External ID: CBX7-Alpha-primary

Protocol: The protocol for the CBX7 AlphaScreen that we use is as follows: We create a standard alpha buffer (50mM HEPES, 150mM NaCl, 0.1% w/v BSA, 0.01% w/v Tween20) at pH 8.0 and make up two stock solutions at 2x final concentration in the alpha buffer. Solution A contains Human His6-CBX7 is used with biotinylated-H3K27me3 (residues 20-34), at 100nM and 50nM respectively. Solution B contains 20nM streptavidin donor beads and 20nM nickel acceptor beads. For 384 well assay formats, 10uL of solution A is added to each well of the assay plate and the plate is spun at 1000 rpm for 30 seconds. 100 nL of experimental ccompounds from stock plates are delivered by robotic pin transfer using a Janus Workstation (PerkinElmer), allowing the compounds to interact with CBX7 binding prior to assay measurement, followed by another spin and an incubation room temperature. Finally, 10uL of solution B is added to each well, the plate is spun again and then incubated at room temperature. AlphaScreen measurements are performed on an Envision 2104 (PerkinElmer) utilizing the manufacturer's protocol that has the correct excitation and emission wavelengths, cutoff filters, delay time, etc. We also do a crosstalk calculation through the Envision software to correct for luminescence for adjacent wells while reading the plate. The signal is then normalized to DMSO control wells on the compound plate prior to creation of the IC50 curves.

Comment:

External ID: ST2_IL33_Inhibitors_Primary_Screening_77700

Protocol: High-throughput screening was performed at Indiana University screening facility (Indiana University, Indianapolis, IN).

In summary, a mixture of ST2 and IL-33 was prepared by adding 0.30 microL of 14.1 microM recombinant human ST2-Fc Chimera and 0.30 microL of 55.25 biotinylated recombinant human IL-33 to 1.4 mL of assay buffer. In the HTS, each well of a 384-well Proxi-plate was first blocked by 100 microL of assay buffer for 1 h at room temperature. After removing the blocking buffer, 20 microL of ST2/IL-33 mixture was pipetted into each well and incubated at room temperature for 1 h followed by addition of compounds at 17 microM (0.8 microL) to each well and incubated at room temperature for 1 h. Ten microliters of 60 microg/mL anti-6xHis-conjugated AlphaLISA acceptor beads were added to each well and incubated at room temperature for 1 h before addition of 10 microL of 60 microg/mL of streptavidin-labeled AlphaLISA donor beads for incubation at room temperature for 30 min. Incubation of acceptor and receptor beads was conducted in darkness. The well with 3 nM ST2 alone was used as a negative control, whereas the ST2/IL-33 mixture with a human ST2 antibody added at 0.45 ng/microL was used as the positive control. Plates were read using the Envision Plate Reader. The buffer used in the assay contains 14.37 mL PBS, 30 microL Tween 20, and 600 microL of 5% bovine serum albumin in PBS.

Comment: PubChem active indicates >= 30% inhibition of ST2/IL-33 at 17 uM of the compound. Inconclusive: >=10% and < 30% inhibition.

External ID: MScreen:TargetID_600

Protocol: C-terminally 6xHis tagged CDK2/Cyclin A complex and N-terminally Flag tagged CDC25B C473S (372-566) were expressed and purified. Proteins were incubated together at a final concentration of 125 nM each for 1 hr prior to incubation with compound for 1 hr, followed by addition of anti-6xHis europium cryptate donor beads (Cisbio) and anti-Flag XL-665 acceptor beads (Cisbio) at a final dilution of 1:350 for 1 hr. 20mM potassium fluoride was added 10 minute prior to plate reading. Assay reagents were dispensed using a multidrop liquid dispenser (Thermo Scientific) onto uncoated, black, low-volume, 384-well plates (Corning). Assay plates were quantified using an Envision plate reader (Perkin-Elmer) with excitation of the europium crytate donor at 337 nm wavelength and emission of the donor at 620 nm and emission of the XL-665 acceptor at 665 nm in 18 uL volumes. Assays were performed in a buffer containing 50 mM Tris (pH 7.5), 50 mM NaCl, 10mM MgCl2, 1mM TCEP, with addition of and 1mM ATP, 0.05% BSA, and 0.05% Tween-20 immediately prior to the start of the assay.

Comment: The activity outcome is based on a Z-score (number of standard deviations from the negative control mean) of 3 or higher on at least 50% times that the sample was screened.
For instance, if the sample was screened in n=4 runs, it would be considered active only if it had a Z-score of 3 or above in at least 2 runs.

This screen was funded by NIH grant number: R01CA181185