Screening for LXR agonists-inhibitors of brain amyloidosis and inflammation

筛选 LXR 激动剂 - 脑淀粉样变性和炎症抑制剂

• 批准号: 7449780
• 负责人: ILIYA LEFTEROV
• 金额: $ 22.42万
• 依托单位: UNIVERSITY OF PITTSBURGH AT PITTSBURGH
• 依托单位国家: 美国
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-04-15 至 2010-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7449780
• 关键词: Academia; Accounting; Active Sites; Address; Affect; Agonist; Alzheimer' s Disease; Amyloid; Amyloid deposition; Amyloidosis; Apolipoprotein E; Astrocytes; Behavioral; Biological Assay; Biological Models; Brain; Cell Line; Cells; Chemicals; Cholesterol; Cholesterol Homeostasis; Classification; Clinical; Clinical Research; Clinical Trials; Complex; Data; Deposition; Development; Disease; Disease model; Drug Industry; Endopeptidases; Evaluation; Fatty Acids; Gene Expression; Generations; Genes; Genetic Transcription; Goals; Impaired cognition; In Vitro; Industry; Inflammation; Inflammatory; Knock-out; Laboratories; Lead; Ligands; Link; Lipoproteins; Liver; Mediating; Membrane; Messenger RNA; Metabolic Pathway; Microglia; Molecular; Mus; Nerve Degeneration; Neurons; Nuclear; Numbers; Outcome; Pathogenesis; Pathway interactions; Patients; Peptide Hydrolases; Pharmaceutical Preparations; Phospholipids; Physiological; Preclinical Drug Evaluation; Process; Production; Proteolytic Processing; Public Health; Reaction; Reporter; Screening procedure; Testing; Therapeutic; Transgenic Mice; Triglycerides; Up-Regulation; Vaccination; activating transcription factor; amyloid formation; base; cholesterol transporters; cytokine; design; disease phenotype; drug discovery; extracellular; in vivo; in vivo Model; inhibitor/antagonist; neuronal survival; novel therapeutics; prevent; receptor; response; secretase; small molecule; transcription factor

DESCRIPTION (provided by applicant): Despite the enormous efforts in academia and in pharmaceutical industry, Ab vaccination, y- and b-secretase inhibitors are still far from clinical use. Drugs that ameliorate AD phenotypes by interfering cholesterol metabolism have been also suggested, but the rationale for using those is poorly defined and in all of the cases the molecular mechanisms which account for their beneficial effects are poorly understood. Therefore there remains a great need for other strategies of lowering Ab. Nuclear Liver X receptors (LXRa and LXRb) are transcription factors that control the expression of genes involved in cholesterol metabolism. We have found that activated LXR regulate metabolic pathways of brain cholesterol intra- and extracellular transport that influence APP processing, b-amyloid deposition and its clearance from brain. Moreover, we and others have shown, that treatments of neuronal cell lines and primary neurons with natural or synthetic LXR ligands decrease Ab secretion, and that in vivo treatment of young AD model mice with a synthetic LXR ligand, increased the expression of LXR responsive genes in CNS and decreased soluble b-amyloid levels in their brains. We have also found that the application of LXR ligands inhibited secretion of inflammatory cytokines and increased neuronal survival following Ab or LPS treatment. The ultimate beneficial outcome of LXR ligand treatment on AD phenotype in vivo is a combination of effects mediated by genes expressed in neurons and astrocytes influencing Ab generation, b-amyloid formation and clearance, and by genes expressed in microglia which are tightly related to both - Ab clearance and inflammation. The data therefore substantiate the design of a drug discovery study for identification of LXR activators/agonists and their systematic evaluation in well established in vitro and in vivo model systems. In Specific aim 1, the activated status of LXR will be evaluated by their ability to increase dramatically the transcription of ABCA1 - a major LXR response gene. Thus, the increased amount of ABCA1 mRNA following in vitro application of a given compound (altogether >50,000 for screening) will serve as a reporter for LXR activation. Compounds that meet the criteria for LXR activation will be further screened for their ability to reduce Ab production in vitro. "Hits" with dual stimulatory effect on ABCA1 expression and apoE secretion, ability to reduce Ab and to facilitate cholesterol efflux will be further characterized in LXR knockout cell based assays. In addition, potent compounds will be characterized for their inhibitory effects on cytokine expression and regulatory effects on transcriptional activity of genes with undesired effects on fatty acids and triglyceride synthesis. In Specific Aim 2, the two most potent compounds will be chosen for initial in vivo tests in PS1APP transgenic mice. PUBLIC HEALTH RELEVANCE: Despite the enormous efforts in academia and in pharmaceutical industry, drugs based on the recent progress in our understanding for Alzheimer disease are still not available for clinical use. Brain cholesterol metabolism and its relation to different aspects of the disease pathogenesis substantiates the development of new therapeutic approaches based on complex regulatory networks controlled by transcription factors and their responsive genes. We are proposing a drug screening approach for identification of natural or synthetic compounds that activate transcription factors called Nuclear Liver X receptors (LXRa and LXRb) and therefore lead to upregulation and increased expression of genes involved in cholesterol metabolism. This drug discovery study is based on data generated in our and other laboratories which confirm that LXR controlled cholesterol transporters and lipoproteins in brain are involved in b-amyloid aggregation, deposition and clearance. Therefore, LXR activators can be used for lowering Ab inhibition of inflammation and improvement of behavioral deficits.

描述（由申请人提供）：尽管学术界和制药行业做出了巨大的努力，但Ab疫苗接种，y和b分泌酶抑制剂仍远未临床应用。通过干扰胆固醇代谢来改善阿尔茨海默病表型的药物也被提出，但使用这些药物的基本原理尚不明确，而且在所有情况下，解释其有益作用的分子机制尚不清楚。因此，仍然需要其他降低Ab的策略。核肝X受体（LXRa和LXRb）是控制胆固醇代谢相关基因表达的转录因子。我们发现激活的LXR调节脑内和细胞外胆固醇运输的代谢途径，影响APP加工、b-淀粉样蛋白沉积及其从脑内清除。此外，我们和其他人已经证明，用天然或合成LXR配体处理神经元细胞系和原代神经元会减少Ab的分泌，并且用合成LXR配体处理年轻AD模型小鼠，会增加中枢神经系统中LXR应答基因的表达，降低其大脑中可溶性b-淀粉样蛋白的水平。我们还发现LXR配体的应用抑制了Ab或LPS处理后炎症细胞因子的分泌，增加了神经元的存活率。LXR配体治疗AD体内表型的最终有益结果是神经元和星形胶质细胞中表达的影响Ab生成、b-淀粉样蛋白形成和清除的基因，以及小胶质细胞中表达的与- Ab清除和炎症密切相关的基因介导的作用的结合。因此，这些数据证实了一项药物发现研究的设计，该研究旨在鉴定LXR激活剂/激动剂，并在已建立的体外和体内模型系统中对其进行系统评估。在Specific aim 1中，LXR的激活状态将通过其显著增加ABCA1转录的能力来评估。ABCA1是LXR的一个主要应答基因。因此，在体外应用给定化合物（共筛选50万）后，ABCA1 mRNA的数量增加将作为LXR激活的报告基因。满足LXR激活标准的化合物将进一步筛选其体外减少Ab产生的能力。“命中”对ABCA1表达和apoE分泌具有双重刺激作用，降低Ab和促进胆固醇外排的能力将在基于LXR敲除细胞的实验中进一步表征。此外，有效的化合物将以其对细胞因子表达的抑制作用和对脂肪酸和甘油三酯合成有不良影响的基因的转录活性的调节作用为特征。在Specific Aim 2中，将选择两种最有效的化合物在PS1APP转基因小鼠中进行初始体内试验。公共卫生相关性：尽管学术界和制药行业做出了巨大的努力，但基于我们对阿尔茨海默病的理解的最新进展的药物仍然无法用于临床。脑胆固醇代谢及其与疾病发病机制不同方面的关系，证实了基于转录因子及其应答基因控制的复杂调控网络的新治疗方法的发展。我们正在提出一种药物筛选方法，用于鉴定天然或合成化合物，这些化合物可以激活称为核肝X受体（LXRa和LXRb）的转录因子，从而导致参与胆固醇代谢的基因表达上调和增加。这项药物发现研究是基于我们和其他实验室产生的数据，这些数据证实LXR控制的胆固醇转运蛋白和大脑中的脂蛋白参与了b-淀粉样蛋白的聚集、沉积和清除。因此，LXR激活剂可用于降低Ab对炎症的抑制和改善行为缺陷。