Soria Federico N, Engeln Michel, Martinez-Vicente Marta, Glangetas Christelle, López-González María José, Dovero Sandra, Dehay Benjamin, Normand Elisabeth, Vila Miquel, Favereaux Alexandre, Georges François, Lo Bianco Christophe, Bezard Erwan, Fernagut Pierre-Olivier
UMR 5293, Institut des Maladies Neurodégénératives, Université de Bordeaux, 33076 Bordeaux, France.
CNRS, UMR 5293, Institut des Maladies Neurodégénératives, 33076 Bordeaux, France.
Hum Mol Genet. 2017 Jul 15;26(14):2603-2615. doi: 10.1093/hmg/ddx120.
Mutations in the GBA1 gene encoding the lysosomal enzyme glucocerebrosidase (GBA1) are important risk factors for Parkinson's disease (PD). In vitro, altered GBA1 activity promotes alpha-synuclein accumulation whereas elevated levels of alpha-synuclein compromise GBA1 function, thus supporting a pathogenic mechanism in PD. However, the mechanisms by which GBA1 deficiency is linked to increased risk of PD remain elusive, partially because of lack of aged models of GBA1 deficiency. As knocking-out GBA1 in the entire brain induces massive neurodegeneration and early death, we generated a mouse model of GBA1 deficiency amenable to investigate the long-term consequences of compromised GBA1 function in dopaminergic neurons. DAT-Cre and GBA1-floxed mice were bred to obtain selective homozygous disruption of GBA1 in midbrain dopamine neurons (DAT-GBA1-KO). Mice were followed for motor function, neuronal survival, alpha-synuclein phosphorylation and glial activation. Susceptibility to nigral viral vector-mediated overexpression of mutated (A53T) alpha-synuclein was assessed. Despite loss of GBA1 and substrate accumulation, DAT-GBA1-KO mice displayed normal motor performances and preserved dopaminergic neurons despite robust microglial activation in the substantia nigra, without accumulation of endogenous alpha-synuclein with respect to wild-type mice. Lysosomal function was only marginally affected. Screening of micro-RNAs linked to the regulation of GBA1, alpha-synuclein or neuroinflammation did not reveal significant alterations. Viral-mediated overexpression of A53T-alpha-synuclein yielded similar neurodegeneration in DAT-GBA1-KO mice and wild-type mice. These results indicate that loss of GBA1 function in mouse dopaminergic neurons is not critical for alpha-synuclein accumulation or neurodegeneration and suggest the involvement of GBA1 deficiency in other cell types as a potential mechanism.
编码溶酶体酶葡萄糖脑苷脂酶（GBA1）的GBA1基因突变是帕金森病（PD）的重要风险因素。在体外，GBA1活性改变会促进α-突触核蛋白的积累，而α-突触核蛋白水平升高则会损害GBA1功能，从而支持了PD的致病机制。然而，GBA1缺乏与PD风险增加相关的机制仍然难以捉摸，部分原因是缺乏GBA1缺乏的老年模型。由于在整个大脑中敲除GBA1会导致大量神经退行性变和早期死亡，我们构建了一种GBA1缺乏的小鼠模型，以便研究多巴胺能神经元中GBA1功能受损的长期后果。将DAT-Cre和GBA1-floxed小鼠进行杂交，以在中脑多巴胺神经元中获得GBA1的选择性纯合缺失（DAT-GBA1-KO）。对小鼠的运动功能、神经元存活、α-突触核蛋白磷酸化和胶质细胞活化进行跟踪观察。评估黑质病毒载体介导的突变型（A53T）α-突触核蛋白过表达的易感性。尽管GBA1缺失且底物积累，但DAT-GBA1-KO小鼠表现出正常的运动性能，并且尽管黑质中有强烈的小胶质细胞活化，但多巴胺能神经元得以保留，与野生型小鼠相比，内源性α-突触核蛋白没有积累。溶酶体功能仅受到轻微影响。对与GBA1、α-突触核蛋白或神经炎症调节相关的微小RNA进行筛选，未发现明显改变。病毒介导的A5T-α-突触核蛋白过表达在DAT-GBA1-KO小鼠和野生型小鼠中产生了相似的神经退行性变。这些结果表明，小鼠多巴胺能神经元中GBA1功能的丧失对于α-突触核蛋白的积累或神经退行性变并不关键，并提示GBA1缺乏在其他细胞类型中的参与可能是一种潜在机制。
