Deletion of Gba in neurons, but not microglia, causes neurodegeneration in a Gaucher mouse model. Deletion of Gba in neurons, but not microglia, causes neurodegeneration in a Gaucher mouse model

Gaucher disease, the most prevalent lysosomal storage disease, is caused by homozygous mutations at the GBA gene, which is responsible for encoding the enzyme glucocerebrosidase. Neuronopathic Gaucher disease is associated with microgliosis, astrogliosis, and neurodegeneration. However, the role that microglia, astrocytes, and neurons play in the disease remains to be determined. In the current study, we developed inducible, cell-type specific Gba KO mice to understand the individual impacts of Gba deficiencies on microglia and neurons. Gba was conditionally knocked out either exclusively in microglia or neurons, or throughout the body. These mouse models were developed using a tamoxifen-inducible Cre system, with tamoxifen administration commencing at weaning. Microglia-specific Gba KO mice showed no signs of disease. However, the neuron-specific Gba KO resulted in a shortened lifespan, severe weight loss, and ataxia. These mice also had significant neurodegeneration, microgliosis, and astrogliosis accompanied by the accumulation of glucosylceramide and glucosylsphingosine, recapitulating Gaucher disease-like symptoms. These surprising findings reveal that, unlike the neuron-specific Gba deficiency, microglia-specific Gba deficiency alone does not induce disease. The neuronal Gaucher disease mouse model, with a median survival of 16 weeks, may be useful for future studies of pathogenesis and the evaluation of therapies. Overall design: In order to explore mechanisms of Gba deficiencies, cell-specific (microglial and neuronal) Gba KO mice were developed. We then performed bulk RNAseq from brain tissue. Each group (neuron-specific Gba KO (Gba nKO), microglia-specific Gba KO (Gba mKO), Gba nKO littermate controls, Gba mKO littermate controls) consisted of 6 samples. CD11b+ cells were also isolated from 4 Gba mKO (Gba mmKO) and 4 control mice for bulk RNAseq.

戈谢病（Gaucher disease）是最常见的溶酶体贮积病，由编码葡糖脑苷脂酶（glucocerebrosidase）的GBA基因纯合突变引发。神经病变型戈谢病与小胶质细胞增生、星形胶质细胞增生及神经退行性变密切相关，但目前小胶质细胞、星形胶质细胞和神经元在该病中的具体作用仍有待明确。本研究构建了可诱导的细胞类型特异性Gba基因敲除（KO）小鼠模型，旨在解析Gba缺失对小胶质细胞与神经元的独立影响。本模型采用他莫昔芬（tamoxifen）诱导的Cre重组酶系统构建，于小鼠断奶后启动他莫昔芬给药，分别实现仅小胶质细胞、仅神经元，或全身的Gba条件性敲除。小胶质细胞特异性Gba敲除小鼠未表现出任何疾病相关体征。而神经元特异性Gba敲除小鼠则出现寿命缩短、严重体重减轻及共济失调症状，同时伴随显著的神经退行性变、小胶质细胞增生与星形胶质细胞增生，以及葡糖脑苷脂和葡糖鞘氨醇的蓄积，完整重现了戈谢病样病理表型。该研究的意外结果表明，与神经元特异性Gba缺失不同，仅小胶质细胞的Gba缺失并不会诱发疾病。本神经元型戈谢病小鼠模型的中位生存期为16周，可用于未来的疾病发病机制研究及治疗方案评估。总体实验设计：为探究Gba缺失的致病机制，本研究构建了细胞类型特异性（小胶质细胞与神经元）Gba敲除小鼠模型。随后对脑组织开展批量RNA测序（bulk RNAseq）。每组实验包含6个样本，分别为神经元特异性Gba敲除（Gba nKO）组、小胶质细胞特异性Gba敲除（Gba mKO）组、Gba nKO同窝对照组及Gba mKO同窝对照组。此外，本研究还从4只Gba mKO（Gba mmKO）小鼠与4只对照小鼠中分离CD11b+细胞，进行批量RNA测序。