DUSP9 alleviates hepatic ischemia/reperfusion injury by restraining both mitogen-activated protein kinase and IKK in an apoptosis signal-regulating kinase 1-dependent manner: Role of DUSP9 in hepatic ischemia/reperfusion injury

Hepatic ischemia/reperfusion (I/R) injury occurs frequently in various liver operations and diseases, but its effective treatment remains inadequate because the key switch that leads to hepatic explosive inflammation has not been well disclosed. Dual specificity phosphatase 9 (DUSP9) is widely involved in the innate immune response of solid organs and is sometimes regulated by ubiquitin. In the present study, we find that DUSP9 is reduced in mouse hepatic I/R injury. DUSP9 enrichment attenuates hepatic inflammation both in vivo and in vitro as revealed by western blot analysis and qRT-PCR. In contrast, DUSP9 depletion leads to more severe I/R injury. Mechanistically, DUSP9 inhibits the phosphorylation of apoptosis signal-regulating kinase 1 (ASK1) by directly binding to ASK1, thereby decreasing tumor necrosis factor receptor-associated factor 6 (TRAF6), K63 ubiquitin and the phosphorylation of p38/JNK1 instead of ERK1. The present study documents a novel role of DUSP9 in hepatic I/R injury and implies the potential of targeting the DUSP9/ASK1 axis towards mitogen-activated protein kinase and TRAF6/inhibitor of κB kinase pathways.