著者

Yuki Manabe Takashi Hirata Tatsuya Sugawara

出版者

Japan Oil Chemists' Society

雑誌

Journal of Oleo Science (ISSN:13458957)

巻号頁・発行日

vol.68, no.2, pp.149-158, 2019 (Released:2019-02-01)

参考文献数

39

被引用文献数

5 9

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Lipid rafts are microdomains present in the plasma membrane, which are enriched in sphingolipids and cholesterol. Certain kinases and adaptor proteins, which are important for cellular signaling, are also concentrated in lipid rafts. Several immunoreceptors are known to translocate into lipid rafts upon binding with their ligands to efficiently induce the signaling pathways, and hence, receptor translocation could be the new target for pleiotropic suppression of inflammatory responses. In this study, we evaluated the effects of carotenoids on ligand-induced lipid raft translocation of the receptors using B cell receptors (BCRs) as a model. Since all lipid raft-translocated BCRs were clustered at one pole of the cell, called capping, in our experimental condition, we screened the carotenoids for their inhibitory effect on lipid raft translocation of receptors using BCR capping as a parameter. Eleven out of twenty carotenoids significantly inhibited anti-IgM-induced BCR capping without cytotoxicity. Having no polar groups or a keto group at the C-8 position might be an important factor for inhibition. Treatment with lycopene, a non-polar carotenoid, and fucoxanthinol, a C-8-keto carotenoid, also suppressed lipopolysaccharide-induced translocation of Toll-like receptor 4 into lipid rafts, and subsequent nitric oxide production in RAW264 macrophages. These results indicated that some carotenoids, but not all, can modulate inflammatory responses via suppression of ligand-induced lipid raft translocation of immunoreceptors, and also showed that our assay using BCR capping has the potential for screening compounds that inhibit lipid raft translocation of receptors.

著者

Hidehiro Furumoto Tharnath Nanthirudjanar Takashi Hirata Tatsuya Sugawara

出版者

公益社団法人 日本油化学会

雑誌

Journal of Oleo Science (ISSN:13458957)

巻号頁・発行日

pp.ess15227, (Released:2016-02-15)

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Numerous studies have shown that dietary omega-3 polyunsaturated fatty acids (PUFAs), particularly eicosapentaenoic acid (EPA), improve lipid metabolism. The beneficial effects of PUFA-derived oxidation products have been increasingly reported. However, EPA is easily oxidized in food products and in the human body, generating various derivatives of oxidized EPA (oxEPA), such that these oxidation products may partially contribute to EPA’s effect. We previously reported that oxEPA was more potent than intact EPA in reducing liver-X-receptor α (LXRα)-induced cellular triacylglycerol (TG) accumulation. However, the in vivo hypolipidemic effects of oxEPA remain unclear. In the present study, we evaluated the effect of oral administration of EPA and oxEPA on hepatic steatosis in mice induced by a high-sucrose diet and a synthetic LXRα agonist, TO-901317. Both EPA and oxEPA reduced TG accumulation in the liver and plasma biomarkers of liver injury. Furthermore, they suppressed the expression of lipogenic genes, but not β-oxidation genes, in a similar pattern as the biomarkers. Our results suggest that oxEPA and intact EPA suppress de novo lipogenesis to ameliorate hepatic steatosis.

著者

Tatsuya SUGAWARA Kazuhiko AIDA Jingjing DUAN Nami TOMONAGA Yuki MANABE Takashi HIRATA

出版者

Center for Academic Publications Japan

雑誌

Journal of Nutritional Science and Vitaminology (ISSN:03014800)

巻号頁・発行日

vol.65, no.Supplement, pp.S228-S230, 2019-10-11 (Released:2019-10-16)

参考文献数

27

被引用文献数

7

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Sphingolipids recently attract more attentions because of their distinctiveness on structures and expected functions. Liquid chromatography-mass spectrometry is one of the most powerful methods for the identification of chemical structures of sphingolipids. Glucosylceramides prepared from various foodstuffs including rice are generally used for functional foods and their structures are quite different from mammals. For structural analysis of glucosylceramides by LC-MS/MS, the typical signals which are characteristic for the sphingoid base moieties can be obtained as product ions. Using this method for rice and maize, glucosylceramides containing 4,8-sphingadienine (d18:2) acylated to hydroxy-fatty acids were detected as the predominant molecules. In addition, the presence of the triene type of sphingoid base (sphingatrienine, d18:3) in rice and maize was also emphasized.