多囊蛋白1调控补体B因子表达机制的探讨

Autosomal dominant polycystic kidney disease (ADPKD) is the most common monogenic inherited disease, 85% of ADPKD patients are caused by the dysfunction of polycystin-1. However, the pathogenesis of ADPKD caused by polycystin-1 dysfunction still remains further exploration. In our previous study, we found excessive activation of the alternative complement pathway in the kidney tissue of ADPKD patients and animal models of polycystic kidney disease. The expression pattern of alternative complement pathway in ADPKD was different from autoimmune diseases such as IgA nephropathy, and lupus nephritis. Inhibiting the expression and activity of the alternative complement pathway significantly delayed the progression of polycystic kidney disease, indicating that the excessive activation of alternative complement pathway in the polycystic kidney was associated with the progression of the disease. Based on our previous findings, we will further explore the role and the mechanism of polycystin-1 in the regulation of expression of complement factor B, the initial factor of alternative complement pathway, by utilizing various biological techniques such as RNA interference, molecular probes and luciferase reporter gene. We will prove the hypothesis that polycystin-1 regulates the expression of complement factor B through JAK2-STAT3 pathway, or through polycystin-1 C-terminal cleavage fragment P30 together with STAT3. Our study will further elucidate the pathogenesis of polycystic kidney disease, and will provide a cutting-edge theory and experimental basis for finding novel intervention targets in the polycystic kidney disease.

常染色体显性多囊肾病(ADPKD)是最常见的单基因遗传病，其中约85％患者由多囊蛋白1功能异常引起，其对ADPKD发生的作用机制至今未能完全阐明。我们在前期研究中发现补体替代途径在ADPKD患者和模型动物多囊肾组织中异常活跃，其补体表达谱与自身免疫性疾病如IgA肾病、狼疮性肾炎等不同，抑制其补体表达或活性显著延缓多囊肾病进展，说明补体替代途径过度活化与多囊肾病进展相关。本项目拟在前期研究基础上采用基因敲除、过表达或突变细胞和动物模型，应用RNA干扰、分子探针及荧光素酶报告基因等多项技术进一步探讨多囊蛋白1对补体替代途径启动因子－补体B因子的调控作用及机制，以证实多囊蛋白1经JAK2-STAT3通路，或多囊蛋白1胞内羧基端游离肽段P30作用STAT3，调控补体B因子的假设，以进一步阐明多囊肾病的发病和进展机制，为临床寻找干预多囊肾病的新靶标提供新颖的理论和实验依据。

常染色体显性多囊肾病(ADPKD)是最常见的单基因遗传病，其中约85％患者由多囊蛋白1 功能异常引起，其对ADPKD 发生的作用机制至今未能完全阐明。我们在前期研究中发现补体替代途径在ADPKD 患者和模型动物多囊肾组织中异常活跃，抑制其补体表达或活性显著延缓多囊肾病进展，说明补体替代途径过度活化与多囊肾病进展相关。本项目研究发现在多囊肾病肾脏中补体B因子(CFB)的表达上调与JAK2/STAT1通路的活化成正相关。过表达或抑制STAT1会增加或减少CFB表达和其启动子活性。此外在肾小管上皮细胞中过表达多囊蛋白1胞内段（PC1-CTT）增强JAK2/STAT1活性并增加CFB表达。过表达PC1-CTT增加CFB启动子活性，而同时转染STAT1突变质粒或突变CFB启动子上STAT1结合位点会降低PC1-CTT诱导的CFB启动子活性。体外实验发现具有生物学活性的CFB能剂量依赖性的促进巨噬细胞M2型转化。PC1-CTT转染的肾小管上皮细胞条件培养液促进巨噬细胞M2型转化，但被STAT1抑制剂fludarabine或CFB抗体抑制。本项目揭示了在ADPKD中CFB表达调控的新机制和PC1-CTT在ADPKD炎症中的作用。此外我们的实验提示STAT1可以作为抑制多囊肾炎症的新靶点，本项目为临床寻找干预多囊肾病的新靶标提供新颖的理论和实验依据。