Luminescence-based cell-based high throughput dose response assay for biased ligands (agonists) of the melanocortin 4 receptor (MC4R)
Name: Luminescence-based cell-based high throughput dose response assay for biased ligands (agonists) of the melanocortin 4 receptor (MC4R). ..more
BioActive Compounds: 14
Source (MLPCN Center Name): The Scripps Research Institute Molecular Screening Center (SRISMC)
Center Affiliation: The Scripps Research Institute, TSRI
Assay Provider: Scott DeWire, Trevena Inc
Network: Molecular Library Probe Production Center Network (MLPCN)
Grant Proposal Number: 1 RC2 MH090877-01
Grant Proposal PI: Scott DeWire, Trevena Inc
External Assay ID: MC4R_AG_LUMI_1536_3XEC50 DRUN
Name: Luminescence-based cell-based high throughput dose response assay for biased ligands (agonists) of the melanocortin 4 receptor (MC4R).
Heterotrimeric G-protein coupled receptors (GPCRs) are major targets for disease therapeutics, due in part to their broad tissue distribution, structural diversity, varied modes of action, and disease-associated mutations (1-4). However, it has recently been demonstrated that GPCRs do not only signal in this simplistic fashion, but rather activate a network of downstream effects comprised of parallel signal transduction pathways. GPCR ligands biased towards induction or blockade of specific signaling pathways may have different physiology compared with unbiased molecules, through selective engagement of a desired subset of signal cascades. For example, the melanocortin 4 receptor (MC4R) transduces its signal via coupling to Gs and adenylyl cyclase activation, and is involved in the regulation of energy homeostasis and chronic disease-associated cachexia. Recent studies indicate that classical antagonists do not mimic MC4R regulation by its endogenous ligand, Agouti-Related Protein (AgRP). Indeed, AgRP has several actions including antagonizing Gs-mediated adenylyl cyclase activation, inducing beta-arrestin recruitment and MC4R endocytosis (5), as well as stimulating Gi-mediated activation of adenylyl cyclase (6). As a result, the identification of small molecules that act as biased MC4R ligands, by blocking Gs protein coupling but stimulating beta-arrestin functions and/or Gi protein coupling, may lead to a better understanding of this receptor and its role in metabolic/wasting diseases.
1. Pan, H.L., Wu, Z.Z., Zhou, H.Y., Chen, S.R., Zhang, H.M., and Li, D.P., Modulation of pain transmission by G-protein-coupled receptors. Pharmacol Ther, 2008. 117(1): p. 141-61.
2. Lagerstrom, M.C. and Schioth, H.B., Structural diversity of G protein-coupled receptors and significance for drug discovery. Nat Rev Drug Discov, 2008. 7(4): p. 339-57.
3. Thompson, M.D., Cole, D.E., and Jose, P.A., Pharmacogenomics of G protein-coupled receptor signaling: insights from health and disease. Methods Mol Biol, 2008. 448: p. 77-107.
4. Bosier, B. and Hermans, E., Versatility of GPCR recognition by drugs: from biological implications to therapeutic relevance. Trends Pharmacol Sci, 2007. 28(8): p. 438-46.
5. Breit, A., Wolff, K., Kalwa, H., Jarry, H., Buch, T., and Gudermann, T. 2006. The natural inverse agonist agouti-related protein induces arrestin-mediated endocytosis of melanocortin-3 and -4 receptors. J Biol Chem 281:37447-37456.
6. Buch, T.R., Heling, D., Damm, E., Gudermann, T., and Breit, A. 2009. Pertussis toxin-sensitive signaling of melanocortin-4 receptors in hypothalamic GT1-7 cells defines agouti-related protein as a biased agonist. J Biol Chem 284:26411-26420.
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The purpose of this assay is to determine dose response curves for compounds that confirmed MC4R agoinst activity in a set of previous experiments entitled, "Luminescence-based cell-based primary high throughput confirmation assay to identify biased ligands of the melanocortin 4 receptor (MC4R): agonists of MC4R" (AID 602192).
This assay monitors melanocortin 4 receptor (MC4R) activation, resulting in membrane recruitment of beta-arrestin. The assay monitors GPCR-beta-arrestin proximity using low affinity fragment complementation of beta-galactosidase (beta-gal). This assay employs U2OS cells which express MC4R fused to a beta-gal peptide fragment (enzyme donor), and beta-arrestin fused to the complementary beta-gal fragment (enzyme acceptor). Cells are incubated with test compound, followed by measurement of well luminescence. As designed, compounds that activate MC4R will cause beta-arrestin recruitment, resulting in reconstitution of the beta-gal holoenzyme. The reconstituted holoenzyme can then catalyze the hydrolysis of a substrate which yields a chemiluminescent signal, resulting in increased well luminescence. Melanotan II will be used as the high (100% RLU) control for agonists, and wells containing cells treated with DMSO will be used as the low (0% RLU) control. Compounds are tested in triplicate using a 10-point, 1:3 dilution series starting at a maximum nominal concentration of 89 uM.
The MC4R cell line was routinely cultured in T-175 sq cm flasks at 37 C and 95% relative humidity (RH). The growth media consisted of a 1:1 mixture of Ham's F-12 Nutrient Media (F-12) and Dulbecco's Modified Eagle Media (DMEM) supplemented with 10% v/v heat-inactivated certified fetal bovine serum, 25 mM HEPES, 250 ug/mL Geneticin, 250 ug/mL Hygromycin B, and 1X antibiotic mix (penicillin, streptomycin, and neomycin).
The day before the assay 1000 cells in 3 uL of cell plating media were seeded into each well of 1536 well microtiter plates and allowed to incubate at 37 C, 5% CO2, and 95 % RH for 23 hours. Next, 27 nL of test compound in DMSO, or DMSO alone were dispensed to the appropriate wells. The plates were then incubated for 3 hours at 37 C, 5% CO2, and 95 % RH. The assay was started by adding 2 uL of PathHunter reagent (prepared according to the manufacturer's protocol); followed by 1 hour incubation at room temperature. Then, Well Luminescence was read on the ViewLux plate reader. The percent activation for each compound was calculated as follows:
%_Activation = ( ( Luminescence_Test_Compound - Median_ Luminescence_Low_Control ) / ( Median_ Luminescence_High_Control - Median_ Luminescence_Low_Control ) ) * 100
High_Control is defined as wells containing cells, Melanotan II and DMSO.
Test_Compound is defined as wells containing cells, test compounds and DMSO.
Low_Control is defined as wells containing cells and DMSO.
PubChem Activity Outcome and Score:
For each test compound, percent activation was plotted against compound concentration. A four parameter equation describing a sigmoidal dose-response curve was then fitted with adjustable baseline using Assay Explorer software (Symyx Technologies Inc). The reported EC50 values were generated from fitted curves by solving for the X-intercept value at the 50% activation level of the Y-intercept value. In cases where the highest concentration tested (i.e. 89 uM) did not result in greater than 50% activation, the EC50 was determined manually as greater than 89 uM. Compounds with an EC50 greater than 10 uM were considered inactive. Compounds with an EC50 equal to or less than 10 uM were considered active.
Activity score was then ranked by the potency of the compounds with fitted curves, with the most potent compounds assigned the highest activity scores.
The PubChem Activity Score range for active compounds is 100-92, and for inactive compounds 89-0.
List of Reagents:
U2OS MC4R cell line (DiscoveRx, part 93-0211C3)
PathHunter Detection Kit (DiscoveRx, part, 93-0558C3)
Melanotan II (control agonist, Anaspec, part 61188)
Ham's F-12 media (Invitrogen, part 11765)
DMEM media (Invitrogen, part 11995)
Detachin (Genlantis, part T100100)
Heat Inactivated Fetal Bovine Serum (Invitrogen, part 10082)
Hygromycin B (Invitrogen, part 10687)
Geneticin (Invitrogen, part 10131)
100X Penicillin-Streptomycin-Neomycin mix (Invitrogen, part 15640)
T-175 tissue culture flasks (Nunc, part 159910)
1536-well plates (Corning, part 7298)
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. 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, and compounds that quench or emit luminescence within the well. All test compound concentrations reported are nominal; the specific concentration for a particular test compound may vary based upon the actual sample provided by the MLSMR. The MLSMR was not able to provide all compounds selected for testing in this assay.
Categorized Comment - additional comments and annotations
From BioAssay Depositor:
Assay: CurveFit : Equation: =( ( [Maximal Response] * [Concentration]^[Hill Slope] ) / ( [Inflection Point Concentration]^[Hill Slope] + [Concentration]^[Hill Slope] ) ) + [Baseline Response]
Assay: CurveFit : Mask: Excluded Points
Assay: Dictionary: Version: 0.1
BAO: assay design: redistribution reporter: second messenger: cyclic amp
BAO: assay format: cell-based format
BAO: bioassay specification: assay biosafety level: bsl1
BAO: bioassay specification: assay footprint: microplate: 1536 well plate
BAO: bioassay specification: assay measurement throughput quality: concentration response multiple replicates
BAO: bioassay specification: assay measurement type: endpoint assay
BAO: bioassay specification: assay readout content: assay readout method: regular screening
BAO: bioassay specification: assay readout content: content readout type: single readout
BAO: bioassay specification: assay stage: confirmatory
BAO: bioassay specification: bioassay type: binding
BAO: detection technology: luminescence: chemiluminescence
BAO: meta target detail: binding reporter specification: interaction: protein-small molecule
BAO: meta target: biological process target: regulation of molecular function
BAO: meta target: molecular target: protein target: receptor: transmembrane receptor: g protein coupled receptor
BAO: version: 1.4b1090
Assay Format: Cell-based
Assay Cell Type: U-2 OS
Assay Format: Cell-based
Assay Type: Functional
* Activity Concentration. ** Test Concentration.
Data Table (Concise)