Fat Accumulation in the Liver of Obese Rats is Alleviated by Soy Protein Isolate through β-catenin signaling

OBJECTIVES: The current study aim to investigate the effects of SPI on Wnt/β-catenin signaling in the liver of obese rats, as well as the roles of this pathway in regulating the hepatic fat accumulation. DESIGN AND METHODS: Obese and lean Zucker rats were fed diets containing either casein or SPI as protein source for 17 weeks. Histology and biochemical analysis, real-time PCR, Western blot, immunostaining, short interfering RNA assay were performed for liver samples. RESULTS: Our study showed that fat content was significantly lowered in the liver of SPI-fed obese rats, accompanied by a reduction in hepatocellular vacuolation, compared to the casein-fed control. β-catenin protein level in the liver of obese rats was down-regulated compared to the lean group, indicating that the obese genotype exhibits an overall reduction in Wnt signaling. Importantly the repression of β-catenin in the obese rats was alleviated by feeding the SPI diet. siRNA treatment in rat hepatoma cells confirmed that silencing of β-catenin exacerbated fatty acid-induced fat accumulation, which implicated an important function of Wnt/β-catenin signaling in hepaticfat metabolism. CONCLUSIONS: SPI intake restored β-catenin signaling and alleviated hepatic fat accumulation and liver damage in the obese rats.