Sesamolin suppresses adipocyte differentiation through Keap1-dependent Nrf2 activation in adipocytes.

Sesamolin, a lignan isolated from sesame oils, has been found to possess neuroprotective, anticancer, and free radical scavenging properties. We hypothesized that sesamolin could stimulate the activity of nuclear factor erythroid-derived 2-like 2 (Nrf2) and inhibit adipocyte differentiation of preadipocytes. The objective of this study was to investigate effects of sesamolin on adipocyte differentiation and its underlying molecular mechanisms. In this study, we determined the effects of treatment with 25 to 100 µM sesamolin on adipogenesis in cell culture systems. Sesamolin inhibited lipid accumulation and suppressed the expression of adipocyte markers during adipocyte differentiation of C3H10T1/2, 3T3-L1, and primary preadipocytes. Mechanism studies revealed that sesamolin increased Nrf2 protein expression without inducing its mRNA, leading to an increase in the expression of Nrf2 target genes such as heme oxygenase 1 and NAD(P)H:quinone oxidoreductase 1 (Nqo1) in C3H10T1/2 adipocytes and mouse embryonic fibroblasts. These effects were significantly attenuated in Nrf2 knockout (KO) mouse embryonic fibroblasts, indicating that effects of sesamolin were dependent on Nrf2. In H1299 human lung cancer cells with KO of Kelch like-ECH-associated protein 1 (Keap1), a negative regulator of Nrf2, sesamolin failed to further increase Nrf2 protein expression. However, upon reexpressing Keap1 in Keap1 KO cells, the ability of sesamolin to elevate Nrf2 protein expression was restored, highlighting the crucial role of Keap1 in sesamolin-induced Nrf2 activation. Taken together, these findings show that sesamolin can inhibit adipocyte differentiation through Keap1-mediated Nrf2 activation. • Sesamolin inhibits lipid accumulation during adipocyte differentiation. • Sesamolin inhibits adipocyte markers expression in C3H10T1/2 adipocytes. • Seasmolin enhances Nrf2 protein levels and its target genes expression. • The effects of sesamolin on Nrf2 activation are dependent on Keap1 protein. The effects of sesamolin on adipogenesis in C3H10T1/2 cells and molecular mechanisms were investigated in Nrf2 KO and Keap1 KO cells. Sesamolin at 50 to 100 µM activated the Nrf2, inhibited lipid accumulation and suppressed adipocyte markers expression. Sesamolin's inability to activate the Nrf2 pathway in Keap1 KO lung carcinoma cells can be rescued by reexpression of Keap1. Abbreviations: Keap1, Kelch-like ECH-associated protein 1; Nrf2, Nuclear factor erythroid-2-related factor 2; KO, knockout. [Display omitted] [ABSTRACT FROM AUTHOR]