Autoimmunity to RNA polymerase II is focused at the carboxyl terminal domain of the large subunit.
Autoimmunity to RNA polymerase II is focused at the carboxyl terminal domain of the large subunit.
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RNA 聚合酶 II 的自身免疫集中在大亚基的羧基末端结构域。
DOI：
10.1002/art.1780391115
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发表时间：
1996
影响因子：
--
通讯作者：
Hardin,JA
中科院分区：
文献类型：
--
作者：
Hirakata,M;Kanungo,J;Suwa,A;Takeda,Y;Craft,J;Hardin,JA
目标。先前的研究已经证实在某些硬皮病患者的血清中存在RNA聚合酶II （Pol II）的大（220 kd）多肽亚基抗体。在本研究中，我们试图确定该多肽的自身抗原区。重组融合蛋白与Pol II大亚基羧基末端结构域（CTD）中发现的52 -七肽重复序列相对应，用于鉴定含有自身抗体的15例患者血清。合成肽CTD7（代表一个七肽）和CTD18（代表2½七肽重复）被用于竞争性抑制实验，以确定这些血清的特异性和CTD作为自身抗原的重要性。所有15种血清均从放射性标记的细胞提取物中免疫沉淀Pol II亚基，其中11种血清在免疫印迹中结合CTD融合蛋白。CTD18在5个血清中完全抑制Pol II的免疫沉淀，在另外4个血清中部分抑制其免疫沉淀。这些结果表明，CTD七肽重复是硬皮病自身免疫反应的一个焦点。这可能是该结构的重复序列和高含量的带电残基有助于其作为自身抗原的作用。
Objective. Previous studies have demonstrated antibodies to the large (220 kd) polypeptide subunit of RNA polymerase II (Pol II) in sera from certain patients with scleroderma. In the present study, we sought to identify the autoantigenic region on this polypeptide.Methods. A recombinant fusion protein, corresponding to the 52‐heptapeptide repeat found in the carboxyl terminal domain (CTD) of the large Pol II subunit, was used to identify 15 patient sera that contained autoantibodies. Synthetic peptides CTD7 (representing a single heptapeptide) and CTD18 (representing 2½ heptapeptide repeats) were used in a competitive inhibition assay to define the specificity of these sera and the importance of the CTD as an autoantigen.Results. All 15 sera immunoprecipitated the Pol II subunit from radiolabeled cell extracts, and 11 of them bound the CTD fusion protein in immunoblots. Immunoprecipitation of Pol II was completely inhibited by CTD18 in 5 sera and partially inhibited in 4 additional sera.Conclusion. These results indicate that the CTD heptapeptide repeat is a focal point for autoimmune responses in scleroderma. It is likely that the repetitive sequence and high content of charged residues of this structure contribute to its role as an autoantigen.