1998 Fiscal Year Final Research Report Summary
Pharmacological study on NO and biopterin synthesis in osteoblastic cells
| Project/Area Number |
09671912
|
|---|
| Research Category |
Grant-in-Aid for Scientific Research (C)
|
| Allocation Type | Single-year Grants |
|---|
| Section | 一般 |
|---|
| Research Field |
Functional basic dentistry
|
|---|
| Research Institution | Aichi-Gakuin University |
|---|
Principal Investigator |
TOGARI Akifumi Aichi-Gakuin University, School of Dentistry Department of Pharamcology Professor, 歯学部, 教授 (80126325)
|
|---|
| Co-Investigator(Kenkyū-buntansha) |
KONDO Ayami Aichi-Gakuin University, School of Dentistry Department of Pharamcology Research, 歯学部, 助手 (70301629)
MOGI Makio Aichi-Gakuin University, School of Dentistry Department of Pharamcology Assistan, 歯学部, 講師 (00174334)
ARAI Michitsugu Aichi-Gakuin University, School of Dentistry Department of Pharamcology Assistan, 歯学部, 講師 (20097538)
|
|---|
| Project Period (FY) |
1997 – 1998
|
| Keywords | Osteoblast / Nitric Oxide / Biopterin / Apoptosis / Cytokine |
|---|
| Research Abstract |
Proinflammatory cytokines, a combination of IL-1beta, TNF-alpha, and IFN-gamma, caused mRNA expression of GTP cyclohydrolase I (GTP-CH), the rate-limiting enzyme in tetrahydrobiopterin (BH_4) biosynthesis, as well as that of inducible nitric oxide synthase (iNOS) in a well-characterized osteoblastic clone MC3T3-E1 cell line. We found the expression of GTP-CH gene in osteoblasts for the first time. The expression of GTP-CH and iNOS mRNAs was found to be maximal at 3 and 9 hr, respectively. The expression of both genes elicited increases in BH_4 and NO levels. Pharmacological studies using 2, 4-diamino-6-hydroxypyrimidine (DAHP), an inhibitor of GTP-CH activity showed that BH_4 is involved in the activity of iNOS, but not in the induction of iNOS mRNA.The results using an inhibitor of nuclear factor (NF)-kappaB and activating protein-1 (AP-1) activation suggested that coinduction of the two genes in response to cytokines occurred via activation of NF-kappaB and AP-1.
Cytokines as well as
… More
S-nitroso-N-acetyl-D, L-penicillamine (SNAP), an NO generator, decreased cell viability ; but sepiapterin, which was converted intracellularly to BH_4, increased it. The examination of cytotoxicity measured in terms of lactate dehydrogenase (LDH) release and apoptotic cell death assessed by flow cytometric analysis showed that cytokine-induced reduction of cell viability may be based upon cell death by apoptosis, but not lytic death as in necrosis. In the presence of sepiapterin, cytokine treatment resulted in a statistically pronounced reduction in the amount of DNA fragmentation. Furthermore, the DNA fragmentation could be blocked by 2-(4-carboxy-phenyl)-4, 4, 5, 5-tetramethylimidazole-1-oxyl 3-oxide (carboxy-PTIO), a NO scavenger. These results suggest that cytokine-induced apoptotic cell death is attributed to NO and is protected by BH_4, and that osteoblastic cells in response to proinflammatory cytokines operate both a stimulatory process resulting in NO production and an inhibitory one resulting in BH_4 production for apoptotic cell death. Cytokine-induced apoptotic cell death may be a consequence of the predominance of the stimlatory process over the inhibitory process. Less
|
Research Products
(4 results)
