Abstract
Steroid receptors which include estrogen receptor (ER) a andb, progesterone receptors (PR) A and B, androgen receptor (AR), glucocorticoid receptor (GR), and mineralocorticoid receptor (MR) are ligand-dependent transcriptional factor. With the advent of green fluorescent protein (GFP) and its color variants, the subcellular distribution of many steroid receptors has been found to be much more dynamic than previously thought. These receptors are localized wither in the cytoplasm or nucleus at the unliganded condition, but in all cases, the addition of a ligand leads to almost complete nuclear translocation of the receptors. Upon estradiol treatment ER a and b in the same cell were relocalized to show discrete pattern, and they were localized at the same discrete cluster, suggesting that both subtypes of ERs were bound to the same nuclear sites. In the presence of the estradiol, however, the discrete staining pattern of ER a and b were mostly overlapped with Brg-1, indicating that most of the ERs clusters are involved in the chromatin remodeling machinery. FRAP analysis showed that nuclear ER a and b, PRA and B and, AR are dynamic and mobile, but its mobility was different. Transgenic (Tg) mice in which GFP was expressed under the ER a promoter activity were generated. Ovariectomy caused significant reduction of cell bodies of GFP neurons containing ERa in the medial preoptic area, but not in the ventromedial nucleus. These results suggest that estrogen affects ERa cells at the region specific manner. [Jpn J Physiol 54 Suppl:S29 (2004)]
