A Cholesterol metabolite functions as an endogenous neuroprotectant through blockade of ASIC

项目摘要/摘要 氧化甾醇是胆固醇的含氧衍生物，已被鉴定为几种 然而，几十年来，它们在生理和病理过程中的作用，特别是在 神经系统，在很大程度上是未知的。我们之前的研究表明，主要的胆固醇 代谢物Cholestane-3β，5α，6β-Triol(三醇)是一种重要的内源激素 神经保护剂。这里，我们假设酸敏感离子通道(ASIC)1a被阻断 作为其神经保护作用的一种新机制，基于以下几点 论点和初步数据：(1)脑缺血后血三醇浓度升高 预适应(IPC)，有助于IPC介导的神经保护；(2)激活 钙通透性ASIC1a加重缺血损伤，而药物阻断或 敲除ASIC1a产生显著的保护作用；(3)在脑缺血中，阻断ASIC1a 治疗时间窗为~5h，与Triol(&gt；4h)接近；(4)我们的初步 数据清楚地表明，Triol显著抑制ASIC1a电流及其表面 在缺血预适应期间发生的浓度下的表达；(5)初步的 数据表明，ASIC的抑制是三醇所特有的，因为它的前体胆固醇没有 对ASIC电流的影响。严格检验三醇作为内源性激素发挥作用的假设 通过阻断ASIC1a作为神经保护剂，将检查以下具体目标： 目的1.测定三醇对ASIC电流和钙内流的影响。 目的2.检测三醇对ASIC1a细胞表面表达的抑制作用。 目的3.确定三醇的神经保护作用是否通过抑制 ASIC1a. 目的4.研究其构效关系，并鉴定其介导的氨基酸。 三醇对ASIC1a的抑制作用。

Project Summary/Abstract Oxysterols, the oxygenated derivatives of cholesterol, have been identified for several decades, however, their roles in the physiology and pathological processes, particularly in nervous system, are largely unknown. Our previous study showed that the major cholesterol metabolite, cholestane-3β, 5α, 6β-triol (Triol), functions as an important endogenous neuroprotectant. Here, we hypothesize that blockade of acid-sensing ion channel (ASIC) 1a serves as a novel mechanism underlying its neuroprotective effect, based on the following arguments and preliminary data: (1) The concentration of Triol increases after ischemic preconditioning (IPC), which contributes to IPC mediated neuroprotection; (2) The activation of calcium permeable ASIC1a exacerbates ischemic injury, and that pharmacological blockade or knockout of ASIC1a produces a significant protection; (3) In brain ischemia, blockade of ASIC1a has a therapeutic time window of ~5h, which is close to that of Triol (> 4h); (4) Our preliminary data clearly demonstrated that Triol significantly inhibits ASIC1a currents as well as its surface expression, at a concentration that occurs during ischemic preconditioning; (5) The preliminary data suggest that the inhibition of ASIC is specific to Triol, as its precursor cholesterol has no effect on ASIC currents. To rigorously test the hypothesis that Triol functions as an endogenous neuroprotectant through blockade of ASIC1a, the following specific aims will be examined: Aim 1. Determine the effect of Triol on ASIC current and calcium entry. Aim 2. Determine the inhibitory effect of Triol on ASIC1a surface expression. Aim 3. Determine whether the neuroprotection caused by Triol is mediated through inhibition of ASIC1a. Aim 4. Study the structure-activity relationship, and identify the amino acids that mediate the inhibitory effect of Triol on ASIC1a.