Aggregate-prone proteins with polyglutamine and polyalanine expansions are degraded by autophagy
Aggregate-prone proteins with polyglutamine and polyalanine expansions are degraded by autophagy
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DOI：
10.1093/hmg/11.9.1107
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发表时间：
2002-05-01
影响因子：
3.5
通讯作者：
Rubinsztein, DC
中科院分区：
文献类型：
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作者：
Ravikumar, B;Duden, R;Rubinsztein, DC
蛋白质构象障碍（PCD），如阿尔茨海默病、亨廷顿病（HD）、帕金森病和眼咽肌营养不良，与错误折叠和聚集的蛋白质相关。在这里，我们使用了HD基因的外显子1与扩展的聚谷氨酰胺[poly（Q）]重复序列和增强的绿色荧光蛋白标记的19丙氨酸作为模型的聚集倾向蛋白，调查介导其降解的途径。自噬参与这些模型蛋白的降解，因为它们在两种不同细胞系中用作用于自噬-溶酶体途径的不同阶段的不同抑制剂处理细胞时积累。此外，刺激自噬的雷帕霉素增强了我们的聚集倾向蛋白的清除。雷帕霉素还减少了与聚（Q）和聚丙氨酸[聚（A）]扩增相关的聚集体的出现和细胞死亡。由于雷帕霉素在临床上使用，这种药物或相关类似物可能是HD和相关疾病治疗研究的合适候选者。我们还重新检查了蛋白酶体的作用，因为以前在poly（Q）疾病中的研究使用lactacystin作为抑制剂-最近的研究表明lactacystin也可能影响溶酶体功能。lactacystin和特异性蛋白酶体抑制剂epoxomicin都增加了poly（Q）构建体的可溶性蛋白水平，表明这些蛋白也被蛋白酶体清除。然而，在我们的诱导型PC 12细胞模型中，虽然lactacystin增强了poly（Q）聚集，但环氧霉素减少了聚集，这表明环氧霉素诱导的一些其他蛋白质可能调节poly（Q）聚集。
Protein conformational disorders (PCDs), such as Alzheimer's disease, Huntington's disease (HD), Parkinson's disease and oculopharyngeal muscular dystrophy, are associated with proteins that misfold and aggregate. Here we have used exon 1 of the HD gene with expanded polyglutamine [poly(Q)] repeats and enhanced green fluorescent protein tagged to 19 alanines as models for aggregate-prone proteins, to investigate the pathways mediating their degradation. Autophagy is involved in the degradation of these model proteins, since they accumulated when cells were treated with different inhibitors acting at distinct stages of the autophagy-lysosome pathway, in two different cell lines. Furthermore, rapamycin, which stimulates autophagy, enhanced the clearance of our aggregate-prone proteins. Rapamycin also reduced the appearance of aggregates and the cell death associated with the poly(Q) and polyalanine [poly(A)] expansions. Since rapamycin is used clinically, this drug or related analogues may be suitable candidates for therapeutic investigation in HD and related diseases. We have also re-examined the role of the proteasome, since previous studies in poly(Q) diseases have used lactacystin as an inhibitor - recent studies have shown that lactacystin may also affect lysosomal function. Both lactacystin and the specific proteasomal inhibitor epoxomicin increased soluble protein levels of the poly(Q) constructs, suggesting that these are also cleared by the proteasome. However, while poly(Q) aggregation was enhanced by lactacystin in our inducible PC12 cell model, aggregation was reduced by epoxomicin, suggesting that some other protein(s) induced by epoxomicin may regulate poly(Q) aggregation.