| Project/Area Number |
07458178
|
|---|
| Research Category |
Grant-in-Aid for Scientific Research (B)
|
| Allocation Type | Single-year Grants |
|---|
| Section | 一般 |
|---|
| Research Field |
Molecular biology
|
|---|
| Research Institution | Kanazawa University |
|---|
Principal Investigator |
MURAKAMI Seishi Cancer Research Institute, Kanazawa University Professor, がん研究所, 教授 (90019878)
|
|---|
| Co-Investigator(Kenkyū-buntansha) |
NOMURA Takahiro Cancer Research Institute, Kanazawa University Assistant professor, がん研究所, 助手 (80115261)
|
|---|
| Project Period (FY) |
1995 – 1996
|
| Project Status |
Completed (Fiscal Year 1996)
|
| Budget Amount *help |
¥7,000,000 (Direct Cost: ¥7,000,000)
Fiscal Year 1996: ¥2,400,000 (Direct Cost: ¥2,400,000)
Fiscal Year 1995: ¥4,600,000 (Direct Cost: ¥4,600,000)
|
|---|
| Keywords | RNA polymerase / RPB5 / Hepafitis B uirus X protein / Tramsactivation / Tramscirption initiation / General transcription fuctor TFIIB / Transcriptional cofactor / RPB5-mediating-factor / B型肝炎ウイルス / 肝細胞がん / X蛋白(HBx) / 転写活性化 |
|---|
| Research Abstract |
Our previous finding that HBx directly interacts with RPB5, a common subunit of RNA polymerases, implies that HBx modulates the function of RNA polymerase directly. This project addressed the molecular mechanism of transcriptional modulation of RPB5 by HBx. 1.We found that both HBx and RPB5 specifically bound to TFIIB in vitro and in vivo. We could detect the ternary complex consisting of RPB5, HBx, and TFIIB in vivo and in vitro. 2.Some HBx substitution mutants, which were severely impaired in transacting activity, exhibited reduced binding affinity with either TFIIB or RPB5 in a mutually exclusive manner, suggesting that HBx transactivation requires the interactions of both RPB5 and TFIIB.The results indicate that HBx is a novel virus modulator that facilitates transcriptional initiation by stabilizing the association between RNA polymerase and TFIIB through communication with RPB5 and TFIIB.3.We addressed whether HBx acts as a transcriptional activator when it is recruited to a distal cis-element, and whether HBx positively affects in vitro transcription. The results indicated that HBx can not act as a transcriptional transactivator but can act as a cofactor involving in transcription through protein-protein interaction. 4.To understand the function of RPB5, we tried to isolate RPB5-binding protein by direct cDNA cloning using far-Western blotting. We successed to isolate a cCNA redundantly which was found unreported and unique. The gene was designated as RPB5 mediating protein (RMP). Preliminarily experiments showed that RMP may interfer transactivation of HBx in mammalian cells. The results suggest that RMP may antagonize HBx. Further characterization of RMP is on going.
|
