Early Delivery of Misfolded PrP from ER to Lysosomes by Autophagy.
Early Delivery of Misfolded PrP from ER to Lysosomes by Autophagy.
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DOI：
10.1155/2013/560421
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发表时间：
2013
影响因子：
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通讯作者：
Mastrianni JA
中科院分区：
文献类型：
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作者：
Cortes CJ;Qin K;Norstrom EM;Green WN;Bindokas VP;Mastrianni JA
朊病毒疾病与朊病毒蛋白（PrP）错误折叠异构体（PrPSc）的积累有关。有证据表明，溶酶体是降解终点和PrPSc积累的位点。我们质疑溶酶体是否参与新生成的错误折叠PrP的早期质量控制。我们发现携带疾病相关的T182A突变（Mut-PrP）的PrP以高尔基不依赖的方式传递给溶酶体。延时活细胞成像显示gfp标记的mutp - prp聚集物早期形成并被吸收到LysoTracker标记的囊泡中。与Wt-PrP相比，Mut-PrP的表达与自噬-溶酶体途径的几个标记物的升高有关，并且它广泛地与自噬体特异性标记物LC3B共定位。在自噬缺陷（ATG5−/−）小鼠胚胎成纤维细胞中，或在自噬抑制剂3-MA处理的正常细胞中，Mut-PrP与溶酶体共定位的减少程度相似。此外，3-MA选择性地破坏了不溶性Mut-PrP的降解，导致蛋白酶抗性PrP的增加，而雷帕霉素诱导的自噬则减少了PrP。这些发现表明，自噬可能作为一种质量控制机制来限制错误折叠PrP的积累，而错误折叠PrP通常会导致PrPSc的产生。
Prion diseases are linked to the accumulation of a misfolded isoform (PrPSc) of prion protein (PrP). Evidence suggests that lysosomes are degradation endpoints and sites of the accumulation of PrPSc. We questioned whether lysosomes participate in the early quality control of newly generated misfolded PrP. We found PrP carrying the disease-associated T182A mutation (Mut-PrP) was delivered to lysosomes in a Golgi-independent manner. Time-lapse live cell imaging revealed early formation and uptake of GFP-tagged Mut-PrP aggregates into LysoTracker labeled vesicles. Compared with Wt-PrP, Mut-PrP expression was associated with an elevation in several markers of the autophagy-lysosomal pathway, and it extensively colocalized with the autophagosome-specific marker, LC3B. In autophagy deficient (ATG5−/−) mouse embryonic fibroblasts, or in normal cells treated with the autophagy-inhibitor 3-MA, Mut-PrP colocalization with lysosomes was reduced to a similar extent. Additionally, 3-MA selectively impaired the degradation of insoluble Mut-PrP, resulting in an increase in protease-resistant PrP, whereas the induction of autophagy by rapamycin reduced it. These findings suggest that autophagy might function as a quality control mechanism to limit the accumulation of misfolded PrP that normally leads to the generation of PrPSc.