Roquin-1 Regulates Macrophage Immune Response and Participates in Hepatic Ischemia–Reperfusion Injury

Abstract

With the development of liver surgery, ischemia–reperfusion (IR) injury has received increasing attention. Roquin-1 has been shown to play an important role in innate immune and immune balance. We demonstrate that Roquin-1 expression increased at 1 h after IR and then decreased in C57B/L mice. The immunofluorescence double-label showed that Roquin-1 was mainly expressed in macrophages (mø). Furthermore, we used clodronate liposomes to remove mø, and injected the bone marrow–derived mø (BMDM) through the tail vein in 1 h before IR. We found that liver IR injury was aggravated by Roquin-1 interference. The results of PCR and ELISA suggested that after interference with Roquin-1, mø increased toward M1 and decreased toward M2. Then, interference with Roquin-1 promoted the polarization of mø to M1 and inhibited the polarization of M2. By Western blot technology and AMPKα and mTOR inhibitors, we found that Roquin-1 promotes the phosphorylation of mTOR and STAT3 by inhibiting the phosphorylation of AMPKα. We used AICAR to activate AMPKα in mø and found that the level of ubiquitination of AMPKα was decreased after activation of AMPKα. Furthermore, by bioinformatics methods, we identified potential ubiquitination sites on AMPKα. By the point mutation experiments in vitro, we confirmed that the ubiquitination of these sites is regulated by Roquin-1. Meanwhile, Roquin-1 interference inhibited the activation and function of AMPKα. This topic describes the protection of liver IR injury by Roquin-1 and discusses its main mechanism for regulating AMPKα activity through ubiquitination and affecting the polarization of mø.