狼疮间质干细胞中OAZ基因高表达的分子遗传机制研究

Intrinsic defects in human mesenchymal stem cells (MSC) may impair their immunoregulatory function, resulting in excessive activation of B cells and thus contributing to the onset of systemic lupus erythematosus (SLE). Previously we have shown that transcription level of OAZ (Olf1/EBF associated zinc finger protein), of which expression abundance was much higher in MSCs than in peripheral blood cells, was elevated in SLE patients. OAZ expression was gradually normalized in patients transplanted with normal MSC, with the decline of antinuclear antibody level. After silencing OAZ expression, SLE MSC could regain the ability to inhibit B cell proliferation and terminal differentiation, implying that OAZ hyper- expression is one of the main causes accounting for MSC abnormality in SLE. The mechanisms involved in OAZ regulation in MSCs are still unclear. Through fine mapping study, we have found a link between OAZ gene polymorphisms and SLE disease. Here we will continue delineating disease-related loci in OAZ gene by applying new screening strategy, and find out the effect of genotype alteration on OAZ transcription level in MSC. The role of RAS/MEK signal pathway in OAZ expression and the downstream pathways of OAZ to control CCL2 production will also be investigated through in vitro and in vivo studies. This project will help us better understand the molecular genetic mechanisms that regulate OAZ gene expression in lupus MSCs.

由于系统性红斑狼疮(SLE)患者间质干细胞(MSC)自身存在异常，其免疫调控能力大大减弱，可导致B细胞过度活化和疾病发生。前期我们观察到狼疮患者OAZ基因表达增高，且在MSC中的表达丰度要远高于外周血；正常MSC移植后OAZ转录水平逐步下降并伴随抗核抗体水平减低。体外研究显示OAZ基因沉默能恢复狼疮MSC对B细胞增殖、分化的抑制能力，减少抗核抗体产生，提示OAZ高表达是引起狼疮MSC异常的重要原因。MSC中OAZ表达调控的机制尚不清楚，通过基因定位研究我们已发现狼疮中该基因在结构上存在异常。本项目拟在此基础上应用新的多态性标记筛选策略寻找OAZ基因中的疾病相关位点，并弄清位点基因型变化对MSC中OAZ转录的影响，同时通过体内外研究解析RAS/MEK信号通路对OAZ基因表达的调控，探讨OAZ下游信号通路在抑制CCL2产生中的作用，从而较为完整地阐明狼疮MSC中OAZ高表达的分子遗传机制。

前期我们观察到，OAZ基因表达增高可引起系统性红斑狼疮（SLE）患者间质干细胞（MSC）功能异常，不能有效抑制B细胞活化，从而使自身抗体产生增多。在本研究中，我们首次发现SLE患者OAZ基因序列中存在SLE相关的多态性位点，其在功能上主要参与了细胞内转录、转录调控、小分子代谢、信号转导等进程；动物体内实验显示阻断OAZ有助于恢复体内免疫平衡，减少蛋白尿，提示OAZ有望成为SLE治疗的新靶点。研究期间已发表SCI论文6篇，获引用28次，另有1篇被接受，总影响因子25.8；同时，项目负责人入选了江苏省科教强卫工程医学重点人才，并作为参与人获得教育部科学技术二等奖1项。