Prdx5在大鼠小体积肝移植物损伤中保护作用及机制研究

The small-for-size liver graft syndrome has seriously hampered the promotion and development of living donor liver transplantation, and its molecular mechanisms have not been revealed completely. In our previous proteomic study, we found decreased expression of Prdx5 was closely related to the small size liver graft injury in rats. Further bioinformatics analysis revealed that Prdx5 was associated with cell processes such as oxidative stress, apoptosis, necrosis. We further overexpressed Prdx5 in the small-for-size liver grafts through adenoviral vectors, we found the injury of small-for-size liver grafts was significantly alleviated. Prdx5 is an important antioxidative protein in various cell types, and its protective role of small-for-size liver grafts was first reported by us. Some investigators found that decreased expression of Prdx5 might activate signaling pathways of p53, JNK, p38 MAPK and et.al, to induce cell apoptosis. Other researchers found that transcriptional factors, such as Nrf2, NF-КB, Ets1/2 and Foxo3a, could bind to antioxidative response elements localized in promoter region of Prdx5 to regulate expression of Prdx5. Further studies of these factors related to Prdx5 in small-for-size liver grafts may help us understand the potential mechanisms of Prdx5. Based on these studies, Prdx5 could be a new target for prevention of the small-for-size syndrome in the future.

小肝综合症严重制约活体肝脏移植的深入发展，目前对其分子机制尚无系统研究。申请人首次发现Prdx5低表达和小体积肝移植物损伤密切相关，生物信息学分析发现Prdx5主要与氧化应激、凋亡、坏死等细胞进程相关，通过Prdx5腺病毒载体提高小肝移植物中的表达水平，能明显减轻小肝移植物的损伤（已发表于J Hepatology，2010）。Prdx5是生物体内重要的抗氧化应激蛋白，一方面Prdx5表达量下降后可激活下游p53、JNK、p38 MAPK等信号通路，启动细胞凋亡；另一方面Nrf2、NF-КB、Ets1/2以及Foxo3a等可与Prdx5启动子区域的抗氧化效应元件结合，调控Prdx5表达。目前在小肝移植物中对Prdx5及上下游相关因子的研究尚处于空白。本项目研究小肝移植物中Prdx5与上下游相关因子的相互作用，揭示Prdx5在小肝移植物损伤中的作用和潜在机制，为临床防治小肝综合症提供理论基础。

小肝综合征可能的分子机制一直是活体肝脏移植研究的热点和难点。在本研究中，我们通过构建相关因子的腺病毒载体及其shRNA慢病毒载体，建立相关因子超表达及低表达的体外细胞系模型，建立H2O2诱导肝细胞系损伤的模型以及建立大鼠小体积肝移植物及小鼠热缺血再灌注损伤模型，系统阐明了大鼠小体积肝移植物中Prdx5表达降低的上游调控机制，以及下游相关信号通路激活加重小肝移植物损伤的可能机制，并将Prdx5作为干预靶点，以多种策略上调Prdx5的表达，比较几种策略对大鼠小体积肝移植的保护作用的差异，从而为降低临床活体肝移植中小肝综合症的危害提供新的依据和靶点。在本项目中，我们首次探索了抗氧化应激蛋白Prdx5对大鼠小体积肝移植的保护作用及可能的分子机制，并从细胞水平和动物水平探讨了基于Prdx5的多种治疗策略对大鼠小体积肝移植物的保护作用，从而为发现新的预防小肝综合症治疗方法提供线索。