BIX-01294 trihydrochloride is an inhibitor of G9a histone methyltransferase.In a cell-free assay, the IC50=2.7 μM for G9a histone methyltransferase.

G9a:2.7 μM

In wild-type embryonic stem (ES) cells, mouse embryonic fibroblasts, and HeLa cells, BIX-01294 (4.1 μM) reduces the levels of H3K9me2. BIX-01294 can specifically inhibit G9a (IC50=1.7 μM) and GLP (IC50=38 μM).

ATR for use in the in vitro enzyme assay is obtained from HeLa nuclear extract by immunoprecipitation with rabbit polyclonal antiserum raised to amino acids 400-480 of ATR contained in the following buffer: 25 mM HEPES (pH 7.4), 2 mM MgCl2, 250 mM NaCl, 0.5 mM EDTA, 0.1 mM Na3VO4, 10% v/v glycerol, and 0.01% v/v Tween 20. ATR-antibody complexes are isolated from nuclear extract by incubating with protein A-Sepharose beads for 1 h and then through centrifugation to recover the beads. In the well of a 96-well plate, 10 μL ATR-containing Sepharose beads are incubated with 1 μg of substrate glutathione?S-transferase-p53N66 (NH2-terminal 66 amino acids of p53 fused to glutathione?S-transferase are expressed in?E. coli) in ATR assay buffer (50 mM HEPES (pH 7.4), 150 mM NaCl, 6 mM MgCl2, 4 mM MnCl2, 0.1 mM Na3VO4, 0.1 mM DTT, and 10% (v/v) glycerol) at 37°C in the presence or absence of inhibitor. After 10 min with gentle shaking, ATP is added to a final concentration of 3 μM and the reaction continued at 37°C for an additional 1 h. The reaction is stopped by addition of 100 μL of PBS, and the reaction is transferred to a white opaque glutathione coated 96-well plate and incubated overnight at 4°C. This plate is then washed with PBS/0.05% (v/v) Tween 20, blotted dry, and analyzed by a standard ELISA technique with a phosphoserine 15 p53 antibody. The detection of phosphorylated glutathione?S-transferase-p53N66 substrate is performed in combination with a goat anti-mouse horseradish peroxidase-conjugated secondary antibody. Enhanced chemiluminescence solution is used to produce a signal, and chemiluminescent detection is carried out via a TopCount plate reader. The resulting calculated % enzyme activity is then used to determine the IC50?values for the compounds (IC50?taken as the concentration at which 50% of the enzyme activity is inhibited).