Blood-brain barrier P-glycoprotein: a new target for Alzheimer's disease

血脑屏障P-糖蛋白：阿尔茨海默病的新靶点

• 批准号: 8194624
• 负责人: Anika M.S. Hartz
• 金额: $ 30.96万
• 依托单位: UNIVERSITY OF MINNESOTA
• 依托单位国家: 美国
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-09-01 至 2016-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8194624
• 关键词: Affect; Alzheimer' s Disease; Amyloid; Amyloid beta-Protein Precursor; Autopsy; Biological Assay; Blood - brain barrier anatomy; Blood Vessels; Blood capillaries; Brain; Brain Diseases; Cell Line; Clinic; Clinical; Cognition; Data; Deposition; Development; Disease Progression; Duct (organ) structure; Goals; Human; Impaired cognition; Knowledge; Lead; Marketing; Measures; Mediating; Mission; Molecular; Monitor; Mus; National Institute of Neurological Disorders and Stroke; Neurodegenerative Disorders; Outcome; P-Glycoprotein; P-glycoprotein 2; Pathogenesis; Pathology; Patients; Perfusion; Pharmaceutical Preparations; Play; Public Health; Receptor Activation; Research; Research Personnel; Role; Sampling; System; Tail; Testing; Therapeutic; Therapeutic Effect; Transgenic Organisms; Translating; Ubiquitin; Ubiquitination; United States National Institutes of Health; Work; base; capillary; design; effective therapy; feeding; improved; in vivo; inhibitor/antagonist; innovation; mouse model; multicatalytic endopeptidase complex; nervous system disorder; new therapeutic target; novel therapeutics; overexpression; pregnane X receptor; prevent; protein transport; restoration; therapeutic target

DESCRIPTION (provided by applicant): We have a fundamental lack in understanding the mechanism that reduces P-glycoprotein (P-gp) expression and transport activity at the blood-brain barrier in Alzheimer's disease (AD). Lack of this knowledge is a significant clinical problem since it prevents development of an effective therapy to enhance AB clearance from the brain, lower AB brain levels, and thus prevent cognitive decline in AD. The long-term goal of the investigator is to better understand the molecular mechanisms that regulate blood-brain barrier function in neurodegenerative disorders, a goal which may lead to new therapeutic strategies to treat AD. The objectives of this particular application are to identify the mechanism responsible for P-gp reduction in AD, to validate this mechanism as a target to protect P-gp, and to test a novel therapeutic strategy for restoring P-gp. Accomplishing these objectives is expected to reduce A¿ brain levels and improve cognition in AD. Based on preliminary data, the central hypothesis is that A¿ mediates proteasomal degradation of P-gp, that blocking proteasomal degradation protects P-gp, and that restoring P-gp levels through PXR activation reduces A¿ brain burden and improves cognition in mice with AD. The rationale for the proposed research is that identifying the mechanism that reduces brain capillary P-gp and protecting and/or restoring P-gp to improve A¿ brain clearance will potentially provide novel therapeutic targets to lower A¿ brain levels in AD. To accomplish the objectives of this application, we will test our central hypothesis by pursuing the following three specific aims: 1) Identify the mechanism of A¿-mediated P-gp reduction at the blood-brain barrier. 2) Validate the ubiquitin-proteasome system as a target to protect P-gp in an AD mouse model. 3) Develop a therapeutic strategy to reduce cognitive decline in an AD mouse model. In Aim 1, we will inhibit the ubiquitin-proteasome system to identify the steps involved in A¿-mediated P-gp reduction, and determine expression, transport activity, and ubiquitination of P-gp. In Aim 2, we will treat hAPP mice with inhibitors of the ubiquitin-proteasome system, monitor P-gp expression, transport activity, and ubiquitination, and measure A¿ brain levels. We will conduct brain perfusion to assess P-gp activity in vivo and perform tail-flick assays to determine the consequence of changes in P-gp. In Aim 3, we will con- duct a 2-year PCN-feeding study with hAPP mice to assess the long-term therapeutic effect of PXR-mediated P-gp restoration on AB brain levels. P-gp expression and transport activity, A¿ brain load, and cognition will be periodically determined. The proposed research is innovative because it focuses on two independent strategies designed specifically to enhance A¿ clearance from the brain in AD. The proposed research is significant because it holds the promise of two new therapeutic strategies to lower A¿ brain burden and slow progression of AD. The proposed research is translational because drugs for either strategy, inhibition of the ubiquitin- proteasome system and PXR activation, are currently on the market, and both therapeutic strategies could potentially be translated into the clinic for the treatment of AD patients. PUBLIC HEALTH RELEVANCE: The proposed research is relevant to public health because it will significantly advance understanding of blood-brain barrier function in brain diseases and potentially provide new opportunities for improving treatment of Alzheimer's disease. Worldwide, millions of people are currently affected by Alzheimer's disease and patient numbers will increase tremendously over the next decades. Thus, the proposed research is relevant to the mission of the NIH/NINDS, which is to reduce the burden of neurological disease.

描述（由申请人提供）：我们对阿尔茨海默病（AD）中降低P-糖蛋白（P-gp）表达和血脑屏障转运活性的机制缺乏基本了解。缺乏这种知识是一个重要的临床问题，因为它阻止了有效治疗的发展，以提高AB从大脑中清除，降低AB脑水平，从而防止AD的认知下降。研究者的长期目标是更好地了解调节神经退行性疾病中血脑屏障功能的分子机制，这一目标可能导致治疗AD的新治疗策略。本申请的目的是确定AD中P-gp减少的机制，验证该机制作为保护P-gp的靶点，并测试恢复P-gp的新治疗策略。实现这些目标有望降低AD患者的A脑水平并改善其认知能力。基于初步数据，中心假设是A？介导P-gp的蛋白酶体降解，阻断蛋白酶体降解可保护P-gp，通过PXR激活恢复P-gp水平可降低A？脑负荷并改善AD小鼠的认知能力。这项研究的基本原理是，确定降低脑毛细血管P-gp的机制，保护和/或恢复P-gp以改善A <$脑清除率，将可能为降低AD患者A <$脑水平提供新的治疗靶点。为了实现本申请的目的，我们将通过追求以下三个具体目标来测试我们的中心假设：1）确定血脑屏障处A？介导的P-gp减少的机制。2)以泛素-蛋白酶体系统为靶点保护AD小鼠模型中的P-gp。3)开发治疗策略以减少AD小鼠模型中的认知下降。在目标1中，我们将抑制泛素-蛋白酶体系统，以确定参与A？介导的P-gp还原的步骤，并确定P-gp的表达，转运活性和泛素化。在目标2中，我们将用泛素-蛋白酶体系统的抑制剂治疗hAPP小鼠，监测P-gp表达、转运活性和泛素化，并测量A？脑水平。我们将进行脑灌注以评估体内P-gp活性，并进行甩尾试验以确定P-gp变化的后果。在目标3中，我们将对hAPP小鼠进行为期2年的PCN喂养研究，以评估PXR介导的P-gp恢复对AB脑水平的长期治疗效果。将定期测定P-gp表达和转运活性、A？脑负荷和认知。这项研究是创新的，因为它专注于两种独立的策略，专门用于增强AD患者大脑中A？的清除。这项拟议中的研究意义重大，因为它有望提供两种新的治疗策略，以降低大脑负担和减缓AD的进展。拟议的研究是转化的，因为用于任一策略的药物，抑制泛素-蛋白酶体系统和PXR激活，目前已上市，并且两种治疗策略都可能转化为临床治疗AD患者。 公共卫生关系：这项拟议中的研究与公共卫生有关，因为它将大大促进对脑疾病中血脑屏障功能的理解，并可能为改善阿尔茨海默病的治疗提供新的机会。在世界范围内，数百万人目前受到阿尔茨海默病的影响，患者人数将在未来几十年内大幅增加。因此，拟议的研究与NIH/NINDS的使命有关，即减少神经系统疾病的负担。