2000 Fiscal Year Final Research Report Summary
Molecular mechanism (s) responsible for species difference in dioxin toxicity
| Project/Area Number |
11672225
|
|---|
| Research Category |
Grant-in-Aid for Scientific Research (C)
|
| Allocation Type | Single-year Grants |
|---|
| Section | 一般 |
|---|
| Research Field |
Environmental pharmacy
|
|---|
| Research Institution | Hokkaido University |
|---|
Principal Investigator |
TAKAHASHI Yoshiki Hokkaido University Pharmaceutical Sciences Instructor, 大学院・薬学研究科, 助手 (80292019)
|
|---|
| Co-Investigator(Kenkyū-buntansha) |
ARIYOSHI Noritaka Hokkaido University Pharmaceutical Sciences Associate Professor, 大学院・薬学研究科, 助教授 (00243957)
FUJITA Kenichi Hokkaido University Pharmaceutical Sciences Instructor, 大学院・薬学研究科, 助手 (60281820)
|
|---|
| Project Period (FY) |
1999 – 2000
|
| Keywords | Aryl hydrocarbon / receptor / Xenobiotic-responsive element |
|---|
| Research Abstract |
A xenobiotic-responsive element (XRE)-binding factor (s) other than aromatic hydrocarbon receptor (AhR)/AhR nuclear translocator (Arnt) complex was found to inhibit the transcription of the guinea pig NAD (P) H : quinone oxidoreductase_1 (NQO_1) gene. Within the 5'-flanking region up to -1.6 kilobase of this gene, there were two possible XREs, designated as XRE1 and XRE2. XRE1 but not XRE2 interacted with AhR/Arnt complex in vitro. Interestingly, the activation of 10xXRE1-Luc reporter gene with ten copies of XRE1 by AhR/Arnt complex was seen in Drosophila Schneider line 2 (SL2) cells but not in human hepatoblastoma HepG2 cells. A super shift assay using antibodies to AhR and nuclear extracts from HepG2 cells treated with 2, 3, 7, 8-tetrachlorodibenzofuran revealed that XRE1 bound to an unknown factor (s), which was distinct from AhR/Arnt complex. Searching the sequence similar to XRE1, the sequence of XRE1 overlapped with that of specificity protein 1 (Sp1)-binding site. Our super shift assay showed that the unknown factor (s) was identical to Sp1. Furthermore, the AhR/Arnt-mediated activation of the 10xXRE1-Luc in SL2 cells was blocked with the amount of Sp1 expression plasmid transfected. Thus, we conclude that Sp1 and AhR/Arnt complex bind to the XRE1 of the guinea pig NQO_1 gene in a mutually exclusive manner.
|
