External ID: SBCCG-A462-APJ-Agonist-DryPowder-Assay
Protocol:
A. Brief Description of the Assay:
The purpose of this assay is to detect agonists that cause the activation the Angiotensin II receptor-like 1 (Apelin receptor) in the CHO-K1 AGTRL-1 beta-Arrestin Cell Line in 1536-well plate format in uHTS mode.
B. Materials:
Angiotensin II receptor-like 1 (AGTRL-1) Cell Line (DiscoveRx, Cat# 93-0250C2)
F12 nutrient mix HAMs (Invitrogen, Cat# 11765)
Fetal Bovine Serum, heat-inactivated (Hyclone, Cat# SH30396)
100X Penicillin/Streptomycin Solution (Invitrogen, Cat#15140-122)
Hygromycin B (Roche, Cat# 10843555001)
Geneticin (MPBiomedicals, Cat# 1672548)
Trypsin-EDTA 0.25% (Invitrogen, Cat# 25200-056)
Cell Dissociation Buffer (Invitrogen, Cat# 13151)
DPBS (Hyclone, Cat# 30028.02)
T225 TC Flask (Nunc, Cat# 159934)
Cell strainer, 40 um (BD, Cat# 352340)
1536-well, white, solid-bottom, Kalypsys compatible, TC plate (Corning)
Apelin-13 (Sigma-Aldrich, Cat# A6469)
PathHunter Detection Reagents (DiscoveRx, Cat# 93-0001)
Galacton Star
Emerald 11
Cell Assay Buffer
D. Dose Response Procedures:
Day1 -Cell Seeding
1) Plate 1000 cells/well in 4 uL of assay media into columns 1-48 of a 1536-well assay plate, using straight tip dispense on a Kalypsys dispenser.
2) Centrifuge plates at 500 rpm for 1 minute on a Vspin centrifuge. Use Kalypsys metal lids.
3) Incubate overnight at 37 degrees, 100% relative humidity, 5% CO2 for 16-18 hours.
Day2 -Compound Addition
1) Centrifuge compound plates at 500 rpm for 1 minute on a Vspin centrifuge.
2) Using LabCyte Echo, transfer varying volumes from a 2 mM Echo qualified plate containing test compounds into assay plate Col. 5 - 48 to achieve the desired dose response concentrations and range. Backfill with DMSO to equalize final DMSO concentrations in all test wells. Transfer equal volume of DMSO to positive and negative control wells in Columns 1 - 4.
3) Immediately following compound/DMSO transfer via the Echo, using the Kalypsys Dispenser, transfer 2ul/well of Assay media to Col. 3-48 for the negative control and test compound wells.
4) Using the Kalypsys Dispenser, add 2ul/well of 30 nM Apelin-13 in assay media to Col. 1-2 for the positive control .
5) Centrifuge plates at 500 rpm for 1 minute on a Vspin centrifuge.
6) Incubate plates at 25 degrees in the dark for 90 minutes.
7) Following 90 minute incubation, deliver 3.0 uL of Detection Reagent solution to each assay plate (Columns 1 - 48) using a Kalypsys dispenser.
8) Centrifuge plates at 2000 rpm for 3 minute on a Vspin centrifuge.
9) Incubate plates for 60 minutes at 25 degrees in the dark.
10) Read plates using the Viewlux using a luminescence protocol.
E. Recipes:
Growth Media
F12 nutrient mix HAMs supplemented with 10% hi-FBS, 1X Penicillin/Streptomycin; selection reagents: 300ug/ml Hygromycin B, 800ug/ml Geneticin
Assay Media
Same as Growth Media without the selection reagents
Trypsin
Dilute 0.25% Trypsin/EDTA to 0.05% Trypsin/EDTA using DPBS
Positive Control
Growth Media with 30 nM Apelin-13
Detection Reagent
Use the following ratio to prepare the detection reagent:
Galacton Star : Emerald II : Assay Buffer = 1 : 5 : 19
Comment:
Compounds with an EC50_Mean < 10 are considered to be active
Activity Scoring
Activity scoring rules were devised to take into consideration compound efficacy, its potential interference with the assay and the screening stage that the data was obtained. Details of the Scoring System will be published elsewhere. Briefly, the outline of the scoring system utilized for the assay is as follows:
1) First tier (0-40 range) is reserved for primary screening data and is not applicable in this assay.
2) Second tier (41-80 range) is reserved for dose-response confirmation data and is not applicable in this assay.
3) Third tier (81-100 range) is reserved for resynthesized true positives and their analogues.
a. Inactive compounds of the confirmatory stage are assigned a score value equal 81.
b. The score is linearly correlated with a compound potency and, in addition, provides a measure of the likelihood that the compound is not an artifact based on the available information.
c. The Hill coefficient is taken as a measure of compound behavior in the assay via an additional scaling factor QC:
QC = 2.6*[exp(-0.5*nH^2) - exp(-1.5*nH^2)]
This empirical factor prorates the likelihood of target-specific compound effect vs. its non-specific behavior in the assay. This factor is based on expectation that a compound with a single mode of action that achieved equilibrium in this assay demonstrates the Hill coefficient value of 1. Compounds deviating from that behavior are penalized proportionally to the degree of their deviation.
d. Summary equation that takes into account the items discussed above is
Score = 82 + 3*(pEC50 - 3)*QC,
where pEC50 is a negative log(10) of the EC50 value expressed in mole/L concentration units. This equation results in the Score values above 85 for compounds that demonstrate high potency and predictable behavior. Compounds that are inactive in the assay or whose concentration-dependent behavior are likely to be an artifact of that assay will generally have lower Score values.