Work

2-O-Methylhonokiol Suppresses 3T3-L1 Adipogenesis Through Metabolic Stress Signaling and Early Cell Cycle Restriction

Year: 2026

Type: article

Abstract: Excessive adipose tissue expansion contributes to metabolic dysfunction, highlighting the need to identify compounds that restrain adipocyte differentiation without causing nonspecific cytotoxicity. This study investigated whether 2-O-methylhonokiol suppresses adipogenesis in 3T3-L1 preadipocytes and examined its effects on adipogenic transcription, metabolic signaling, ER stress-related responses, kinase activity, and early cell cycle progression. 3T3-L1 cells were induced to differentiate with an MDI cocktail and treated with 25 or 50 µM 2-O-methylhonokiol during differentiation. Lipid accumulation was evaluated by Oil Red O staining, protein expression and phosphorylation were analyzed by immunoblotting, cell cycle distribution was assessed 24 h after MDI induction, and basal viability was measured using the CCK-8 assay. 2-O-methylhonokiol markedly reduced neutral lipid accumulation and suppressed key adipogenic regulators and maturation markers, including C/EBPβ, PPARγ, C/EBPα, FABP4, and FASN. At the signaling level, 2-O-methylhonokiol increased AMPKα phosphorylation without altering total AMPKα and reduced FASN expression, whereas mTOR phosphorylation was reduced at 50 µM. These findings suggest that 2-O-methylhonokiol is associated with metabolic and lipogenic signaling remodeling during adipocyte differentiation. 2-O-methylhonokiol also modified kinase-associated responses, increasing AKT and JNK phosphorylation while reducing the detectable phosphorylated ERK signal, with total AKT, ERK, and JNK remaining largely unchanged. ER stress-related signaling displayed a selective profile, characterized by increased IRE1α expression, XBP1s induction, elevated p-eIF2α, unchanged total eIF2α, and no compensatory increase in GRP78. During early adipogenesis, 2-O-methylhonokiol attenuated MDI-induced cell cycle redistribution by preserving a larger G0/G1 population and limiting progression toward later cell cycle phases, consistent with impaired mitotic clonal expansion. These effects occurred at concentrations that did not significantly reduce basal cell viability. Overall, 2-O-methylhonokiol suppresses 3T3-L1 adipogenesis by reducing adipogenic and lipogenic execution, accompanied by AMPK-associated metabolic remodeling, kinase signaling changes, selective ER stress-related responses, and restriction of early cell cycle progression. Further pathway-specific studies are required to define the causal contribution of each signaling axis.

Source: International Journal of Molecular Sciences

DOI: 10.3390/ijms27146529