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

项目总结/摘要 氧化固醇，胆固醇的氧化衍生物，已经被鉴定用于几种用途。 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，大部分是未知的。我们之前的研究表明， 代谢产物胆甾烷-3 β，5α，6β-三醇（Triol）是一种重要的内源性代谢物， 神经保护剂在此，我们假设阻断酸敏感离子通道（ASIC）1a 作为其神经保护作用的一种新机制，基于以下内容 论点和初步资料：（1）缺血后三醇浓度增加， 预处理（IPC），这有助于IPC介导的神经保护;（2）激活 钙渗透性ASIC 1a加剧缺血性损伤，并且药理学阻断或 ASIC 1a基因敲除对脑缺血有明显的保护作用;（3）在脑缺血时，阻断ASIC 1a基因， 治疗时间窗约为5 h，与Triol（> 4 h）接近;（4）我们初步的 数据清楚地表明，三醇显著抑制ASIC 1a电流以及其表面 表达，在缺血预处理过程中发生的浓度;（5）初步的 数据表明，ASIC的抑制是特异性的三醇，因为它的前体胆固醇没有 对ASIC电流的影响。为了严格检验三醇作为内源性 通过阻断ASIC 1a，使用神经保护剂，将检查以下具体目的： 目标1.测定Triol对ASIC电流和钙内流的影响。 目标2.测定Triol对ASIC 1a表面表达的抑制作用。 目标3.确定Triol引起的神经保护作用是否通过抑制 ASIC 1a。 目标4。研究构效关系，并鉴定介导该作用的氨基酸。 Triol对ASIC 1a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.