肝X受体下调BAFF表达的分子机制研究

发布时间：2018-09-18 21:20

【摘要】：研究背景：B细胞活化因子（B cell activating factor belonging to theTNF family，BAFF）是TNF家族的成员之一，它是B淋巴细胞表达的重要致炎因子，BAFF的过表达与多种疾病（如白血病，类风湿性关节炎等）的发生与发展密切相关。因此抑制BAFF的表达和/或相关的生物学功能，对BAFF相关疾病的防治具有重要的意义。核受体超家族成员肝X受体（liver X receptor，LXR）是典型的核受体。作为一个多功能转录因子,其可通过调控诸多靶基因的表达而发挥调节代谢和抗肿瘤功能。近年研究表明，抗炎作用是LXR的一项新功能，但其抗炎机制还亟待阐明；尤其是关于LXR是否可通过下调BAFF来发挥抗炎作用，目前未见报道。阐明该问题，将为深入揭示LXR的抗炎机制积累新的理论资料，乃至为探索以BAFF为靶点防治炎症的新措施提供科学依据。研究目的：探讨LXR对BAFF表达的影响及其机制。研究方法及结果：选取人B淋巴细胞系的Namalwa细胞和Daudi细胞为模型，用LXR的特异性激动剂GW3965处理24h后，，经RT-PCR和Real-time PCR技术证实LXR可在转录水平上抑制BAFF的表达；Western blot检测显示LXR可在蛋白水平上抑制BAFF的表达。荧光素酶报告基因检测实验证实LXR可抑制BAFF基因启动子的转录活性，且该抑制作用与BAFF基因启动子区的-1082～-361区域关系密切。经电泳迁移阻滞实验(Electrophoresis mobility shift，EMSA)实验和染色质免疫沉淀(Chromatin immunoprecipitation assay，ChIP)实验证实，LXR可抑制转录因子NF-κB的结合活性，提示LXR可能通过负性调节NF-κB信号通路来抑制BAFF的表达。用LXR的特异性激动剂GW3965灌胃喂养小鼠一周后，取脾脏经RT-PCR和Western blot检测，证实LXR可下调小鼠脾脏组织中BAFF的表达。结论：LXR激动剂处理B淋巴细胞系后可使BAFF mRNA和蛋白的表达呈剂量依赖性降低，且该下调作用的可能机制是抑制了NF-κB信号通路。动物实验显示LXR可在小鼠体内下调BAFF的表达。
[Abstract]:Background: (B cell activating factor belonging to theTNF family,BAFF, a member of the TNF family, is a member of the TNF family. It is an important inflammatory factor in the expression of B lymphocytes and is associated with many diseases such as leukemia. Rheumatoid arthritis (RA) is closely related to development. Therefore, the inhibition of BAFF expression and / or related biological functions is of great significance in the prevention and treatment of BAFF related diseases. Liver X receptor (liver X receptor,LXR, a member of the nuclear receptor superfamily, is a typical nuclear receptor. As a multifunctional transcription factor, it can regulate metabolism and antitumor function by regulating the expression of many target genes. Recent studies have shown that the anti-inflammatory effect is a new function of LXR, but its anti-inflammatory mechanism needs to be clarified, especially whether LXR can play an anti-inflammatory effect by down-regulating BAFF, which has not been reported at present. The elucidation of this problem will provide a scientific basis for further revealing the anti-inflammatory mechanism of LXR and for exploring new measures to prevent and treat inflammation with BAFF as its target. Objective: to investigate the effect of LXR on BAFF expression and its mechanism. Methods and results: Namalwa cells and Daudi cells of human B lymphocytes were selected as models. After treated with LXR specific agonist GW3965 for 24 hours, RT-PCR and Real-time PCR techniques confirmed that LXR could inhibit the expression of BAFF at the transcriptional level. Western blot analysis showed that LXR could inhibit the expression of BAFF at protein level. The detection of luciferase reporter gene confirmed that LXR could inhibit the transcriptional activity of BAFF gene promoter, and the inhibitory effect was closely related to the region of -1082 ~ (-1) -361 in the promoter region of BAFF gene. Electrophoretic migration arrest assay (Electrophoresis mobility shift,EMSA) and chromatin immunoprecipitation (Chromatin immunoprecipitation assay,ChIP) assay confirmed that LXR could inhibit the binding activity of transcription factor NF- 魏 B, suggesting that LXR may inhibit BAFF expression by negatively regulating NF- 魏 B signaling pathway. Mice were fed with GW3965, a specific agonist of LXR, for one week. RT-PCR and Western blot assays showed that LXR could down-regulate the expression of BAFF in spleen of mice. Conclusion the expression of BAFF mRNA and protein decreased in a dose-dependent manner after the treatment of B lymphocyte cell line with the agonist of 1: LXR, and the mechanism of this downregulation may be the inhibition of NF- 魏 B signaling pathway. Animal experiments showed that LXR could down-regulate the expression of BAFF in mice.
【学位授予单位】：重庆医科大学
【学位级别】：硕士
【学位授予年份】：2012
【分类号】：R392.1

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