Mechanisms of BACE1 Up-regulation in Response to Energy Deprivation

BACE1 上调响应能量剥夺的机制

• 批准号: 7332611
• 负责人: TRACY L O'CONNOR
• 金额: $ 2.77万
• 依托单位: NORTHWESTERN UNIVERSITY AT CHICAGO
• 依托单位国家: 美国
• 财政年份: 2007
• 资助国家: 美国
• 起止时间: 2007-06-01 至 2009-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7332611
• 关键词: 5' Untranslated Regions; Acute; Alzheimer' s Disease; Amyloid; Biological Assay; Brain; Cells; Cellular Stress; Chronic; Cleaved cell; Complex; Condition; Cultured Cells; Data; Development; Drug Delivery Systems; Elevation; Enzymes; Glucose; Health Priorities; Human; In Vitro; Incubated; Knowledge; Luciferases; Mediating; Metabolic stress; Molecular; Mus; Neurons; Pathogenesis; Pathway interactions; Patients; Peptide Initiation Factors; Pharmaceutical Preparations; Phosphoric Monoester Hydrolases; Phosphorylation; Phosphotransferases; Physiologic pulse; Plasmids; Production; Prokaryotic Initiation Factor-2; Protein Overexpression; Proteins; Public Health; Pulse taking; Rate; Regulation; Reporter; Reporting; Role; Senile Plaques; Signal Pathway; Site; Source; Stress; Testing; Thapsigargin; Transcriptional Activation; Transgenes; Transgenic Mice; Translation Initiation; Translations; Up-Regulation; beta-site APP cleaving enzyme 1; biological adaptation to stress; cell type; deprivation; glucose metabolism; in vivo; novel; prevent; research study; response

DESCRIPTION (provided by applicant): Beta-site APR cleaving enzyme (BACE1) is the rate-limiting enzyme in the production of amyloid (3 (Ap), the primary constituent of senile plaques in the brains of Alzheimer's disease (AD) patients. Evidence that BACE1 is up-regulated post-transcriptionally in response to energy inhibition, studies indicating that glucose metabolism is reduced in AD brains, and the observation that BACE1 protein levels are increased in post- mortem AD brains all support the hypothesis that post-transcriptional up-regulation of BACE1 in response to energy deprivation in the brain may, in part, be responsible for AP accumulation in sporadic Alzheimer's disease (SAD)- the predominant form of AD. The aim of this study is to identify the specific post- transcriptional mechanism and signaling pathway(s) leading to BACE1 up-regulation in response to energy deprivation in vitro and in vivo. Preliminary studies in 293 cells indicate that BACE1 protein increases in response to energy deprivation are mediated by the BACE1 5'-untranslated region (UTR). First, we will determine whether a similar mechanism controls BACE1 protein levels in response to energy deprivation in cultured neurons. Then, luciferase reporter assays will be used to determine whether the BACE1 5'UTR is responsible for BACE1 protein increases under glucose-deficient conditions in both 293 cells and cultured neurons. Acute pharmacological induction of metabolic stress in a transgenic mouse line lacking the BACE1 5'UTR will be used to confirm this mechanism in vivo. Preliminary experiments indicate that phosphorylation of the alpha subunit of the eukaryotic translation initiation factor 2 (elF2alpha) may be mediating post-transcriptional increases in BACE1 protein under conditions of energy deprivation. We will use 293 cells and neurons deprived of glucose in vitro, as well as brains from mice subjected to acute and chronic energy deprivation to test for activation of kinases known to phosphorylate elF2alpha. We will then determine whether pharmacological induction of elF2alpha phosphorylation through treatment with thapsigargin leads to post-transcriptional increases in BACE1 protein in vitro. Finally, to establish this pathway as potential AD drug target, we will inhibit elF2alpha phosphorylation in vitro to determine whether BACE1 protein up-regulation can be blocked under glucose-deficient conditions. The predicted increase in AD occurrence and the current lack of effective treatment options have made the development of new and more effective drugs for AD treatment a public health priority. Completion of these aims will identify novel drug targets for the development of preventative AD therapies.

描述（由申请人提供）：β-位点APR裂解酶（BACE 1）是淀粉样蛋白β（Ap）产生的限速酶，淀粉样蛋白β（Ap）是阿尔茨海默病（AD）患者脑中老年斑的主要成分。BACE 1响应于能量抑制而转录后上调的证据、表明AD大脑中葡萄糖代谢减少的研究以及死后AD大脑中BACE 1蛋白水平增加的观察结果都支持这一假设：BACE 1响应于能量抑制而转录后上调大脑中的能量剥夺可能在一定程度上在散发性阿尔茨海默病（SAD）-AD的主要形式中，AP的积累是由其引起的。本研究的目的是鉴定导致BACE 1在体外和体内响应于能量剥夺而上调的特异性转录后机制和信号通路。在293细胞中的初步研究表明，BACE 1蛋白在响应能量剥夺时的增加是由BACE 1 5 '非翻译区（UTR）介导的。首先，我们将确定是否有类似的机制控制BACE 1蛋白水平，以响应培养神经元中的能量剥夺。然后，将使用荧光素酶报告基因测定来确定BACE 1 5 'UTR是否是293细胞和培养的神经元中葡萄糖缺乏条件下BACE 1蛋白增加的原因。在缺乏BACE 1 5 'UTR的转基因小鼠系中代谢应激的急性药理学诱导将用于在体内证实该机制。初步实验表明，磷酸化的α亚基的真核生物翻译起始因子2（eIF 2 α）可能是介导的转录后增加BACE 1蛋白的能量剥夺的条件下。我们将使用293个体外葡萄糖剥夺的细胞和神经元，以及急性和慢性能量剥夺小鼠的大脑来测试已知磷酸化eIF 2 α的激酶的激活。然后，我们将确定通过用毒胡萝卜素处理的eIF 2 α磷酸化的药理学诱导是否导致体外BACE 1蛋白的转录后增加。最后，为了将该途径确立为潜在的AD药物靶标，我们将在体外抑制eIF 2 α磷酸化以确定BACE 1蛋白上调是否可以在葡萄糖缺乏条件下被阻断。AD发生率的预测增加和目前缺乏有效的治疗选择，使得开发新的和更有效的AD治疗药物成为公共卫生的优先事项。这些目标的完成将为预防性AD疗法的开发确定新的药物靶点。