Division of Zoonoses, Center for Immunology & Pathology, National Institutes of Health, Korea Centers for Disease Control & Prevention, Osong Health Technology Administration Complex, 187 Osongsaengmyeong2-ro, Gangoe-myeon, Cheongwon-gun, Chungcheongbuk-do 363-951, Republic of Korea.
Biochem Biophys Res Commun. 2012 Jul 27;424(2):214-20. doi: 10.1016/j.bbrc.2012.06.056. Epub 2012 Jun 26.
Misfolding of prion protein (PrP to PrPSc) can cause neurodegenerative prion diseases. As a glycosylphosphatidylinositol (GPI)-anchored membrane protein, the normal form of PrP (PrPC) can function as a receptor for ligands in the extracellular space. PrPC was suggested to be involved in memory, synaptic neuronal communication, and anti-oxidation as a neuroprotective agent. The recently identified interaction between PrPC and Aβ(1-42) oligomers suggested another role for PrP as a receptor for Aβ(1-42) oligomers, thereby influencing cytotoxicity and apoptosis. Here, the association between PrPC and Aβ(1-42) oligomers was investigated by visualizing protein localization in neuronal cells by immunocytochemistry. Aβ(1-42) oligomer-induced cytotoxicity was tested in respective expressions of PrPC by using mouse neuroblastoma-2a (N2a) cells, the prion protein overexpressed cells (L2-2B1), and a Prnp-null mouse hippocampal cell line (HpL 3-4). Moreover, apoptotic proteins such as caspase-8 were used to assess the effect of PrPC on Aβ(1-42) oligomer-mediated apoptosis. In L2-2B1 and HpL 3-4 cells, the difference in the cytotoxicity of Aβ(1-42) oligomers could be clearly distinguished. In addition, Aβ(1-42) oligomers induced mitochondria dysfunction, reactive oxygen species (ROS) generation, and calcium influx PrPC-dependently. Apoptosis, related to mitochondria dysfunction, was further investigated to determine the cytotoxic pathway; the results suggest that PrPC could be involved in both the intrinsic and extrinsic apoptotic pathways. Finally, cells with abundant PrPC expression seemed to be more susceptible to Aβ(1-42) oligomer toxicity, suggesting the importance of the level of PrPC expression in the induction of apoptosis.
朊病毒蛋白（PrP 向 PrPSc 的错误折叠）可导致神经退行性朊病毒病。作为一种糖基磷脂酰肌醇（GPI）锚定膜蛋白，正常形式的 PrP（PrPC）可以作为细胞外空间配体的受体发挥作用。PrPC 被认为参与记忆、突触神经元通讯和抗氧化作用，作为一种神经保护剂。最近发现 PrPC 与 Aβ（1-42）寡聚体之间的相互作用表明 PrP 具有作为 Aβ（1-42）寡聚体受体的另一个作用，从而影响细胞毒性和细胞凋亡。在这里，通过免疫细胞化学观察神经元细胞中蛋白质定位，研究了 PrPC 与 Aβ（1-42）寡聚体之间的关联。在过表达 Prnp 基因的小鼠神经母细胞瘤-2a（N2a）细胞（L2-2B1）和 Prnp 缺失型小鼠海马细胞系（HpL 3-4）中，通过检测 PrPC 的各自表达，测试了 Aβ（1-42）寡聚体诱导的细胞毒性。此外，还使用凋亡蛋白如半胱天冬酶-8 来评估 PrPC 对 Aβ（1-42）寡聚体介导的细胞凋亡的影响。在 L2-2B1 和 HpL 3-4 细胞中，Aβ（1-42）寡聚体的细胞毒性差异可以明显区分。此外，Aβ（1-42）寡聚体诱导 PrPC 依赖的线粒体功能障碍、活性氧（ROS）生成和钙内流。进一步研究与线粒体功能障碍相关的凋亡，以确定细胞毒性途径；结果表明，PrPC 可能参与内在和外在的凋亡途径。最后，表达丰富 PrPC 的细胞似乎更容易受到 Aβ（1-42）寡聚体毒性的影响，这表明 PrPC 表达水平在诱导凋亡中的重要性。
