| Budget Amount *help |
¥3,500,000 (Direct Cost: ¥3,500,000)
Fiscal Year 2006: ¥1,200,000 (Direct Cost: ¥1,200,000)
Fiscal Year 2005: ¥2,300,000 (Direct Cost: ¥2,300,000)
|
|---|
| Research Abstract |
Adrenal corticosteroids (cortisol in humans or corticosterone in rodents) exert numerous effects in the central nervous system that regulate the stress response, mood, learning and memory, and various neuroendocrine functions. Corticosterone (CORT) actions in the brain are mediated by two corticosteroid receptors, glucocorticoid receptor (GR) and mineralocorticoid receptor (MR), and they show a high degree of colocalization in the hippocamal region. These receptors are predominantly resided in the cytoplasm without ligand and translocated into the nucleus upon ligand binding to act as transcriptional factors. Thus their subcellualr localizations are important component of their biological activity. Given the differential action of MR and GR in the central nervous system, it is important to elucidate how the trafficking of these receptors between cytoplasm and nucleus and their interaction are regulated by ligand or other molecules to exert transcriptional activity. Molecules less than 20-40 kDa can passively diffuse through the nuclear pore complex (NPC) from the cytoplasm to the nucleus, whereas those more than 40 kDa are transported through gated-channels of the NPC by active mechanisms. Importin a and importin β are docking proteins for karyopherin-mediated binding of substrate in a nuclear import pathway across the NPC. In the present study, we first investigated the trafficking of GR and MR, and importins in living cultured hippocampal neurons and COS-1 cells with GFP color variants, and the interaction of these receptors and importin α using fluorescent resonance energy transfer technique. We also examined dynamics of importin α subtypes, importin α 1, 2, and 3 in living cells. Next, we made dominant-negative forms of importin α s, which bind to GR, but cannot transport GR to the nucleus, and find out a putative motor protein involved in the nuclear transport of a complex of corticosteroid receptor and importin α.
|
