Detergent-resistant membrane domains but not the proteasome are involved in the misfolding of a PrP mutant retained in the endoplasmic reticulum
Detergent-resistant membrane domains but not the proteasome are involved in the misfolding of a PrP mutant retained in the endoplasmic reticulum
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DOI：
10.1242/jcs.02768
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发表时间：
2006-02-01
影响因子：
4
通讯作者：
Zurzolo, C
中科院分区：
文献类型：
--
作者：
Campana, V;Sarnataro, D;Zurzolo, C
遗传性PrP病是一种与PrP基因突变有关的神经退行性病变，PrP基因突变有利于PrPC转化为构象改变的致病形式PrPsc。PrPC/PrPSc转换的分子基础，它发生的细胞内间隔，以及这个过程如何导致神经功能障碍尚不清楚。我们研究了与克雅病(CJD)遗传形式相关的PrP突变体PrPT182a在转基因的FRT细胞中的合成、降解和定位。PrPT182a保留在内质网(ER)中，主要与抗洗涤剂微区(DRM)相关，并部分抵抗蛋白酶K的消化。虽然该突变体的未转位形式是多泛素化的，并经历内质网相关的降解，但蛋白酶体不负责其错误折叠形式的降解，这表明它在遗传病的发病机制中没有作用。相反，胆固醇耗竭导致PrPT182A与DRM的结合受损，导致其在内质网中积聚，并显著增加其错误折叠。这些数据支持了之前的假设，即DRM对于PrP的正确折叠是重要的，并表明它们可能在PrP突变体的病理性瘙痒样转换中起到保护作用。
Inherited prion diseases are neurodegenerative pathologies related to genetic mutations in the prion protein (PrP) gene, which favour the conversion of PrPC into a conformationally altered pathogenic form, PrPsc. The molecular basis of PrPC/PrPSc conversion, the intracellular compartment where it occurs and how this process leads to neurological dysfunction are not yet known.We have studied the intracellular synthesis, degradation and localization of a PrP mutant associated with a genetic form of Creutzfeldt-Jakob disease (CJD), PrPT182A, in transfected FRT cells. PrPT182A is retained in the endoplasmic reticulum (ER), is mainly associated with detergent-resistant microdomains (DRMs) and is partially resistant to proteinase K digestion. Although an untranslocated form of this mutant is polyubiquitylated and undergoes ER-associated degradation, the proteasome is not responsible for the degradation of its misfolded form, suggesting that it does not have a role in the pathogenesis of inherited diseases. On the contrary, impairment of PrPT182A association with DRMs by cholesterol depletion leads to its accumulation in the ER and substantially increases its misfolding. These data support the previous hypothesis that DRMs are important for the correct folding of PrP and suggest that they might have a protective role in pathological scrapie-like conversion of PrP mutants.