Primers for H95X mutations.

Prion diseases are neurodegenerative disorders caused by a change in conformation of the prion protein from the cellular form (PrPC) to a misfolded isoform (PrPSc). PrPC is a copper binding protein via histidine residues in the octapeptide repeats (OR) and the non-OR region located at the N-terminus. Although the functional implication of copper binding to PrPC is still under investigation, copper may play a role in prion disease. In this study, we describe transgenic mice expressing mouse prion protein replacing histidine 95 by tyrosine (PrP H95Y) to disrupt the non-OR copper-binding site. Transgenic mice overexpressing PrP H95Y showed clinical signs and died at about 100 days with spongiform degeneration and PK-resistant PrP. Inoculation of brain homogenate from mice overexpressing PrP H95Y to Tga20 mice expressing wild-type PrP also causes lethal, spongiform encephalopathy. We conclude that this substitution could promote PrPC-PrPSc conversion and induce spontaneous prion disease in vivo.

朊病毒疾病（Prion diseases）是一类由朊蛋白（prion protein）构象从细胞型朊蛋白（PrP^C）转变为错误折叠亚型（PrP^Sc）所引发的神经退行性疾病。细胞型朊蛋白是一种铜结合蛋白，可通过八肽重复序列（OR）区域与N端非OR区域内的组氨酸残基结合铜离子。尽管铜离子与细胞型朊蛋白结合的功能意义仍在研究之中，但铜离子可能在朊病毒疾病的发生发展中发挥作用。本研究中，我们报道了表达小鼠朊蛋白的转基因小鼠，通过将第95位组氨酸残基替换为酪氨酸（PrP H95Y）以破坏非OR区域的铜结合位点。过表达PrP H95Y的转基因小鼠出现临床症状，并在约100日龄时死亡，其脑组织呈现海绵状变性且存在蛋白酶K抗性朊蛋白（PK-resistant PrP）。将过表达PrP H95Y的小鼠脑匀浆接种至表达野生型朊蛋白的Tga20小鼠体内，同样可引发致死性海绵状脑病。综上，我们认为该氨基酸替换可促进细胞型朊蛋白向错误折叠亚型的转化，并在体内诱导自发性朊病毒疾病。