Uric acid is the end metabolite derived from the oxidation of
purine compounds. Overwhelming evidence shows the vital interrelationship between
hyperuricemia (HUA) and
nonalcoholic fatty liver disease (
NAFLD). However, the mechanisms for this association remain unclear. In this study, we established a
urate oxidase-knockout (Uox-KO) mouse model by clustered regularly interspaced short palindromic repeats (CRISPR)-Cas9 technology. To study the correlation between HUA and
NAFLD, human HepG2
hepatoma cells were treated in culture medium with high level of
uric acid. In vivo, the Uox-KO mice spontaneously developed
hyperuricemia and aberrant lipid-metabolism, concomitant with abnormal hepatic fat accumulation. HUA activated
c-Jun N-terminal kinase (JNK) in vivo and in vitro. Furthermore, inhibiting JNK activation by a JNK-specific inhibitor,
SP600125, decreased fat accumulation and lipogenic gene expression induced by HUA. Overexpression of the lipogenic
enzymes fatty acid synthase and
acetyl-CoA carboxylase 1 was via activation of JNK, which was blocked by the JNK inhibitor
SP600125. HUA activated
AP-1 to upregulate lipogenic gene expression via JNK activation. In addition, HUA caused
mitochondrial dysfunction and
reactive oxygen species production. Pretreatment with the
antioxidant N-acetyl-l-cysteine could ameliorate HUA-activated JNK and hepatic steatosis. These data suggest that ROS/JNK/AP-1 signaling plays an important role in HUA-mediated fat accumulation in liver.NEW & NOTEWORTHY
Hyperuricemia and
nonalcoholic fatty liver disease are global public health problems, which are strongly associated with
metabolic syndrome. In this study, we demonstrate that
uric acid induces hepatic fat accumulation via the ROS/JNK/AP-1 pathway. This study identifies a new mechanism of
NAFLD pathogenesis and new potential therapeutic strategies for HUA-induced
NAFLD.