Vitamin E Trafficking.
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| Title: | Vitamin E Trafficking. |
|---|---|
| Authors: | TRABER, MARET G.1 (AUTHOR), BURTON, GRAHAM W.2 (AUTHOR), HAMILTON, ROBERT L.3 (AUTHOR) |
| Source: | Annals of the New York Academy of Sciences. 2004, Vol. 1031 Issue 1, p1-12. 12p. |
| Subjects: | Vitamin E, Proteins, Golgi apparatus, Endoplasmic reticulum, Cholesterol |
| Abstract: | The α-tocopherol transfer protein (α-TTP) is required to prevent vitamin E deficiency in humans and in α-TTP null mice. Whereas αTTP is not required to facilitate intestinal absorption of vitamin E, it is required to maintain normal αtocopherol concentrations in plasma and extrahepatic tissues. αTocopherol secretion from the liver in very low density lipoproteins (VLDLs) is impaired in humans with a defect in the αTTP gene. In perfusions of isolated cynomolgus monkey livers, VLDLs were preferentially enriched in RRR-α-tocopherol. The mechanism by which α-TTP incorporates α-tocopherol into nascent VLDLs is the topic of this report. VLDL assembly is a multistep secretory process that occurs within the membrane compartments of the endoplasmic reticulum and Golgi apparatus. Thus, we postulated that α-TTP might transfer α-tocopherol onto nascent VLDLs either in the endoplasmic reticulum or in the Golgi apparatus. To test these possibilities, we isolated nascent VLDLs from highly purified RER and Golgi apparatus membrane fractions from livers of rats fed equimolar ratios of RRR- and SRR-α-tocopherols labeled with different amounts of deuterium. Although the plasma was enriched in RRR-α- tocopherol 14 hours after the dose, no enrichment of nascent VLDL precursors from either of the secretory compartments was detected, indicating that VLDL enrichment with α-tocopherol may occur as a post-VLDL secretory process. Therefore, we hypothesize that α-TTP may facilitate movement of α-tocopherol to the hepatocyte plasma membrane (by unknown mechanisms) where newly secreted, nascent VLDLs could acquire both α-tocopherol and unesterified cholesterol while within the space of Disse. Clearly, critical information is lacking in our understanding of the mechanism by which α-TTP facilitates the preferential enrichment of VLDLs with α-tocopherol. [ABSTRACT FROM AUTHOR] |
| Copyright of Annals of the New York Academy of Sciences is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites without the copyright holder's express written permission. Additionally, content may not be used with any artificial intelligence tools or machine learning technologies. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.) | |
| Database: | Engineering Source |
| FullText | Text: Availability: 0 |
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| Header | DbId: egs DbLabel: Engineering Source An: 25254185 AccessLevel: 6 PubType: Academic Journal PubTypeId: academicJournal PreciseRelevancyScore: 0 |
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| Items | – Name: Title Label: Title Group: Ti Data: Vitamin E Trafficking. – Name: Author Label: Authors Group: Au Data: <searchLink fieldCode="AR" term="%22TRABER%2C+MARET+G%2E%22">TRABER, MARET G.</searchLink><relatesTo>1</relatesTo> (AUTHOR)<br /><searchLink fieldCode="AR" term="%22BURTON%2C+GRAHAM+W%2E%22">BURTON, GRAHAM W.</searchLink><relatesTo>2</relatesTo> (AUTHOR)<br /><searchLink fieldCode="AR" term="%22HAMILTON%2C+ROBERT+L%2E%22">HAMILTON, ROBERT L.</searchLink><relatesTo>3</relatesTo> (AUTHOR) – Name: TitleSource Label: Source Group: Src Data: <searchLink fieldCode="JN" term="%22Annals+of+the+New+York+Academy+of+Sciences%22">Annals of the New York Academy of Sciences</searchLink>. 2004, Vol. 1031 Issue 1, p1-12. 12p. – Name: Subject Label: Subjects Group: Su Data: <searchLink fieldCode="DE" term="%22Vitamin+E%22">Vitamin E</searchLink><br /><searchLink fieldCode="DE" term="%22Proteins%22">Proteins</searchLink><br /><searchLink fieldCode="DE" term="%22Golgi+apparatus%22">Golgi apparatus</searchLink><br /><searchLink fieldCode="DE" term="%22Endoplasmic+reticulum%22">Endoplasmic reticulum</searchLink><br /><searchLink fieldCode="DE" term="%22Cholesterol%22">Cholesterol</searchLink> – Name: Abstract Label: Abstract Group: Ab Data: The α-tocopherol transfer protein (α-TTP) is required to prevent vitamin E deficiency in humans and in α-TTP null mice. Whereas αTTP is not required to facilitate intestinal absorption of vitamin E, it is required to maintain normal αtocopherol concentrations in plasma and extrahepatic tissues. αTocopherol secretion from the liver in very low density lipoproteins (VLDLs) is impaired in humans with a defect in the αTTP gene. In perfusions of isolated cynomolgus monkey livers, VLDLs were preferentially enriched in RRR-α-tocopherol. The mechanism by which α-TTP incorporates α-tocopherol into nascent VLDLs is the topic of this report. VLDL assembly is a multistep secretory process that occurs within the membrane compartments of the endoplasmic reticulum and Golgi apparatus. Thus, we postulated that α-TTP might transfer α-tocopherol onto nascent VLDLs either in the endoplasmic reticulum or in the Golgi apparatus. To test these possibilities, we isolated nascent VLDLs from highly purified RER and Golgi apparatus membrane fractions from livers of rats fed equimolar ratios of RRR- and SRR-α-tocopherols labeled with different amounts of deuterium. Although the plasma was enriched in RRR-α- tocopherol 14 hours after the dose, no enrichment of nascent VLDL precursors from either of the secretory compartments was detected, indicating that VLDL enrichment with α-tocopherol may occur as a post-VLDL secretory process. Therefore, we hypothesize that α-TTP may facilitate movement of α-tocopherol to the hepatocyte plasma membrane (by unknown mechanisms) where newly secreted, nascent VLDLs could acquire both α-tocopherol and unesterified cholesterol while within the space of Disse. Clearly, critical information is lacking in our understanding of the mechanism by which α-TTP facilitates the preferential enrichment of VLDLs with α-tocopherol. [ABSTRACT FROM AUTHOR] – Name: AbstractSuppliedCopyright Label: Group: Ab Data: <i>Copyright of Annals of the New York Academy of Sciences is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites without the copyright holder's express written permission. Additionally, content may not be used with any artificial intelligence tools or machine learning technologies. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract.</i> (Copyright applies to all Abstracts.) |
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| RecordInfo | BibRecord: BibEntity: Identifiers: – Type: doi Value: 10.1196/annals.1331.001 Languages: – Code: eng Text: English PhysicalDescription: Pagination: PageCount: 12 StartPage: 1 Subjects: – SubjectFull: Vitamin E Type: general – SubjectFull: Proteins Type: general – SubjectFull: Golgi apparatus Type: general – SubjectFull: Endoplasmic reticulum Type: general – SubjectFull: Cholesterol Type: general Titles: – TitleFull: Vitamin E Trafficking. Type: main BibRelationships: HasContributorRelationships: – PersonEntity: Name: NameFull: TRABER, MARET G. – PersonEntity: Name: NameFull: BURTON, GRAHAM W. – PersonEntity: Name: NameFull: HAMILTON, ROBERT L. IsPartOfRelationships: – BibEntity: Dates: – D: 04 M: 12 Text: 2004 Type: published Y: 2004 Identifiers: – Type: issn-print Value: 00778923 Numbering: – Type: volume Value: 1031 – Type: issue Value: 1 Titles: – TitleFull: Annals of the New York Academy of Sciences Type: main |
| ResultId | 1 |
