Environmental Effects on the Dynamism of Receptors of Lipophilic Signal Molecules in the Brain and its Functional Significance

点击翻译按钮获取中文摘要

The present research project was undertaken to investigate two types of steroid hormone receptors (glucocorticoids and sex steroids) dynamism by using real-time imaging with fluorescence recovery after photobleaching (FRAP) and fluorescent resonance energy transfer (FRET.) Glucocorticod receptor (GR) and mineralocorticoid receptor (MR) were localized in the cytoplasm in the absence of the ligand and they translocate to the nucleus after ligand binding. FRET demonstrated that importin a was involved in GR/MR translocation from the cytoplasm to the nucleus and GR and MR dimerize within the nucleus. FRAP showed that the movement of ligand-binded GR/MR was restricted in the nucleus. Upon estradiol treatment ERa and b were relocalized to show discrete pattern, and they were localized at the same discrete cluster. FRET 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 showed that nuclear ERa and b were dynamic and mobile in the absence of the ligand, but its mobility was slightly decreased after the ligand treatment. Nuclear matrix which was scaffolding sites within the nucleus was composed of actin and actin-related peptides. Treatment by detergent caused complete loss of ERa in the unliganded condition, but liganded ERa stick to the nuclear matrix. Nuclear matrix was an important factor to determine the dynamism of unliganded and liganded ERa.