TR-FRET-based primary biochemical high throughput screening assay to identify agonists of nuclear receptor subfamily 2, group E, member 3 (NR2E3).
Name: TR-FRET-based primary biochemical high throughput screening assay to identify agonists of nuclear receptor subfamily 2, group E, member 3 (NR2E3). ..more
BioActive Compounds: 380
Source (MLPCN Center Name): The Scripps Research Institute Molecular Screening Center
Affiliation: The Scripps Research Institute, TSRI
Assay Provider: Konstantin Petrukhin, Columbia University
Network: Molecular Library Probe Production Centers Network (MLPCN)
Grant Proposal Number: 1 R21 NS061718-01 Fast Track
Grant Proposal PI: Konstantin Petrukhin, Columbia University
External Assay ID: NR2E3_AG_TR-FRET_1536_1X%INH
Name: TR-FRET-based primary biochemical high throughput screening assay to identify agonists of nuclear receptor subfamily 2, group E, member 3 (NR2E3).
Nuclear receptors are small molecule- and hormone-regulated transcription factors with discrete DNA-binding and ligand-binding domains, and are essential during development and for maintenance of proper cell function in adults. Small pharmacological compounds that bind to the cleft of the ligand-binding domain could alter receptor conformation and subsequently modify transcription of target genes. Such ligands (agonists and antagonists) have been designed for 23 nuclear receptors among the 48 identified in the human genome (1-3). NR2E3 is an orphan nuclear receptor expressed exclusively in rod and cone photoreceptor cells of the retina (4-7). In its unliganded state, NR2E3 acts as a transcriptional repressor (4, 8, 9) due to interaction with co-repressors such as retinal RetCOR (10), NCOR (11) or SMRT (11). Defects in this gene are a cause of several retinopathies (12-15). Studies showing that mice with a spontaneous deletion in the Nr2e3 gene develop late-onset, progressive retinal degeneration (7), suggest that this nuclear receptor is essential for photoreceptor development and survival. The identification of selective NR2E3 agonists would provide useful tools for the understanding of the biological role of NR2E3 in retinal diseases.
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6. Haider, N.B., Naggert, J.K., and Nishina, P.M., Excess cone cell proliferation due to lack of a functional NR2E3 causes retinal dysplasia and degeneration in rd7/rd7 mice. Hum Mol Genet, 2001. 10(16): p. 1619-26.
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nuclear receptor subfamily 2, group E, member 3, NR2E3; RetCOR, corepressor, photoreceptor-specific nuclear receptor; PNR, blindness, age-related macular degeneration, AMD, primary, primary screen, orphan nuclear receptor, fluorescence, TR-FRET, agonist, activator, HTS, 1536, Scripps, Scripps Florida, Research Institute Molecular Screening Center, SRIMSC, Molecular Libraries Probe Production Centers Network, MLPCN.
The purpose of this biochemical assay is to identify compounds that activate NR2E3 through disruption of the binding to its corepressor, RetCOR. The assay employs GST-NR2E3 and its interaction partner, a biotinylated corepressor RetCOR. These reagents are added together in the presence of test compounds and Eu(K)-anti GST antibody and Streptavidin-D2. Interaction between the RetCOR and NR2E3 partners brings the fluorophore-tagged antibodies together, leading to FRET between the fluorophores. As designed, test compounds that act as NR2E3 agonists will lead to release of RetCOR from NR2E3, thereby preventing interaction of the fluorescent tags, leading to reduced well FRET. Compounds are tested in singlicate at a final nominal concentration of 4.8 micromolar.
Prior to the start of the assay 5 microliters of Assay Buffer (10 mM Tris-HCL, pH 7.5, 0.05% NP-40 alternative, 6% glycerol, 100 mM potassium fluoride, 1 mM dithiothreitiol and 0.05% w/v bovine serum albumin) were dispensed into columns 1 and 2 of 1536-well assay plates. Next, 5 microliters of 1.05X Assay Mixture containing 1.42 nM GST-tagged NR2E3 and 7.35 biotinylated RetCOR in Assay Buffer were dispensed into the remaining 46 columns. The compounds were then pinned into each assay plate. Column 3 of each plate contained 10 #M biotin as high control. Next, 1 microliter of 6X Detection Mix containing 4.5 nM Eu(K)-anti-GST and 252 nM Streptavidin-D2 in Assay Buffer was dispensed into all wells. After dispensing, final concentrations of the different reagents were: 0.75 nM Eu(K)-anti GST, 42 nM Streptavidin-D2, 1.35nM GST-tagged NR2E3 and 7 nM biotinylated RetCOR. The plates were then incubated for 5 hours at 4 degrees Celsius and well FRET was measured. After excitation at 340 nm, well fluorescence was monitored at 617 nm (Eu(K)) and 671 nm (D2) with the ViewLux microplate reader (Perkin Elmer). For each well, a fluorescence ratio was calculated according to the following mathematical expression:
Ratio = I671nm / I617nm x 10,000
I671nm represents the measured fluorescence emission at 671nm and;
I617nm represents the measured fluorescence emission at 617nm.
The percent inhibition for each compound was calculated using as follows:
% Inhibition = 100 x ( 1 - ( ( Ratio_TestCompound - Median_Ratio_HighControl ) / ( Median_Ratio_LowControl - Median_Ratio_HighControl ) )
Test_Compound is defined as wells containing test compound.
Positive_Control is defined as wells containing biotin.
Negative_Control is defined as wells containing 0.6% DMSO.
A mathematical algorithm was used to determine nominally inhibiting compounds in the primary screen. Two values were calculated: (1) the average percent inhibition of all compounds tested, and (2) three times their standard deviation. The sum of these two values was used as a cutoff parameter, i.e. any compound that exhibited greater %inhibition than the cutoff parameter was declared active.
The reported PubChem Activity Score has been normalized to 100% observed primary inhibition. Negative % inhibition values are reported as activity score zero.
The PubChem Activity Score range for active compounds is 100-20, for inactive 20-0.
List of Reagents:
GST-NR2E3 (supplied by Assay Provider)
Biotinylated RetCoR (supplied by Assay Provider)
Eu(K)-antiGST (Cisbio, 61GSTKLB)
Streptavidin-D2 (Cisbio, 61OSADAB)
Tris-HCl, pH 7.5, 1 M solution (Invitrogen, 15567-027)
BSA, 30% solution (Sigma, A8327-50ML)
Biotin (Sigma, B4501-1G)
Glycerol (Invitrogen, 15514-011)
NP-40 alternative, 10% solution (Calbiochem, 492018)
DTT, 1M solution (Fluka, 43816)
Potassium fluoride powder (Fluka, 60238)
1536-well plates (Greiner, part 789173)
Due to the increasing size of the MLPCN compound library, this assay may have been run as two or more separate campaigns, each campaign testing a unique set of compounds. In this case the results of each separate campaign were assigned "Active/Inactive" status based upon that campaign's specific compound activity cutoff value. The IC50 of biotin was 50 nM. All data reported were normalized on a per-plate basis. Possible artifacts of this assay can include, but are not limited to: dust or lint located in or on wells of the microtiter plate, compounds that modulate well fluorescence. All test compound concentrations reported above and below are nominal; the specific test concentration(s) for a particular compound may vary based upon the actual sample provided by the MLSMR.
** Test Concentration.
Data Table (Concise)