Farnesoid X Receptor (FXR; NR1H4)
| Product Family | Product Number | Product Description | Technical Manual |
| IB0060 FXR (NR1H4) |
IB00601-32 | Human FXR Reporter Assay System, 3 x 32 assays in 96-well format | Technical Manual |
| IB00601 | Human FXR Reporter Assay System, 1 x 96-well format assays | Technical Manual | |
| IB00602 | Human FXR Reporter Assay System, 1 x 384-well format assays | Technical Manual |
Farnesoid X Receptor Assay Kit 
This Farnesoid X Receptor (FXR) assay kit is an all-inclusive FXR reporter assay system that includes, in addition to FXR Reporter Cells, two optimized media for use during cell culture and (optionally) in diluting the test samples, a reference agonist, Luciferase Detection Reagent, a cell culture-ready assay plate, and a detailed protocol.
INDIGO’s cell-based reporter assays allow scientists to detect any biological activity that their test samples may exert against a specific receptor present in the cell. They utilize firefly luciferase reporter gene technology which provides superior precision and sensitivity. Since the receptor binding controls the expression of the luciferase reporter gene, luciferase activity in the cells can be correlated directly with the activity of the receptor. The strength of an interaction of a chemical with the target receptor is quantified using a luminometer to measure the level of light emitted.
Fast, reproducible, easy-to-analyze results are only four steps away
Many luciferase reporter assays require the user to grow their own cells and take time to optimize the results. INDIGO’s reporter cells contain the receptor of interest and the luciferase reporter gene. Reporter cells have been optimized to provide extreme sensitivity to quantify even small changes in receptor activity. With INDIGO’s cell-based reporter assays, the process is as easy as Thaw, Feed, Dose, and Read.
Farnesoid X Receptor Reporter Cells
FXR Reporter Cells are prepared using INDIGO’s proprietary CryoMite™ process. This proprietary cryopreservation process, enables long-term preservation of our unique reporter cells, so we can ship our cryopreserved reporter cells and assay reagents to you via overnight delivery, for your immediate use. Or, you can store the assay kits at -80°C. Once thawed, reporter cells are ready for immediate use so there is no need to take time on intermediate spin-and-wash steps, viability determinations, or cell titer adjustments.
Farnesoid X Receptor Luciferase Reporter
INDIGO’s FXR assay kits feature a luciferase detection reagent specially formulated to provide stable light emission between 5 and 90+ minutes after initiating the luciferase reaction. Incorporating a 5-minute reaction-rest period ensures that light emission profiles attain maximal stability, thereby allowing assay plates to be processed in batch. By doing so, the signal output from all sample wells, from one plate to the next, may be directly compared within an experimental set.
Assay Kit & PlatformsBulk assay reagents can be custom manufactured to accommodate any scale of HTS. Please inquire.
FXR assay kit also available in: Mouse, Rat, Cyn Monkey, Dog
Farnesoid X Receptor Assay Services
The primary application of INDIGO’s cell-based Farnesoid X Receptor assays are to quantitatively assess the bioactivity of a test compound as an agonist (activator) or antagonist (inhibition of an agonist response) of Farnesoid X Receptor. Service assays include a positive control reference compound and ‘vehicle’ control for every experiment. A formal study report and all data files are provided to the client upon completion of the study. To receive a quote for your proposed study, complete & submit the online “Request a Quote” form, or, contact an INDIGO Customer Service Representative to discuss your desired study parameters.
FXR Service Assays: Human, Mouse, Rat, Cyn Monkey, Dog
Farnesoid X Receptor Background
The farnesoid X receptor (FXR), also known as NR1H4 is a nuclear hormone receptor with activity similar to that seen in other steroid receptors such as estrogen or progesterone receptor, but more similar in form to PPAR, LXR and RXR. Encoded by the NR1H4 gene, FXR is expressed at high levels in the liver and intestine. Chenodeoxycholic acid and other bile acids are natural ligands for FXR.
Like other steroid receptors, when activated, FXR translocates to the cell nucleus, forms a heterodimer with RXR and binds to hormone response elements on DNA (FXEs) to elicit expression or transrepression of gene products. One of the primary functions of FXR activation is the suppression of cholesterol 7 alpha-hydroxylase (CYP7A1), the rate-limiting enzyme in bile acid synthesis from cholesterol. FXR does not directly bind to the CYP7A1 promoter. Rather, FXR induces expression of small heterodimer partner (SHP) which then functions to inhibit transcription of the CYP7A1 gene. In this way a negative feedback pathway is established in which synthesis of bile acids is inhibited when cellular levels is already high.
INDIGO's FXR Reporter Assay Systems utilize proprietary mammalian cells engineered to express human NR1H4 protein, commonly referred to as FXR.
The principle application of this FXR assay is in the screening of test samples to quantify functional activities, either as agonist or antagonist, that they may exert against the human farnesoid x receptor.
Synonyms: Farnesoid X Receptor, FXR, Human Farnesoid X Receptor, Human FXR, NR1H4
Farnesoid X Receptor Assay Data
Agonist and Antagonist dose-responses of the FXR Assay. Dose-response assays were performed as described in the assay Technical Manual. FXR reference agonists GW4064 (provided), Fexaramine and CDCA (Cayman Chemical), Obeticholic acid (OCA) and WAY-362450 (Selleckchem) were analyzed. For antagonist analyses the suspension of FXR reporter cells were pre-treated with a sub-maximal (~ EC80) concentration of the agonist GW4064; prepared treatment media supplemented with the antagonist references Z-Guggulsterone (Cayman Chemical) and DY 268 (Tocris) were dispensed into assay wells. Luminescence was quantified using a GloMax-Multi+ luminometer (Promega). Average relative light units (RLU) and corresponding standard deviation (SD) values were determined for each treatment concentration. Z’ values were calculated as described by Zhang, et al. (1999). Non-linear regression and EC50 analyses were performed using GraphPad Prism software. RESULTS: The large response range and high Z' values confirm the robust performance of both agonist-mode and antagonist-mode setups for this FXR assay, and demonstrate its suitability for use in HTS applications.
Farnesoid X Receptor Assay Research Areas
Dyslipidemia; Bile Acid and Xenobiotic; Metabolic Disease; Toxicology; NASH/NAFLD; Drug-Nutrient Interaction