miR-34a在缺血/再灌注诱导的肝细胞损伤中的作用及机制研究

Hepatic Ischemia-Reperfusion (HIR) injury is a dynamic process that frequently occurs during a variety of clinical situations, including liver transplantation and liver surgery. It is well known that apoptosis of hepatocytes is one of important pathological features in HIR injury. However, the molecular mechanism of HIR injury is still unclear. Our preliminary results showed that levels of miR-34a were significantly increased but those of Nrf2 were significantly decreased in liver tissue of mice and hepatocytes suffering HIR. Downregulation of miR-34a could increase the Nrf2 expression and improve liver damage in HIR mice and decrease apoptosis of hepatocytes. Overexpression of miR-34a could increase the hepatocytes injury. In addition, treatment with Bay 11-7082, an inhibitor of NF-κB, reversed the increase of miR-34a expression in hepatocytes following HIR. Based on the foregoing issues, we speculated that miR-34a down-regulating Nrf2 expression might play an important role in HIR injury via NF-κB-dependent pathway. In present study, we aim to demonstrate the effect of miR-34a on hepatocytes injury induced by HIR using a series of molecular biology methods in vivo and in vitro, including the establishment of miR-34a knockout mice and transgenic mice. And we will further explore the molecular mechanism of miR-34a on hepatocytes injury induced by HIR, trying to provide a potential target for the treatment of hepatic injury in the future.

肝脏缺血再灌注（Hepatic Ischemia-Reperfusion, HIR）损伤多见于肝移植、肝切除等手术过程中，肝细胞凋亡是其重要病理特征，但具体分子机制仍不清楚。本课题的前期研究显示：HIR引起小鼠肝组织和肝细胞内miR-34a表达增加、Nrf2表达降低；干扰miR-34a可增加Nrf2的表达并改善HIR造成的肝细胞损伤；过表达miR-34a可加剧HIR造成的肝细胞损伤；抑制NF-κB的活性能逆转肝细胞损伤造成的miR-34a表达增加。由此，我们推测，HIR可能通过NF-κB增加miR-34a的表达，进而抑制Nrf2表达，从而在HIR损伤中发挥重要作用。本项目旨在细胞和动物水平上，借助多种分子生物学和基因工程小鼠的技术手段，研究miR-34a在HIR诱导的肝细胞损伤中的作用。本项目的完成将有助于阐明miR-34a在HIR损伤中的作用机制，并为防治肝细胞损伤提供一个直接的作用靶点。

肝脏缺血再灌注（Hepatic Ischemia-Reperfusion, HIR）损伤多见于肝移植、肝切除等手术过程中，肝细胞凋亡是其重要病理特征，但具体分子机制仍不清楚。我们的研究显示：HIR引起小鼠肝组织和肝细胞内MEG3表达显著降低，miR-34a表达增加、Nrf2表达降低；体外细胞缺氧/再给氧后，MEG3表达显著降低，miR-34a表达显著升高，Nrf2的mRNA和蛋白表达水平降低；进一步的研究证明MEG3与miR-34a可特异结合，MEG3过表达可以逆转体外H/R诱导的miR-34a表达升高，并能逆转体外H/R诱导的Nrf2表达降低，改善体外H/R诱导的肝细胞凋亡。本项目在体外和体内水平上，研究了miR-34a在HIR诱导的肝细胞损伤中的作用。将有助于阐明miR-34a在HIR损伤中的作用机制，并为防治肝细胞损伤提供一个直接的作用靶点。此外，在肝缺血再灌注损伤动物模型和细胞模型中，我们发现miR-214表达均显著下调，miR-214通过TRAF1/ASK1/JNK通路抑制肝细胞凋亡，从而缓解肝缺血再灌注损伤。