Saikosaponin A Attenuates Obesity and Promotes Browning of White Adipose Tissue Via Modulation of the miR-26b-5p/MOB1B Axis.

This study focused on the role of Saikosaponin A (SSA), a triterpenoid saponin derived from Bupleurum root, in regulating lipid metabolism and obesity. Sprague-Dawley rats were fed a high-fat diet, and 3T3-L1 preadipocytes were transformed into mature adipocytes. SSA was administered to both rats and mature adipocytes at different concentrations. Dual-luciferase reporter assays and RNA immunoprecipitation were conducted to explore the interaction between MOB1B and miR-26b-5p. The protein expression levels of key browning markers, including peroxisome proliferator-activated receptor gamma (PPARγ), CCAAT/enhancer-binding protein alpha (C/EBPα), cytochrome c (CytoC), and peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC1α), were quantified via Western blotting. Oil Red O staining was utilized to evaluate the effect of SSA on lipid deposition, while hematoxylin and eosin staining was employed to assess lipid droplet accumulation in epididymal white adipose tissue (eWAT). Immunohistochemistry was used to determine MOB1B in eWAT. As detected, SSA promoted the browning of eWAT and 3T3-L1 adipocytes by modulating the miR-26b-5p/MOB1B axis. The browning effect was demonstrated by a decrease in lipid droplet buildup and an increase in thermogenic and adipogenic markers such as PPARγ, C/EBPα, CytoC, and PGC1α. This study not only clarifies the novel mechanism of SSA induced eWAT browning through miR-26b-5p/MOB1B axis, but also provides experimental basis for the development of obesity therapeutic strategies based on natural components.