Bosze Szilvia, Hudecz Ferenc, Igaz Péter, Ortutay Zsuzsanna, Csík Gabriella, Falus András, Tóth Sára
Research Group of Peptide Chemistry, Hungarian Academy of Sciences, Eötvös L. University, P.O. Box 32, H-1518 Budapest 112, Hungary
Biol Chem. 2003 Mar;384(3):409-21. doi: 10.1515/BC.2003.047.
Interleukin-6 (IL-6) is a helical cytokine exerting pleiotropic activities including the regulation of hematopoiesis, B cell activation and acute-phase reaction. The structure-function relationship of the molecule is the subject of intensive investigation using point and deletion mutants. Our objective was to analyse the role of the N-terminal 18-46 region in IL-6-mediated expression of junB protooncogene and fibrinogen production, reflecting the acute phase response, with synthetic overlapping peptides. mRNA expression of junB was monitored by competitive RT-PCR, while sandwich ELISA was used for the detection of fibrinogen in the supernatant of HepG2 human hepatoma cells. We found that even short synthetic octapeptides can be stimulatory (in the absence of IL-6) or inhibitory (in the presence of IL-6) in both assays. To establish the molecular mechanism by which synthetic peptides exert their biological effects electromobility shift assay was carried out using HepG2 nuclear extracts. Peptides inducing junB expression initiate gel shifts of STAT3/DNA complexes, which may indicate the involvement of this signal transduction pathway. Circular dicroism spectroscopy data suggest that 8-11-mer peptides representing different parts of the 18-46 region have a marked tendency to adopt ordered conformations in a water/trifluoroethanol (1:1 v/v) mixture. Competition studies with rhIL-6 and selected fluorophore-labelled peptides indicate the presence of more than one binding site on soluble IL-6 receptor. Considering the possible multiple etiologic role of IL-6 in the pathogenesis of various diseases, these peptides could be useful for dissection of IL-6 related biological effects.
白细胞介素-6（IL-6）是一种螺旋细胞因子，具有多种功能，包括调节造血作用、B细胞活化和急性期反应。利用点突变和缺失突变体对该分子的结构-功能关系进行了深入研究。我们的目的是用合成重叠肽分析IL-6介导的原癌基因junB表达及纤维蛋白原产生中N端18 - 46区域的作用，纤维蛋白原产生反映急性期反应。通过竞争性逆转录-聚合酶链反应监测junB的mRNA表达，而夹心酶联免疫吸附测定法用于检测人肝癌细胞系HepG2上清液中的纤维蛋白原。我们发现，即使是短的合成八肽在这两种测定中也可以是刺激性的（在无IL-6时）或抑制性的（在有IL-6时）。为了确定合成肽发挥其生物学效应的分子机制，使用HepG2核提取物进行了电泳迁移率变动分析。诱导junB表达的肽引发STAT3/DNA复合物的凝胶迁移，这可能表明该信号转导途径的参与。圆二色光谱数据表明，代表18 - 46区域不同部分的8 - 11肽段在水/三氟乙醇（1:1 v/v）混合物中有明显的形成有序构象的倾向。用重组人IL-6和选定的荧光团标记肽进行的竞争研究表明，可溶性IL-6受体上存在多个结合位点。考虑到IL-6在各种疾病发病机制中可能的多种病因学作用，这些肽可能有助于剖析与IL-6相关的生物学效应。
