Panoply™ Human FFAR1 Knockdown Stable Cell Line

Non-alcoholic fatty liver disease (NAFLD) is the most common cause of chronic liver disease. G protein-coupled receptor 40 (GPR40), also named fatty acid receptor 1 (FFAR-1), is a membrane protein that can be activated by medium-chain fatty acids and long-chain fatty acids. GPR40 is a potential therapeutic target for energy metabolism disorders. SZZ15-11 is a newly synthesized GPR40 agonist. Here, researchers evaluated the effectiveness of SZZ15-11 in the treatment of NFLD. The study found that SZZ15-11 not only reduced hyperglycemia and hyperlipidemia in DIO mice but also improved NFLD. Furthermore, SZZ15-11 reduced triglyceride and total cholesterol levels in HepG2 cells. In both DIO mouse livers and HepG2 cells, SZZ15-11 upregulated AMPKα phosphorylation, which in turn downregulated the expression of 3-hydroxy-3-methylglutaryl-CoA reductase, a key enzyme in cholesterol production, and inhibited the activity of acetyl-CoA carboxylase. Furthermore, SZZ15-11 promoted AMPK activity through [cAMP]i accumulation. These results suggest that the novel GPR40 agonist SZZ15-11 can improve hyperlipidemia and fatty liver, partly through Gs signaling and the AMPK pathway in hepatocytes.

Similar to livers from DIO mice, SZZ15-11 also upregulated AMPKα phosphorylation in HepG2 cells. Furthermore, both SZZ15-11 and TAK875 significantly accelerated [cAMP]i accumulation in HepG2 cells, whereas the Gsα antagonist NF44923 inhibited this accumulation (Figure 1A). However, SZZ15-11 and TAK875 had no effect on intracellular calcium levels. Notably, the SZZ15-11-induced increase in AMPKα phosphorylation was reversed by NF449 (Figure 1B, C). Furthermore, SZZ15-11 significantly accelerated AMPKα phosphorylation regardless of whether the cells were cultured under normal conditions or in the presence of excess oleic acid (OA) (Figure 1D, E), indicating that AMPK activation in liver tissue from SZZ15-11-treated mice is not only caused by hypoglycemia but also by the action of the compound itself. To further verify whether SZZ15-11 promotes AMPK activation by activating GPR40, the researchers co-cultured GPR40-knockdown HepG2 cells with SZZ15-11. AMPKα phosphorylation levels in SZZ15-11-treated HepG2 cells were completely reduced in GPR40-knockdown HepG2 cells (Figure 1F, G). Taken together, these data suggest that SZZ15-11, as a GPR40 agonist, may activate the AMPK pathway by promoting the elevation of intracellular cAMP.

Figure 1. SZZ15-11 increases cAMP production and AMPKα phosphorylation levels in HepG2 cells. (Lei L, et al., 2024)