Cytosolic prion protein is not toxic and protects against Bax-mediated cell death in human primary neurons
Cytosolic prion protein is not toxic and protects against Bax-mediated cell death in human primary neurons
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DOI：
10.1074/jbc.m306177200
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发表时间：
2003-10-17
影响因子：
4.8
通讯作者：
LeBlanc, AC
中科院分区：
文献类型：
--
作者：
Roucou, X;Guo, Q;LeBlanc, AC
最近有研究发现，胞质内PrP和胞质内PrP表达可诱导神经元快速死亡（Ma， J., Wollmann， R., and Lindquist， S. (2002) Science 298, 1781 - 1785）。在本研究中，我们研究了朊病毒蛋白（PrP）在细胞质中积累是否对原代培养的人类神经元有毒性。我们发现，在这些神经元中，缺乏信号肽的单一PrP异构体在经过环氧霉素（一种特异性蛋白酶体抑制剂）处理的神经元细胞质中积累。因此，内源性表达的PrP受到内质网相关降解（ERAD）途径的影响，并在人类初级神经元中被蛋白酶体降解。与其在N2a细胞中的毒性相反，即使向神经元微注射过表达野生型PrP或突变型PrPD178N的cDNA构建物，反向易位PrP （rad -PrP）也没有毒性。我们发现，与N2a细胞中的拉德- prp不溶性和蛋白酶k抗性状态相比，人类神经元中的拉德- prp保持洗涤剂溶性和蛋白酶k敏感性。此外，微注射表达cyrp的cDNA构建体不仅无毒，而且可以保护这些神经元免受bax介导的细胞死亡。我们得出结论，在人类神经元中，rad -PrP不会自然转化为一种类似痒病PrP的形式，并且位于细胞质中的PrP保留了对Bax的保护功能。因此，单纯的PrP在细胞质中的积累不太可能导致朊病毒疾病的神经退行性变。
Recently, it was observed that reverse-translocated cytosolic PrP and PrP expressed in the cytosol induce rapid death in neurons (Ma, J., Wollmann, R., and Lindquist, S. ( 2002) Science 298, 1781 - 1785). In this study, we investigated whether accumulation of prion protein ( PrP) in the cytosol is toxic to human neurons in primary culture. We show that in these neurons, a single PrP isoform lacking signal peptide accumulates in the cytosol of neurons treated with epoxomicin, a specific proteasome inhibitor. Therefore, endogenously expressed PrP is subject to the endoplasmic reticulum-associated degradation (ERAD) pathway and is degraded by the proteasome in human primary neurons. In contrast to its toxicity in N2a cells, reverse-translocated PrP (ERAD-PrP) is not toxic even when neurons are microinjected with cDNA constructs to overexpress either wild-type PrP or mutant PrPD178N. We found that ERAD-PrP in human neurons remains detergent-soluble and proteinase K-sensitive, in contrast to its detergent-insoluble and proteinase K-resistant state in N2a cells. Furthermore, not only is microinjection of a cDNA construct expressing CyPrP not toxic, it protects these neurons against Bax-mediated cell death. We conclude that in human neurons, ERAD-PrP is not converted naturally into a form reminiscent of scrapie PrP and that PrP located in the cytosol retains its protective function against Bax. Thus, it is unlikely that simple accumulation of PrP in the cytosol can cause neurodegeneration in prion diseases.