Genetic and Functional Mechanisms in Citrate Transporter Disorder associated with SLC13A5

与 SLC13A5 相关的柠檬酸转运蛋白紊乱的遗传和功能机制

• 批准号: 10651203
• 负责人: STEPHEN L HELFAND
• 金额: $ 65.22万
• 依托单位: BROWN UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-06-01 至 2028-05-31
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10651203
• 关键词: Affect; Alleles; Animal Diseases; Animal Model; Astrocytes; Behavioral Symptoms; Biological Assay; Brain; Cell membrane; Cells; Central Nervous System; Citrates; Code; Complex; Cytoplasm; DNA; Data; Defect; Development; Disease; Disease model; Drosophila genus; Electroencephalography; Electrophysiology (science); Epilepsy; Genes; Genetic; Genotype; Human; Human Genetics; Immunohistochemistry; Knock-out; Knockout Mice; Life; Measures; Metabolism; Methods; Missense Mutation; Modeling; Molecular; Molecular Genetics; Mus; Mutation; Nature; Neurobehavioral Manifestations; Neuronal Dysfunction; Neurons; Neurotransmitters; Oligodendroglia; Partial Epilepsies; Pathogenicity; Pathway interactions; Patients; Phenotype; Physiological; Physiology; Plasma; Point Mutation; Proteins; RNA Interference; Recurrence; Research; Rodent; Role; Seizures; Severities; Slice; Structure; Syndrome; System; Techniques; Testing; Therapeutic; Therapeutic Intervention; Tissues; Toxic effect; autosome; causal variant; cell type; cellular pathology; citrate carrier; design; early onset; epileptic encephalopathies; epileptiform; fly; gain of function; gene therapy; genome editing; individualized medicine; interdisciplinary approach; loss of function; metabolomics; motor symptom; mouse genetics; mouse model; mutant; neural circuit; neurotransmitter metabolism; novel; novel therapeutic intervention; patch clamp; preclinical study; recessive genetic trait; reduce symptoms

Scientific Abstract: SLC13A5 epilepsy is a newly recognized form of Developmental Epileptic Encephalopathy 25 (DEE25) with seizures beginning within the first days of life along with subsequent intellectual and motor symptoms. In these patients, mutations in the SLC13A5 gene, which encodes a plasma membrane citrate transporter, result in a severe, early onset multi-focal epilepsy and cognitive and behavioral symptoms. How disruption of SLC13A5 function results in dysfunction of neural circuitry is unknown. In patients and in rodent loss of function models of SLC13A5, plasma citrate concentrations are elevated and cytoplasmic citrate is decreased. Since citrate is a precursor to neurotransmitters, diminished glial and neuronal citrate may result in abnormal neuro-transmitter metabolism, contributing to functional defects. However, SLC13A5 loss of function may not account for the full severity of the disorder, and truncations of SLC13A5 are rarely observed in patients. Instead, human genetics show that certain mutations are over-represented as known causative mutations; SLC13A5 G219R (DNA G655A) and T227M (DNA C680T) are the most common recurrent mutations found in approximately two-thirds of all known patients. While the epilepsy is associated with bi-alleleic mutations, the presence of recurrent missense mutations suggests mechanisms more complex than simple autosomal recessive genetics. However, these have not been fully investigated, and no specific treatments for these patients exist. In order to better understand the genetics of SLC13A5 epilepsy, we have developed novel experimental systems. In fly, the entire Drosophila Slc13A5 gene was replaced with the human SLC13A5 coding region. This results in expression of only the human SLC13A5 expressed in the central nervous system. In the humanized line, the G219R mutation causes lethality in contrast to the null, suggesting gain of function mechanisms. In rodents, we show that the equivalent mutation to G219R in mouse SLC13A5 causes more severe epilepsy in direct comparison to the null, again suggesting the over-arching hypothesis of this proposal: that pathogenic mutations in SLC13A5 have gain of function effects, as well as, loss of function effects. However, the understanding of the mechanisms underlying these effects is incomplete, and the determination of both genetic and functional mechanisms are highly important for developing treatments for SLC13A5 epilepsy. We will determine in three Aims to determine:1) what is the normal function of SLC13A5 in brain physiology 2) how do pathogenic mutations in SLC13A5 result in neural dysfunction 3) if novel therapeutic strategies may ameliorate symptoms in SLC13A5 syndrome.

科学摘要： SLC13A5癫痫是一种新发现的发育性癫痫脑病25(DEE25) 癫痫在出生后的头几天就开始发作，并伴随着随后的智力和运动症状。在……里面 这些患者的SLC13A5基因突变，编码一种质膜柠檬酸转运蛋白，导致 出现严重、发病早的多灶性癫痫及认知和行为症状。SLC13A5如何中断 功能导致神经回路功能障碍的原因尚不清楚。在患者和啮齿动物中丧失的功能模型 SLC13A5，血浆柠檬酸浓度升高，细胞质柠檬酸浓度降低。由于柠檬酸盐是一种 神经递质前体、神经胶质细胞和神经元柠檬酸减少可能导致神经递质异常 新陈代谢，导致功能缺陷。然而，SLC13A5功能丧失可能并不能完全解释 患者很少观察到疾病的严重性和SLC13A5的截断。相反，人类遗传学 显示某些突变被过度表示为已知的致病突变；SLC13A5 G219R(DNA G655A)和T227M(DNA C680T)是最常见的复发突变，约三分之二 在所有已知的病人中。虽然癫痫与双等位基因突变有关，但复发的 错义突变暗示了比简单的常染色体隐性遗传更复杂的机制。然而， 这些还没有得到充分的调查，也没有针对这些患者的特定治疗方法。 为了更好地了解SLC13A5癫痫的遗传学，我们开发了新的实验 系统。在果蝇中，整个果蝇SLC13A5基因被人的SLC13A5编码区取代。这 结果只有人SLC13A5在中枢神经系统表达。在人性化的 与零突变相比，G219R突变会导致致命性，这表明功能机制的获得。在……里面 ，我们发现小鼠SLC13A5中与G219R等同的突变会导致更严重的癫痫 与零的直接比较，再次表明了这一提议的总体假设：致病 SLC13A5突变既有功能效应的获得，也有功能效应的丧失。然而， 对这些影响的潜在机制的了解是不完整的，而且两种基因的确定 其作用机制对SLC13A5癫痫的治疗具有重要意义。我们会 确定三个目的：1)SLC13A5在脑生理学中的正常功能2)如何 SLC13A5致病突变导致神经功能障碍3)新的治疗策略是否可以改善 SLC13A5综合征的症状。