ALZHEIMERS ABETA, APOLIPOPROTEINS & BLOOD-BRAIN BARRIER

阿尔茨海默病 ABETA，载脂蛋白

• 批准号: 2735675
• 负责人: Berislav V Zlokovic
• 金额: $ 27.53万
• 依托单位: UNIVERSITY OF SOUTHERN CALIFORNIA
• 依托单位国家: 美国
• 财政年份: 1995
• 资助国家: 美国
• 起止时间: 1995-09-01 至 2000-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/2735675
• 关键词: Alzheimer's disease; Baculoviridae; aging; amyloid proteins; apolipoprotein E; blood brain barrier; guinea pigs; high density lipoproteins; high performance liquid chromatography; immunocytochemistry; intermolecular interaction; membrane transport proteins; protein isoforms; protein sequence; recombinant proteins; synthetic peptide; very low density lipoprotein; western blottings

Amyloid beta (Abeta) is a fibrillar component of amyloid in senile plaques and cerebral blood vessels in Alzheimer's Disease (AD), and a soluble peptide (sAbeta) normally present in body fluids. The origin of Abeta deposited in brain and blood vessels in AD is uncertain, and whether or not sAbeta is the direct precursor of amyloid it is not known. The current concept states that a key question in amyloidogenesis is to determine what factors are responsible for the conformational alteration of sAbeta into its fibrillar form. The unifying hypothesis of this proposal is that the blood-brain barrier (BBB) may play an important role in cerebrovascular and brain amyloidogenesis by regulating transport of sAbeta and two amyloid-associated proteins shown to bind sAbeta, apolipoproteins E (apo E) and J (apo J). In support of this hypothesis we have recently provided the evidence that a synthetic peptide homologous to major form of circulating sAbeta, sAbeta(1-40), is taken up into the brain via specific mechanism, and possibly as an sAbeta-apo J complex. In contrast, blood- brain transport of sAbeta-apo E was negligible. Cerebrovascular permeability to apo J was significant, while apo E had a limited access across the BBB, indicating that the apo E found within the brain is produced locally. Our pilot in vitro experiments demonstrated that sAbeta(1-40) binds to apo J with the affinity that is about 10 times higher than for apo E. Studies conducted in vivo indicated that sAbeta(1- 40) binding to apo J and apo E results in remarkable 114-fold difference in barrier permeability to their respective complexes. In the present proposal, we plan to characterize the mechanisms of sAbeta transport at the BBB in greater detail. Specific hypotheses to be tested are: 1. Binding of sAbeta to apo J and apo E isoforms 2, 3 and 4 modulates cerebrovascular permeability to sAbeta; 2. sAbeta peptides are transported across the BBB by a specific transporter and/or receptor; 3. Transport of sAbeta complexed to apo J and apo E isoforms incorporated into high and very low density lipoprotein particles, i.e., HDL and VLDL, may be mediated by HDL and/or low density lipoprotein (LDL) BBB receptors; 4. Aging alters transport mechanisms at the BBB predisposing to accumulation of sAbeta and amyloid-associated proteins in cerebral microvessels and brain parenchyma. The guinea-pig with the Abeta sequence identical to humans will be used. The affinity of sAbeta binding to apolipoproteins will be determined in vitro. Transport studies will be performed in the in situ vascular perfused brain, in conjunction with the capillary depletion technique, radio-HPLC end immunocytochemical analysis. The putative sAbeta transporter and/or receptor will be isolated from BBB plasma membranes. Proposed studies should help us understand transport mechanisms of sAbeta at the BBB, with an ultimate goal to develop strategies that may reduce accumulation of sAbeta and amyloid-associated proteins in brain and cerebral microvessels, thereby decelerating and/or preventing conformational transformation of sAbeta and its potential cytotoxic effects.

淀粉样β（ABETA）是老年斑块中淀粉样蛋白的原纤维成分 和阿尔茨海默氏病（AD）中的脑血管和可溶性 通常存在于体液中的肽（sabeta）。 Abeta的起源 沉积在AD中的大脑和血管中是不确定的，是否或是否 不是sabeta是淀粉样蛋白的直接前体，而不是知道。电流 概念指出，淀粉样生成的关键问题是确定什么 因素是导致sabeta构象变化的因素 它的纤维形式。该提议的统一假设是 血脑屏障（BBB）可能在脑血管中起重要作用 通过调节sabeta和两个的运输来调节大脑淀粉样蛋白发生 与淀粉样蛋白相关的蛋白质结合了sabeta，载脂蛋白E（Apo e）和J（apo j）。为了支持这一假设，我们最近提供了 与主要形式的合成肽同源的证据 循环的sabeta，sabeta（1-40）通过特定的 机理，可能是Sabeta-apo J复合物。相反，血液 - Sabeta-Apo E的脑运输可以忽略不计。脑血管 对Apo J的渗透性很重要，而Apo e的访问有限 跨过BBB，表明大脑中发现的apo e是 本地生产。我们的体外实验飞行员表明 Sabeta（1-40）与Apo J结合，亲和力约为10次 在体内进行的研究高于Apo E.表明sabeta（1- 40）与apo j和apo e结合导致明显的114倍差 以屏障对各自的复合物的渗透性。现在 提案，我们计划表征Sabeta运输机制 BBB更详细。要测试的特定假设为：1。 Sabeta与Apo J和Apo E同工型2、3和4调节结合 脑血管对Sabeta的渗透性； 2。sabeta肽被运输 特定转运蛋白和/或受体跨越BBB； 3。运输 Sabeta与Apo J和Apo e同工型复合到高中，并 非常低密度的脂蛋白颗粒，即HDL和VLDL，可能是 由HDL和/或低密度脂蛋白（LDL）BBB受体介导； 4。 老化改变了BBB处的运输机制，易于积累 脑微血管中的Sabeta和淀粉样蛋白相关蛋白 脑实质。带有Abeta序列的豚鼠与 人类将被使用。 Sabeta与载脂蛋白结合的亲和力 将在体外确定。运输研究将在IN中进行 毛细管耗竭 技术，无线电HPLC终端免疫细胞化学分析。推定的sabeta 转运蛋白和/或受体将从BBB质膜中分离出来。 拟议的研究应有助于我们了解Sabeta的运输机制 在BBB，其最终目标是制定可能减少的策略 大脑中Sabeta和淀粉样蛋白相关蛋白的积累 脑微血管，从而减速和/或阻止 Sabeta及其潜在细胞毒性的构象转化 效果。