HMTase Assays

Dissociation Enhanced Lanthanide Fluoro-Immuno Assay (DELFIA) was performed in white, opaque 384-well plates coated with Neutravidin. Test compounds were diluted to 12 μg/mL in 50mM Tris-HCl (pH 8.5) containing 4% DMSO and 10 μL was dispensed into the wells. Blank and control wells received only compound buffer. GST-G9a at 10 μg/mL and SAM at 40 μM were diluted in 50mM Tris HCl (pH 8.5)/10 mM DTT and added in a volume of 20 μL. Blank wells received Tris/DTT buffer only. The reactions were initiated by the addition of 800 nM H3(1-20)-cysbiotin substrate in 50 mM Tris (pH 8.5) in a volume of 10 μL, and incubated at room temperature for 60 mins. The plates were washed 3 times with 100 μL of Wash Buffer. Next, 50 μL of Fluoroimmunoassay (FI) Buffer containing 5 ng α-2X-di-meth H3-K9 and 5 ng goat anti-rabbit Eu chelate was added to all wells of the plate, and the plate was incubated for an additional 1 hr at room temperature. The plates were washed 3 times with 100 μL of Wash Buffer, and 50 μL of Enhancement Solution was added to each well. Time resolved fluorescence was measured after 45 mins on a Viewlux Microplate Imager imaging for 15 seconds.

Cell lines

Wild-type and G9a deficient mouse embryonic stem (ES) cells, mouse embryonic fibroblasts and human HeLa cells

Preparation method

The solubility of this compound in DMSO is >10 mM. General tips for obtaining a higher concentration: Please warm the tube at 37℃ for 10 minutes and/or shake it in the ultrasonic bath for a while. Stock solution can be stored below -20℃ for several months.

Reaction Conditions

4.1 μM; over 2 days

Applications

BIX-01294 (4.1 μM) reduced the H3K9me2 Levels in Bulk Histone Preparations from wild-type mouse ES cells, mouse embryonic fibroblasts and human HeLa cells, but not in G9a deficient mouse ES cells.

BIX-01294 is a small molecule inhibitor of G9a and GLP (a H3K9 PKMT that shares 80% sequence identity with G9a in their respective SET domains) that was discovered via screening of a library of 125,000 synthetic compounds. BIX-01294 is selective for G9a and GLP over several H3K9 PKMTs including SUV39H1 and ESET, other KMTs such as SET7/9, and the arginine methyltransferase PRTM1. The X-ray crystal structure of GLP and BIX-01294 confirmed that BIX-01294 bound to the histone peptide binding pocket but failed to interact with the lysine binding channel. Cells dosed with BIX-01294 at 4.1 μM were characterized by reduced H3K9me2 levels in several cell lines but toxicity to cells at > 4.1 μM was observed.

Reference

[1].William P. Janzen, Tim J. Wigle, Jian Jin, Stephen V. Frye. Epigenetics: tools and technologies. Drug Discov Today Technol. 2010 ; 7(1): 59 – 65.