神经型戈谢氏病发病机制及诱导性干细胞治疗策略探讨

Gaucher's disease (GD) is a common autosomal recessive disorder, which caused by a functional deficiency of β-glucocerebrosidase and lead to multiple types of organ injury beacause of accumulation of glucocerebroside in lysosome. GD can be classified into three clinical types, type II and type III belong to neuropathic types which are the main fatal types and their etiological mechanisms remain elusive so far.Although the enzyme replacement therapy can be used in the treatment of GD, it has no therapeutic effect on the brain damage and the cost is too high. The emergence of induced stem cells (iPSCs) and induced neural precursor cells (iNPCs) brought the dawn for the treatment of GD ,while the curative efficacy and tumorigenicity are still unclear.In our lab, we have established iPSCs, iNPCs and conditional gene-knockout neuronopathic mouse model of Gaucher's disease. Based on our previous work, we will carry out further research in the following aspects：1.epigentic mechanisms of abnormal gene expression in bain injury of GD; 2. alteration in cell self-renew and differention of iPSCs and iNPCs from GD. 3.Comparing curative effects of iPSCs and iNPCs on brain injury of neuronopathic GD mousee model.The project will calrify the mechanisms of GD brain injury, and provide a theoretical and practical basis for induced stem cell-based therapeutic methods of GD and other lysosomal storage diseases.

戈谢氏病（GD）是一种最常见的溶酶体贮积病，属常染色体隐性遗传，病因为β-葡糖脑苷脂酶基因突变，导致葡糖脑苷脂聚积在网状内皮细胞的溶酶体中，引起多脏器损伤。GD分三型，II型和III型属神经型，发病机制尚未明了，是致死的主要类型，而且相同的突变存在多种表型。GD虽已有酶替代疗法，但对神经型无效,且价格过于昂贵。诱导性干细胞（iPSCs）和诱导性神经前体细胞（iNPCs）的建立为GD的治疗带来了曙光，但缺乏确切的评价。课题组前期已建立GD iPSCs及基因条件敲除神经型GD小鼠模型。课题拟在前期工作的基础上研究：1.GD脑损伤基因表达异常的表观遗传学机制；2.GDiPSCs和GDiNPCs自我更新及分化的特点；3.在神经型GD小鼠模型上对比iPSCs/GFP和iNPCs/GFP的疗效，探索最佳治疗方案。课题的实施将部分明确GD脑损伤的机制，为该病及其它溶酶体贮积病脑损伤的干细胞治疗奠定基础。

戈谢氏病（GD）是一种相对常见的溶酶体贮积病，病因为β-葡糖脑苷脂酶(GBA)基因突变，导致葡糖脑苷脂聚积在巨噬细胞的溶酶体中，引起多脏器损伤。GD分三型，II型和III型属神经型，是致死的主要类型，发病机制尚未明了且缺乏有效治疗手段。首先，我们从戈谢氏病患儿中发现了一种GBA新的突变c.655A>G（p.T219A)，经三维结构模拟、突变体表达纯化、酶活性测定，确认突变体较野生型的GBA活性降低了77%；其次，我们先后建立了神经型GD小鼠模型和全身性诱导型GD小鼠，建立了诱导性干细胞（iPSCs）及其分化而来的神经前体细胞（NPCs），构建了携带正常GBA的腺相关病毒9（AAV-9/GBA），结果发现iPSC和NPCs对GD小鼠模型治疗效果有限，而AAV-9/GBA基因治疗在两种小鼠疾病模型上都取得了满意的治疗效果；第三，经全基因组甲基化测序和表达谱芯片检测，发现神经型GD小鼠皮层组织中有18个基因出现DNA甲基化变化及相应的基因表达异常，因此我们推测GD发病的部分原因是由于葡糖脑苷脂的堆积影响了DNA甲基转移酶的活性，导致某些神经细胞存活的关键基因表达异常，最终损伤神经细胞功能，导致GD患者发病。