Peroxisome Proliferator-Activated Receptor-α Control of Lipid and Glucose Metabolism in Human White Adipocytes

This work aimed at characterizing the role of peroxisome proliferator-activated receptors (PPAR)α in human white adipocyte metabolism and at comparing PPARα and PPARγ actions in these cells. Primary cultures of human fat cells were treated with the PPARα agonist GW7647 or the PPARγ agonist rosiglitazone. Changes in gene expression were determined using DNA microrrays and quantitative RT-PCR. Western blot and metabolic studies were performed to identify the biological effects elicited by PPAR agonist treatments. GW7647 induced an up-regulation of β-oxidation gene expression and increased palmitate oxidation. Unexpectedly, glycolysis was strongly reduced at transcriptional and functional levels by GW7647 leading to a decrease in pyruvate and lactate production. Glucose oxidation was decreased. Triglyceride esterification and de novo lipogenesis were inhibited by the PPARα agonist. GW7647-induced alterations were abolished by a treatment with a PPARα antagonist. Small interfering RNA-mediated extinction of PPARα gene expression in hMADS adipocytes attenuated GW7647 induction of palmitate oxidation. Rosiglitazone had no major impact on glycolysis and β-oxidation. Altogether these results show that PPARα can selectively up-regulate β-oxidation and decrease glucose utilization in human white adipocytes. Activation of the nuclear receptor PPARα stimulates fatty acid oxidation and decreases glucose utilization in human adipocytes.