Validating a Novel Lipid Phosphatase Target in Alzheimer's Disease

验证阿尔茨海默氏病的新型脂质磷酸酶靶点

• 批准号: 8212249
• 负责人: TAE-WAN KIM
• 金额: $ 35万
• 依托单位: COLUMBIA UNIVERSITY HEALTH SCIENCES
• 依托单位国家: 美国
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-01-15 至 2015-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8212249
• 关键词: AMPA Receptors; Address; Aftercare; Alzheimer' s Disease; Amyloid; Amyloid beta-Protein Precursor; Amyloid deposition; Animal Model; Behavioral; Biochemical; Biological Models; Brain; Cell surface; Cognition Disorders; Crossbreeding; Cyclic AMP-Responsive DNA-Binding Protein; Data; Development; Disease; Disease Progression; Elements; Enzymes; Functional disorder; Future; Genes; Genetic; Genotype; Goals; Hippocampus (Brain); Impaired cognition; Impairment; In Vitro; Knockout Mice; Lead; Learning; Link; Lipids; Long-Term Potentiation; Mediator of activation protein; Memory; Memory impairment; Metabolism; Molecular; Mus; Neuronal Dysfunction; Neurons; Neurophysiology - biologic function; Pathogenesis; Pathway interactions; Patients; Peptides; Phosphatidylinositols; Phospholipids; Phosphoric Monoester Hydrolases; Phosphorylation; Phosphorylation Site; Play; Predisposition; Property; Protein Binding Domain; Proteins; Publishing; Radial; Resistance; Role; Series; Short-Term Memory; Signal Pathway; Signal Transduction; Slice; Solid; Staging; Synapses; Synaptic plasticity; System; Testing; Tg2576; Therapeutic; Therapeutic Agents; Transgenic Mice; Water; Work; arm; base; behavior test; conditioned fear; in vivo; inhibitor/antagonist; mouse model; mutant; novel; overexpression; public health relevance; pup; reconstitution; research study; small molecule; synaptojanin; therapeutic target; transcription factor

DESCRIPTION (provided by applicant): The amyloid ¿-peptide (A¿), which originates from the proteolytic cleavage of amyloid precursor protein (APP), plays a central role in the pathogenesis of Alzheimer's disease (AD). Mounting evidence indicates that different species of A¿, such as A¿ oligomers and fibrils, may contribute to AD pathogenesis via distinct mechanisms at different stages of the disease. Importantly, elevated levels of A¿ oligomers closely correlate with cognitive decline and disease progression in animal models of AD. At the cellular level, A¿ disrupts synaptic plasticity, including the impairment of long-term potentiation (LTP), an electrophysiological correlate of learning and memory in the mammalian hippocampus. Our recently published work demonstrated that A¿ oligomers caused a decrease in the levels of phosphatidylinositol 4,5-bisphosphate [PI(4,5)P2], a phospholipid that regulates key aspects of neural function. The destabilizing effect of A¿ on PI(4,5)P2 metabolism was not observed in neurons derived from mice containing higher brain levels of PI(4,5)P2 levels owing to the hemizygous deletion of synaptojanin 1 (Synj1 +/-). Synj1 is the main PI(4,5)P2 phosphatase [PI(4,5)P2 degrading enzyme] in the brain and synapses. Furthermore, the well characterized inhibitory effect of A¿ on LTP was strongly suppressed in brain slices from the Synj1 +/- mice. Furthermore, our preliminary results showed that A¿-induced suppression of phosphorylation of cAMP response element-binding protein (CREB), a critical transcription factor associated with synaptic plasticity and memory, was absent in primary neurons derived from Synj1+/- mice. Thus, based on these results, we hypothesize that inhibition of Synj1 may ameliorate A¿-induced synaptic dysfunction and memory impairment in AD. To this end, the main goals of this proposal are to employ biochemical and mouse genetic approaches to investigate the role of Synj1 in A¿-induced disruption of neuronal signaling and further validate Synj1 as a therapeutic target using cultured neurons and in vivo mouse models of AD. Specifically, we will investigate the role of Synj1 in A¿2-induced alterations in neuronal signaling, and will also determine if hemizygous deletion of Synj1 can ameliorate learning and memory impairments in an animal model of AD. Thus, our study will establish Synj1 as a validated target based on a molecular and system level target characterization study. Successful completion of this work will establish a solid rationale for the development of small molecule inhibitors that could selectively target Synj1, as potential therapeutic agents in AD. PUBLIC HEALTH RELEVANCE: Alzheimer's disease is characterized clinically by memory impairment and pathologically by the deposition of amyloid-2 peptide (A2) in the brains of AD patients. Evidence is accumulating which supports the hypothesis that A2 may be a factor in early neuronal dysfunction associated with AD. Specifically, levels of A2 correlate with disease progression in animal models of AD. In the brain, A2 interferes with normal neuronal function by mechanisms that are not yet fully understood. We have recently published data indicating that a specific lipid, phosphatidylinositol 4,5-bisphosphate [PI(4,5)P2], which regulates key aspects of neural function, is altered after treatment of neurons with A2. Additionally, mice with low levels of a specific lipid phosphatase, synaptojanin 1 (Synj1), responsible for metabolizing PI(4,5)P2, are resistant to A2-induced neuronal dysfunction. We propose to further investigate the role Synj1 in A2-induced neuronal dysfunction by using mutants of Synj1 to probe its function in neurons lacking endogenous Synj1. Additionally, we propose to cross a mouse model of AD with mice lacking one copy of Synj1. Since this genotype was protective in vitro, we expect these mice to have ameliorated AD-associated behavioral deficits in learning and memory tasks. Completion of these studies will determine if Synj1 can be a valid target for future AD therapeutic strategies.

描述（由申请人提供）：淀粉样蛋白 ¿ β-肽 (A¿) 源自淀粉样前体蛋白 (APP) 的蛋白水解裂解，在阿尔茨海默病 (AD) 的发病机制中发挥着核心作用。越来越多的证据表明，不同种类的 A¿ ，如 A¿低聚物和原纤维可能通过疾病不同阶段的不同机制促进 AD 发病，重要的是，A¿ 水平升高。在细胞水平上，寡聚物与 AD 动物模型中的认知能力下降和疾病进展密切相关。破坏突触可塑性，包括损害长时程增强（LTP），这是哺乳动物海马学习和记忆的电生理相关性。寡聚物导致磷脂酰肌醇 4,5-二磷酸 [PI(4,5)P2] 水平下降，磷脂是调节神经功能关键方面的磷脂。由于 synaptojanin 1 的半合子缺失（Synj1 +/-），在来自含有较高 PI(4,5)P2 水平的小鼠的神经元中未观察到对 PI(4,5)P2 代谢的影响。大脑和突触中的 (4,5)P2 磷酸酶 [PI(4,5)P2 降解酶] 此外，A¿ 的抑制作用已得到充分表征。 Synj1 +/- 小鼠的脑切片中 LTP 受到强烈抑制。此外，我们的初步结果表明 A¿诱导的 cAMP 反应元件结合蛋白 (CREB) 磷酸化抑制是与突触可塑性和记忆相关的关键转录因子，在来自 Synj1+/- 小鼠的原代神经元中不存在。因此，基于这些结果，我们捕获了这种抑制。 Synj1 可能会改善 A¿为此，本提案的主要目标是采用生化和小鼠遗传学方法来研究 Synj1 在 A¿ -诱导神经元信号破坏，并使用培养的神经元和 AD 体内小鼠模型进一步验证 Synj1 作为治疗靶标。具体来说，我们将研究 Synj1 在 A¿ 2 诱导的神经元信号改变，并且还将确定 Synj1 的半合子缺失是否可以改善 AD 动物模型中的学习和记忆障碍。因此，我们的研究将基于分子和系统水平的靶标表征将 Synj1 确立为经过验证的靶标。这项工作的成功完成将为开发可选择性靶向 Synj1 作为 AD 潜在治疗药物的小分子抑制剂奠定坚实的基础。 公共健康相关性：阿尔茨海默病的临床特征是记忆障碍，病理学特征是淀粉样蛋白 2 肽 (A2) 在 AD 患者大脑中的沉积，越来越多的证据支持 A2 可能是早期神经元功能障碍相关因素的假设。具体而言，A2 水平与 AD 动物模型中的疾病进展相关。在大脑中，A2 通过尚未完全了解的机制干扰正常神经功能。表明调节神经功能关键方面的特定脂质磷脂酰肌醇 4,5-二磷酸 [PI(4,5)P2] 在用 A2 处理神经元后发生改变。此外，特定脂质磷酸酶水平较低的小鼠。 , synaptojanin 1 (Synj1) 负责代谢 PI(4,5)P2，对 A2 诱导的神经元功能障碍具有抵抗力。 Synj1 在 A2 诱导的神经元功能障碍中的作用，通过使用 Synj1 突变体来探测其在缺乏内源性 Synj1 的神经元中的功能。此外，我们建议将 AD 小鼠模型与缺乏 Synj1 副本的小鼠进行交叉，因为该基因型在体外具有保护性。我们期望这些小鼠能够改善 AD 相关的学习和记忆任务行为缺陷，这些研究的完成将确定 Synj1 是否可以成为未来 AD 治疗策略的有效靶点。