mTOR hyperactivity mediates lysosomal dysfunction in Gaucher's disease iPSC-neuronal cells
mTOR hyperactivity mediates lysosomal dysfunction in Gaucher's disease iPSC-neuronal cells
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DOI：
10.1242/dmm.038596
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发表时间：
2019-10-01
影响因子：
4.3
通讯作者：
Awad, Ola
中科院分区：
文献类型：
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作者：
Brown, Robert A.;Voit, Antanina;Awad, Ola
双等位基因GBA 1突变导致戈谢病（GD），最常见的溶酶体储存疾病。GD中的神经元病理表现包括神经变性，其可以是严重的且快速进行性的。GBA 1突变也是帕金森病最常见的遗传危险因素。自噬-溶酶体途径的功能障碍代表GBA 1相关神经变性中的关键致病事件。使用GD的诱导多能干细胞（iPSC）模型，我们先前证明GD神经元中的溶酶体改变与转录因子EB（TFEB）的功能障碍有关。TFEB控制自噬和溶酶体基因的协调表达，并由雷帕霉素复合物1（mTORC 1）的哺乳动物靶负调控。为了进一步研究神经元病性GD中自噬-溶酶体途径功能障碍的机制，我们检测了GD iPSC神经元祖细胞和分化的神经元中的mTORC 1激酶活性。我们发现mTORC 1在GD细胞中过度活跃，其下游蛋白底物的磷酸化增加证明了这一点。我们还发现，药理学抑制葡糖神经酰胺合酶逆转mTORC 1超活化，这表明mTORC 1活性增加是由突变细胞中鞘糖脂的异常积累介导的。用mTOR抑制剂Torin 1处理上调了GD神经元中的溶酶体生物发生并增强了自噬清除，证实了溶酶体功能障碍是由mTOR超活化介导的。进一步的分析表明，通过mTORC 1增加的TFEB磷酸化导致GD细胞中TFEB稳定性降低。我们的研究揭示了导致GD中自噬-溶酶体途径功能障碍的新机制，并将mTOR复合物确定为治疗GBA 1相关神经变性的潜在治疗靶点。
Bi-allelic GBA1 mutations cause Gaucher's disease (GD), the most common lysosomal storage disorder. Neuronopathic manifestations in GD include neurodegeneration, which can be severe and rapidly progressive. GBA1 mutations are also the most frequent genetic risk factors for Parkinson's disease. Dysfunction of the autophagy-lysosomal pathway represents a key pathogenic event in GBA1-associated neurodegeneration. Using an induced pluripotent stem cell (iPSC) model of GD, we previously demonstrated that lysosomal alterations in GD neurons are linked to dysfunction of the transcription factor EB (TFEB). TFEB controls the coordinated expression of autophagy and lysosomal genes and is negatively regulated by the mammalian target of rapamycin complex 1 (mTORC1). To further investigate the mechanism of autophagy-lysosomal pathway dysfunction in neuronopathic GD, we examined mTORC1 kinase activity in GD iPSC neuronal progenitors and differentiated neurons. We found that mTORC1 is hyperactive in GD cells as evidenced by increased phosphorylation of its downstream protein substrates. We also found that pharmacological inhibition of glucosylceramide synthase enzyme reversed mTORC1 hyperactivation, suggesting that increased mTORC1 activity is mediated by the abnormal accumulation of glycosphingolipids in the mutant cells. Treatment with the mTOR inhibitor Torin1 upregulated lysosomal biogenesis and enhanced autophagic clearance in GD neurons, confirming that lysosomal dysfunction is mediated by mTOR hyperactivation. Further analysis demonstrated that increased TFEB phosphorylation by mTORC1 results in decreased TFEB stability in GD cells. Our study uncovers a new mechanism contributing to autophagy-lysosomal pathway dysfunction in GD, and identifies the mTOR complex as a potential therapeutic target for treatment of GBA1-associated neurodegeneration.