|Budget Amount *help
¥3,900,000 (Direct Cost : ¥3,900,000)
Fiscal Year 1998 : ¥1,600,000 (Direct Cost : ¥1,600,000)
Fiscal Year 1997 : ¥2,300,000 (Direct Cost : ¥2,300,000)
Glucocorticoids perform these functions by binding to a cytoplasmic receptor protein glucocorticoid receptor (GR), which is a member of the nuclear receptor superfamily and acts as a ligand-inducible transcription factor. UDCA, which has widely been used as a therapeutic drug for patients with cholesterol gall stones, is currently indicated for various liver diseases including primary biliary cirrhosis, primary scierosing cholangitis, and viral hepatitis. We showed that UDCA-dependent promotion of translocation of the GR may be associated with, at least in part, its immunomodulatory action through GR-mediated gene regulation. On the other hand, nuclear import is an essential step in transcriptional regulation of gene expression by the GR.Green fluorescent protein (GFP) has been developed as a protein tag for in situ and real time visualization of desired proteins, and subcellular localization of the GR has been studied in living cells using GFP-GR chimera. We confirmed that GFP-GR docks in the cytoplasm in the absence of hormonal ligands and that the translocation of GFP-GR is strictly controlled in a ligand-dependent fashion. The kinetics of GFP-GR translocation appears to be similar to those reported in native GR.Since not only nuclear transport but also transactivational potential of GFP-GR is comparable to those of native GR, the translocation assay system using GFP-GR appears to be suitable for analyzing effects of various ligands and pharmacological reagents on glucocorticoid signal transduction pathway. Indeed, using this GFP-GR system, we have already shown that nuclear import of the GR is redox-sensitive. This system may also be applicable to clinical specimens to analyze tissue- or cell-type specific glucocorticoid responsiveness. Therefore, we are planning to initially screen thousands of compounds in terms of promotion of nuclear translocation of the GR using this GFP-GR system.