Western blot analysis

Liver tissue (50 mg) was lysed using RIPA buffer containing protease and phosphatase inhibitor (Sigma-Aldrich, St. Louis, MO). For nuclear protein extraction, an EpiSeeker Nuclear Extraction Kit from Abcam (Abcam, Cambridge, MA) was used. Proteins (25 μg) were analysed by SDS-polyacrylamide gel electrophoresis using a Bio-Rad (Hercules, CA) electrophoresis system. Western blot membranes were stripped using Restore^™ PLUS Stripping Buffer (Thermo Scientific, Rockford, IL) and re-probed using another antibody. Immunoreactive bands were visualized using enhanced chemiluminescence light detection reagents (Amersham, Arlington Heights, IL). Quantification was performed with Image LabTMSoftware (BioRad, Life Science Research, Hercules, CA). PPARα, CPT1A, PGC1, SIRT1, PDE4C, PDE4D, β-actin and Histone 3 antibodies were purchased from Santa Cruz Biotechnology, Inc. (Dallas, TX). PDE4B antibody was a kind gift from Dr. Marco Conti; PDE4A antibody was a gift from FabGennix Inc. (FabGennix Inc. International, Frisco, TX). The information about the source and dilution of primary antibodies is presented in Supplementary Table S1.