Labrador M, Algueró A, Díaz C, Geli C, Pérez E, García-Valero J, Rodriguez-Sanchez J L, Gelpí C
Department of Immunology, Hospital de la Santa Creu i Sant Pau, Autónoma University, Barcelona, Spain.
Clin Exp Immunol. 1998 Nov;114(2):301-10. doi: 10.1046/j.1365-2249.1998.00725.x.
We identified three patients (two of them relatives) with RA and signs of scleroderma whose sera contained a high titre of IgG class antibodies against the nucleoli and the nucleoplasm of cells of different mammalian origins. Sera from these patients uniformly immunoprecipitated four polypeptides, from a 35S-methionine-labelled HeLa cell extract, whose mol. wts were 120, 105, 95 and 42 kD. Of these, the 95-kD protein was highly phosphorylated. By immunoblotting, these sera reacted with 105-, 95- and 42-kD proteins and affinity-purified antibodies from these, demonstrating that 105- and 95-kD proteins shared cross-reactive epitopes. Moreover, affinity-purified antibodies from each of these proteins immunoprecipitated the whole complex. Localization studies using immunoelectron microscopy and in vivo actinomycin-D-treated cells demonstrated that the 105-, 95- and 42-kD proteins were present in the granular component of the nucleolus and the nucleoplasm. In addition, the 105- and 95-kD were present in free polyribosomes as well as ribosomes attached to endoplasmic reticulum. Pulse/chase experiments strongly suggested that the complex was accomplished shortly after a 10-min pulse. It was preferentially present in the nucleus after a 2 h chase and in both nucleus and cytoplasm after a 5 h chase. We conclude that a protein complex with a main nucleolar distribution is a new autoantigen (p105-p42) recognized by autoantibodies present in the serum of a subgroup of patients with RA and scleroderma signs. These antibodies could be useful as diagnostic markers and as tools for further studies involving the biology of the nucleolus.
我们鉴定出三名患有类风湿性关节炎（RA）且有硬皮病体征的患者（其中两名是亲属），他们的血清中含有高滴度的IgG类抗体，这些抗体针对不同哺乳动物来源细胞的核仁和核质。这些患者的血清一致地从35S-甲硫氨酸标记的HeLa细胞提取物中免疫沉淀出四种多肽，其分子量分别为120、105、95和42kD。其中，95kD的蛋白质高度磷酸化。通过免疫印迹法，这些血清与105kD、95kD和42kD的蛋白质发生反应，并且从这些血清中亲和纯化的抗体也能与之反应，这表明105kD和95kD的蛋白质具有交叉反应性表位。此外，从这些蛋白质中亲和纯化的抗体各自都能免疫沉淀整个复合物。使用免疫电子显微镜和体内放线菌素-D处理细胞进行的定位研究表明，105kD、95kD和42kD的蛋白质存在于核仁和核质的颗粒成分中。此外，105kD和95kD的蛋白质还存在于游离多核糖体以及附着在内质网上的核糖体中。脉冲/追踪实验强烈表明，该复合物在10分钟脉冲后不久即形成。在2小时追踪后，它优先存在于细胞核中，而在5小时追踪后，则同时存在于细胞核和细胞质中。我们得出结论，一种主要分布于核仁的蛋白质复合物是一种新的自身抗原（p105-p42），可被患有RA且有硬皮病体征的患者亚组血清中的自身抗体识别。这些抗体可用作诊断标志物以及用于涉及核仁生物学的进一步研究的工具。
