Hormone receptor-based assays

So far, we have reviewed the various ways in which complex dose-response curves in intact-tissue bioassays can be the result, the pharmacological resultant, of two or more interacting activities. Now, if all that these bioassays achieved was to blur and obscure the underlying activities, they would have to give way to the newer, analytically simpler assays based on chemistry and biochemistry. However, the beauty of intact-tissue bioassays is that they are analytically tractable by using families of dose-response curves and appropriate mathematical models, the complexity of intact hormone-receptor systems can, indeed, be interpreted. Bioassay allows them to be studied as systems in ways denied to simple biochemical assays. 

Gaido, K.W., Leonard, L.S., Lovell, S., Gould, J.C., Babai, D., Portier, C.J., and McDonnell, D.P., Evaluation of chemicals with endocrine modulating activity in a yeast-based steroid hormone receptor gene transcription assay, Toxicol. Appl. Pharmacol., 143, 205-212, 1997. 

Wilkinson, J.M. et al. 2008. Compound profiling using a panel of steroid hormone receptor cell-based assays. J. Biomol. Screen. 13, 755-765. 

Here are a few textbooks that cover a number of the specific hormone signaling systems and protocols for both measuring receptor-ligand interactions and cell-based assays. 

Fig. 8.3 Yeast-based screen for agonists or antagonists of the human estrogen receptor. The hormone estrogen (estradiol) binds to the estrogen receptor which is expressed from a gene driven by the PGK promoter. The hormone-receptor complex binds to an estrogen-responsive element (ERE) that controls the expression of the p-galactosidase reporter gene. The assay measures the activity of the enzyme using a substrate that forms a colored product on conversion.

This review siunmarizes approaches based on multiple peptide synthesis for the determination of structural and conformational requirements of peptide hormones for binding at and activation of their specific receptors. These include various systematic scans, several methods to stabihze distinct local conformations as well as secondary or even tertiary structures. Examples of their application are mainly taken from various midti-hgand/multi-receptor systems including that of the neuropeptide Y (NPY) family. Moreover, basic ligand-receptor binding assays and functional cell-based in vitro assays, which are used to investigate the interaction of native and modified peptide ligands with their receptors, are briefly reviewed. 

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