SCREENING FOR LIGANDS OF HUMAN RETINOID X RECEPTOR-α USING ULTRAFILTRATION MASS SPECTROMETRY

摘要

Retinoid X receptors (RXRs) function as ligand-activated transcription factors and are obligatory components of a large number of nuclear receptor heterodimers. RXRs help regulate diverse physiological responses including the cancer prevention responses of cell proliferation, inflammation, cell differentiation, and apoptosis. Since RXRs represent important targets for cancer chemoprevention, an ultrafiltration mass spectrometry-based assay was developed to facilitate the discovery of potential chemoprevention agents that bind to human RXRα. Natural and synthetic ligands for RXRα including 9-cis-retinoic acid, docosahexaenoic acid and could be detected and identified in DMSO or even complex matrices such as extracts of marine bacteria. Specific binding of ligands to RXRα was demonstrated through competitive binding using ultrafiltration LC-MS-MS, and ligands could be ranked in order of affinity for RXRα. Therefore, ultrafiltration LC-MS-MS is suitable for the screening of complex mixtures such as natural product extracts for the discovery of new ligands to RXRα.