Herms J W, Madlung A, Brown D R, Kretzschmar H A
Department of Neuropathology, University of Göttingen, Germany.
Glia. 1997 Oct;21(2):253-7. doi: 10.1002/(sici)1098-1136(199710)21:2<253::aid-glia8>3.0.co;2-7.
A synthetic peptide consisting of amino acid residues 106 to 126 of the human prion protein (PrPc) that forms fibrils in vitro is toxic to cultured neurons. We have previously shown that the neurotoxic effect of this peptide is related to microglia activation (Brown et al., 1996a). For closer insight into this process of activation, we investigated the effect of the peptide on the intracellular free Ca2+ concentration ([Ca2+]i) in cultured microglia using Fura-2. Cultured microglia from wild-type as well as from PrPc gene-ablated mice (Prn-p0/0) responded to exposure to PrP106-126 with an increase in intracellular free calcium within 30 min. We observed two types of responses. Both in wild-type and Prn-p0/0 mice about half of the tested cells presented a small and often transient calcium increase after peptide application which was found to be independent of the extracellular calcium concentration. However, a further 33% of wild-type cells showed a strong and often permanent calcium increase depending on the extracellular calcium concentration, which was only rarely observed in Prn-p0/0 cells. To determine whether the response depended on the activation state of the microglia, we also examined LPS-treated activated microglia. The character of the calcium response remained unchanged, but significantly fewer cells responded. Our findings demonstrate the earliest reaction of microglia to a PrP fragment known to date.
一种由人朊蛋白（PrPc）106至126位氨基酸残基组成的合成肽，其在体外能形成原纤维，对培养的神经元有毒性。我们之前已经表明，该肽的神经毒性作用与小胶质细胞激活有关（Brown等人，1996a）。为了更深入了解这一激活过程，我们使用Fura-2研究了该肽对培养的小胶质细胞内游离钙离子浓度（[Ca2+]i）的影响。来自野生型以及朊蛋白基因敲除小鼠（Prn-p0/0）的培养小胶质细胞在暴露于PrP106-126后30分钟内细胞内游离钙增加。我们观察到两种类型的反应。在野生型和Prn-p0/0小鼠中，大约一半的受试细胞在施加肽后呈现出小幅度且通常是短暂的钙增加，这被发现与细胞外钙浓度无关。然而，另外33%的野生型细胞显示出强烈且通常是永久性的钙增加，这取决于细胞外钙浓度，而在Prn-p0/0细胞中很少观察到这种情况。为了确定该反应是否取决于小胶质细胞的激活状态，我们还检查了经脂多糖处理的活化小胶质细胞。钙反应的特征保持不变，但反应的细胞明显减少。我们的研究结果证明了小胶质细胞对迄今已知的朊蛋白片段的最早反应。
