The cause and effect of reduced ò-glucocerebrosidase activity in the setting of progranulin deficiency

项目总结 拟议研究项目的目标是进一步了解原颗粒(Grn)和β是如何- 葡萄糖脑苷酶(GCase)的相互作用及其对额颞叶痴呆(FTD)的意义 是由原颗粒突变引起的。额颞叶痴呆症是早发性痴呆症的主要原因， 功能缺失前颗粒蛋白突变是三种主要遗传原因之一。原颗粒是一种分泌的溶酶体- 常驻糖蛋白，缺乏会导致患者和小鼠的溶酶体功能障碍。原颗粒增强作用 治疗FTD-GRN的方法很有希望，但交付是一个问题，安全性尚不清楚。这 强调了继续寻找具有已知安全性的靶向治疗药物的迫切需要。因此，一个 靶向治疗减少原颗粒缺乏引起的溶酶体功能障碍可能有治疗作用 预防或延迟FTD-GRN的好处。 为了了解原颗粒缺乏引起的潜在溶酶体功能障碍，我们的实验室 对FTD-GRN患者脑内几种溶酶体酶的活性和原颗粒蛋白进行了研究。 有缺陷的小鼠。我们发现神经元GCase的活性降低，这是一种溶酶体酶，而其他溶酶体 酶表现出更高的活性。GCase是一个有趣的目标，因为它参与了 神经退行性疾病，因为GCase突变是帕金森病和 高谢病的单基因病因，这是一种具有神经退行性亚型的溶酶体储存疾病。 FTD-GRN的GCase缺乏似乎是由于糖基化障碍导致GCase聚集。 这项建议将确定原颗粒缺乏是否会损害GCase的运输，从而导致溶酶体减少 本地化。最重要的假设是，受损的原颗粒介导的GCasase交易 导致溶酶体功能障碍和其他由原颗粒缺乏引起的缺陷。这项建议 将测试以下两个目标：(1)确定原颗粒如何调节GCase的贩运和(2)确定 如果GCase缺陷导致溶酶体功能障碍和其他由原颗粒缺乏引起的缺陷。更多 需要开展工作来了解原颗粒蛋白-GCase相互作用的细节和影响。我会先确定 负责GCase相互作用的原颗粒蛋白结构域，然后将测试这种相互作用对 GCase稳定性和溶酶体转运。然后，我将确定增加GCase是否足以减少 前颗粒蛋白缺陷小鼠的溶酶体功能障碍和行为异常。 这项建议将通过帮助我：1)提高能力，促进我的科学和专业发展 在严格的实验设计和假设检验中，2)改进已知的实验技术并开发 翻译研究的技能，以及3)获得向科学和非科学受众展示数据的经验。

PROJECT SUMMARY The objective of the proposed research project is to further understand how progranulin (GRN) and β- glucocerebrosidase (GCase) interact and the implications of these interactions in frontotemporal dementia (FTD) caused by progranulin mutations. Frontotemporal dementia is a leading cause of early-onset dementia, and loss- of-function progranulin mutations are one of three main genetic causes. Progranulin is a secreted and lysosome- resident glycoprotein, and deficiency causes lysosomal dysfunction in patients and in mice. Progranulin-boosting therapies have promise for treating FTD-GRN, but delivery is an issue and the safety profile is unclear. This underscores a critical need to continue to search for targeted therapeutics with known safety profiles. Thus, a targeted therapy that reduces progranulin deficiency-induced lysosomal dysfunction may have therapeutic benefits for preventing or delaying FTD-GRN. In order to understand the underlying lysosomal dysfunction caused by progranulin deficiency, our lab has characterized the activities of several lysosomal enzymes in the brains of FTD-GRN patients and progranulin- deficient mice. We found decreased activity of neuronal GCase, a lysosomal enzyme, whereas other lysosomal enzymes show increased activity. GCase is an interesting target because of its known involvement in neurodegenerative disease, as GCase mutations are the leading genetic risk factor for Parkinson disease and the monogenic cause of Gaucher disease, a lysosomal storage disease with neurodegenerative subtypes. GCase deficiency in FTD-GRN appears to be due to an impairment in glycosylation causing GCase aggregation. This proposal will determine if progranulin deficiency impairs GCase trafficking, resulting in decreased lysosomal localization. The overarching hypothesis is that impaired progranulin-mediated GCase trafficking contributes to lysosomal dysfunction and other deficits caused by progranulin deficiency. This proposal will test the following two aims: (1) Determine how progranulin regulates trafficking of GCase and (2) Determine if GCase deficits contribute to lysosomal dysfunction and other deficits caused by progranulin deficiency. More work is needed to understand the specifics and effects of the progranulin-GCase interaction. I will first determine the domain of progranulin responsible for GCase interaction and will then test the effects of this interaction on GCase stability and lysosomal trafficking. I will then determine if increasing GCase is sufficient to reduce lysosomal dysfunction and behavioral abnormalities in progranulin-deficient mice. This proposal will facilitate my scientific and professional development by helping me: 1) improve competency in rigorous experimental design and hypothesis testing, 2) refine known experimental techniques and develop skills for translational research, and 3) gain experience presenting data to both scientific and lay audiences.