A comparison of the biochemical modifications caused by toxic and non-toxic protein oligomers in cells
A comparison of the biochemical modifications caused by toxic and non-toxic protein oligomers in cells
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DOI：
10.1111/j.1582-4934.2010.01239.x
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发表时间：
2011-10-01
影响因子：
5.3
通讯作者：
Cecchi, Cristina
中科院分区：
文献类型：
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作者：
Zampagni, Mariagioia;Cascella, Roberta;Cecchi, Cristina
多肽和蛋白质可以从其可溶性形式转化为高度有序的纤维聚集体，导致从神经退行性疾病到系统性淀粉样变性的各种病理情况。越来越多的人认识到，在纤维聚集过程中早期形成的蛋白质低聚物是蛋白质沉积性疾病的致病物种。大肠杆菌HypF蛋白(HypF-N)的N-末端结构域在不同的条件下形成两种类型的HypF-N寡聚体，其形态难以区分，但在分子水平上具有明显的结构特征。只有暴露在疏水表面并具有足够结构可塑性的低聚物类型是有毒的(A类)，而另一种类型对培养的细胞是良性的(B类)。在这里，我们发现只有A型寡聚体能够诱导钙离子从细胞培养基内流到胞浆，穿透质膜，增加细胞内活性氧的产生，脂质过氧化和细胞内钙蛋白的释放，从而激活细胞凋亡途径。值得注意的是，当这些寡聚体注射到大鼠大脑中时，也会导致胆碱能神经元的损失。相比之下，在培养的和暴露于B型寡聚体的大鼠神经元细胞中，细胞应激和活性的标志没有受到影响。对这些效应的时间尺度的分析表明，两种低聚物之间的毒性差异涉及毒性级联的早期事件，这为蛋白质低聚物的作用机制和蛋白质沉积疾病治疗干预的分子靶点提供了新的线索。
Peptides and proteins can convert from their soluble forms into highly ordered fibrillar aggregates, giving rise to pathological conditions ranging from neurodegenerative disorders to systemic amyloidoses. It is increasingly recognized that protein oligomers forming early in the process of fibril aggregation represent the pathogenic species in protein deposition diseases. The N-terminal domain of the HypF protein from Escherichia coli (HypF-N) has previously been shown to form, under distinct conditions, two types of HypF-N oligomers with indistinguishable morphologies but distinct structural features at the molecular level. Only the oligomer type exposing hydrophobic surfaces and possessing sufficient structural plasticity is toxic (type A), whereas the other type is benign to cultured cells (type B). Here we show that only type A oligomers are able to induce a Ca2+ influx from the cell medium to the cytosol, to penetrate the plasma membrane, to increase intracellular reactive oxygen species production, lipid peroxidation and release of intracellular calcein, resulting in the activation of the apoptotic pathway. Remarkably, these oligomers can also induce a loss of cholinergic neurons when injected into rat brains. By contrast, markers of cellular stress and viability were unaffected in cultured and rat neuronal cells exposed to type B oligomers. The analysis of the time scales of such effects indicates that the difference of toxicity between the two oligomer types involve the early events of the toxicity cascade, shedding new light on the mechanism of action of protein oligomers and on the molecular targets for the therapeutic intervention against protein deposition diseases.