PGC-1alpha and Pitx3 as individual and combined targets for neuroprotection

PGC-1alpha 和 Pitx3 作为神经保护的单独和组合靶标

• 批准号: 9256551
• 负责人: DAVID K. SIMON
• 金额: $ 38万
• 依托单位: BETH ISRAEL DEACONESS MEDICAL CENTER
• 依托单位国家: 美国
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-04-01 至 2019-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9256551
• 关键词: Animal Model; Antioxidants; Binding; Biogenesis; Brain-Derived Neurotrophic Factor; Cell Line; Cells; Data; Data Set; Development; Dopamine; Down-Regulation; Gene Expression; Gene therapy trial; Genetic; Genetic Transcription; Impairment; Individual; Injection of therapeutic agent; Lead; Link; Maintenance; Measures; Mediating; Mitochondria; Mus; Neurons; Oxidative Stress; Parkinson Disease; Pathogenesis; Pathogenicity; Patients; Phenotype; Play; Predisposition; Proteins; Role; Series; Substantia nigra structure; Testing; Therapeutic; Toxin; Transcription Coactivator; Transgenic Mice; Tyrosine 3-Monooxygenase; Up-Regulation; Viral; Viral Vector; adeno-associated viral vector; alpha synuclein; dopaminergic neuron; experimental study; gene therapy; in vivo; mitochondrial dysfunction; mouse model; neuroprotection; novel; overexpression; parkin gene/protein; prevent; promoter; public health relevance; synuclein; therapeutic evaluation; therapeutic target; transcription factor; vector

DESCRIPTION (provided by applicant): Mitochondrial dysfunction and oxidative stress play important roles in Parkinson's disease (PD). PGC-1alpha, a transcriptional coactivator, upregulates mitochondrial biogenesis and antioxidant defenses, and thus is an attractive target for neuroprotection in PD. Susceptibility to MPTP, a mitochondrial toxin, is increased in mice lacking PGC-1alpha, whereas overexpressing PGC-1alpha protects against an oxidative challenge in cell lines. Levels of expression of genes regulated by PGC-1alpha are low in substantia nigra (SN) neurons in early PD. Two important genetic causes of PD now have been linked to low PGC-1alpha. First, a recent study showed that loss of Parkin function leads to increased levels of novel protein called "PARIS" which transcriptionally inhibits expression of PGC-1alpha. And recently it was demonstrated that alpha-synuclein binds to the PGC-1alphha promoter and also suppresses its transcription. Together, these data strongly implicate a pathogenic role for low PGC-1alpha activity in PD, and raise the hope that correction of the PGC-1alpha deficit in PD will be neuroprotective. However, unexpectedly, we and others find that overexpressing PGC-1alpha at very high levels leads to reduced Bdnf and suppression of the dopaminergic phenotype. Our preliminary data suggest that this may result from suppression of Pitx3, a transcription factor that is critical for maintaining the dopaminergic phenotype and also for expression of Bdnf. Vulnerability to MPTP is increased by the very high levels of PGC-1alpha achieved using our AAV-PGC-1alpha vector. Thus, either low or very high levels of PGC-1alpha can be deleterious. Together, these data reveal that maintenance of PGC-1alpha activity levels within a "therapeutic" range is critical for the survival and function of dopaminergic neurons. We hypothesize that very high levels of PGC-1alpha lead to suppression of Pitx3, leading to loss of the dopaminergic phenotype and to enhanced vulnerability to MPTP due to loss of Bdnf. We further hypothesize that it will be possible to harness the neuroprotective potential of viral vector- mediated increases in PGC-1alpha activity while avoiding the potentially deleterious effects associated with very high levels of overexpression. We propose to test this by studying the impact in dopaminergic neurons on mitochondrial function, oxidative stress, the dopaminergic phenotype, and susceptibility to MPTP following more modest levels of upregulation of PGC-1alpha, or following co-expression of Pitx3 to prevent the deleterious effects of higher PGC-1alpha levels. The potential neuroprotective effects of Pitx3 on its own also will be studied. These experiments will test our hypothesis that suppression of Pitx3 mediates the PGC-1alpha-induced downregulation of Bdnf and of the dopaminergic phenotype. In addition, multiple gene therapy trials have been conducted in PD patients, and thus the proposed studies also will serve as initial tests of therapeutic strategies with translational potential.

描述（由申请人提供）：线粒体功能障碍和氧化应激在帕金森病（PD）中发挥重要作用。 PGC-1α 是一种转录共激活因子，可上调线粒体生物发生和抗氧化防御，因此是 PD 神经保护的一个有吸引力的靶点。缺乏 PGC-1α 的小鼠对 MPTP（一种线粒体毒素）的敏感性增加，而过度表达 PGC-1α 可以保护细胞系免受氧化挑战。在早期 PD 黑质 (SN) 神经元中，PGC-1α 调节的基因表达水平较低。目前，PD 的两个重要遗传原因已与 PGC-1α 水平降低有关。首先，最近的一项研究表明 Parkin 功能的丧失会导致称为“PARIS”的新型蛋白质水平增加，该蛋白质在转录上抑制 PGC-1α 的表达。最近证明，α-突触核蛋白与 PGC-1α 启动子结合并抑制其转录。总之，这些数据强烈暗示 PGC-1α 活性低在 PD 中的致病作用，并提出了纠正 PD 中 PGC-1α 缺陷将具有神经保护作用的希望。然而，出乎意料的是，我们和其他人发现，以非常高的水平过度表达 PGC-1α 会导致 Bdnf 减少和多巴胺能表型抑制。我们的初步数据表明，这可能是由于 Pitx3 的抑制所致，Pitx3 是一种转录因子，对于维持多巴胺能表型以及 Bdnf 的表达至关重要。使用我们的 AAV-PGC-1alpha 载体实现的极高水平的 PGC-1alpha 会增加 MPTP 的脆弱性。因此，PGC-1α 水平过低或过高都可能是有害的。总之，这些数据表明，将 PGC-1α 活性水平维持在“治疗”范围内对于多巴胺能神经元的生存和功能至关重要。我们假设非常高水平的 PGC-1alpha 会导致 Pitx3 的抑制，从而导致多巴胺能表型的丧失，并由于 Bdnf 的丧失而增强对 MPTP 的脆弱性。我们进一步假设，有可能利用病毒载体介导的 PGC-1α 活性增加的神经保护潜力，同时避免与非常高水平的过度表达相关的潜在有害影响。我们建议通过研究多巴胺能神经元对线粒体功能、氧化应激、多巴胺能表型和在PGC-1α上调水平更适度或在共表达Pitx3以防止有害影响后对MPTP的易感性的影响来测试这一点较高的 PGC-1α 水平。 Pitx3 本身的潜在神经保护作用也将被研究。这些实验将检验我们的假设，即抑制 Pitx3 介导 PGC-1α 诱导的 Bdnf 和多巴胺能表型的下调。此外，多项基因治疗试验已在PD患者中进行，因此拟议的研究也将作为具有转化潜力的治疗策略的初步测试。