation Recombinant adeno-associated virus (rAAV)Regulation Risk Seizures Signal Transduction Site Specificity Succinate-semialdehyde dehydrogenase deficiency Survival Rate Symptoms Terminator Codon Testing Tetracyclines Therapeutic Time Tissues Trans-Activators Treatment Efficacy Urine Viral Vector Wild Type Mouse age related aldehyde dehydrogenases cell type enzyme activity enzyme deficiency enzyme replacement therapy extracellular gamma hydroxybutyrate gamma-Aminobutyric Acid gene replacement therapy gene therapy human old age (65+)improved insight intraperitoneal mortality motor deficit mouse model novel overexpression postnatal development pre-clinical preclinical development proteostasis receptor receptor downregulation receptor expression receptor-mediated signaling reconstitution response restoration risk variant sudden unexpected death in epilepsy translational study

项目摘要

Project summary/abstract (30 lines) Succinic Semialdehyde Dehydrogenase Deficiency (SSADHD) is a rare inborn metabolic disorder caused by aldh5a1 mutations. Aldh5a1 encodes SSADH which is essential for the catabolism of the inhibitory neurotransmitter γ-aminobutyric acid (GABA). In SSADHD, pathologic accumulation of GABA and its metabolite γ-hydroxybutyrate (GHB) leads to broad spectrum encephalopathy. Paradoxically, despite ambient GABA is heightened, SSADHD patients are susceptible to seizures and sudden unexpected death in epilepsy (SUDEP), highlighting the significance of compensatory GABA receptor reduction over pathologic GABA build- up. A major unmet medical need for SSADHD is treatment directly addressing the underlying enzyme deficiency such as enzyme replacement therapy (ERT) and gene therapy. Proof-of-concept systemic ERT and liver-directed aldh5a1 over-expression increased aldh5a1-/- mice survival. However, enzyme or viral vector injections in aldh5a1-/- mice lead to uncontrollable, non-specific SSADH restoration difficult to evaluate therapeutic efficacy and dose-response relationship. It is unclear restoring SSADH at what time, rate or in what cell types would suffice for phenotype reversal. We thus propose to develop a novel mouse model which allows conditional aldh5a1 reactivation under independent Cre or doxycycline regulation. In this novel mouse strain, aldh5a1 gene activity is disrupted at basal level, but is reconstituted upon Cre-mediated recombination or is reversibly regulated by the level of doxycycline. Our specific aims in this two-year exploratory grant are to: 1) Develop the aldh5a1lox-rtTA-STOP mouse model and characterize its baseline phenotype trajectory across development. 2) Test for an age-dependent therapeutic window when SSADH restoration is safe and effective, by injecting AAV-Cre into this mouse at contrasting developmental time points. 3) Test whether abrupt SSADH restoration leads to epileptic seizures, and whether gradual SSADH restoration has a therapeutic advantage, by injecting single dose versus multiple lower doses of AAV-Cre across days in early postnatal development. 4) Test whether inhibitory cell-directed partial SSADH restoration might be sufficient for phenotype reversal, by breeding aldh5a1lox-rtTA-STOP mice with Gad2-IRES-Cre mice. This novel mouse model enables testing of preclinical readiness of SSADH-restoring strategies such as gene therapy and ERT in a controlled, quantifiable and cell-specific manner. This project's long-term objectives are two-fold: 1) Provision of mechanistic insights into SSADH pathophysiology and how SSADH restoration might rescue symptoms. The proposed mouse model allows conditional SSADH depletion and restoration, so that pathological mechanisms of SSADHD and the impacts of SSADH restoration can be studied in great details. 2) Establishment of key parameters for therapeutic SSADH restoration. The proposed model provides necessary insights into the dose, pace and cell-specificity of SSADH restoration, advancing future translational and clinical studies including ERT and gene therapy for SSADHD patients.

项目摘要/摘要（30行）琥珀酸半醛脱氢酶缺乏症（SSADHD）是一种罕见的先天性代谢紊乱， ALDH 5A 1突变。Aldh 5a 1编码SSADH，SSADH对于抑制蛋白的催化是必需的。神经递质γ-氨基丁酸（GABA）。在SSADHD中，代谢物γ-羟基丁酸（GHB）导致广谱脑病。奇怪的是，尽管环境 GABA升高，SSADHD患者易发生癫痫发作和突发意外死亡（SUDEP），强调了代偿性GABA受体减少对病理性GABA生成的意义- 起来SSADHD的一个主要未满足的医疗需求是直接针对潜在酶的治疗如酶替代疗法（ERT）和基因疗法。概念验证系统性ERT和肝脏定向的ALDH 5A 1过表达增加了ALDH 5A 1-/-小鼠的存活率。然而，酶或病毒载体在aldh 5a 1-/-小鼠中注射导致难以控制的、非特异性SSADH恢复，疗效和量效关系。目前还不清楚恢复SSADH的时间，速度或在什么细胞类型足以进行表型逆转。因此，我们建议开发一种新的小鼠模型，允许在独立Cre或强力霉素调节下条件性aldh 5a 1再活化。在这部小说中，菌株aldh 5a 1基因活性在基础水平被破坏，但在Cre介导的重组后被重建或由强力霉素水平可逆调节。我们在这项为期两年的探索性赠款中的具体目标是 1）开发aldh 5a 1 lox-rtTA-STOP小鼠模型并表征其基线表型轨迹，发展2)当SSADH恢复是安全的，有效，通过在对比的发育时间点将AAV-Cre注射到该小鼠中。3)测试是否突然SSADH恢复导致癫痫发作，以及逐渐SSADH恢复是否具有在早期，通过在几天内注射单剂量相对于多个较低剂量的AAV-Cre，产后发育4)测试抑制性细胞定向的部分SSADH恢复是否可能是通过用Gad 2-IRES-Cre小鼠繁殖aldh 5a 1 lox-rtTA-STOP小鼠，足以逆转表型。这本小说小鼠模型能够测试SSADH恢复策略的临床前准备，如基因治疗和以受控、可量化和细胞特异性的方式进行ERT。该项目的长期目标有两个方面： 1)提供SSADH病理生理学的机制见解以及SSADH恢复如何可能抢救症状所提出的小鼠模型允许条件性SSADH耗竭和恢复，使得可以更详细地研究SSADHD的病理机制以及SSADH修复的影响。 2)建立治疗性SSADH恢复的关键参数。该模型提供了对SSADH恢复的剂量、速度和细胞特异性的必要见解，推进未来包括用于SSADHD患者的ERT和基因治疗的转化和临床研究。