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High-Throughput Agonist Shift Assay Development for the Analysis of M1-Positive Allosteric Modulators
Michelle F Homsher1, Douglas C Beshore2, Jason Cassaday1
11 Screening and Protein Sciences, Merck and Co, North Wales, PA, USA.
SLAS Discovery : Advancing Life Sciences R & D
|April 21, 2017
Summary
Automating agonist shift assays allows for the comprehensive characterization of over 1000 positive allosteric modulators (PAMs) for the M1 receptor. This approach reveals that standard potency measurements do not always correlate with detailed allosteric parameters, crucial for drug discovery.
Area of Science:
- Pharmacology
- Drug Discovery
- Biochemistry
Background:
- Agonist shift assays are resource-intensive, limiting the characterization of allosteric modulators in drug discovery.
- Traditional assays often focus on limited compound subsets due to complexity and data handling demands.
- Understanding allosteric parameters like potency (alpha), efficacy (beta), direct activity (tauB), and binding affinity (KB) is critical.
Purpose of the Study:
- To automate agonist shift assays for high-throughput evaluation of allosteric modulators.
- To determine comprehensive allosteric parameters for a large set of positive allosteric modulators (PAMs).
- To assess the correlation between standard potency measurements and detailed allosteric parameters for M1 receptor modulators.
Main Methods:
- Development and implementation of a high-throughput calcium-imaging agonist shift assay.
- Cross-titration of allosteric modulators and orthosteric ligands for over 1000 PAMs targeting the human muscarinic acetylcholine receptor 1 (M1).
- Inclusion of control compounds for repeated runs to ensure internal consistency and assay reliability.
Main Results:
- Successfully determined allosteric parameters for over 1000 PAM molecules.
- Demonstrated assay consistency through repeated control compound analysis.
- Revealed a lack of direct correlation between standard potency measurements and detailed allosteric parameter results.
Conclusions:
- Automation of agonist shift assays enables the evaluation of a larger compound library.
- This data-rich analysis can differentiate compound classes earlier in drug discovery.
- Comprehensive characterization of allosteric properties, beyond simple potency, is essential for effective lead prioritization.