Characterization of karyopherins in androgen receptor intracellular trafficking in the yeast model.

BACKGROUND Mechanisms regulating androgen receptor (AR) subcellular localization represent an essential component of AR signaling. Karyopherins are a family of nucleocytoplasmic trafficking factors. In this paper, we used the yeast model to study the effects of karyopherins on the subcellular localization of the AR. METHODS Yeast mutants deficient in different nuclear transport factors were transformed with various AR based, GFP tagged constructs and their localization was monitored using microscopy. RESULTS We showed that yeast can mediate androgen-induced AR nuclear localization and that in addition to the import factor, Importinα/β, this process required the import karyopherin Sxm1. We also showed that a previously identified nuclear export sequence (NES(AR)) in the ligand binding domain of AR does not appear to rely on karyopherins for cytoplasmic localization. CONCLUSIONS These results suggest that while AR nuclear import relies on karyopherin activity, AR nuclear export and/or cytoplasmic localization may require other undefined mechanisms.