Rottlerin Suppresses Fat Accumulation by Inhibiting Adipogenesis and De Novo Lipogenesis in 3T3-L1 Adipocytes

Abstract

ObjectivesRottlerin is isolated from Mallotus japonicus, a rich-in polyphenol. Rottlerin is a PKC delta inhibitor known for an uncoupler of oxidative phosphorylation and anti-neoplastic agent. However, the effect of anti-obesity is not conclusive. This study hypothesized that rottlerin inhibits lipid accumulation in adipocytes. Methods3T3-L1 cells were maintained with DMEM containing 10% BCS and 1% penicillin. The cells were seeded in a 6-well plate with a density of 8 × 104 followed by cultured for 4 days until reaching 120% confluency and incubated in a differentiation medium for 6 days. Rottlerin was incubated with differentiation media (0, 1, 2, and 4 μM). Cells were harvested after treatment for measurement of Oil Red O stating, immunoblotting, and RT-PCR. ResultsDifferentiated 3T3-L1 adipocytes were stained using the Oil Red O, which stains triglycerides into the red. Lipid accumulation was significantly inhibited in 4 μM of rottlerin (P < 0.001). In protein levels, PPARγ, an adipogenesis marker, was reduced dose-dependently decreased (P < 0.001), indicating lipid droplet formation reduced. FAS and SCD1 were diminished by rottlerin treated groups (all P < 0.001). ACC-pS79/ACC was increased by rottlerin (P = 0.02). In mRNA gene expressions, C/EBPα was reduced by rottlerin in a dose-dependent manner (P < 0.001), and PPARγ tend to be decreased by rottlerin (P = 0.06). FAS and SREBP1 were inhibited by rottlerin (P < 0.01). SCD1 was dramatically reduced by rottlerin (P < 0.001). ConclusionsWe found that rottlerin reduces lipid accumulation by inhibiting adipogenesis in differentiated 3T3-L1 adipocytes. This suggests that rottlerin is a potential nutraceutical for treating dyslipidemia, non-alcoholic fatty liver disease, and obesity. Funding SourcesThis work was supported by the National Research Foundation of Korea (NRF) grant funded by the Korea government (Ministry of Science and ICT; MSIT).