| Project/Area Number |
09670074
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Environmental physiology (including Physical medicine and Nutritional physiology)
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| Research Institution | University of Shizuoka |
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Principal Investigator |
TAKASE Sachiko University of Shizuoka, School of Food and Nutritional Sciences, Department of Nutrition, Professor, 食品栄養科学部・栄養学科, 教授 (10046196)
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| Co-Investigator(Kenkyū-buntansha) |
GODA Toshinao University of Shizuoka, School of Food and Nutritional Sciences, Department of N, 食品栄養科学部・栄養学科, 助手(学内講師) (70195923)
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| Project Period (FY) |
1997 – 1998
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| Project Status |
Completed (Fiscal Year 1998)
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| Budget Amount *help |
¥3,700,000 (Direct Cost: ¥3,700,000)
Fiscal Year 1998: ¥1,100,000 (Direct Cost: ¥1,100,000)
Fiscal Year 1997: ¥2,600,000 (Direct Cost: ¥2,600,000)
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| Keywords | Cellular retinol-binding protein, type II / Fatty acid-binding protein / Peroxisome proliferator-activated receptor (PPAR) / Fatty acids / Small intestine / Beta-carotene / Gene expression / 細胞性レチノール結合たんぱく質Type II / 絶食 / β-カロテン開裂酵素 / レチナール還元酵素 / 細胞性レチメール結合たんぱく質II / mRNA / レチノイドレセプター(RXR) / Caco-2細胞 |
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| Research Abstract |
1) We investigated the mechanism whereby dietary fatty acids modulate the gene expression of cellular retinol-binding protein, type II (CRBP(II)) in the small intestine. The rats fed the high-fat diet showed a parallel increase in the transcription of CRBP(II) gene and the level of PPAROalpha mRNA, which was accompanied by an increase in the amount of nuclear proteins (including PPAR-RXR heterodimer) binding to the nuclear receptor-response elements located in the promoter of CRBP(II) gene. The mRNA level of a PPAR subtype (PPARdelta) was reduced in the small intestine by dietary fat. Inhibitors of enzymes involved in arachidonic acid metabolism did not influence the dietary fat- induced increase in the CRBP(II) gene expression. Transfection experiments revealed that CRBP(II) gene expression is induced by fatty acids through activation of PPAR-RXR heterodimer.
2) Gene expressions of CRBP(II) and L-type fatty acid-binding protein (L-FABP) exhibited a coordinated diurnal variation in rat small intestine. Both CRBP(II) and L-FABP mRNA levels were elevated at feeding periods, attributable to the dietary fat-induced increase in the transcription of these two genes.
3) Effects of starvation on the mRNA levels of CRBP(II), L-FABP and I-FABP were investigated in rat jejunum. The mRNA levels of these three genes decreased in parallel on day 1, but increased above the non- starved control level on day 3 of starvation. These variations corresponded with the changes in the amount of triacylglycerols in jejunal tissue, and may have reflected the amount of fatty acids coming into the enterocytes.
4) Feeding excessive beta-carotene to rats enhanced the beta-carotene cleavage enzyme activity in the jejunum, while it caused a decrease in retinal reductase activity in the jejunum. This result suggests that the conversion of retinal to retinol is down-regulated by excesive intake of dietary beta-carotene.
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