环状RNAcircRSF1通过吸附miR-146a-5p和结合HuR蛋白调控肝星状细胞功能影响放射性肝病发病的分子机制

As the common complication of liver cancer radiotherapy, radiation-induced liver disease (RILD) is mainly characterized by radiation-induced hepatitis and liver fibrosis. Previous research has clarified that microRNA (miR)-146a-5p negatively regulates TLR4 pathway of hepatic stellate cell (HSC) to inhibit inflammatory and fibrotic phenotype of HSC and thus attenuates RILD. Previous experiments showed that the circular RNA RSF1 (circRSF1), which has binding sites with miR-146a-5p, is elevated in irradiated and lipopolysaccharide stimulated HSC, and its high expression promotes the inflammatory and fibrotic phenotype of HSC and up-regulates the expression of TLR4 pathway gene. In addition, circRSF1 binds to HuR protein and hinders HuR binding to the anti-inflammatory gene, and that repressing the expression of HuR promotes the inflammatory phenotype of HSC. Therefore, it is speculated that circRSF1 regulates HSC function by adsorbing miR-146a-5p and binding to HuR to affect the pathogenesis of RILD. This project is to investigate the role of circRSF1 in the regulation of TLR4 pathway via adsorbing miR-146a-5p, and the mechanism by which circRSF1 promotes the activation of inflammatory pathways through binding to HuR. Animal experiments and clinical data are used to verify the relationship between circRSF1 expression and RILD pathogenesis. It will provide strategies for the prevention and treatment of RILD.

以放射性肝炎和肝纤维化为主要表现的放射性肝病（RILD）是肝癌放疗的常见并发症。前期研究发现小RNA（miR）-146a-5p负调控肝星状细胞（HSC）TLR4通路抑制HSC炎性和纤维化表型，缓解RILD。预实验显示：与miR-146a-5p有结合点的环状RNA RSF1（circRSF1）在接受辐射和脂多糖刺激的HSC中表达升高，且其高表达促进HSC炎性和纤维化表型并上调TLR4通路基因表达；circRSF1能结合HuR蛋白并阻遏HuR结合抑炎基因，且抑制HuR表达促进HSC炎性表型，因此推测circRSF1通过吸附miR-146a-5p和结合HuR调控HSC功能影响RILD发病。本项目拟探讨circRSF1吸附miR-146a-5p对TLR4通路的调控作用，以及结合HuR促进炎症通路激活的机制，并利用动物和临床资料验证circRSF1表达与RILD发病的关系，为RILD的防治提供策略。

放射性肝病（RILD）是肝癌放疗常见并发症之一。辐射诱导的肝星状细胞（HSC）炎性和纤维化表型促进RILD的发生发展。本项目发现：（1）转录自RSF1的环状RNA(circRNA)hsa_circ_0023706作为miR-146a-5p海绵上调RAC1表达，激活下游NF-κB和JNK/SMAD2通路，促进辐射诱导的HSC炎性和纤维化表型。（2）hsa_circ_0023706能够与HuR蛋白结合，减少HuR蛋白与抑炎基因IκB的结合，参与调控下游炎症通路的激活，促进HSC炎性表型。（3）转录自RSF1的另一个circRNA hsa_circ_0096498在人和小鼠体内具有较好的保守性。hsa_circ_0096498在受照的HSC中明显上调，并通过结合EIF4A3阻遏EIF4A3与CDC42 mRNA结合，导致CDC42的稳定性和表达下调，从而抑制CDC42介导的HSC炎性及纤维化表型。本项目发现来源于同一个转录本的不同circRNA可以发挥截然不同的调控功能。该发现进一步丰富了RILD发病过程中的circRNA调控网络，加深对亲本基因同源的circRNA发挥不同调控效应的理解，有望为RILD诊治标志物的筛选提供新见解。