Fluorescence-based counterscreen for antagonists of the G-protein coupled receptor 7 (GPR7): cell-based high throughput dose response assay to identify antagonists of the melanin-concentrating hormone receptor 1 (MCHR1).
Name: Fluorescence-based counterscreen for antagonists of the G-protein coupled receptor 7 (GPR7): cell-based high throughput dose response assay to identify antagonists of the melanin-concentrating hormone receptor 1 (MCHR1). ..more
BioActive Compounds: 7
Source (MLPCN Center Name): The Scripps Research Institute Molecular Screening Center (SRIMSC)
Affiliation: The Scripps Research Institute, TSRI
Assay Provider: Olivier Civelli, University of California, Irvine
Network: Molecular Library Probe Production Centers Network (MLPCN)
Grant Proposal Number: 1-R03-DA026557-01
Grant Proposal PI: Olivier Civelli
External Assay ID: MCHR1_ANT_FLUO8_1536_3X%IC50
Name: Fluorescence-based counterscreen for antagonists of the G-protein coupled receptor 7 (GPR7): cell-based high throughput dose response assay to identify antagonists of the melanin-concentrating hormone receptor 1 (MCHR1).
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). For example, targeting of opiod receptors by opiates such as morphine is a widespread clinical application for GPCR modulation in pain management. The recently de-orphanized GPR7 (5) is localized predominantly in the cerebellum and prefrontal cortex (6), with additional expression in the pituitary, hippocampus, amygdala, and spinal cord (7-9). GPR7 is highly conserved in humans and rodents (6), and exhibits structural features of both GPCRs and somatostatin receptors (7). Studies identifying the energy-regulating neuropeptides Neuropeptide W (NPW) and Neuropeptide B (NPB) as endogenous ligands of GPR7 (5, 10), and the development of hyperphagia and obesity in male GPR7 knockout mice (11, 12), implicate GPR7 in feeding behavior. Additional studies identifying GPR7 expression in peripheral Schwann cells (13) and increased GPR7 expression in rat models and human patients with inflammation-associated neuropathic pain (11, 13), suggest a role for GPR7 in mediating the inflammatory pain response. The identification of modulators of GPR7 will provide useful tools to elucidate the diverse roles of this receptor in central neuropeptide signaling and nociception in general.
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. Tanaka, H., Yoshida, T., Miyamoto, N., Motoike, T., Kurosu, H., Shibata, K., Yamanaka, A., Williams, S.C., Richardson, J.A., Tsujino, N., Garry, M.G., Lerner, M.R., King, D.S., O'Dowd, B.F., Sakurai, T., and Yanagisawa, M., Characterization of a family of endogenous neuropeptide ligands for the G protein-coupled receptors GPR7 and GPR8. Proc Natl Acad Sci U S A, 2003. 100(10): p. 6251-6.
6. O'Dowd, B.F., Scheideler, M.A., Nguyen, T., Cheng, R., Rasmussen, J.S., Marchese, A., Zastawny, R., Heng, H.H., Tsui, L.C., Shi, X., and et al., The cloning and chromosomal mapping of two novel human opioid-somatostatin-like receptor genes, GPR7 and GPR8, expressed in discrete areas of the brain. Genomics, 1995. 28(1): p. 84-91.
7. Brezillon, S., Lannoy, V., Franssen, J.D., Le Poul, E., Dupriez, V., Lucchetti, J., Detheux, M., and Parmentier, M., Identification of natural ligands for the orphan G protein-coupled receptors GPR7 and GPR8. J Biol Chem, 2003. 278(2): p. 776-83.
8. Singh, G., Maguire, J.J., Kuc, R.E., Fidock, M., and Davenport, A.P., Identification and cellular localisation of NPW1 (GPR7) receptors for the novel neuropeptide W-23 by [125I]-NPW radioligand binding and immunocytochemistry. Brain Res, 2004. 1017(1-2): p. 222-6.
9. Lee, D.K., Nguyen, T., Porter, C.A., Cheng, R., George, S.R., and O'Dowd, B.F., Two related G protein-coupled receptors: the distribution of GPR7 in rat brain and the absence of GPR8 in rodents. Brain Res Mol Brain Res, 1999. 71(1): p. 96-103.
10. Fujii, R., Yoshida, H., Fukusumi, S., Habata, Y., Hosoya, M., Kawamata, Y., Yano, T., Hinuma, S., Kitada, C., Asami, T., Mori, M., Fujisawa, Y., and Fujino, M., Identification of a neuropeptide modified with bromine as an endogenous ligand for GPR7. J Biol Chem, 2002. 277(37): p. 34010-6.
11. Kelly, M.A., Beuckmann, C.T., Williams, S.C., Sinton, C.M., Motoike, T., Richardson, J.A., Hammer, R.E., Garry, M.G., and Yanagisawa, M., Neuropeptide B-deficient mice demonstrate hyperalgesia in response to inflammatory pain. Proc Natl Acad Sci U S A, 2005. 102(28): p. 9942-7.
12. Ishii, M., Fei, H., and Friedman, J.M., Targeted disruption of GPR7, the endogenous receptor for neuropeptides B and W, leads to metabolic defects and adult-onset obesity. Proc Natl Acad Sci U S A, 2003. 100(18): p. 10540-5.
13. Zaratin, P.F., Quattrini, A., Previtali, S.C., Comi, G., Hervieu, G., and Scheideler, M.A., Schwann cell overexpression of the GPR7 receptor in inflammatory and painful neuropathies. Mol Cell Neurosci, 2005. 28(1): p. 55-63.
14. Qu, D., Ludwig, D.S., Gammeltoft, S., Piper, M., Pelleymounter, M.A., Cullen, M.J., Mathes, W.F., Przypek, R., Kanarek, R., and Maratos-Flier, E., A role for melanin-concentrating hormone in the central regulation of feeding behaviour. Nature, 1996. 380(6571): p. 243-7.
15. Bradley, R.L., Mansfield, J.P., Maratos-Flier, E., and Cheatham, B., Melanin-concentrating hormone activates signaling pathways in 3T3-L1 adipocytes. Am J Physiol Endocrinol Metab, 2002. 283(3): p. E584-92.
16. Ludwig, D.S., Tritos, N.A., Mastaitis, J.W., Kulkarni, R., Kokkotou, E., Elmquist, J., Lowell, B., Flier, J.S., and Maratos-Flier, E., Melanin-concentrating hormone overexpression in transgenic mice leads to obesity and insulin resistance. J Clin Invest, 2001. 107(3): p. 379-86.
GPR7, NPBWR1, neuropeptides B/W receptor, G-protein coupled receptor 7, MCHR1, melanin-concentrating hormone receptor 1, GPR24, pain, feeding, counterscreen, dose response, HTS, high throughput screen, 1536, antagonist, antagonism, inhibitor, inhibition, fluorescence, calcium, Fluo-8, fluorescence, dye, plate-based, Scripps, Scripps Florida, The Scripps Research Institute Molecular Screening Center, SRIMSC, Molecular Libraries Probe Production Centers Network, MLPCN.
The purpose of this assay is to determine dose response curves for compounds identified as active in a set of previous experiments entitled, "Fluorescence-based counterscreen for antagonists of the G-protein coupled receptor 7 (GPR7): cell-based high throughput screening assay to identify antagonists of the melanin-concentrating hormone receptor 1 (MCHR1)" (AID 2148). MCHR1 (GPR24) is the receptor for MCH, a cyclic hypothalamic neuropeptide that promotes food intake (14), increases leptin and insulin release (15), and modulates energy metabolism (16). This assay also serves as a counterscreen for compounds identified as active in a previous set of experiments entitled, "Fluorescence-based primary cell-based high throughput screening assay to identify antagonists of the G-protein coupled receptor 7 (GPR7)" (AID 1861), and that confirmed activity in a previous set of experiments entitled, "Fluorescence-based confirmation cell-based high throughput screening assay to identify antagonists of the G-protein coupled receptor 7 (GPR7)" (AID 1952). This assay employs HEK cells stably co-transfected with human MCHR1 and a chimeric Gaqi3. Cells are treated with test compounds followed by measurement of intracellular calcium as monitored by the FLUO-8 fluorescent, cell permeable calcium indicator dye. As designed, compounds that act as human MCHR1 antagonists will decrease calcium mobilization, resulting in decreased relative fluorescence of the indicator dye, and thus decreased well fluorescence. Test compounds were assayed in triplicate in a 10-point 1:3 dilution series starting at a nominal test concentration of 44 micromolar.
The hMCHR1 HEK293T/Gqi3 cell line was routinely cultured in T-175 sq cm flasks at 37 degrees C and 95% relative humidity (RH). The growth media consisted of Dulbecco's Modified Eagle's Media (DMEM) supplemented with 10% v/v heat-inactivated qualified fetal bovine serum, 25 mM HEPES, 200 micrograms/mL Hygromycin-B, 100 micrograms/mL Zeocin, 200 micrograms/mL Geneticin and 1X antibiotic mix (penicillin, streptomycin, and neomycin).
The day before the assay 1500 cells in 3 microliters of growth media were seeded into each well of 1536 well microtiter plates and allowed to incubate at 37 degrees C, 5% CO2, and 95 % RH for 23 hours. Next, 2 microliters of the fluorogenic Fluo-8 intracellular calcium indicator mixture with 1 mM trypan red plus (prepared according to the manufacturer's protocol) was added to each well. After incubation for 1 hour at 37 degrees C, 5% CO2, and 95 % RH, 22 nL of test compound in DMSO, or DMSO alone were dispensed to the appropriate wells. The assay was started after an additional 30 minute incubation at room temperature, by performing a basal read of plate fluorescence (470-495 nm excitation and 515-575 nm emission) for 5 seconds on the FLIPR Tetra (Molecular Devices). Next, 15 nL of MCH peptide agonist (0.2 nM final concentration) in DMSO, or DMSO alone were dispensed to the appropriate wells. Then a real time fluorescence measurement was immediately performed for the remaining 180 seconds of the assay.
A ratio for each well was calculated to normalize assay data, according to the following mathematical expression:
Ratio = I_Max / I_Min
I_Max represents the maximum measured fluorescence emission intensity over the 185 second read and;
I_Min represents the minimum (basal) measured fluorescence emission intensity before compound was added.
Percent inhibition was calculated from the median ratio as follows:
% Inhibition = [1-((Ratio Test_Compound - Median_Ratio_High_Control)/ (Median_Ratio_Low_Control - Median_Ratio_High_Control))]*100
Test_Compound is defined as wells containing test compound.
Low_Control is defined as wells containing DMSO, MCH peptide.
High_Control is defined as wells containing DMSO.
For each test compound, percent inhibition 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 IC50 values were generated from fitted curves by solving for the X-intercept value at the 50% inhibition level of the Y-intercept value. In cases where the highest concentration tested (i.e. 44 micromolar) did not result in greater than 50% inhibition, the IC50 was determined manually as greater than 44 uM. Compounds with an IC50/EC50 greater than 10 uM were considered inactive. Compounds with an IC50/EC50 equal to or less than 10 uM were considered active.
Any compound with a percent activity value <50% at all test concentrations was assigned an activity score of zero. Any compound with a percent activity value >50% at any test concentration was assigned an activity score greater than zero. Activity score was then ranked by the potency, with the most potent compounds assigned the highest activity scores.
The activity score range for active compounds is 100-96, for inactive 96-0.
List of Reagents:
hMCHR1 HEK293T/Gqi3 cell line (provided by Assay Provider)
Fluo-8 No Wash Calcium Assay Kit (ABD Bioquest, part 36316)
Trypan red plus (ABD Bioquest, part 2456)
DMEM (Invitrogen, part 11965)
Geneticin (Invitrogen, part 10131-027)
Hygromycin-B (Invitrogen, part 10687-010)
Zeocin (Invitrogen, part 46-0509)
Trypsin-EDTA solution (Invitrogen, part 25200-056)
Fetal Bovine Serum (Omega scientific, part FB-02)
100X Penicillin-Streptomycin-Neomycin mix (Invitrogen, part 15640-055)
T-175 tissue culture flasks (Corning, part 431080)
1536-well plates (Aurora, part 19326)
MCH peptide (Phoenix, part 070-47)
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. 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 non-specifically modulate cAMP and CNG activity or membrane potential, and compounds that quench or emit fluorescence 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 AID.
* Activity Concentration. ** Test Concentration.
Data Table (Concise)