Altered TFEB-mediated lysosomal biogenesis in Gaucher disease iPSC-derived neuronal cells
Altered TFEB-mediated lysosomal biogenesis in Gaucher disease iPSC-derived neuronal cells
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DOI：
10.1093/hmg/ddv297
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发表时间：
2015-10-15
影响因子：
3.5
通讯作者：
Feldman, Ricardo A.
中科院分区：
文献类型：
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作者：
Awad, Ola;Sarkar, Chinmoy;Feldman, Ricardo A.
戈谢病（GD）是由GBA 1基因突变引起的，该基因编码溶酶体酶葡萄糖脑苷脂酶（GCase）。GD的严重形式与快速（2型）或缓慢进展（3型）的神经变性相关。虽然GD中的神经退行性过程与溶酶体功能障碍有关，但所涉及的机制在很大程度上是未知的。为了鉴定GD神经元中的溶酶体改变并揭示所涉及的机制，我们使用了来自GD患者的诱导多能干细胞（iPSC）。在GD iPSC衍生的神经元细胞（iPSC-NC）中，GBA 1突变引起广泛的溶酶体耗竭，以及由于自噬体的溶酶体清除缺陷而导致的自噬通量阻断。在GD iPSC-NC中通过雷帕霉素处理的自噬诱导导致细胞死亡。进一步分析显示，在GD iPSC-NC中，转录因子EB（TFEB）（溶酶体基因的主调节因子）的表达和溶酶体基因表达显著下调。还存在TFEB蛋白的稳定性降低和溶酶体蛋白生物合成改变。用重组GCase（rGCase）处理突变iPSC-NC恢复了溶酶体消耗和自噬阻断。rGCase对恢复突变细胞中溶酶体数量的作用在存在过表达的TFEB的情况下增强，但单独的TFEB过表达并不逆转溶酶体耗竭表型。我们的研究结果表明，GBA 1突变干扰TFEB介导的溶酶体生物合成，并在维持一个功能池的溶酶体的GCase的行动是通过TFEB部分施加。这里描述的溶酶体改变可能是GBA 1相关神经变性的主要决定因素。
Gaucher disease (GD) is caused by mutations in the GBA1 gene, which encodes the lysosomal enzyme glucocerebrosidase (GCase). The severe forms of GD are associated with neurodegeneration with either rapid (Type 2) or slow progression (Type 3). Although the neurodegenerative process in GD has been linked to lysosomal dysfunction, the mechanisms involved are largely unknown. To identify the lysosomal alterations in GD neurons and uncover the mechanisms involved, we used induced pluripotent stem cells (iPSCs) derived from patients with GD. In GD iPSC-derived neuronal cells (iPSC-NCs), GBA1 mutations caused widespread lysosomal depletion, and a block in autophagic flux due to defective lysosomal clearance of autophagosomes. Autophagy induction by rapamycin treatment in GD iPSC-NCs led to cell death. Further analysis showed that in GD iPSC-NCs, expression of the transcription factor EB (TFEB), the master regulator of lysosomal genes, and lysosomal gene expression, were significantly downregulated. There was also reduced stability of the TFEB protein and altered lysosomal protein biosynthesis. Treatment of mutant iPSC-NCs with recombinant GCase (rGCase) reverted the lysosomal depletion and autophagy block. The effect of rGCase on restoring lysosomal numbers in mutant cells was enhanced in the presence of overexpressed TFEB, but TFEB overexpression alone did not reverse the lysosomal depletion phenotype. Our results suggest that GBA1 mutations interfere with TFEB-mediated lysosomal biogenesis, and that the action of GCase in maintaining a functioning pool of lysosomes is exerted in part through TFEB. The lysosomal alterations described here are likely to be a major determinant in GBA1-associated neurodegeneration.