Assay Method Information

Assay Name:  PRMT5 Cell Target Engagement (TE) Assay
Description:  The PRMT5 TE assay is a biomarker assay for identifying compounds that inhibit symmetric dimethylation of arginine (SDMA) of PRMT5 substrates. This assay detects symmetrically dimethylated nuclear proteins using high content imaging technology. Detection of the expression of symmetrically dimethylated nucleo proteins is through a mixture of primary rabbit monoclonal antibodies to SDMA (CST 13222), which in turn recognized by an Alexafluor 488 dye-conjugated anti-rabbit IgG secondary antibody. The IN Cell Analyzer 2200 measures nuclear Alexafluor 488 fluorescent dye intensity that is directly related to the level of expression of symmetrically dimethylated nuclear proteins at the single cell level. Nuclear AF488 dye intensities are compared to the mean value for DMSO treated cells (MIN) to report percent of inhibition for each compound-treated well.In this assay, the cell potency (EC50) of each compound was determined from a ten point (1:3 serial dilution; top compound concentration of 10000 nM) titration curve using the following outlined procedure. Each well of a BD falcon collagen coated black/clear bottom 384-well plate was seeded with 4000 MCF-7 cells and allowed to attach for 5 hours. Media from cell plate was removed at 0.5 mm above the bottom of the plate and replaced with 30 μL of fresh media containing 1.2× compounds in 0.1% DMSO. Cells were treated for 3 days in 37° C. CO2 incubator. On day 3, cells were fixed with Cytofix, permeablized with 0.4% Triton-X-100/Cytofix, and washed with D-PBS without Ca/Mg. Cells were blocked with Licor Odessey blocking reagent for one hour at room temperature, followed by incubation with anti-SDMA (1:1000) antibody at 4° C. overnight. 1° antibody was removed, followed by three washings with DPBS without Ca/Mg and 0.05% Tween20. Hoechst (5 μg/ml), Cell Mask deep stain (1:2000) and Alexa488-conjugated goat anti-rabbit IgG (2 μg/mL) was added for 1 hour at room temperature. A final washing step (three washes) was performed before sealing plate for imaging on In Cell Analyzer 2200. Images from analyzer were uploaded to Columbus (at WP) for image analysis. IC50 values were determined by 4 parameters robust fit of percent fluorescence units vs. (Log10) compound concentrations.
Affinity data for this assay
 

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