Kasturi K N, Hatakeyama A, Spiera H, Bona C A
Department of Microbiology, Mount Sinai School of Medicine, New York 10029-6574.
J Exp Med. 1995 Mar 1;181(3):1027-36. doi: 10.1084/jem.181.3.1027.
Autoantibodies specific against fibrillarin, a 34-kD nucleolar protein associated with U3-snRNP, are present in patients with systemic sclerosis (SSc). To understand the mechanisms involved in the induction of these autoantibodies, we prepared a series of human fibrillarin recombinant proteins covering the entire molecule and analyzed their interaction with the autoantibodies present in various connective tissue diseases. Our results showed that antifibrillarin autoantibodies are present not only in SSc, as previously reported, but also in a variety of other connective tissue diseases. Patients with SSc (58%), mixed connective tissue diseases (60%), CREST syndrome (calcinosis, Raynaud phenomenon, esophageal dismotility, sclerodactyly, and telangiectasia syndrome) (58%), systemic lupus erythematosus (39%), rheumatoid arthritis (60%), and Sjogern's syndrome (84%) showed presence of antifibrillarin autoantibodies. Results obtained from competitive inhibition radioimmunoassay and Western blot analyses with purified recombinant fusion proteins revealed that these autoantibodies react primarily with epitope(s) present in the NH2- (AA 1-80) and COOH-terminal (AA 276-321) domains of fibrillarin. Autoantibodies reacting with internal regions of fibrillarin are less frequent. Analysis of the hydrophilicity profiles of reactive peptides showed presence of three potential antigenic sites in the NH2- and two in the COOH-terminal regions. While a hexapeptide sequence NH2 terminus of fibrillarin is shared with an Epstein-Barr virus-encoded nuclear antigen, the COOH-terminal region shares sequence homology with P40, the capsid protein encoded by herpes virus type 1. Interestingly, these two regions of fibrillarin also contain the most immunodominant sequences, as predicted by surface probability and the Jameson and Wolf antigenic index. These observations suggest that molecular mimicry might play an important role in the induction of antifibrillarin autoantibodies.
抗核仁纤维蛋白（一种与U3 - snRNP相关的34-kD核仁蛋白）的自身抗体存在于系统性硬化症（SSc）患者体内。为了解这些自身抗体诱导过程中的相关机制，我们制备了一系列覆盖整个分子的人核仁纤维蛋白重组蛋白，并分析了它们与各种结缔组织疾病中存在的自身抗体的相互作用。我们的结果表明，抗核仁纤维蛋白自身抗体不仅如先前报道的那样存在于SSc中，还存在于多种其他结缔组织疾病中。患有SSc（58%）、混合性结缔组织病（60%）、CREST综合征（钙质沉着、雷诺现象、食管动力障碍、指端硬化和毛细血管扩张综合征）（58%）、系统性红斑狼疮（39%）、类风湿性关节炎（60%）和干燥综合征（84%）的患者体内均存在抗核仁纤维蛋白自身抗体。用纯化的重组融合蛋白进行竞争性抑制放射免疫测定和蛋白质印迹分析的结果显示，这些自身抗体主要与核仁纤维蛋白NH2端（氨基酸1 - 80）和COOH端（氨基酸276 - 321）结构域中存在的表位发生反应。与核仁纤维蛋白内部区域发生反应的自身抗体较少见。对反应性肽段亲水性图谱的分析表明，在NH2端区域存在三个潜在的抗原位点，在COOH端区域存在两个。虽然核仁纤维蛋白的NH2端六肽序列与爱泼斯坦 - 巴尔病毒编码的核抗原相同，但COOH端区域与1型疱疹病毒编码的衣壳蛋白P40具有序列同源性。有趣的是，正如表面概率以及詹姆森和沃尔夫抗原指数所预测的那样，核仁纤维蛋白的这两个区域也包含最具免疫优势的序列。这些观察结果表明，分子模拟可能在抗核仁纤维蛋白自身抗体的诱导中起重要作用。
