| Project/Area Number |
06680618
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
Functional biochemistry
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| Research Institution | The University of Tokushima |
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Principal Investigator |
OKA Tatsuzo University of Tokushima, School of Medicine Associate professor, 医学部, 助教授 (50116795)
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| Co-Investigator(Kenkyū-buntansha) |
NATORI Yasuo University of Tokushima, School of Medicine Professor, 医学部, 教授 (30035381)
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| Project Period (FY) |
1994 – 1995
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| Project Status |
Completed (Fiscal Year 1995)
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| Budget Amount *help |
¥2,100,000 (Direct Cost: ¥2,100,000)
Fiscal Year 1995: ¥400,000 (Direct Cost: ¥400,000)
Fiscal Year 1994: ¥1,700,000 (Direct Cost: ¥1,700,000)
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| Keywords | rat / vitamin B6 / pyridoxal phosphate / gene expression / transcription factor / HNF1 / C / EBP / ビタミンB_6 |
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| Research Abstract |
It was generally known that the physiologically active form of the vitamin B6, pyridoxal 5'-phosphate (PLP), is derived from inactive dietary precursors and functions as a cofactor in numerous enzyme reactions of amino acid metabolism. In the present study, we provide evidence to suggest that PLP modulates gene expression in rat liver through a novel mechanism that involves inactivation of transcrioption factors.
1. The level of several mRNA icluding aspartate aminotransferase mRNA and albumin mRNA in the liver of vitamin B6-deficient rats were found to be higher than that of control rats.
2. Scince the transcriptional activities of these genes were increased in vitamin B6 deficiency, the higher concentration of each mRNAs in the liver of vitamin B6-deficient rats could be attributed to the enhanced rate of transcription.
3. The binding activities of liver nuclear extracts to the glucocorticoid receptor-binding site which is cis-element of AST gene and HNF1- and C./EBP-binding sites which
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are cis-element of albumin gene were examined by gel mobility shift assay. The activities of the extract prepared from liver of vitamin B6-deficient rats were greater than those of controls. As the concentration of C/EBP in nuclear extracts from control and vitamin B6-deficient rats, estimated by Western-blot analysis were essentially the same, the lower binding activity of the extract from control liver is probably due to inactivation of transcrition factors by PLP and/or its analogues.
4. The inhibition of DNA-binding of transcription factors were observed by pre-incubation with 1 mM PLP for 5min.
5. The effect of PLP and its analogues on the binding activity of nuclear extract in vitro was examined, and resulted the only PLP effectively inhibited the binding. Same results were obtained using recombinant HNF1.
6. The inhibition of DNA-binding of the other transcription factors such like HNF3, HNF4 and SP1 were observed.
The incestigation as to the binding site of the transcription factors which is recognize by PLP and the physiological significance on the modulation of gene expression by PLP is actively progressed. Less
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