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Assay Method Information

Assay Name:  RORgammat (LBD) Reporter Assay
Description:  A reporter assay was used to test functional activity of RORγt modulatory compounds on transcriptional activation driven by the RORγt LBD. Cells used in the assay were co-transfected with two constructs. The first construct, pBIND-RORγt LBD, contained the wild type human RORγt LBD fused to the DNA binding domain of the GAL4 protein. The second construct, pGL4.31 (Promega Cat no. C935A), contained multiple GAL4 responsive DNA elements upstream of firefly luciferase. To generate a background control, cells were similarly co-transfected with two constructs, but in the first construct the AF2 amino acid motif in the RORγt LBD was changed from LYKELF (SEQ ID NO:5) to LFKELF (SEQ ID NO:6). The AF2 mutation has been shown to prevent co-activator binding to the RORγt LBD, thus preventing transcription of firefly luciferase. The mutant construct was called pBIND-RORγt-AF2.For the RORγt constructs used in the reporter assay, numbering for the nucleotide sequences was also based on the reference sequence for human RORγt, transcript variant 2, NCBI Accession: NM_001001523.1 (SEQ ID NO:1). For the wild type human RORγt LBD construct, pBIND-RORγt LBD, nucleotides 850-1635 (SEQ ID NO:2) coding for the wild type human RORγt LBD were cloned into EcoRI and NotI sites in the pBIND vector (Promega cat. No E245A). The pBIND vector contains the GAL4 DNA Binding Domain (GAL4 DBD) and the renilla luciferase gene under control of the SV40 promoter. Renilla luciferase expression serves as a control for transfection efficiency and cell viability. For the background control construct, pBIND-RORγt-AF2, the AF2 domain of RORγt LBD was mutated using the Quik Change II Site Directed Mutagenesis System (Stratagene Cat. No. 200519). The nucleotide sequence coding for the RORγt LBD sequence with the mutated AF2 domain is shown as SEQ ID NO:7. The amino acid sequences for the wild type RORγt LBD and RORγt LBD with the mutated AF2 domain are shown as SEQ ID NO:8 and SEQ ID NO:9, respectively.The reporter assay was performed by transiently transfecting HEK293T cells with 5 μg of pBIND-RORγt LBD or pBIND-RORγt LBD-AF2 and 5 μg pGL4.31 (Promega Cat no. C935A) using Fugene 6 (Invitrogen Cat no. E2691) at a 1:6 ratio of DNA:Fugene 6 in a T-75 flask in which cells were at least 80% confluent. Twenty four hours after bulk transfection, cells were plated into 96-well plates at 50,000 cells/well in phenol-red free DMEM containing 5% Lipid Reduced FCS and Pen/Strep. Six hours after plating, cells were treated with compounds for 24 hours. Media was removed and cells were lysed with 50 μL 1 Glo Lysis Buffer (Promega). Dual Glo Luciferase Reagent (50 μL/well) was then added and firefly luciferase luminescence was read on an Envision after a ten minute incubation. Finally, Stop and Glo reagent (50 L/well) was added and renilla luciferase luminescence was read on an Envision after a ten minute incubation. To calculate the effect of compounds on RORγt activity, the ratio of firefly to renilla luciferase was determined and plotted against compound concentration. Agonist compounds increase RORγt-driven luciferase expression, and antagonist or inverse agonist compounds decrease luciferase expression.
Affinity data for this assay
 

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Last update November 1, 2007
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