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: 7452303
• 负责人: TRACY L O'CONNOR
• 金额: $ 1.91万
• 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 2008-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7452303
• 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 (BACE1) 是淀粉样蛋白 (3 (Ap) 生成过程中的限速酶，淀粉样蛋白是阿尔茨海默病 (AD) 患者大脑中老年斑的主要成分。证据表明 BACE1 在转录后响应能量抑制而上调，研究表明葡萄糖代谢降低 AD 大脑中 BACE1 蛋白水平在 AD 死后大脑中增加的观察结果都支持这样的假设：大脑中能量剥夺导致的 BACE1 转录后上调可能在一定程度上导致了散发性阿尔茨海默病 (SAD)（AD 的主要形式）中 AP 的积累。本研究的目的是确定特定的转录后机制和信号传导 体内外能量剥夺导致 BACE1 上调的途径。对 293 细胞的初步研究表明，能量剥夺时 BACE1 蛋白的增加是由 BACE1 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 BACE1 蛋白水平以响应培养神经元中的能量剥夺。然后，荧光素酶 报告基因检测将用于确定 BACE1 5'UTR 是否导致 293 细胞和培养神经元中葡萄糖缺乏条件下 BACE1 蛋白增加。在缺乏 BACE1 5'UTR 的转基因小鼠系中对代谢应激的急性药理学诱导将用于在体内证实这一机制。初步实验表明，α亚基的磷酸化 真核翻译起始因子 2 (elF2alpha) 可能在能量剥夺条件下介导 BACE1 蛋白转录后增加。我们将使用体外缺乏葡萄糖的 293 细胞和神经元，以及遭受急性和慢性能量剥夺的小鼠的大脑来测试已知磷酸化 eF2α 的激酶的激活情况。然后我们将确定是否有药理作用 通过毒胡萝卜素处理诱导 eF2α 磷酸化会导致体外 BACE1 蛋白转录后增加。最后，为了将该通路确立为潜在的 AD 药物靶点，我们将在体外抑制 eF2α 磷酸化，以确定是否可以在葡萄糖缺乏的条件下阻断 BACE1 蛋白的上调。 AD 发病率的预测增加和目前缺乏有效的治疗方案 使开发新的、更有效的 AD 治疗药物成为公共卫生优先事项。完成这些目标将为开发预防性 AD 疗法确定新的药物靶点。