2011 Fiscal Year Final Research Report
Molecular Mechanism of selective transport for carotenoid in the silkworm, Bombyx mori
| Project/Area Number |
21380045
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Applied entomology
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| Research Institution | National Institute of Infectious Diseases |
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Principal Investigator |
TSUCHIDA Kozo 国立感染症研究所, 放射能管理室, 室長 (40231435)
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| Co-Investigator(Kenkyū-buntansha) |
YAMAMOTO Kimiko 独立行政法人農業生物資源研究所, 昆虫ゲノム報解析ユニット, ユニット長 (40370689)
SEZUTSU Hideki 独立行政法人農業生物資源研究所, 遺伝子組換えカイコ研究センター, センター長 (70342805)
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| Project Period (FY) |
2009 – 2011
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| Keywords | カロテノイド / 脂質の選択的輸送 / CD36 / SR-BI / リポホリン / カイコ |
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| Research Abstract |
The silkworm, Bombyx mori provides very clear examples of tissue-specific delivery for certain carotenoid species from the midgut lumen to the silk gland via hemolymph lipoprotein, lipophorin. Lipophorin contains lutein and beta-carotene as a complex mixture of lipids in the hydrophobic core. The yellow(C) or flesh color cocoon(F) mutants accumulate lutein or beta-carotene in the middle silk gland from lipophorin, respectively. We have reported that the C gene encodes Cameo2, a member of CD36 gene family which has been known to function as as lutein specific transporter and transmembrane non-internalizing lipophorin receptor in the middle silk gland. The nature of the F gene was defined by positional cloning and transgenic rescue experiments with the binary GAL4-UAS expression system. The F gene encodes SCRB15, a paralog of Cameo2 with 26% amino acid identity. SCRB15 may be responsible for beta-carotene specific non-internalizing lipophorin receptor. In the F mutant, SCRB15 is not expressed because the mRNA structure of SCRB15 is severely disrupted due to a 1.4 kb insertion in a coding exon. This finding that both C and F genes encode CD36 homologs raises questions how CD36-homolog proteins recoginize the difference of carotenoid species which permits to uptake the middle silk gland from lipophorin.
We believe the molecular machineries are for delivery of specific lipids from lipophorin to target tissues. Furthermore, functional coordination of transmembrane lipoprotein receptors and intracellular lipid-binding proteins has been proposed to achieve the selective cellular transport from HDL for general lipids, such as cholesteryl ester and fatty acids. Thus, our data also provide genetic evidence for this general mechanism in lipid biology.
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