In vitro activity: In C2C12 myoblasts stably transfected with small hairpin RNA to knock-down SIRT1, SRT2104 increased AP activity, a marker for osteogenic differentiation. This effect was totally dependent on SIRT1 expression.

Kinase Assay: In the SIRT1 FP assay, SIRT1 activity is monitored using a 20 amino acid peptide (Ac-Glu-Glu-Lys(biotin)-Gly-Gln-Ser-Thr-Ser-Ser-His-Ser-Lys(Ac)-Nle-Ser-Thr-Glu-Gly–Lys(MR121 or Tamra)-Glu-Glu-NH2 ) derived from the sequence of p53. The peptide is N-terminally linked to biotin and C-terminally modified with a fluorescent tag. The reaction for monitoring enzyme activity is a coupled enzyme assay where the first reaction is the deacetylation reaction catalyzed by SIRT1 and the second reaction is cleavage by trypsin at the newly exposed lysine residue. The reaction is stopped and streptavidin is added in order to accentuate the mass differences between substrate and product. The fluorescence polarization reaction conditions are as follows: 0.5 μM peptide substrate, 150 μM βNAD +, 0-10 nM SIRT1, 25 mM Tris-acetate pH 8, 137 mM Na-Ac, 2.7 mM K-Ac, 1 mM Mg-Ac, 0.05% Tween-20, 0.1% Pluronic F127, 10 mM CaCl 2 , 5 mM DTT, 0.025% BSA, and 0.15 mM nicotinamide. The reaction is incubated at 37°C and stopped by addition of nicotinamide, and trypsin is added to cleave the deacetylated substrate. This reaction is incubated at 37 ℃ in the presence of 1 μM streptavidin. Fluorescent polarization is determined at excitation (650 nm) and emission (680 nm) wavelengths.

Cell Assay: Cells (C2C12 cell line) are cultured in low glucose Dulbecco's modified Eagle's medium (DMEM) supplemented with 10% fetal bovine serum and penicillin–streptomycin. Cells are treated with vehicle (0.1% DMSO) or 3 μM SRT2104 for 24 h and then harvested for protein and Western blotting.

Aging Cell. 2014 Oct;13(5):787-96; Ann Clin Transl Neurol. 2014 Dec;1(12):1047-52.