Western Blot Analysis of Kidney Proteins

Protein extracts were obtained from kidneys using T-PER Mammalian Protein Extraction Reagent (Pierce, Thermo Scientific, Rockford, USA), as indicated by the manufacturer, in the presence of a cocktail of protease and phosphatase inhibitors (Sigma-Aldrich, Milan, Italy). Protein content was determined with bicinchoninic acid protein assays (BCA, Pierce, Euroclone, Milan, Italy). An appropriate amount of protein was run on SDS-PAGE under reducing conditions for immunoblotting. The separated proteins were then semi-dry transferred to a nitrocellulose membrane (Bio-Rad Laboratories) and proteins of interest were revealed with specific antibodies: anti-p-S6 (Ser235/236), anti-S6, anti-p-AKT (Ser473), anti-AKT, anti-p-eNOS (Ser1177), anti-eNOS, anti-COX IV, anti-Cyt c, and anti-Grp78 (all from Cell Signaling, Euroclone, Milan, Italy); anti-SIRT1, anti-Grp75, and anti-Bcl-2 (all from Santa Cruz); and anti-PGC-1α (Abcam, Cambridge, UK) each at 1:1,000 dilution. Anti-β-Actin (1:10,000; Cell Signaling) and anti-Vinculin (1:10,000; Sigma-Aldrich) were used as loading controls. Immunostaining was detected using horseradish peroxidase conjugated anti-rabbit or anti-mouse immunoglobulin for 1 h at room temperature (Tedesco et al. 2010 (link)). Amounts of each protein were measured using SuperSignal Substrate (Pierce) and densitometrically quantified with an IMAGEJ software image analyzer.