Effects Of PPARγ2 Pro12Ala Variant On Adipocyte Phenotype Dependent Of DHA

Peroxisome proliferator-activated receptor γ2 (PPARγ2) plays a critical role in the regulation of adipocyte differentiation and adipocytokine production. The Pro12Ala variant is the most common mutation in the PPARγ2 gene. Its effect appears to be sensitive to dietary factors, such as docosahexaenoic acid (DHA) level. The purpose of this study was to investigate the interaction effect between PPARγ2 Pro12Ala variant and DHA on the phenotypes of adipocytes.

We generated stable 3T3-L1 cell lines expressing wild-type PPARγ2 or PPARγ2 Pro12Ala variant. These two cell lines were cultured with different concentrations of DHA (0, 50, 200 umol/L). Then Oil red O staining was used to observe cell differentiation and the degree of lipid accumulation, TUNNEL assay was used to detect cell apoptosis, and ELISA assays were used to detect the changes of TNF-α, resistin and adiponectin levels in cell culture supernatant.

PPARγ2 Pro12Ala variant reduced lipid droplet accumulation in 3T3-L1 preadipocytes treated with or without 50 μmol/L DHA, but not with 200 μmol/L DHA, compared to that of wild-type PPARγ2. PPARγ2 reduced resistin production and increased adiponectin production in 3T3-L1 adipocytes, whereas PPARγ2 Pro12Ala variant diminished these effects. However, the absence of DHA blocked PPARγ2 Ala12 variant-induced effects on adiponectin production. There was no significant difference in TNF-α secretion between wild-type PPARγ2 and PPARγ2 Pro12Ala cells whether with or without DHA.

These results indicated that the effects of PPARγ2 Pro12Ala variant were dependent on DHA concentration.