Topical Area: Obesity
Both obesity and obesogenic environments(OE) to induce the fat accumulation are being the risk factors of various metabolic diseases. By 6 year-cohort study, we found that MEK6 gene and salt intake were positively related with inducing obese as part of OE factors such as lifestyle, genes, and eating habits etc. Objectives of study are to find the effects of MEK6 gene and salt treatment on adipogenesis using MEK6 over-expressed 3T3-L1 cells.
Methods : After transformation for MEK6 over-expressed 3T3-L1 with lipofectamine 3000 (Invitrogen, California, USA) was confirmed by PCR method, salt was treated as 50mM in the form of NaCl without cytotoxicity (MTT assay). Cell differentiation and TG synthesis(Oil Red O;ORO & DAPI/Nile red staining), and protein expression (western blotting analysis) associated with adipogenesis genes (PPAR-γ, C/EBP-α & aP2) and adipocytokines (adiponectin & leptin) were performed. ELISA kits were used for estimating inflammatory factors such as TNF-α, IL-1β, IL-10, MCP-1, PAI-1 etc. Real-time oxygen consumption in alive cells was measured every 17 seconds for 100 minutes. (Mito-Xpress O2 consumption array kit) All analyses were performed using SAS9.1 software and p-values of < 0.05 were interpreted as statistically significant.
We confirmed the salt induced the protein expression associated with adipogenesis (PPAR-γ, C/EBP-α and aP2) in both control and MEK6 over-expressed cells. The levels of inflammatory cytokine factors (TNF-α, IL-1β, IL-10) were also increased by salt treatment in both groups. We found that obesity-linked metabolism such as lipolysis, insulin resistance, and adipocyte production were significantly higher in MEK6 over-expressed cells than them in the control. However, the leptin level did not seem to be associated with MEK6 gene. Salt also increased O2 consumption in both groups but the time to reach maximum of O2 consumption in MEK6 over-expressed cells was slower than the case of control. MEK6 might be associated with mitochondria function to control O2 consumption.
The obesity metabolism related adiopgenesis in 3T3-L1 was activated by MEK6 expression and salt treatment. These findings will contribute to a future study for finding MEK6 linked mechanisms involved in adipogenesis and for setting DRI of salt intake in obese Koreans.
Funding Sources : This work was funded by the Ministry of Health&Welfare, Republic of Korea grant number: HI17C0863.