| Assay Method Information | |
| | Biological Assay for RORgammaT Activity |
| Description: | The compounds of the invention inhibit RORgammaT activity. Activation of RORgammaT activity can be measured using, e.g., biochemical TR-FRET assay. In such an assay, interaction of cofactor-derived peptides with human RORgammaT-Ligand Binding Domain (LBD) can be measured. The TR-FRET technique is a sensitive biochemical proximity assay that will give information concerning the interaction of a ligand with the LBD, in the presence of cofactor-derived peptides (Zhou et al., Methods 25:54-61, 2001).To identify novel antagonists of RORgammaT, an assay was developed which employs the interaction of RORgammaT with its co-activator peptide SRC1_2. This peptide mimics the recruitment of co-activators to RORgammaT through its interaction with the LXXLL (e.g., NR box) motifs (Xie et al., J. Immunol. 175: 3800-09, 2005; Kurebayashi et al., Biochem. Biophys. Res. Commun. 315: 919-27, 2004; Jin et al., Mol. Endocrinology 24:923-29, 2010). The RORγ-Ligand Binding Domain TR-FRET Assay was run according to the following protocol.HIS-tagged RORγ-LBD protein was recombinantly expressed in Escherichia coli. The RORγ-LBD protein was purified by Ni2+-affinity resin. Purified protein was then diluted in assay buffer (50 mM Tris pH 7.0, 50 mM KCl, 1 mM EDTA, 0.1 mM DTT, 100 mg/ml bovine serum albumin, delipidated) to obtain a RORγ-LBD final concentration of 3 nM. Europium tagged anti-HIS antibody was also added to this solution (1.25 nM). Separately, SF9 cells not expressing any recombinant protein were lysed (32,000 cells per ml in 25 mM Tris, 50 mM NaCl) and the previously frozen lysate was added to the diluted RORγ-LBD solution at a ratio of 0.75 ml SF9 lysate per 15 ml of diluted RORγ-LBD.Compounds to be tested were injected to the 384-well assay plate using Acoustic Droplet Ejection technology by Echo 550 liquid handler (Labcyte, Calif.).A stock of biotinylated-LXXLL peptide from coactivator SRC1 (Biotin-SPSSHSSLTERHKILHRLLQEGSP) (SEQ ID NO: 1) and APC-conjugated streptavidin (final concentrations 100 nM and 8 nM respectively) were also added to each well.The final assay mixture was incubated overnight at 4° C., warmed to room temperature and the fluorescence signal was measured on an Envision plate reader: (Excitation filter=340 nm; APC emission=665 nm; Europium emission=615 nm; dichroic mirror=D400/D630; delay time=100 μs, integration time=200 μs). IC50 values for test compounds were calculated from the quotient of the fluorescence signal at 665 nm divided by the fluorescence signal at 615 nm. |
| Affinity data for this assay | |
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