Role of BACE stabilization in Alzheimer's disease

BACE 稳定化在阿尔茨海默病中的作用

• 批准号: 8253822
• 负责人: GIUSEPPINA TESCO
• 金额: $ 35.48万
• 依托单位: TUFTS UNIVERSITY BOSTON
• 依托单位国家: 美国
• 财政年份: 2007
• 资助国家: 美国
• 起止时间: 2007-02-01 至 2016-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8253822
• 关键词: Address; Affect; Alzheimer' s Disease; American; Amyloid beta-Protein Precursor; Aspartic Endopeptidases; BACE stabilization; Binding; Binding Proteins; Brain; C-terminal; Cerebrum; Chimera organism; Cleaved cell; Data; Dementia; Drug Delivery Systems; Ear; Endocytosis; Engineering; Enzymes; Event; Goals; Golgi Apparatus; Hippocampus (Brain); Human; Impairment; In Vitro; Inherited; Knockout Mice; Leucine; Link; Lysine; Lysosomes; Mediating; Membrane; Mono-S; Mouse Cell Line; Mus; Neurons; Pathology; Pathway interactions; Peptides; Production; Protein Family; Proteins; Proteolysis; Proteomics; RNA Interference; Regulation; Role; Sampling; Signal Transduction; Site; Sorting - Cell Movement; Ubiquitin; Ubiquitination; Viral; autosomal dominant trait; beta-site APP cleaving enzyme 1; familial Alzheimer disease; human subject; in vivo; inhibitor/antagonist; knock-down; member; mouse model; mutant; novel; prevent; secretase; small molecule; trafficking

DESCRIPTION (provided by applicant): Alzheimer's Disease (AD) is the most common form of dementia that affects 5.3 million Americans. In a small percentage (>1%) of cases AD is inherited as an autosomal dominant trait (Familial AD), however the majority of cases are sporadic. A key neuropathological event in AD is the cerebral accumulation of A¿, a ~4kDa peptide derived by serial proteolysis of the amyloid precursor protein (APP) by ¿- and ?-secretase. Beta-site APP-cleaving enzyme (BACE1) is a membrane-tethered member of the aspartyl proteases that has been identified as ¿-secretase. Several studies have shown that BACE1 protein levels and ¿-secretase activity are increased in AD brains. Thus, BACE1 elevation may be the first step in increasing A¿ and triggering AD pathology, at least in the sporadic cases. Our studies have elucidated a novel post-translational mechanism of regulation of BACE1 mediated by the BACE1-interacting molecule, GGA3 (Golgi-localized ?-ear-containing ARF binding protein 3). We have determined that GGA3 depletion stabilizes BACE1 and increases ¿-secretase activity. We also found that levels of GGA3 are decreased in post-mortem AD brains and are inversely correlated with BACE1 levels. We have shown that BACE1 is degraded via the lysosomal pathway and demonstrated that GGA3 regulates the delivery of BACE1 to the lysosomes. The BACE1-C-terminal fragment (CTF) contains a specific di-leucine (DXXLL) sorting signal that has been shown to bind the VHS domain of the three members of the GGA family of proteins, GGA1, 2, and 3. We have found that, unexpectedly, direct binding of GGA3 VHS domain to the BACE1 di-leucine motif is not necessary for this regulation. Instead, GGA3 interaction with ubiquitin is essential for regulating BACE1 levels. Accordingly, we have found that BACE1 is mainly mono- and K63-linked polyubiquitinated at lysine 501. The central hypothesis of this proposal is that the impairment of BACE1 degradation is the underlying mechanism of BACE1 elevation in the brains of subjects affected by AD. The overarching goal of this proposal is to determine the extent to which GGA- and ubiquitin-mediated regulation of BACE1 represent a potential target for the treatment of AD. Thus, we propose to specifically address the following aims: 1) To determine the extent to which BACE1 ubiquitination regulates BACE1 trafficking, activity and degradation via the proteasomal or lysosomal pathway; 2) To determine the extent to which over-expression of GGA3 reduces levels of BACE1 and A2 in a ubiquitin-dependent fashion in vivo; 3) To determine the extent to which GGA1, another member of the GGA family of proteins, regulates levels of BACE1 and A¿ independently and in association with GGA3 in vitro and in vivo. PUBLIC HEALTH RELEVANCE: BACE1 is a primary drug target for AD therapy. However, after a decade since the discovery of ¿-secretase the identification of effective BACE1 inhibitors that are active in the CNS has been very difficult. An alternative approach to BACE1 small-molecule inhibitors is the indirect inhibition of BACE1 through the modulation of regulatory mechanisms that control BACE1 levels or BACE1 trafficking to acidic compartments where it is mostly active. Our studies have elucidated a novel post-translational mechanism of regulation of BACE1 mediated by GGA3 and ubiquitin. Our studies are expected to determine the extent to which impaired degradation of BACE1 is the underlying mechanism of BACE1 elevation in AD and to determine the extent to which GGA- and ubiquitin-mediated regulation of BACE1 is a potential target for the treatment of AD.

描述（由适用提供）：阿尔茨海默氏病（AD）是影响530万美国人的最常见痴呆形式。在一小部分（> 1％）的病例中，AD遗传为常染色体显性特征（家族性AD），但是大多数病例是零星的。 AD中的一个关键神经病理事件是a a的脑积累，〜4kDa剥离，通过淀粉样蛋白前体蛋白（APP）的串行蛋白水解衍生而来。 β位点应用裂解酶（BACE1）是已鉴定为`` - 分泌酶的膜束缚成员）。几项研究表明，AD大脑中的BACE1蛋白水平和 - 分泌酶活性有所增加。这至少在零星的情况下，BACE1升高可能是增加A和触发AD病理学的第一步。我们的研究阐明了由BACE1相互作用分子GGA3（GLAGI-localized？ - 含含ARF的ARF ARF结合蛋白3）介导的新型BACE1调节后的调节机理。我们已经确定GGA3耗尽可以稳定BACE1并增加 - 分泌酶活性。我们还发现，验尸后的大脑中的GGA3水平降低，并且与BACE1水平成反比。我们已经表明，BACE1通过溶酶体途径降解，并证明GGA3调节BACE1向溶酶体的递送。 The BACE1-C-terminal fragment (CTF) contains a specific di-leucine (DXXLL) sorting signal that has been shown to bind the VHS domain of the three members of the GGA family of proteins, GGA1, 2, and 3. We have found that, unexpectedly, direct binding of GGA3 VHS domain to the BACE1 di-leucine motif is not necessary for this regulation.相反，GGA3与泛素的相互作用对于控制BACE1水平至关重要。据此，我们发现BACE1主要是赖氨酸501的单一和K63连接的多泛素化。该提议的中心假设是BACE1降解的损害是受AD受试者大脑中Bace1升高的基本机制。该提案的总体目标是确定GGA和泛素介导的BACE1调节的程度，代表了AD治疗的潜在目标。这是我们建议专门解决以下目的：1）确定通过蛋白酶体或溶酶体途径调节BACE1泛素化调节BACE1运输，活性和降解的程度； 2）确定GGA3过度表达的程度在体内以泛素依赖性方式降低BACE1和A2的水平； 3）为了确定GGA1，GGA蛋白质家族的另一个成员，独立地调节BACE1和A的水平，并与GGA3在体外和体内相关。 公共卫生相关性：BACE1是广告疗法的主要药物目标。但是，自从发现 - 分泌酶以来十年后，在中枢神经系统中活跃的有效BACE1抑制剂的鉴定一直非常困难。 BACE1小分子抑制剂的另一种方法是通过调节控制BACE1水平或BACE1运输到其主要是活性的酸性隔室的调节机制的间接抑制。我们的研究阐明了GGA3和泛素介导的BACE1调节的新型翻译后机制。我们的研究有望确定BACE1降解的程度是AD中BACE1升高的潜在机制，并确定GGA和泛素介导的BACE1调节的程度是AD治疗的潜在靶标。