Novel marine-derived ligands for probing GluR function

描述(由申请人提供)：区分相似亚型受体蛋白的天然来源化合物是现代神经科学中的关键工具，通常作为治疗应用的有价值的先导分子。在中枢神经系统快速兴奋性神经传递的基础上的亲离子谷氨酸受体尤其如此；从许多不同的生物体中分离出具有药理活性的谷氨酸受体化合物。最近，从海绵Dyside a herbacea中分离到一种新的红藻氨酸(KA)和a-amino-3-hydroxy-5-methyl-4-isoxazolepropionic酸(AMPA)型谷氨酸受体的配基--Dysiherbaine(DH)。HD被证明是一种强大的惊厥剂，对KA受体的一个子集具有异常高的亲和力；这种化合物以及它的天然和合成类似物，代表了一套新的工具，用于研究兴奋性氨基酸受体的生物物理和生理特性。谷氨酸受体表达的多样性和复杂性，以及这些蛋白在大脑功能中的核心作用，突显了分离和表征具有独特选择性图谱的新药理工具的重要性。本项目将表征一组新的药理工具--水解酶及其类似物，并使用这些化合物在生物物理和神经元水平上检测谷氨酸受体活性的功能方面。在第一个特定目标中，将测定新的水解酶类似物的生物活性。在第二个具体目标中，我们将利用水解酶作为一种工具来了解红藻氨酸受体的结构与功能关系。海人藻酸受体亚单位对水解酶的反应表现出高度的变异性，这为利用海洋毒素作为揭示受体蛋白重要功能结构域的关键探针提供了机会。第三个具体目标将侧重于使用药理学和遗传学相结合的方法来确定神经元海人酸受体的亚单位组成，我们最重要的工具包括基因靶向的小鼠和亚单位选择性海洋毒素。

DESCRIPTION (provided by applicant): Natural source compounds that differentiate between similar subtypes of receptor proteins are critical tools in modern neuroscience and often serve as valuable lead molecules for therapeutic applications. This has been particularly true with respect to lonotropic glutamate receptors, the receptors that underlie fast excitatory neurotransmission in the central nervous system; pharmacologically active glutamate receptor compounds have been isolated from a number of diverse organisms. Most recently, dysiherbaine (DH), a novel ligand for kainate (KA) and a-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) type glutamate receptors, was isolated from the marine sponge Dysidea herbacea. DH was shown to be a potent convulsant with an unusually high affinity for a subset of KA receptors; this compound, as well as its natural and synthetic analogues, represents a novel set of tools for investigating biophysical and physiological properties of excitatory amino acid receptors. The diversity and complexity of glutamate receptor expression, as well as the central role of these proteins in brain function, underscore the importance of isolation and characterization of new pharmacological tools with unique selectivity profiles. This project will characterize a new set of pharmacological tools - DH and its analogues - and use these compounds to examine functional aspects of glutamate receptor activity at the biophysical and neuronal level.In the first specific aim, the biological activity of novel analogues of DH will be determined. In the second specific aim, we will use DH as a tool for understanding structure-function relationships of kainate receptors. Kainate receptor subunits exhibit a high degree of variability in their responses to DH, which affords an opportunity to use the marine toxin as a key probe for uncovering important functional domains of the receptor proteins. The third specific aim will be focused on determining the subunitcomposition of neuronal kainate receptors using a combined pharmacological and genetic approach, with our most important tools consisting of gene-targeted mice and subunit-selective marine toxins.