抄録
With the advent of green fluorescent protein (GFP), the subcellular distribution of sex steroid hormone receptors has been found to be more dynamic than previously thought. Upon estradiol treatment ERa and b in the same cell were colocalized to show discrete pattern, suggesting that both subtypes of ERs were bound to the same nuclear sites. In fact, FRET (fluorescence resonance energy transfer) clearly showed the interaction of ERa and ERb. In the presence of the estradiol, however, the discrete staining pattern of ERa and b were mostly overlapped with Brg-1, indicating that most of the ERs clusters are involved in the chromatin remodeling machinery. FRAP (fluorescence recovery after photobleaching) analysis showed that nuclear ERa and b are most dynamic and mobile in the absence of the ligand, but its mobility was decreased after the ligand treatment. When ATP was deleted from the culture medium, even liganded ERa significantly lost its free mobility in the nucleus, indicating that ERa dynamism is ATP-dependent. Transgenic mice in which GFP was expressed under the ERa 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 containing cells at the region-specific manner. Sexually dimorphic nucleus of the preoptic area (SDN-POA) showed distinct male-female difference and contained estrogen receptor a (ERa). Relationship between the intrauterine position of fetuses and the volume of the SDN-POA is discussed. [J Physiol Sci. 2007;57 Suppl:S52]
