Subunit dependent properties of kainate receptors

描述（由申请人提供）：红藻氨酸受体是谷氨酸门控离子通道，介导突触传递并调节中枢神经系统中的细胞兴奋性。它们通过参与海马神经元以行为相关频率产生节律振荡来促进认知处理。红藻氨酸受体也与许多神经系统疾病有关，包括颞叶癫痫、精神分裂症、自闭症和神经性疼痛。针对这些受体的新疗法的合理开发取决于对其功能的更好理解。红藻氨酸受体是四聚体，由低亲和力GluR 5 -7和高亲和力KA 1和KA 2亚基组成。钾盐镁矾受体的功能特性取决于其亚基组成。特别地，含有KA 2的红藻氨酸受体在神经元兴奋中发挥独特的作用。在含有KA 2的红藻氨酸受体上的电流比在缺乏KA 2的红藻氨酸受体上的电流表现出更高的电导和更慢的衰减。此外，含有KA 2的红藻氨酸受体通过非典型的促代谢作用增强内在神经元兴奋性。 也许是因为它们在神经元兴奋中的重要性，含有KA 2亚基的受体对各种内源性试剂（包括质子、多胺和锌）的调节表现出显著增加的敏感性。虽然最近的研究已经阐明了含有KA 2的红藻氨酸受体在生理条件下的作用，但对红藻氨酸受体亚基的表达或这些受体的功能作用在疾病中的变化知之甚少。红藻氨酸受体长期以来一直与颞叶癫痫的潜在机制有关。更好地了解红藻氨酸受体的性质和调节在颞叶癫痫中的变化，将为设计这种疾病的新疗法提供有价值的信息。本项目将研究KA 2亚基在生理条件和癫痫中红藻氨酸受体中的作用。目的1将利用重组受体来确定KA 2亚基对红藻氨酸受体的功能贡献。目的2将使用慢病毒载体和药理学试剂来确定KA 2亚基表达的变化对KAR介导的神经传递的影响。 目的3应用定量真实的时间qRT-PCR和免疫组织化学方法研究匹罗卡品诱导癫痫持续状态（SE）后海马KAR亚基RNA和蛋白的变化。海马切片电生理学与药理学试剂和慢病毒载体相结合，然后将定义SE诱导的亚基表达改变如何在这些相同的时间点改变红藻氨酸受体的功能特性。公共卫生相关性：红藻氨酸受体是谷氨酸门控离子通道，其对于突触传递至关重要，并且可以导致神经系统疾病，例如颞叶癫痫、精神分裂症、自闭症和神经性疼痛。本研究的目的是研究这些受体的亚基依赖性和亚基组成的变化对海马功能的影响。更好地了解红藻氨酸受体的特性是至关重要的，在合理开发新的治疗药物靶向这些受体。

DESCRIPTION (provided by applicant): Kainate receptors are glutamate-gated ion channels that mediate synaptic transmission and regulate cellular excitability in the central nervous system. They contribute to cognitive processing by participating in the generation of rhythmic oscillations of hippocampal neurons at behaviorally relevant frequencies. Kainate receptors have also been implicated in a number of neurological disorders including temporal lobe epilepsy, schizophrenia, autism, and neuropathic pain. Rational development of novel therapies targeting these receptors depends upon a better understanding of their function. Kainate receptors are tetrameric and comprised of low affinity GluR5-7 and high affinity KA1 and KA2 subunits. Functional properties of kainite receptors depend upon their subunit composition. In particular, KA2-containing kainate receptors play a distinctive role in neuronal excitation. Current at KA2-containing kainate receptors exhibits a higher conductance and slower decay than that at KA2-lacking kainate receptors. In addition, KA2-containing kainate receptors enhance intrinsic neuronal excitability through a noncanonical metabotropic action. Perhaps because of their importance in neuronal excitation, receptors containing the KA2 subunit exhibit significantly increased sensitivity to modulation by a variety of endogenous agents, including protons, polyamines and zinc. While recent studies have shed light on the roles of KA2-containing kainate receptors in physiological conditions, little is known about how the expression of kainate receptor subunits or the functional role of these receptors changes in disease. Kainate receptors have long been implicated in mechanisms underlying temporal lobe epilepsy. A better understanding of how the properties and regulation of kainate receptors change in temporal lobe epilepsy would provide valuable information in the design of novel therapies for this disease. This project will examine the role of the KA2 subunit in kainate receptors in physiological conditions and in epilepsy. Aim 1 will use recombinant receptors to define the functional contribution of KA2 subunits to kainate receptors. Aim 2 will use lentiviral vectors and pharmacological agents to determine the effect of changes in KA2 subunit expression on KAR-mediated neurotransmission. Aim 3 will use quantitative real time qRT-PCR and immunohistochemistry to determine the time course of changes in KAR subunit RNA and protein in the hippocampus during the development of epilepsy after pilocarpine-induced status epilepticus (SE). Hippocampal slice electrophysiology combined with pharmacological agents and lentiviral vectors will then define how SE-induced alterations in subunit expression change functional properties of kainate receptors at these same time points. PUBLIC HEALTH RELEVANCE: Kainate receptors are glutamate-gated ion channels that are critical for synaptic transmission and can contribute to neurological diseases, such as temporal lobe epilepsy, schizophrenia, autism, and neuropathic pain. The goals of this study are to examine subunit dependent properties of these receptors and the impact of changes in subunit composition on hippocampal function. A better understanding of kainate receptor properties is essential in the rational development of novel therapeutic agents targeted at these receptors.