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）：药物和手术治疗难治性癫痫发作对许多癫痫患者的生活产生负面影响，并导致显着的发病率和死亡率，但难治性癫痫发作的基本机制仍然难以捉摸。在不同类型的遗传性和获得性癫痫中控制大脑兴奋性的一种候选蛋白是超极化激活的环核苷酸门控（HCN）通道（h通道）蛋白家族。 h 通道介导超极化激活电流 (Ih)，这对于控制神经元兴奋性至关重要。四个亚基 HCN1-4 结合形成 h 通道，并在整个大脑中差异表达。小鼠 Hcn2 基因突变会导致类似于人类失神性癫痫的癫痫发作。 HCN1 和 HCN2 也与颞叶癫痫 (TLE) 有关，颞叶癫痫是医学上难治性癫痫发作的最常见原因。在 TLE 大鼠模型中，Ih 在海马树突中下调，这一变化会导致兴奋性增加，并可能导致这些癫痫动物的癫痫发作倾向增加。 TLE 中 Ih 的减少可以通过 h 通道错误定位远离远端树突并进入体细胞内的亚细胞区室来解释。这种 h 通道运输缺陷与 HCN1 和含有四三肽重复序列 (TPR) 的 Rab8b 相互作用蛋白 (TRIP8b)（大脑中 h 通道辅助亚基）之间的相互作用减少有关。 TRIP8b 存在于多种选择性剪接变体中，对 h 通道运输和功能具有“上调”或“下调”作用，但主要的大脑 TRIP8b 亚型上调 Ih 电流密度和 HCN1 表面表达。由于有证据表明 TRIP8b 在控制 h 通道功能中发挥着关键作用，我们通过对 TRIP8b 编码基因进行操作，产生了三种不同的小鼠品系：1) TRIP8b 完全敲除，2) TRIP8b 有条件敲除，以及 3) 选择性删除外显子，限制表达“上调”TRIP8b 同种型。初步研究表明，TRIP8b 的完全敲除会导致小鼠失神性癫痫。我们假设 TRIP8b 小鼠的癫痫是由于 h 通道错误定位远离质膜而导致丘脑和皮质 h 通道病变所致。我们将通过完成以下具体目标来解决这一假设：1）确定丘脑和皮质中 TRIP8b 的区域特异性消除是否会导致失神性癫痫，2）证明 h 通道表面表达水平控制失神性癫痫发作的易感性。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 TRIP8b 基因编码突变小鼠的癫痫机制，总体目标是表征以前未知的癫痫病因，为未来开发新型癫痫药物奠定基础。癫痫治疗。