Leveraging modulation of polyamine metabolism for therapeutic advantage in genetic disorders

摘要 我们处于研究与多胺相关的新型神经发育障碍的最前沿。我们 总体假设是多胺途径基因的突变导致病理上的不平衡， 受影响的个体中的多胺谱导致神经发育障碍。具体来说，巴赫曼- Bupp综合征（BABS）是一种常染色体显性遗传疾病，由杂合子的新生变异引起 在鸟氨酸脱羧酶1（ODC 1）基因中，Snyder-Robinson综合征（SRS）是一种X连锁遗传病， 由精胺合酶（SMS）基因突变引起的疾病。ODC 1和SMS都是哨兵 多胺代谢调控基因。然而，将多胺与这些分子连接起来的精确途径， 神经发育障碍没有很好的定义。基于我们初步的体外、动物和临床试验， 根据患者数据，我们假设多胺（腐胺、亚精胺、精胺）的失调可能是 正常化，BABS和SRS表型可以通过药物干预逆转。 重要的是，我们有令人信服的数据表明，BABS患者积累了活性ODC酶， 产生大量的腐胺，我们发现FDA批准的ODC抑制剂DFMO （依氟鸟氨酸）显著改善BABS患者症状。我们进一步假设，类似的增益- 功能（GOF）或其他多胺基因中的功能丧失（LOF）变体（例如，eIF5A、DHPS、DOHH、SMOX、 AZ，AZI）的存在，潜在地引起未知的多胺紊乱。不幸的是， 关于控制多胺相关神经发育表型的潜在机制 紊乱鉴于这些事实，本申请的总体目标是揭示分子机制 以及将多胺与BABS和SRS连接的代谢途径和测试多胺靶向剂（DFMO， Me 2Spm，其他）在转基因BABS和SRS鼠模型和人患者来源的原代细胞中的表达，以及 淋巴母细胞样细胞系。以下具体目标旨在实现这些目标。目标1：表征 并对模拟个体ODC 1功能获得性突变的遗传小鼠模型进行重复治疗 与BABS一起询问控制人类BABS患者表型的分子机制。目标二： 在SRS受影响个体的细胞和新型遗传小鼠模型中优化药物治疗 与SRS患者的常见突变相似目标3：扩展对BABS和SRS的临床理解 以改善日益增多的罕见疾病家族的临床护理。由于本提案的主要目的是 定义控制BABS和SRS的分子机制和代谢途径，并测试 为了确定相关模型中治疗的有效性，我们使用疾病特异性小鼠模型至关重要。我们将 使用我们的BABS和SRS小鼠模型和患者来源的细胞系，正如我们以前发表的那样， 测定多胺抑制剂治疗的体内有效性。我们的研究提供了难得的机会， 可能治愈或至少改善BABS和SRS的症状，这两种人类遗传疾病。

ABSTRACT We are at the forefront of investigating novel neurodevelopmental disorders associated with polyamines. Our overarching hypothesis is that mutations in genes of the polyamine pathway result in pathologically unbalanced polyamine profiles in affected individuals that lead to neurodevelopmental disorders. Specifically, Bachmann- Bupp Syndrome (BABS) is an autosomal dominant genetic disorder caused by heterozygous de novo variants in the ornithine decarboxylase 1 (ODC1) gene, and Snyder-Robinson Syndrome (SRS) is an X-linked genetic disorder that results from mutations in the spermine synthase (SMS) gene. Both ODC1 and SMS are sentinel genes in the regulation of polyamine metabolism. However, the precise pathways linking polyamines to these neurodevelopmental disorders are not well defined. Based on our preliminary in vitro, animal, and clinical patient data, we hypothesize that dysregulated polyamines (putrescine, spermidine, spermine) can be normalized, and BABS and SRS phenotypes can be reversed through pharmacological intervention. Importantly, we have compelling data showing that BABS patients accumulate active ODC enzyme and produce large amounts of putrescine, and we showed that the FDA-approved ODC inhibitor DFMO (Eflornithine) significantly improves BABS patient symptoms. We further hypothesize that similar gain-of- function (GOF) or loss-of-function (LOF) variants in other polyamine genes (e.g., eIF5A, DHPS, DOHH, SMOX, AZ, AZI) exist, potentially giving rise to yet unknown polyamine disorders. Unfortunately, very little is known about the underlying mechanisms that govern the phenotypes of polyamine-linked neurodevelopmental disorders. In light of these facts, the overall goals of this application are to unravel the molecular mechanisms and metabolic pathways that link polyamines to BABS and SRS and test polyamine-targeting agents (DFMO, Me2Spm, others) in transgenic BABS and SRS murine models and human patient-derived primary cells and lymphoblastoid cell lines. The following Specific Aims are designed to pursue these goals. Aim 1: Characterize and pharmacologically treat genetic mouse models that mimic ODC1 gain-of-function mutations of individuals with BABS to interrogate the molecular mechanisms that govern the human BABS patient phenotype. Aim 2: Optimize pharmacologic treatment in cells from SRS-affected individuals and in a novel genetic mouse model that mimics a common mutation in SRS patients. Aim 3: Expand the clinical understanding of BABS and SRS to improve clinical care of a growing family of rare diseases. As the primary purpose of this proposal is to define molecular mechanisms and metabolic pathways that govern BABS and SRS as well as to test the effectiveness of treatments in relevant models, it is critical that we use disorder-specific mouse models. We will use our BABS and SRS murine models and patient-derived cell lines, as we have previously published, to determine the in vivo effectiveness of polyamine inhibitor treatments. Our study provides the rare opportunity to potentially cure or at least ameliorate the symptoms of BABS and SRS, two human genetic disorders.