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: 8318590
• 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/8318590
• 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.

描述（由申请人提供）：我们对阿尔茨海默病（AD）血脑屏障中 P-糖蛋白（P-gp）表达和转运活性降低的机制缺乏了解。缺乏这方面的知识是一个重大的临床问题，因为它阻碍了有效疗法的开发，以增强大脑中AB的清除，降低大脑中的AB水平，从而防止AD中的认知能力下降。研究人员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，这一目标可能会导致治疗 AD 的新治疗策略。这一特定应用的目的是确定 AD 中 P-gp 减少的机制，验证该机制作为保护 P-gp 的目标，并测试恢复 P-gp 的新治疗策略。实现这些目标预计将降低 AD 患者大脑中的 A 水平并改善认知能力。根据初步数据，中心假设是 A¿ 介导 P-gp 的蛋白酶体降解，阻止蛋白酶体降解可以保护 P-gp，并且通过 PXR 激活恢复 P-gp 水平可以减轻 A¿ 的大脑负担并改善 AD 小鼠的认知能力。拟议研究的基本原理是，确定减少脑毛细血管 P-gp 的机制并保护和/或恢复 P-gp 以提高 A¿ 大脑清除率，将有可能为降低 AD 患者 A 大脑水平提供新的治疗靶点。为了实现本申请的目标，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 A¿ 介导的血脑屏障 P-gp 还原的机制。 2) 验证泛素-蛋白酶体系统作为 AD 小鼠模型中保护 P-gp 的靶标。 3) 制定治疗策略以减少 AD 小鼠模型的认知能力下降。在目标 1 中，我们将抑制泛素-蛋白酶体系统，以确定 A¿ 介导的 P-gp 还原所涉及的步骤，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，并进行甩尾测定以确定 P-gp 变化的后果。在目标 3 中，我们将用 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。 P-gp 表达和运输活动、A¿ 脑负荷和认知将定期测定。拟议的研究具有创新性，因为它侧重于两种独立的策略，专门设计用于增强 AD 患者大脑中 A¿ 的清除率。这项研究具有重要意义，因为它有望提供两种新的治疗策略来降低 A 脑负担并减缓 AD 的进展。拟议的研究是转化性的，因为抑制泛素蛋白酶体系统和激活 PXR 两种策略的药物目前已上市，并且两种治疗策略都有可能转化为临床治疗 AD 患者。