| Co-Investigator(Kenkyū-buntansha) |
INUZUKA Manabu DEPARTMENT OF BIOCHEMISTRY, FUKUI MEDICAL SCHOOL, ASSOCIATE PROFESSOR, 医学部, 助教授 (00135104)
TSUKAHARA Hirokazu DEPARTMENT OF PEDIATRICS, FUKUI MEDICAL SCHOOL, ASSISTANT PROFESSOR, 医学部, 助手 (90207340)
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| Budget Amount *help |
¥3,200,000 (Direct Cost: ¥3,200,000)
Fiscal Year 1999: ¥900,000 (Direct Cost: ¥900,000)
Fiscal Year 1998: ¥2,300,000 (Direct Cost: ¥2,300,000)
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| Research Abstract |
1: Fructose-1,6-bisphosphatase (FBPase) is a key gluconeogenic enzyme. The data herein show that both enzyme activity and mRNA level of the human FBPase gene are enhanced by 9-cis retinoic acid (9cRA) and all-trans retinoic acid (atRA) as well as 1,25-dihydroxyvitamin D3 (VD3) in human promyelocytic HL60 cells and normal monocytes in peripheral blood, which were used for DNA diagnosis of FBPase deficiency, as an alternative source to liver. To understand the molecular mechanism of this enhancing action, the 2.4 kb 5'-regulatory region of the human FBPase gene was isolated and sequenced. Using luciferase reporter gene assays, a 0.5 kb FBPase basal promoter fragment was found to confer induction by VD3, 9cRA and atRA, which was mediated by vitamin D3 receptor (VDR), retinoid X receptor (RXR), and retinoic acid receptor (RAR). Within this region, a direct repeat sequence, 5'-TAACCTttcTGAACT-3' (-340 to -326), which functions as a common response element for VD3, 9cRA and atRA was identified. The results of electrophoretic mobility shift assays indicated that VDR-RXR and RAR-RXR heterodimers bind this response element. Collectively, these observations indicate that VD3 and RA are important modulators of the human FBPase gene expression in monocytic cells.
2: Putative insulin responsive nuclear sequence was found near a common response element for VD3, 9cRA and atRA. More detailed characterization will be underway to clarify a role of gluconeogensis in non-insulin dependent diabetus mellitus by cultured monocytes.
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