Department of Experimental Medicine, Sapienza University, Rome, Italy.
Prion. 2012 Sep-Oct;6(4):354-8. doi: 10.4161/pri.20479. Epub 2012 Jul 30.
The cellular form of prion protein (PrP (c)) is a highly conserved cell surface GPI-anchored glycoprotein that was identified in cholesterol-enriched, detergent-resistant microdomains, named "rafts." The association with these specialized portions of the cell plasma membrane is required for conversion of PrP (c) to the transmissible spongiform encephalopathy-associated protease-resistant isoform. Usually, PrP (c) is reported to be a plasma membrane protein, however several studies have revealed PrP (c) as an interacting protein mainly with the membrane/organelles, as well as with cytoskeleton network. Recent lines of evidence indicated its association with ER lipid raft-like microdomains for a correct folding of PrP (c), as well as for the export of the protein to the Golgi and proper glycosylation. During cell apoptosis, PrP (c) can undergo intracellular re-localization, via ER-mitochondria associated membranes (MAM) and microtubular network, to mitochondrial raft-like microdomains, where it induced the loss of mitochondrial membrane potential and citochrome c release, after a contained raise of calcium concentration. We suggest that PrP (c) may play a role in the multimolecular signaling complex associated with cell apoptosis Lipid rafts and their components may, thus, be investigated as pharmacological targets of interest, introducing a novel and innovative task in modern pharmacology, i.e., the development of glycosphingolipid targeted drugs.
朊病毒蛋白(PrP(c))的细胞形式是一种高度保守的细胞表面糖基磷脂酰肌醇锚定糖蛋白,它存在于富含胆固醇的去污剂抗性微域中,这些微域被命名为“脂筏”。这种与细胞质膜特殊部分的关联是 PrP(c)转化为可传播海绵状脑病相关蛋白酶抗性异构体所必需的。通常,PrP(c)被报道为一种质膜蛋白,然而,几项研究表明,PrP(c)主要作为一种与膜/细胞器相互作用的蛋白,以及与细胞骨架网络相互作用的蛋白。最近的研究结果表明,它与内质网脂筏样微域相关联,以正确折叠 PrP(c),并将蛋白输出到高尔基体进行适当的糖基化。在细胞凋亡过程中,PrP(c)可以通过内质网-线粒体相关膜(MAM)和微管网络在细胞内重新定位到线粒体脂筏样微域,在那里,它在钙离子含量升高的情况下,诱导线粒体膜电位丧失和细胞色素 c 释放。我们认为,PrP(c)可能在与细胞凋亡相关的多分子信号复合物中发挥作用。脂筏及其组成部分因此可以作为药理学感兴趣的靶标进行研究,为现代药理学引入了一项新的创新任务,即开发糖鞘脂靶向药物。