Mutant p53 aggregates into prion-like amyloid oligomers and fibrils: implications for cancer.
Mutant p53 aggregates into prion-like amyloid oligomers and fibrils: implications for cancer.
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DOI：
10.1074/jbc.m112.340638
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发表时间：
2012-08-10
期刊：
影响因子：
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通讯作者：
Silva JL
中科院分区：
文献类型：
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作者：
Ano Bom AP;Rangel LP;Costa DC;de Oliveira GA;Sanches D;Braga CA;Gava LM;Ramos CH;Cepeda AO;Stumbo AC;De Moura Gallo CV;Cordeiro Y;Silva JL
背景：p53功能在超过50%的肿瘤中丧失。结果如下：p53在体外和乳腺癌组织中聚集成淀粉样蛋白寡聚体和原纤维;突变型p53导致WT p53的淀粉样蛋白聚集，这是朊病毒的典型行为。结论：朊病毒样聚集是突变型p53负显性的关键。意义：抑制聚集可能成为肿瘤治疗的靶点。超过50%的人类癌症失去了p53功能。为了评估聚集在癌症中的作用，我们询问野生型（WT）p53和热点突变体R248 Q是否可以在生理条件下聚集为淀粉样蛋白，以及突变体是否可以引发野生型形式的聚集。两种构建体的中心结构域（p53 C）聚集成寡聚体和原纤维的混合物。R248 Q具有比WT p53更大的聚集趋势。全长p53聚集成淀粉样物质，结合硫磺素T。使用X-射线衍射、电子显微镜、FTIR、动态光散射、细胞活力测定和抗淀粉样蛋白免疫测定证明聚集体的淀粉样蛋白性质。纤维状聚集体的X射线衍射图与交叉β折叠淀粉样蛋白纤维的典型构象一致，反射率为4.7 nm和10 nm。R248 Q p53 C淀粉样蛋白低聚物和纤维的种子加速WT p53 C的聚集，这是朊病毒的典型行为。R248 Q突变体与乳腺癌样本中的淀粉样物质共定位，这进一步支持了其朊病毒样作用。含有突变型p53的肿瘤细胞系也显示p53在细胞核中大量聚集。我们的结论是聚集成的低聚物和原纤维的混合物的p53螯合天然蛋白质成一个非活性的构象，这是典型的一个primycin。致癌p53突变体的这种朊病毒样行为为负显性效应提供了解释，并可能作为癌症治疗的潜在靶点。
Background: p53 function is lost in more than 50% of tumors. Results: p53 aggregates into amyloid oligomers and fibrils in vitro and in breast cancer tissues; mutant p53 seeds amyloid aggregation of WT p53, a behavior typical of a prion. Conclusion: Prion-like aggregation is crucial for the negative dominance of mutant p53. Significance: The inhibition of aggregation could be a target for cancer therapy. Over 50% of all human cancers lose p53 function. To evaluate the role of aggregation in cancer, we asked whether wild-type (WT) p53 and the hot-spot mutant R248Q could aggregate as amyloids under physiological conditions and whether the mutant could seed aggregation of the wild-type form. The central domains (p53C) of both constructs aggregated into a mixture of oligomers and fibrils. R248Q had a greater tendency to aggregate than WT p53. Full-length p53 aggregated into amyloid-like species that bound thioflavin T. The amyloid nature of the aggregates was demonstrated using x-ray diffraction, electron microscopy, FTIR, dynamic light scattering, cell viabilility assay, and anti-amyloid immunoassay. The x-ray diffraction pattern of the fibrillar aggregates was consistent with the typical conformation of cross β-sheet amyloid fibers with reflexions of 4.7 Å and 10 Å. A seed of R248Q p53C amyloid oligomers and fibrils accelerated the aggregation of WT p53C, a behavior typical of a prion. The R248Q mutant co-localized with amyloid-like species in a breast cancer sample, which further supported its prion-like effect. A tumor cell line containing mutant p53 also revealed massive aggregation of p53 in the nucleus. We conclude that aggregation of p53 into a mixture of oligomers and fibrils sequestrates the native protein into an inactive conformation that is typical of a prionoid. This prion-like behavior of oncogenic p53 mutants provides an explanation for the negative dominance effect and may serve as a potential target for cancer therapy.