PPARα: A Master Regulator of Bilirubin Homeostasis
PPARα ligands differentially affect HO-1 protein levels and/or bilirubin secretion in human umbilical vein endothelial cells (HUVEC) and coronary artery smooth muscle cells (CASMC). HUVECs (a–d) and CASMCs (e–g) were cultured in the presence of vehicle (DMSO, 0.1%, v/v), 250 μM gemfibrozil (a, d, and e), 75 μM Wy14,643 (b, d, and f), or 250 μM fenofibrate (c, d, and g) for 48 H. ((a–c) and (e–g)) HO-1 protein levels were visualized in cell homogenates (20 μg–25 μg) through immunoblotting using the anti-HO-1 (1 : 400 dilution) antibody. The same membranes were subsequently hybridized with an anti-actin antibody (1 : 2,000 dilution) to ensure the equal loading of each lane. (d) Bilirubin concentration was determined in culture media through liquid chromatography coupled to tandem mass spectrometry. Statistically significant differences are indicated by asterisks (Student’s -test: ; ).