P-glycoprotein efflux and other factors limit brain amyloid β reduction by β-site amyloid precursor protein-cleaving enzyme 1 inhibitors in mice
P-glycoprotein efflux and other factors limit brain amyloid β reduction by β-site amyloid precursor protein-cleaving enzyme 1 inhibitors in mice
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DOI：
10.1124/jpet.108.138974
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发表时间：
2008-08-01
影响因子：
3.5
通讯作者：
Albright, Charles F.
中科院分区：
文献类型：
--
作者：
Meredith, Jere E., Jr.;Thompson, Lorin A.;Albright, Charles F.
阿尔茨海默病（Alzheimer's disease，AD）是一种进行性神经退行性疾病。基于AD患者的病理学数据、导致AD早发形式的突变的遗传分析和临床前研究，假设淀粉样蛋白β（A β）肽导致AD的发生和进展。基于这一假设，β位点淀粉样前体蛋白（APP）裂解酶1（BACE 1）抑制剂是一种有吸引力的AD治疗方法，因为BACE 1裂解APP是形成A β所必需的。在这项研究中，三个有效的BACE 1抑制剂的特点。所有三种抑制剂均降低培养细胞中的A β形成，IC（50）值小于10 nM。通过免疫印迹分析APP C-末端片段和通过质谱分析A β肽表明，这些抑制剂通过抑制BACE 1降低A β。开发了小鼠中A β 1-40的测定，并用于显示这些BACE 1抑制剂降低了野生型小鼠中的血浆A β 1-40，但不降低脑A β 1-40。由于这些BACE 1抑制剂是P-糖蛋白（P-gp）（外排转运蛋白ATP结合盒超家族成员）的底物，因此将这些抑制剂给予P-gp敲除（KO）小鼠。这些研究表明，所有三种BACE 1抑制剂均降低了P-gp KO小鼠的脑A β 1-40，表明P-gp是开发BACE 1抑制剂以测试淀粉样蛋白假说的主要限制。比较这三种化合物的血浆A β 1-40和脑A β 1-40剂量反应，发现相对艾德（50）值存在差异，表明P-gp以外的因素也可能导致BACE 1抑制剂的脑活性降低。
Alzheimer's disease (AD) is a progressive neurodegenerative disease. Amyloid beta (A beta) peptides are hypothesized to cause the initiation and progression of AD based on pathologic data from AD patients, genetic analysis of mutations that cause early onset forms of AD, and preclinical studies. Based on this hypothesis, beta-site amyloid precursor protein (APP)-cleaving enzyme 1 (BACE1) inhibitors are an attractive therapeutic approach for AD because cleavage of the APP by BACE1 is required to form A beta. In this study, three potent BACE1 inhibitors are characterized. All three inhibitors decrease A beta formation in cultured cells with IC(50) values less than 10 nM. Analysis of APP C-terminal fragments by immunoblotting and A beta peptides by mass spectrometry showed that these inhibitors decreased A beta by inhibiting BACE1. An assay for A beta 1-40 in mice was developed and used to show that these BACE1 inhibitors decreased plasma A beta 1-40, but not brain A beta 1-40, in wild-type mice. Because these BACE1 inhibitors were substrates for P-glycoprotein (P-gp), a member of the ATP-binding cassette superfamily of efflux transporters, these inhibitors were administered to P-gp knockout (KO) mice. These studies showed that all three BACE1 inhibitors decreased brain A beta 1-40 in P-gp KO mice, demonstrating that P-gp is a major limitation for development of BACE1 inhibitors to test the amyloid hypothesis. A comparison of plasma A beta 1-40 and brain A beta 1-40 dose responses for these three compounds revealed differences in relative ED(50) values, indicating that factors other than P-gp can also contribute to poor brain activity by BACE1 inhibitors.