Regulator of G-protein signaling 14 protects the liver from ischemia reperfusion injury by suppressing TAK1 activation

BACKGROUND & AIMS Hepatic ischemia-reperfusion injury (IRI) is a common complication of hepatectomy and liver transplantation. However, the mechanisms underlying hepatic IRI have not been fully elucidated. The regulator of G-protein signaling 14 (RGS14) is a multifunctional scaffolding protein that integrates G-protein and mitogen-activated protein kinase (MAPK) signaling pathways. However, the role of RGS14 in hepatic IRI remains unclear. APPROACH & RESULTS We found that RGS14 expression increased in mice subjected to hepatic IR surgery and during hypoxia reoxygenation in hepatocytes. We constructed global RGS14 knockout (RGS14-KO) and hepatocyte-specific RGS14 transgenic (RGS14-TG) mice to establish 70% hepatic IRI models. Histological H&E staining, levels of alanine aminotransferase (ALT) and aspartate aminotransferase (AST), expression of inflammatory factors, and apoptosis were used to assess liver damage and function in these models. We found that RGS14 deficiency significantly aggravated IR-induced liver injury and activated hepatic inflammatory responses and apoptosis in vivo and in vitro. Conversely, RGS14 overexpression exerted the opposite effect of the RGS14-deficient models. Phosphorylation of transforming growth factor-β-activated kinase 1(TAK1) and its downstream effectors JNK and p38 increased in the liver tissues of RGS14-KO mice, but was repressed in those of RGS14-TG mice. Furthermore, inhibition of TAK1 phosphorylation rescued the effect of RGS14 deficiency on JNK and p38 activation, thus blocking the inflammatory responses and apoptosis. CONCLUSIONS RGS14 plays a protective role in hepatic IR by inhibiting the activation of the TAK1-JNK/p38 signaling pathway. This may be a potential therapeutic strategy for reducing incidences of hepatic IRI in the future.