Fig. 4: SGA binds SIRT1 and improves ethanol-induced cell damage likely via the SIRT1-PPAR-α/mTOR axis.
From: Saikogenin A improves ethanol-induced liver injury by targeting SIRT1 to modulate lipid metabolism
A Molecular modeling analysis of SSa to the catalytic binding site of the SIRT1 kinase domain. Left: Complete view of SSa in the binding site of SIRT1 (cartoon). Right: close-up view of SSa in the binding sites of SIRT1 (surface). B Microscale thermophoretic analysis of SSa and its metabolites SSB1 and SGA and their interactions with SIRT1. The NHS-ester RED dye binds covalently to the Recombination Human SIRT1 protein lysine side chain and was incubated with increasing concentrations of SSa, SSB1, or SGA, and the binding reactions were subjected to MST. SSa, SSB1, and SGA bind to SIRT1 with Kd values of 25.176 μmol/L, 97.617 μmol/L, and 23.764 μmol/L, respectively. C Cells were subjected to various concentrations of SGA or SSa for 24 h. Logarithmic transformation of SGA or SSa concentrations and cell viability data were fitted to a nonlinear regression curve (log(inhibitor) vs. response-variable slope) to ascertain the LC50 of LO2 (n = 6). D, E FCM was employed to analyze the ROS levels with ethanol and/or SGA cotreatment, with or without SIRT1 knockdown in HepG2 cells (n = 3). F, G Oil Red O staining detected lipid droplets with ethanol and/or SGA cotreatment, with or without SIRT1 knockdown in HepG2 cells (Scale Bar:75 µm) (n = 3). H Protein level changes in phosphorylated mTOR, total mTOR, SIRT1, PGC- 1α, and PPAR-α with ethanol and/or SGA cotreatment, with or without SIRT1 knockdown in HepG2 cells (n = 3). I Representative confocal microscopy images (Scale Bar:20 µm) of immunostaining targeting SIRT1 in primary hepatocytes cells from mice (n = 5).
