Role of TRIP8b in epilepsy

TRIP8b 在癫痫中的作用

基本信息

批准号：
8294512
负责人：
Dane M Chetkovich
金额：
$ 19.06万
依托单位：
NORTHWESTERN UNIVERSITY AT CHICAGO
依托单位国家：
美国
项目类别：
财政年份：
2011
资助国家：
美国
起止时间：
2011-07-01 至 2013-12-30
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/8294512
关键词：
Absence Epilepsy Address Adverse effects Affect Alleles Alternative Splicing Animal Model Animals Area Biochemical Brain Brain region Breeding Cell membrane Cessation of life Cyclic Nucleotides Defect Dendrites Development Distal Drug Delivery Systems Electroencephalography Epilepsy Exhibits Exons Foundations Future Gene Mutation Genes Genetic Goals Hippocampus (Brain)Homeostasis Human Intervention Knock-out Lead Mediating Medical Membrane Membrane Potentials Modeling Molecular Morbidity - disease rate Mus Mutation Neurologic Neurons Operative Surgical Procedures Patients Phenotype Play Predisposition Process Protein Family Protein Isoforms Proteins Public Health Rattus Refractory Research Resistance Role Seizures Site Surface Surgical Management Syndrome Techniques Temporal Lobe Epilepsy Thalamic structure Therapeutic Transgenes Transgenic Mice Variant Work base cyclic-nucleotide gated ion channels density disability hippocampal pyramidal neuron improved mind control mortality mouse model neuronal cell body neuronal excitability novel prevent promoter therapy resistant tool trafficking

项目摘要

DESCRIPTION (provided by applicant): Seizures refractory to medical and surgical management negatively affect the lives of many patients with epilepsy and lead to significant morbidity and mortality, but basic mechanisms underlying therapy-resistant seizures remain elusive. One candidate for controlling brain excitability in different types of genetic and acquired epilepsy is the hyperpolarization-activated cyclic nucleotide-gated (HCN) channel (h channel) family of proteins. h channels mediate hyperpolarization-activated current, (Ih), which is critical for control of neuronal excitability. Four subunits, HCN1-4, combine to form h channels and are expressed differentially throughout the brain. Mutation of the Hcn2 gene in mice results in seizures resembling those in human absence epilepsy. HCN1 and HCN2 have also been implicated in temporal lobe epilepsy (TLE), the most common cause of medically refractory seizures. In a rat model of TLE, Ih is downregulated in hippocampal dendrites, a change that leads to increased excitability and may contribute to increased seizure propensity in these epileptic animals. Reduced Ih in TLE can be explained by mislocalization of h channels away from distal dendrites and into subcellular compartments within the soma. This h channel trafficking defect is associated with reduced interaction between HCN1 and tetratricopeptide repeat (TPR)-containing Rab8b interacting protein (TRIP8b), the h channel auxiliary subunit in brain. TRIP8b exists in multiple alternative splice variants with "upregulating" or "downregulating" effects on h channel trafficking and function, but the predominant brain TRIP8b isoforms upregulate Ih current density and HCN1 surface expression. Because of evidence that TRIP8b plays a critical role in controlling h channel function, we generated three distinct lines of mice with manipulations in the gene encoding TRIP8b, 1) Total knockout of TRIP8b, 2) conditional knockout of TRIP8b, and 3) selective deletion of exons, limiting expression to "upregulating" TRIP8b isoform. Preliminary studies reveal that total knockout of TRIP8b leads to absence epilepsy in mice. We hypothesize that epilepsy in TRIP8b mice results from thalamic and cortical h channelopathy due to mislocalization of h channels away from the plasma membrane. We will address this hypothesis by completing the following specific aims: 1) to determine if region-specific elimination of TRIP8b in thalamus and cortex leads to absence epilepsy, and 2) to demonstrate that h channel surface expression levels control susceptibility to absence seizures. This project will utilize genetic, biochemical, immunohistochemical and electrophysiological tools to characterize the mechanisms of epilepsy in mice with mutations of the gene encoding TRIP8b gene, with the overarching goal of characterizing a previously unknown cause of epilepsy to build the foundation for future development of novel epilepsy treatments.

描述（由申请人提供）：对医学和外科手术管理难治性的癫痫发作对许多癫痫病的患者的生活产生了负面影响，并导致了明显的发病率和死亡率，但耐药性癫痫发作的基本机制仍然难以捉摸。在不同类型的遗传和获得性癫痫中控制大脑兴奋性的候选者是超极化激活的环状核苷酸门控通道（HCN）通道（H通道）蛋白质家族。 H通道介导超极化激活的电流（IH），这对于控制神经元兴奋性至关重要。 HCN1-4的四个亚基合并形成H通道，并在整个大脑中差异表达。小鼠中HCN2基因的突变导致癫痫发作类似于人类缺乏癫痫的癫痫发作。 HCN1和HCN2也与颞叶癫痫（TLE）有关，这是医学上难治性癫痫发作的最常见原因。在TLE的大鼠模型中，IH在海马树突中被下调，这种变化会导致兴奋性提高，并可能导致这些癫痫动物的癫痫发作倾向增加。可以通过将H通道从远端树突和躯体内的亚细胞隔室中移出的h通道错误地重新定位来解释。该H通道运输缺陷与HCN1和四肽重复（TPR）的RAB8B相互作用蛋白（TRIP8B）（脑中的H通道辅助亚基）之间的相互作用减少有关。 Trip8b存在于多种替代剪接变体中，其“上调”或“下调”对H通道运输和功能的影响，但是主要的脑Trip8b同工型上调IH IH电流密度和HCN1表面表达。由于有证据表明TRIP8B在控制H通道功能中起着至关重要的作用，因此我们在编码Trip8b的基因中产生了三个不同的小鼠，1）Trip8b的总敲除，2）Trip8b的有条件敲除和3）选择性删除出显子，从而限制了表达表达来“上调” TIB8B ISOFORM。初步研究表明，Trip8b的总敲除导致小鼠缺有癫痫。我们假设Trip8b小鼠中的癫痫病是由丘脑和皮质H通道病变引起的，这是由于H通道从质膜上移开的错误定位而导致的。我们将通过完成以下特定目的来解决这一假设：1）确定丘脑和皮质中Trip8b的特异性消除是否导致缺有癫痫病，以及2）证明H通道表达水平控制缺乏癫痫发作的易感性。该项目将利用遗传，生化，免疫组织化学和电生理学工具来表征小鼠中癫痫的机制，该基因编码TRIP8B基因的基因突变，其总体目标是表征先前未知的癫痫病，以建立新型癫痫治疗的基础。