Zebrafish Retinoic Acid Receptor Alpha A (zRARαa; nr1b1 isoform A)

INDIGO’s Zebrafish Retinoic Acid Receptor, Alpha A (zRARαa) Reporter Assay System utilizes proprietary non-human cells engineered to provide constitutive, high-level expression of Zebrafish (Danio rerio) RARαa (NR1B1 isoform A), a ligand-dependent transcription factor.

INDIGO's Reporter Cells express a hybrid zebrafish RARαa receptor in which the native N-terminal ligand binding domain (LBD) has been substituted with that of the yeast GAL4 LBD sequence. Accordingly the resident luciferase reporter gene is functionally linked to tandem copies of the Gal4 upstream activation sequence. Thus, quantifying changes in luciferase expression in the treated reporter cells provides a sensitive surrogate measure of changes in zRARαa. The principal application of this assay is in the screening of test samples to quantify any functional bioactivity that they may exert against zebrafish RARαa. In particular, zebrafish reporter assays are frequently used in the monitoring of environmental samples for the presence of biohazardous chemical pollutants, such as endocrine disruptors.

Retinoic acid receptors (RARs) are nuclear hormone receptors of the NRB1 class, which function as heterodimers with retinoid X receptors (RXRs). There are three distinct RAR subtypes: RARalpha, RARbeta, and RARgamma. RARalpha is present in most tissue types, whereas RARbeta and RARgamma expression is more selective. RXR-RAR heterodimers act as ligand-dependent transcriptional regulators by binding to the specific retinoic acid response element (RARE) found in the promoter regions of target genes. In the absence of an RAR agonist, RXR-RAR recruits co-repressor proteins such as NCoR and associated factors such as histone deacetylase to maintain a condensed chromatin structure. RAR agonist binding stimulates co-repressor release and co-activator complexes, such as histone acetyltransferase, are recruited to activate transcription. RARs transduce retinoid signals in vivo, which mediates proper embryogenesis, differentiation and growth arrest. Specifically, RXRalpha-RARgamma heterodimers are necessary for growth arrest and viseral and primitive endodermal differentiation, whereas RXRalpha-RARalpha is required for cAMP-dependent parietal endodermal differentiation. In vitro it has been difficult to elucidate the roles of individual subtypes as functional RAR knockouts generate artificial redundancies that are thought not to exist under normal conditions.

For more information on RARα, visit the Nuclear Receptor Resource.

The primary application of INDIGO’s cell-based nuclear receptor assays are to quantitatively assess the bioactivity of a test compound as an agonist (activator) or antagonist (inhibition of an agonist response) of a given 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.