AP1 inhibits adipogenesis through down-regulation of PPARγ and modulation of PI3K/Akt and FoxO pathways in 3T3-L1 cells

Abstract

Abalone has long been used as a valuable food source in East Asian countries. Although the nutritional importance of abalone has been reported through in vitro and in vivo studies, there is little evidence about the potential anti-obesity effects of abalone. The present study investigated the inhibitory effects of AP1 on the differentiation of 3T3-L1 preadipocytes. AP1 potently and dose-dependently suppressed accumulation of lipid droplets in adipocyte. Western blot analysis revealed that AP1 markedly down-regulated the protein levels of adipogenesis regulator peroxisome proliferator-activated receptor (PPAR)γ, CCAAT/enhancer binding protein (C/EBP)α, sterol regulatory element-binding protein (SREBP)1 as well as a key enzyme involved in adipogenesis. In addition, AP1 diminished the insulin-stimulated phsphoinositide 3-kinase (PI3K), phosphorylarion of Akt, glycogen synthase kinase-3 beta (GSK3β) and forkhead transcription factors, which may reduce glucose uptake in response to insulin and lipid accumulation. These results indicate that AP1 suppresses adipocyte differentiation and lipid accumulation through multiple mechanisms and may have applications for the treatment of obesity.