GD3S knockdown to improve cognitive and motor deficits in models of parkinsonism

描述(申请人提供)：帕金森病的特征是运动和认知障碍，以及大脑中称为黑质致密部(SNC)的部分细胞死亡。帕金森氏症患者的大脑中也有1-突触核蛋白的聚集，这可能对脑细胞有毒性。我们的长期目标是更好地了解帕金森氏症的早期生物学事件，以及它们与疾病的认知和运动症状之间的关系。这一特殊应用的目的是初步了解神经节苷脂在与帕金森氏病相关的认知障碍和神经病理中所起的作用。神经节苷脂是一种脂类，存在于体内的每一个组织中。它们在大脑中特别丰富，但在帕金森氏症中它们的大脑分布是异常的。拟议研究的总体假设是，部分减少更复杂的神经节苷脂可以防止细胞死亡，减少1-突触核蛋白聚集，并缓解三种不同特征的帕金森病小鼠的认知和运动障碍。由于帕金森氏症患者表现出的认知障碍类型还没有在小鼠身上进行研究，因此小鼠将首先接受复杂的行为任务的训练，以测量“执行”功能。执行功能是参与高级认知过程所必需的基本认知过程，如注意力、向外转移、冲动控制和短期工作记忆。这些模型包括注射神经毒素MPTP的小鼠，表达突变1-突触核蛋白的转基因小鼠，以及缺乏PARK2的基因敲除小鼠。一旦建立了基线行为和运动能力，小鼠将接受靶向GD3合成酶(GD3S)的小干扰RNA(SiRNA)或干扰对照的注射。GD3S负责合成四种主要脑神经节苷脂中的两种，在阿尔茨海默病小鼠模型中消除这种酶可以恢复良好的认知功能，阻止细胞死亡和氧化应激，并几乎消除淀粉样斑块的形成。GD3S-siRNA将由重组腺相关病毒载体(RAAV)繁殖，并注射到大脑背侧第三脑室以促进弥散。手术后，将进行额外的运动和行为测试，随后对大脑进行神经化学和免疫组织化学处理。在小鼠模型中成功减少1-突触核蛋白聚集、细胞死亡和认知障碍可能为帕金森氏病的新治疗策略提供洞察-治疗可以恢复功能或减缓帕金森氏症患者的疾病进程。公共卫生相关性：目前帕金森氏症的治疗方法侧重于用多巴胺替代来改善运动功能，但对改善帕金森氏症患者常见的认知障碍毫无帮助。本文提出的研究是一种新的治疗方法--抑制GD3合酶。GD3S抑制的作用是减少1-突触核蛋白等蛋白质的聚集，减少氧化应激，防止神经退行性变，改善运动和认知功能。

DESCRIPTION (provided by applicant): Parkinson's disease is characterized by motor and cognitive impairments and cell death in a part of the brain called the substantia nigra pars compacta (SNc). Parkinson's patients also get aggregations of 1-synuclein in the brain, which may be toxic to brain cells. Our long-term goal is to understand better the early biological events in Parkinson's disease and how they relate to the cognitive and motor symptoms of the disease. The objective of this particular application is to get a preliminary understanding of the role that gangliosides play in the cognitive impairments and neuropathology associated with Parkinson's disease. Gangliosides are lipids expressed in every tissue in the body. They are particularly abundant in the brain, but their brain distribution is abnormal in Parkinson's disease. The general hypothesis of the proposed research is that a partial reduction of the more complex gangliosides may prevent cell death, reduce 1-synuclein aggregation, and alleviate cognitive and motor deficits in three mouse lines that model various characteristics of Parkinson's disease. Because the types of cognitive impairments exhibited by Parkinson's patients have not been investigated in mice, mice will first be trained on complex behavioral tasks designed to measure "executive" functions. Executive functions are basic cognitive processes that are necessary for engaging in higher-order cognitive processes, such as attention, extradimensional shift, impulse control, and short-term working memory. The models include mice injected with the neurotoxin MPTP, a transgenic expressing mutant 1- synuclein, and a knockout mouse lacking PARK2. Once baseline behavioral and motor performance is established, mice will receive an injection of a small-interfering RNA (siRNA) construct targeting GD3 synthase (GD3S), or a scrambled control. GD3S is responsible for synthesis of two of the four major brain gangliosides, and elimination of this enzyme in a mouse model of Alzheimer's disease restores good cognitive function, blocks cell death and oxidative stress, and nearly eliminates amyloid plaque formation. The GD3S-siRNA construct will be propagated by a recombinant adeno-associated viral vector (rAAV), and injected into the dorsal third ventricle of the brain to promote dispersion. Following the surgery, additional motor and behavioral tests will be conducted, followed by processing of the brains for neurochemistry and immunohistochemistry. Successfully reducing 1-synuclein aggregation, cell death, and cognitive impairments in the mouse models may provide insight into new treatment strategies for Parkinson's disease-treatments that could restore function or slow the disease process Parkinson's patients. PUBLIC HEALTH RELEVANCE: Current treatments for Parkinson's disease focus on dopamine replacement to improve motor function, but do nothing to improve the cognitive impairments common among Parkinson's patients. The research proposed herein is a novel treatment approach-inhibition of GD3 synthase. The effects of GD3S inhibition are to reduce aggregates of proteins such as 1-synuclein, reduce oxidative stress, prevent neurodegeneration, and improve motor and cognitive function.