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[in Japanese], [in Japanese]
Article type: Article
2010 Volume 84 Issue 8 Pages
361-364
Published: August 25, 2010
Released on J-STAGE: October 10, 2017
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Masato Inazu
Article type: Article
2010 Volume 84 Issue 8 Pages
365-375
Published: August 25, 2010
Released on J-STAGE: October 10, 2017
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Choline is an organic cation that is crucial for the normal function of all cells. It is used as a precursor of acetylcholine, a methyl donor, and osmolyte betaine, and plays an important role in the biosynthesis of phosphatidylcholine and sphingomyelin. Choline is consumed in the diet and insufficient intake may cause choline deficiency, especially under conditions that require large amounts of choline, such as pregnancy, breast-feeding and parenteral nutrition. Choline deficiency affects the expression of genes involved in cell proliferation, differentiation, and apoptosis, and it is associated with liver dysfunction and cancer. Therefore, the study of choline transport and the characteristics of choline transporters are of central importance to understand the mechanisms that underlie membrane integrity and cell signaling. The choline transport system has been categorized into three transporter families. They include (I) polyspecific organic cation transporters (OCTs) with low affinity for choline, (II) high-affinity choline transporter 1 (CHT1), and (III) intermediate-affinity choline transporter-like proteins (CTLs). CHT1 and CTL1 but not OCT transporters are selectively inhibited with hemicholinium-3 (HC-3) and essentially display characteristics of specialized transporters for targeted choline metabolism. CHT1 is thought to play an important role in cholinergic neurons and is also expressed by subpopulations of non-neuronal cholinergic cells. CHT1 is a Na^+-dependent co-transporter that is highly sensitive to the choline analogue, HC-3, and is thought to be part of the rate-limiting step in acetylcholine synthesis. As an organic cation, choline is known to be a substrate for carriers of OCTs. To date, three different OCTs (OCT1-3) have been cloned and they function through Na^+-independent uptake mechanism. OCT1 and OCT2 accept choline as a substrate with comparatively low affinity. However, OCT3 does not recognize choline as a substrate. CTL family are comprised of the five genes, CTL1-5, with CTL1 being the main member of the family. CTL1 is a Na^+-independent, intermediate-affinity transporter of choline that can be completely inhibited by a high concentration of HC-3. They are expressed in different organisms and cell types, and this implies its importance for choline transport for a broader purpose, such as phospholipid synthesis. The function of CTL2-5 is still not precisely known at the molecular level. In this review, the functional expression and physiological role of choline transporters is further discussed.
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Tappei Takada, Hiroshi Suzuki
Article type: Article
2010 Volume 84 Issue 8 Pages
376-383
Published: August 25, 2010
Released on J-STAGE: October 10, 2017
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Niemann-Pick C1-like 1 (NPC1L1) is essential for the intestinal absorption of cholesterol and is recognized as a pharmacological target of ezetimibe (Zetia[○!R]), a cholesterol absorption inhibitor clinically used for the treatment of dyslipidemia. Based on the hypothesis that some lipophilic molecules may be taken up in the intestinal lumen via a pathway shared with cholesterol, we tested some fat-soluble molecules and obtained the data suggesting that NPC1L1 has the ability to transport vitamin E and that ezetimibe is able to inhibit the intestinal absorption of vitamin E. This review article describes the basis and recent topics of NPC1L1 and its vitamin E transport.
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Akira Shibata, Kiyotaka Nakagawa, Yuki Kawakami, Tsuyoshi Tsuzuki, Ter ...
Article type: Article
2010 Volume 84 Issue 8 Pages
384-386
Published: August 25, 2010
Released on J-STAGE: October 10, 2017
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Kenichi Yokota, Shigeki Kato
Article type: Article
2010 Volume 84 Issue 8 Pages
387-389
Published: August 25, 2010
Released on J-STAGE: October 10, 2017
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Tsuyoshi Tsuduki, Keiko Kuriyama, Teruo Miyazawa
Article type: Article
2010 Volume 84 Issue 8 Pages
390-391
Published: August 25, 2010
Released on J-STAGE: October 10, 2017
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Shoji Yamada, Keiko Yamada
Article type: Article
2010 Volume 84 Issue 8 Pages
392-394
Published: August 25, 2010
Released on J-STAGE: October 10, 2017
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[in Japanese], [in Japanese]
Article type: Article
2010 Volume 84 Issue 8 Pages
395-
Published: August 25, 2010
Released on J-STAGE: October 10, 2017
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[in Japanese], [in Japanese], [in Japanese], [in Japanese]
Article type: Article
2010 Volume 84 Issue 8 Pages
396-397
Published: August 25, 2010
Released on J-STAGE: October 10, 2017
JOURNAL
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[in Japanese], [in Japanese], [in Japanese], [in Japanese]
Article type: Article
2010 Volume 84 Issue 8 Pages
397-
Published: August 25, 2010
Released on J-STAGE: October 10, 2017
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[in Japanese]
Article type: Article
2010 Volume 84 Issue 8 Pages
397-398
Published: August 25, 2010
Released on J-STAGE: October 10, 2017
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[in Japanese]
Article type: Article
2010 Volume 84 Issue 8 Pages
398-399
Published: August 25, 2010
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[in Japanese]
Article type: Article
2010 Volume 84 Issue 8 Pages
399-400
Published: August 25, 2010
Released on J-STAGE: October 10, 2017
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[in Japanese]
Article type: Article
2010 Volume 84 Issue 8 Pages
400-
Published: August 25, 2010
Released on J-STAGE: October 10, 2017
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[in Japanese], [in Japanese]
Article type: Article
2010 Volume 84 Issue 8 Pages
400-401
Published: August 25, 2010
Released on J-STAGE: October 10, 2017
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[in Japanese]
Article type: Article
2010 Volume 84 Issue 8 Pages
401-402
Published: August 25, 2010
Released on J-STAGE: October 10, 2017
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[in Japanese], [in Japanese], [in Japanese]
Article type: Article
2010 Volume 84 Issue 8 Pages
402-403
Published: August 25, 2010
Released on J-STAGE: October 10, 2017
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[in Japanese], [in Japanese], [in Japanese], [in Japanese]
Article type: Article
2010 Volume 84 Issue 8 Pages
404-405
Published: August 25, 2010
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[in Japanese], [in Japanese], [in Japanese]
Article type: Article
2010 Volume 84 Issue 8 Pages
405-
Published: August 25, 2010
Released on J-STAGE: October 10, 2017
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[in Japanese], [in Japanese], [in Japanese], [in Japanese]
Article type: Article
2010 Volume 84 Issue 8 Pages
405-406
Published: August 25, 2010
Released on J-STAGE: October 10, 2017
JOURNAL
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[in Japanese]
Article type: Article
2010 Volume 84 Issue 8 Pages
406-407
Published: August 25, 2010
Released on J-STAGE: October 10, 2017
JOURNAL
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[in Japanese]
Article type: Article
2010 Volume 84 Issue 8 Pages
407-
Published: August 25, 2010
Released on J-STAGE: October 10, 2017
JOURNAL
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[in Japanese], [in Japanese], [in Japanese], [in Japanese], [in Japane ...
Article type: Article
2010 Volume 84 Issue 8 Pages
408-
Published: August 25, 2010
Released on J-STAGE: October 10, 2017
JOURNAL
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