| Assay Method Information | |
| | GLP-1 Assay with GLP1 Endogenous Agonist |
| Description: | To assess the effects of test compounds on GLP-1 or glucagon potency and efficacy, a high-throughput calcium mobilization assay was used essentially as previously described (Morris L C, Days E L, Turney M, Mi D, Lindsley C W, Weaver C D, Niswender K D, A Duplexed High-Throughput Screen to Identify Allosteric Modulators of the Glucagon-Like Peptide 1 and Glucagon Receptors. J. Biomol. Screen. 2014 Feb. 13, 19(6):847-858). Briefly, human GLP-1R or Glucagon Receptor 9-3-H cells over-expressing a promiscuous G-protein (Millipore, Billerica, Mass.) were plated at 15,000 cells/well in black-walled 384-well plates (Greiner Bio-one, Monroe, N.C.) in Dulbecco's Modified Eagles Medium (DMEM) with 10% FCS, 4.0 mM L-glutamine, non-essential amino acids (NEAAs), and 10.0 mM HEPES without antibiotics. After overnight attachment, cells were washed twice with assay buffer (HBSS supplemented with 20 mM HEPES and 1.0 mM probenecid) using an ELx405CW cell washer (Bio-Tek, Winooski, Vt.) and then loaded with the calcium sensitive dye fluo-4 AM (Invitrogen, Grand Island, N.Y.) at a final concentration of 2.0 μM in assay buffer. After a 45-minute incubation at room temperature, the dye was removed by washing, leaving 20 μL of assay buffer. Next, the cell plate was introduced alongside a 384-well compound plate containing 0.1% final DMSO control wells and 11-point concentration response curves of putative GLP-1 PAMs created using a non-pipet based liquid transfer instrument, ECH0555 (Labcyte, Sunnyvale, Calif.). After a 20 μL compound addition to the appropriate wells, kinetic fluorescent measurements were collected for 2 minutes using an FDSS6000 (Hamamatsu, Bridgewater, N.J.) with 488 nm excitation and 480/540 emission filters. After 2 minutes, 10 μL of an EC20 concentration of GLP-1 peptide 7-36 amide (Phoenix Pharmaceuticals, Burlingame, Calif.), Glucagon (Phoenix Pharmaceuticals, Burlingame, Calif.) Exendin-4 (Tocris Bioscience, Bristol, UK), or Liraglutide (Victoza , Novo-Nordisk, Denmark) was added and fluorescence was monitored for an additional 2 minutes to observe potentiation of the calcium flux signal. Control wells for vehicle, EC20 peptide, and Emax peptide resided in columns #1 and 24 and rows H and I to account for any plate variations. Recombinant peptides were reconstituted into assay buffer supplemented with 0.1% fatty acid free BSA (Sigma #A6003) and diluted into borosilicate glass tubes to maximize peptide recovery (Goebel-Stengel M, Stengel A, Tache Y, Reeve J R Jr., The importance of using the optimal plasticware and glassware in studies involving peptides. Anal. Biochem. 2011 Jul. 1, 414(1):38-46). |
| Affinity data for this assay | |
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