Generation of hydrogen peroxide from mutant forms of the prion protein fragment PrP121-231.
Generation of hydrogen peroxide from mutant forms of the prion protein fragment PrP121-231.
复制标题
从朊病毒蛋白片段 PrP121-231 的突变形式产生过氧化氢。
作者：
S. Turnbull;B. J. Tabner;David R. Brown;D. Allsop
通过电子自旋共振光谱，结合自旋捕获技术，我们以前已经表明，Abeta和α-突触核蛋白（聚集蛋白，积累在大脑中的阿尔茨海默氏病，帕金森氏病，和相关疾病）都诱导形成羟基自由基孵育后，在溶液中，加入Fe（II）。这些羟基显然是由过氧化氢通过芬顿反应形成的。小鼠朊病毒蛋白的N-末端截短片段（称为PrP 121 -231）对培养的小脑细胞具有毒性，某些导致遗传性朊病毒疾病的人类突变增强了这种毒性。在这里，我们报告说，PrP 121 -231含有三个这样的突变（E200 K，D178 N，和F198 S）也产生羟基自由基，在添加Fe（II）。这些自由基的形成被过氧化氢酶，或金属螯合剂，其中每一个也降低了毒性的PrP 121 -231片段培养的正常小鼠小脑细胞阻断。野生型PrP 121 -231、全长细胞PrP及其同源物doppel未产生任何可检测的羟基自由基。我们的结论是，额外的细胞毒性作用的突变形式的PrP 121 -231可能是由于他们的能力，产生过氧化氢，通过金属依赖性机制。因此，这些（可能还有其他）朊病毒突变的一个影响可能是产生一种特别有毒的朊病毒蛋白，具有增强的诱导氧化损伤、神经变性和细胞损失的能力。
By means of electron spin resonance spectroscopy, in conjunction with the spin trapping technique, we have shown previously that Abeta and alpha-synuclein (aggregating proteins that accumulate in the brain in Alzheimer's disease, Parkinson's disease, and related disorders) both induce the formation of hydroxyl radicals following incubation in solution, upon addition of Fe(II). These hydroxyl radicals are apparently formed from hydrogen peroxide, via Fenton's reaction. An N-terminally truncated fragment of the mouse prion protein (termed PrP121-231) is toxic to cerebellar cells in culture, and certain human mutations, responsible for inherited prion disease, enhance this toxicity. Here we report that PrP121-231 containing three such mutations (E200K, D178N, and F198S) also generated hydroxyl radicals, upon addition of Fe(II). The formation of these radicals was blocked by catalase, or by metal chelators, each of which also reduced the toxicity of the PrP121-231 fragments to cultured normal mouse cerebellar cells. Wild-type PrP121-231, full-length cellular PrP, and its homologue doppel did not generate any detectable hydroxyl radicals. We conclude that the additional cytotoxic effects of the mutant forms of PrP121-231 could be due to their ability to generate hydrogen peroxide, by a metal-dependent mechanism. Thus, one effect of these (and possibly other) prion mutations could be production of a particularly toxic form of the prion protein, with an enhanced capacity to induce oxidative damage, neurodegeneration, and cell loss.