Mutational analysis to understand the role of CHML in developmental regression

突变分析以了解 CHML 在发育回归中的作用

基本信息

批准号：
8877784
负责人：
Eugene Yu
金额：
$ 23.69万
依托单位：
ROSWELL PARK CANCER INSTITUTE CORP
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：
2015-06-01 至 2017-05-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/8877784
关键词：
Affect Affinity Alleles Alzheimer&apos s Disease Amino Acid Sequence Apoptosis Autophagocytosis Behavioral Biological Process Biomedical Research Brain Candidate Disease Gene Cell physiology Cells Choroid Choroideremia Clinical Clustered Regularly Interspaced Short Palindromic Repeats Code Complementary DNA Complex Cytokinesis Development Disease Employee Strikes Engineering Enrollment Event Evolution Exhibits Eye Family Financial compensation Foundations Future GTP-Binding Proteins Genes Genetic Genome Genomics Genotype Goals Guanosine Triphosphate Phosphohydrolases Heterozygote Histocompatibility Testing Human Inherited Knock-out Lead Link Magnetic Resonance Imaging Mammals Mediating Membrane Membrane Protein Traffic Messenger RNA Missense Mutation Modeling Molecular Motor Mus Mutant Strains Mice Mutation Nerve Degeneration Neuraxis Neurodegenerative Disorders Nonsense Mutation Organ Organism Orthologous Gene Parents Patients Peptide Sequence Determination Phenotype Photoreceptors Play Proteins Rab escort protein Rare Diseases Reporting Reverse Transcription Role Siblings Specificity Structure Structure of retinal pigment epithelium System Testing Therapeutic Intervention Therapeutic Studies Time Tissues United States National Institutes of Health Zebrafish autism spectrum disorder base body system brain tissue cell motility cilium biogenesis cognitive function design intercellular communication loss of function mouse model mutant novel novel therapeutic intervention null mutation paralogous gene prenylation prevent programs public health relevance response success white matter

项目摘要

DESCRIPTION (provided by applicant): Studies on rare diseases are important because they help to unravel the underlying mechanisms of diseases which may lead to novel therapies for patients. These efforts also offer rare opportunities to discover novel biological processes with major significance in biomedical research. This application is designed to explore a unique genotype-phenotype relationship based on a patient who is enrolled in the NIH Undiagnosed Disease Program (UDP). The patient harbors two compound heterozygous missense mutations in the CHML gene, with one mutant allele inherited from each parent. The patient exhibits developmental regression and neurodegeneration, including progressive cortical and white matter loss. The abnormal phenotypes are absent in the patient's siblings, who do not carry either mutation, and in their parents. In humans and other mammals, the paralogous genes CHM and CHML code for the Rab escort proteins REP-1 and REP-2, respectively. The Rab family consists of a large number of GTPases, which regulate complex membrane trafficking events. Posttranslational prenylation is required for targeting Rabs to specific subcellular membranes. REPs are essential for appropriate prenylation of Rabs. In zebrafish, there is only a single REP-coding gene, chm, and a nonsense mutation of the gene leads to degeneration of multiple organs. Extensive functional studies have been carried out on mammalian CHM orthologs. Null and missense mutations of CHM lead to degeneration of tissues in the eyes of patients with choroideremia. It has been proposed that tissues outside of the eyes in these patients, such as brain tissues, are likely protected by CHML. However, surprisingly, there are almost no functional studies of CHML orthologs despite their perceived importance until the first evidence of the impact of CHML from this UDP case. In this application, we propose to be the first group to test the related major hypothesis that CHML is an indispensable protector of brain tissues from degeneration using mouse mutations of Chml based on its high conservation with the human ortholog. In Aim 1, we will engineer Chml null alleles and the UDP patient-specific missense mutations in mice. In Aim 2, we will analyze the phenotypic consequences of compound heterozygosity of the missense mutations and the null alleles as loss-of-function controls. Phenotypic characterizations will include magnetic resonance imaging (MRI) and stereology analysis of brain structures as well as behavioral analysis of motor and cognitive functions. We will also analyze Rab prenylation in the mutant mice to explore the mechanistic link between genotypes and phenotypes. The success of this project will reveal for the first time the essential role of CHML in maintaining the integrity of the central nervous system, thereby laying the mechanistic foundation for future studies on the UDP patient, including therapeutic studies. The success of this project will also open up possibilities that CHML mutations and CHML-associated biological processes may play critical roles in other neurodegenerative disorders as well as autism spectrum disorder in which developmental regression is an important clinical feature.

描述（由申请人提供）：对罕见疾病的研究很重要，因为它们有助于揭示疾病的潜在机制，从而为患者带来新的治疗方法。这些努力也为发现在生物医学研究中具有重大意义的新生物过程提供了难得的机会。该应用旨在基于一名参加 NIH 未诊断疾病计划 (UDP) 的患者来探索独特的基因型-表型关系，该患者的 CHML 基因中存在两种复合杂合错义突变，其中一种突变体。患者表现出发育退化和神经退行性变，包括进行性皮质和白质丧失，而患者的兄弟姐妹（不携带这两种突变）及其父母均不存在异常表型。旁系同源基因 CHM 和 CHML 分别编码 Rab 护送蛋白 REP-1 和 REP-2。 Rab 家族由大量 GTPase 组成，调节复杂的膜运输事件。在斑马鱼中，只有一个 REP 编码基因 chm，并且该基因的无义突变会导致多个器官的退化。已经对哺乳动物 CHM 直系同源物进行了研究。CHM 的空义突变和错义突变导致无脉络膜血症患者眼部组织的退化。然而，令人惊讶的是，尽管 CHML 直系同源物被认为很重要，但在本申请中首次证明 CHML 的影响之前，几乎没有对它们进行功能研究。我们建议成为第一个利用 Chml 与人类直系同源物高度保守性的小鼠突变来检验相关主要假设的小组，即 CHML 是脑组织免于退化的不可或缺的保护者。在目标 1 中，我们将设计 Chml null。在目标 2 中，我们将分析错义突变和无效等位基因的复合杂合性的表型后果，作为功能丧失对照，表型特征将包括磁共振成像 (MRI)。）和大脑结构的体视学分析以及运动和认知功能的行为分析，我们还将分析突变小鼠的 Rab 异戊二烯化，以探索基因型和表型之间的机制联系。该项目的研究将首次揭示CHML在维持中枢神经系统完整性方面的重要作用，从而为未来对UDP患者的研究，包括治疗研究奠定机制基础，该项目的成功也将为这一研究打开大门。 CHML 突变和 CHML 相关生物过程可能在其他神经退行性疾病以及自闭症谱系障碍中发挥关键作用，其中发育退化是一个重要的临床特征。