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：
10380224
负责人：
Alexander Rotenberg
金额：
$ 22.13万
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/10380224
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 Protocols documentation Readiness 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 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）琥珀酸半甲醛脱氢酶缺乏症（SSADHD）是由罕见的先天代谢疾病 ALDH5A1突变。 aldh5a1编码ssadh，这对于抑制性的分解代谢至关重要神经递质γ-氨基丁酸（GABA）。在SSADHD中，GABA的病理积累及代谢产物γ-羟基丁酸（GHB）导致广泛的脑病。矛盾的，dospite的环境 GABA升高，SSADHD患者易受癫痫发作和癫痫死亡意外死亡（SUDEP），强调了补偿性GABA受体减少对病理GABA构建的重要性向上。 SSADHD的主要未满足医疗需求是直接解决基础酶的治疗缺乏酶替代疗法（ERT）和基因治疗。概念证明系统性ERT和肝脏定向的ALDH5A1过表达增加了aldh5a1 - / - 小鼠的存活。但是，酶或病毒载体在Aldh5A1 - / - 小鼠中注射导致难以评估的不可控制的，非特异性的SSADH恢复治疗效率和剂量反应关系。尚不清楚恢复SSADH在什么时间，速率或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型的鼠标模型在独立的CRE或强力霉素调节下允许有条件的ALDH5A1重新激活。在这款新颖的老鼠中菌株，ALDH5A1基因活性在基本水平上被破坏，但在CRE介导的重组后重组或受强力霉素的水平可逆地调节。我们在这两年探索性赠款中的具体目标是至：1）开发Aldh5A1lox-rtta-Stop鼠标模型，并表征其基线表型轨迹发展。 2）测试依赖年龄的治疗窗口，当时SSADH修复是安全的，并且在对比的发育时间点上，将AAV-CRE注入该鼠标，有效。 3）测试是否突然的ssadh恢复会导致癫痫发作，以及ssadh级恢复是否具有治疗优势，通过在早期注射单剂量与多种较低剂量的AAV-CRE 产后发展。 4）测试抑制性细胞指导的部分SSADH修复是否可能是足以使表型逆转，通过用GAD2-IRES-CRE小鼠繁殖Aldh5A1lox-RTTA-Stop小鼠。这本小说小鼠模型可以测试SSADH期间的临床前准备策略，例如基因治疗和以受控，可量化和细胞特异性的方式进行ERT。该项目的长期目标是两个方面： 1）提供对萨德病理生理学的机理见解以及萨德氏恢复如何可能救援症状。提出的鼠标模型允许有条件的SSADH部署和修复，以便 SSADHD的病理机制和SSADH恢复的影响可以很好地研究。 2）建立热萨德恢复的关键参数。提出的模型提供对SSADH恢复的剂量，空间和细胞特异性的必要见解，进步未来转化和临床研究，包括针对SSADHD患者的ERT和基因治疗。