Abstract
Excessive lipid accumulation is a critical characteristic in the development of nonalcoholic steatohepatitis (NASH). The underlying molecular mechanism, however, is unclear. In this study, we explored whether and how Krüppel-like factor 14 (KLF14) affects hepatic lipid metabolism in NASH. KLF14 expression was detected in NASH patients and mice fed a choline-deficient, L-amino acid-defined, high-fat diet (CDAHFD). Adeno-associated viruses and adenoviruses were used to alter hepatic KLF14 expression in vivo or in vitro to investigate how KLF14 functions in lipid regulation. The molecular mechanisms were explored using RNA-seq, luciferase reporter, and ChIP assays. The fatty liver phenotype was analyzed histopathologically, and serum and hepatocyte biochemical parameters were measured. The NASH mouse model developed quickly in C57BL/6J mice fed a CDAHFD for 8 weeks. We found that KLF14 expression was decreased in NASH patients and CDAHFD mice. Oleic acid and palmitic acid treatment also reduced KLF14 levels in hepatocytes. KLF14 knockdown downregulated the genes involved in fatty acid oxidation, promoting the progression of hepatic steatosis. In contrast, hepatic KLF14 overexpression alleviated lipid accumulation and oxidative stress in CDAHFD mice. These effects resulted from direct activation of the PPARα signaling pathway. PPARα inhibition diminished the KLF14 overexpression-reduced protective effects against steatosis in OA&PA-treated MPHs and AAV-KLF14-infected CDAHFD mice. These data reveal that hepatic KLF14 regulates lipid accumulation and oxidative stress through the KLF14-PPARα pathway as NASH progresses. KLF14 may be a novel therapeutic target for hepatic steatosis.