CANAVAN DISEASE: SUPPRESSING THE PHENOTYPE BY INHIBITING NAA SYNTHESIS

CANAVAN 病：通过抑制 NAA 合成来抑制表型

基本信息

批准号：
8965565
负责人：
David E. Pleasure
金额：
$ 23.48万
依托单位：
UNIVERSITY OF CALIFORNIA AT DAVIS
依托单位国家：
美国
项目类别：
财政年份：
2015
资助国家：
美国
起止时间：
2015-07-15 至 2017-06-30
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/8965565
关键词：
Abbreviations Acetate-CoA Ligase Acetates Acetyl Coenzyme A Actins Alleles Amino Acids Aspartate Aspartoacylase Brain Brain Stem Breeding Canavan Disease Chickens Child Childhood Cleaved cell Data Diagnosis Diet Disease Enhancers Enzymes Evaluation Family Genetic Recombination Heterozygote Human Inborn Genetic Diseases Intervention Knock-out Knockout Mice Leukoencephalopathy Lipids LoxP-flanked allele Magnetic Resonance Spectroscopy Metabolism Modeling Mus Mutation Myelin N-acetylaspartate Nervous System Physiology Neurologic Neurons Oligodendroglia Onset of illness Phenotype Prion Diseases Prosencephalon Radiolabeled Rattus Recording of previous events Rodent Source Starvation Synthetic Genes Tamoxifen Testing Therapeutic Transgenes astrogliosis dicarboxylate-binding protein dietary supplements dysmyelination early onset human NAT2 protein infancy innovation myelination novel therapeutic intervention prevent promoter public health relevance radiotracer young adult

项目摘要

DESCRIPTION (provided by applicant): Canavan disease is a recessively inherited disorder caused by inactivating aspartoacylase (ASPA) mutations and characterized by forebrain, cerebellar, and brainstem vacuolar degeneration, astrogliosis, and dysmyelination ("spongiform leukodystrophy"). No treatments for children with Canavan disease have yet proven effective. ASPA is an oligodendroglial enzyme that cleaves N-acetyl-L-aspartate (NAA), releasing acetate and L-aspartate. NAA is synthesized by the neuronal enzyme N-acetyltransferase-8 like (NAT8L), and is maintained at approximately 10mM in the normal CNS, but in Canavan disease, CNS NAA climbs far above that level. A popular hypothesis is that acetate released from NAA and converted to acetyl-CoA by oligodendroglial acetyl-CoA synthetase is essential to maintain the oligodendroglial lipogenic acetyl-CoA pool, and that spongiform leukodystrophy in Canavan disease is attributable to oligodendroglial acetyl-CoA "starvation". But our preliminary data challenge the necessity for NAA-derived acetate for CNS myelin lipid synthesis by showing that, in the CNS of homozygous constitutive NAT8L knockout (NAT8LKO/KO) mice, in which NAA is undetectable by 1H-magnetic resonance spectroscopy, acetyl-CoA content and myelination are normal. Specific Aim 1 will evaluate an alternative hypothesis, that spongiform leukodystrophy in Canavan disease is a consequence of persistently elevated CNS concentrations of NAA. We will employ a well characterized mouse Canavan model caused by homozygosity for a nonsense ASPA mutation (ASPAnur7). By crossing mice carrying ASPAnur7 and NAT8LKO alleles, ASPAnur7/nur7 mice carrying 2, 1, or 0 NAT8LKO alleles will be generated, and will be used to test the prediction that suppressing NAA synthesis in ASPAnur7/nur7 mice will prevent spongiform leukodystrophy. In Specific Aim 2, we will administer tamoxifen to symptomatic young adult ASPAnur7/nur7 mice that are homozygous for a conditional NAT8L allele (NAT8Lflox) and carrying a widely expressed tamoxifen-inducible cre transgene to test whether delayed suppression of NAA synthesis will reverse their pre-existing spongiform leukodystrophy. If so, interventions to prevent elevated CNS NAA levels in children with Canavan disease may be of therapeutic value.

描述（由申请人提供）：卡纳万病是一种由失活天冬氨酸酰基转移酶（ASPA）突变引起的隐性遗传性疾病，其特征是前脑、小脑和脑干空泡变性、星形胶质细胞增生和髓鞘形成障碍（“海绵状脑白质营养不良”）。卡纳万病尚未被证明有效。ASPA 是一种少突胶质细胞裂解酶。 N-乙酰-L-天冬氨酸 (NAA)，释放乙酸盐和 L-天冬氨酸，NAA 由神经元酶 N-乙酰转移酶-8 样 (NAT8L) 合成，在正常 CNS 中维持在约 10 mM，但在卡纳万病中。，中枢神经系统 NAA 远远高于该水平。一个流行的假设是，NAA 释放乙酸并通过少突胶质细胞转化为乙酰辅酶 A。乙酰辅酶A合成酶对于维持少突胶质细胞脂肪生成乙酰辅酶A库至关重要，卡纳万病中的海绵状脑白质营养不良可归因于少突胶质细胞乙酰辅酶A“饥饿”，但我们的初步数据质疑NAA衍生的乙酸对于中枢神经系统髓磷脂脂质的必要性。合成表明，在 CNS 中纯合组成型 NAT8L 敲除(NAT8LKO/KO) 小鼠，其中 1H 磁共振波谱检测不到 NAA，乙酰辅酶 A 含量和髓鞘形成正常，具体目标 1 将评估另一种假设，即卡纳万病中的海绵状脑白质营养不良是中枢神经系统持续升高的结果。我们将采用由无义 ASPA 突变 (ASPAnur7) 纯合性引起的良好表征的小鼠 Canavan 模型。携带 ASPAnur7 和 NAT8LKO 等位基因的 ASPAnur7/nur7 小鼠将生成携带 2、1 或 0 个 NAT8LKO 等位基因，并将用于测试抑制 ASPAnur7/nur7 小鼠中的 NAA 合成将预防海绵状脑白质营养不良的预测。我们将对有症状的年轻成年 ASPAnur7/nur7 小鼠施用他莫昔芬，这些小鼠条件性 NAT8L 等位基因 (NAT8Lflox) 纯合并携带广泛表达的他莫昔芬诱导性 cre 转基因，以测试延迟抑制 NAA 合成是否会逆转其先前存在的海绵状脑白质营养不良如果是这样，则采取干预措施以防止 Canavan 儿童中枢神经系统 NAA 水平升高。疾病可能具有治疗价值。