Conformation and interactions of the androgen receptor in living cells

Abstract

Nuclear receptors (NRs) are ligand-regulated transcription factors important in human physiology and disease. In certain NRs, including the androgen receptor (AR), ligand binding to the carboxy terminal domain (LBD) regulates transcriptional activation functions both in the LBD and in the amino terminal domain (NTD). We previously measured fluorescence resonance energy transfer (FRET) between fluorophores attached to the NTD and LBD to establish that agonist binding initiated an intramolecular NTD-LBD interaction in both the nucleus and cytoplasm. This intramolecular folding was followed by AR dimerization, which occurred preferentially in the nucleus and a slower transport of AR from the cytoplasm to the nucleus. Here we have continued these studies by comparing the relative effects of a number of additional AR ligands on intramolecular folding, AR dimerization and transport into the nucleus. Our goal is to define the relative importance of these activities in AR regulation of transcription and prostate tumor growth in order to better define the most relevant molecular targets for androgen therapies. The fine details of AR conformation, interaction and subcellular localization measured by these fluorescence techniques may be crucial in identifying AR pharmaceuticals with unique actions that allow strong improvements in therapy.