Klf15-Activating Twist2 Ameliorated Hepatic Steatosis By Inhibiting Inflammation And Improving Mitochondria! Dysfunction Via Nf-Kappa B-Fgf21 Or Srebp1c-Fgf21 Pathway

Twist-related protein 2 (TWIST2) is identified as a basic helix-loop-helix (b-HLH) transcription repressor by dimerizing with other b-HLH proteins. The significance of TWIST2 has been emphasized in various tumors; however, few studies report its functions in metabolism and metabolic diseases. Here we aimed to explore the novel role and regulation mechanism of TWIST2 in hepatic steatosis. Our results showed that Twist2 knockdown caused mice obesity, insulin resistance, and hepatic steatosis, which were accompanied with inflammation, endoplasmic reticulum stress, and mitochondrial dysfunction. In vitro, TWIST2 overexpression ameliorated hepatocellular steatosis, inhibited inflammation, and improved mitochondrial content and function with a fibroblast growth factor 21 (FGF21) dependent pattern. NF-kappa B negatively regulated FGF21 transcription by directly binding to FGF21 promoter DNA, which was eliminated by TWIST2 overexpression by inhibiting NF-kappa B expression and translocation to nucleus. TWIST2 overexpression decreased intracellular reactive oxygen species level, increased mitochondrial DNA and biogenesis, and enhanced ATP production and antioxidation ability. Additionally, TWIST2 expression was repressed by insulin-targeting sterol regulatory element binding protein 1c (SREBP1c) and forkhead box protein O1 and was enhanced by dexamethasone targeting Kriippel-like factor 15, which directly interacted with Twist2 promoter DNA. Together, our studies identify an important role and regulation mechanism of TWIST2 in maintaining hepatic homeostasis by ameliorating steatosis, inflammation, and oxidative stress via the NF-kappa B FGF21 or SREBP1c-FGF21 pathway, which may provide a new therapeutic scheme for nonalcoholic fatty liver disease.