Thyroid receptor microarray assay for real-time Nuclear Receptor-coregulator interaction

Thyroid hormone signalling plays a key role in many physiological processes, including brain development and metabolism. The thyroid hormone elicits its action via the two types of thyroid hormone receptor (TR), TRα and TRβ. This method characterises TRα-Ligand Binding Domain (LBD) interaction with a range of coregulators, by assessing binding affinity of a defined set of immobilised nuclear receptor coactivator and corepressor peptides. The binding affinity is assessed via interaction with the LXXLL and LXXXIXXXL motifs for coactivators and corepressors respectively. The binding affinity is enhanced by ligand induced activation of the receptor, while ligand-independent binding reduces the binding affinity. The amount of ligand-modulated interaction of coregulators with TRα-LBD is assessed via image analysis, by adding fluorescent antibodies against TRα-LBD. The obtained binding profiles can be used to identify compounds that can activate TRα, thereby differentiating between agonistic and antagonistic action.