| Cholesterol pools in rat adrenal mitochondria: use of cholesterol oxidase to infer a complex pool structure. | |
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MedLine Citation:
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PMID: 1537305 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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ACTH stimulates the side-chain cleavage of cholesterol in the adrenal cortex in a cycloheximide-inhibitable manner. Its mechanism involves mobilizing cholesterol to a "steroidogenic pool" where the sterol can be metabolized to pregnenolone. This pool has been proposed to be in the inner mitochondrial membrane where cytochrome P-450scc resides, and regulation may involve transport of cholesterol from the outer to the inner membrane. To investigate the structure of the mitochondrial cholesterol pools, cholesterol oxidase has been used as a membrane-impermeant probe which should have selective access to outer membrane cholesterol. At 37 C, almost all the cholesterol in mitochondria from ether-stressed rats was metabolized by cholesterol oxidase. Depletion of an intermembrane space but not a matrix marker enzyme indicated partial disruption of the outer membrane. However, at 16 C, mitochondria remained largely intact, and cholesterol oxidase identified a unique pool of cholesterol, which was about two-thirds of the total. In experiments using mitochondria from ether-stressed rats, the size of the 16 C cholesterol oxidase accessible and inaccessible pools was compared with that of the steroidogenic pool. The steroidogenic pool was enhanced by pretreatment of some animals with aminoglutethimide (a P-450scc inhibitor) or eliminated with cycloheximide, both of which increased the total mitochondrial cholesterol. This approach reveals that the steroidogenic pool is not equivalent to the cholesterol oxidase-inaccessible pool. Rather, it overlaps both the cholesterol oxidase accessible and inaccessible pools. These results are not consistent with a simple two pool model, but can be explained by assuming a minimum of three cholesterol pools. |
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Authors:
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V L Stevens; T Xu; J D Lambeth |
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Publication Detail:
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Type: Journal Article; Research Support, U.S. Gov't, P.H.S. |
Journal Detail:
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Title: Endocrinology Volume: 130 ISSN: 0013-7227 ISO Abbreviation: Endocrinology Publication Date: 1992 Mar |
Date Detail:
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Created Date: 1992-04-02 Completed Date: 1992-04-02 Revised Date: 2007-11-14 |
Medline Journal Info:
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Nlm Unique ID: 0375040 Medline TA: Endocrinology Country: UNITED STATES |
Other Details:
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Languages: eng Pagination: 1557-63 Citation Subset: AIM; IM |
Affiliation:
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Department of Biochemistry, Emory University School of Medicine, Atlanta, Georgia 30322. |
Export Citation:
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APA/MLA Format Download EndNote Download BibTex |
| MeSH Terms | |
Descriptor/Qualifier:
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Adrenal Cortex
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chemistry*,
cytology,
ultrastructure Aminoglutethimide / pharmacology Animals Cell Fractionation Cholesterol / analysis*, metabolism Cholesterol Oxidase / analysis*, metabolism Female Intracellular Membranes / chemistry, enzymology, metabolism, ultrastructure Mitochondria / chemistry*, metabolism, ultrastructure Pregnenolone / analysis, metabolism Rats Rats, Inbred Strains |
| Grant Support | |
ID/Acronym/Agency:
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DK 27373/DK/NIDDK NIH HHS |
| Chemical | |
Reg. No./Substance:
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125-84-8/Aminoglutethimide; 145-13-1/Pregnenolone; 57-88-5/Cholesterol; EC 1.1.3.6/Cholesterol Oxidase |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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