通过调控FGFR4二聚化拆分FGF19双重功能的分子设计及功能验证

FGF19调控机体糖脂代谢和胆汁酸代谢，但亦可诱导肝脏肿瘤。因此如何通过设计与优化规避FGF19致瘤性而保留其代谢调控功能是该领域的研究热点。研究表明FGF19在klotho辅助下与肝脏内FGFR4结合，进而由肝素分子诱导FGFR4二聚化，从而启动下游信号并最终发挥胆汁酸调控和致肝癌效应。新近报道调控受体二聚化可解离配体多种生物功能。受其启发，我们猜想：可通过影响FGFR4受体二聚化程度来分离FGF19的致瘤性和胆汁酸调控功能。前期工作我们探索性构建了一种肝素结合位点突变体FGF19K149A，结果表明相比野生型蛋白，突变体保留胆汁酸调控活性而促肝脏增殖显著降低。本课题将通过构建系列新型FGF19突变体，从分子、细胞和动物层面深入研究而验证假设；并采用转录组和基因沉默等方法探索FGFR4介导不同功能发挥的精准机制，进而为适于胆汁淤积等疾病治疗的FGF19突变体药物设计和开发提供理论指引。

FGF19 regulates glycolipid metabolism and bile acid metabolism, but also induces liver tumor. Therefore, how to preserve the metabolic regulatory function and avoid the tumorigenicity of FGF19 by designing and optimizing is a hot topic in this field. Studies have shown that FGF19 selectively binds to fibroblast growth factor 4 (FGFR4) in liver with the assistance of klotho, and then induces FGFR4 dimerization by heparin molecules, thereby triggering downstream signaling and ultimately exerting bile acid regulation and HCC. Recent studies showed that multiple biological functions of ligands could be decoupled by the regulation of receptor dimerization. Inspired by this, we suspect that the tumorigenicity and the regulatory activity of bile acid regulation can be separated by affecting the degree of FGFR4 dimerization. In the previous work, we explored a heparin binding site mutant FGF19K149A. The results showed that compared with wild-type FGF19WT, the mutant maintained bile acid regulatory activity with significantly reduced proliferation. This project will construct a series of new FGF19 mutants and verify the hypothesis at the molecular, cellular, and in vivo levels. Then, the transcriptome and gene silencing method will be applied to explore precise mechanisms of FGFR4 mediated different functions, providing theoretical guidance for drug design and development of FGF19 mutants for the treatment of diseases such as cholestasis.