| Unconjugated bile salts shuttle through hepatocyte peroxisomes for taurine conjugation. | |
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MedLine Citation:
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PMID: 21049545 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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Bile acid-CoA:amino acid N-acyltransferase (BAAT) conjugates bile salts to glycine or taurine, which is the final step in bile salt biosynthesis. In addition, BAAT is required for reconjugation of bile salts in the enterohepatic circulation. Recently, we showed that BAAT is a peroxisomal protein, implying shuttling of bile salts through peroxisomes for reconjugation. However, the subcellular location of BAAT remains a topic of debate. The aim of this study was to obtain direct proof for reconjugation of bile salts in peroxisomes. Primary rat hepatocytes were incubated with deuterium-labeled cholic acid (D(4)CA). Over time, media and cells were collected and the levels of D(4)CA, D(4)-tauro-CA (D(4)TCA), and D(4)-glyco-CA (D(4)GCA) were quantified by liquid chromatography-tandem mass spectrometry (LC/MS/MS). Subcellular accumulation of D(4)-labeled bile salts was analyzed by digitonin permeabilization assays and subcellular fractionation experiments. Within 24 hours, cultured rat hepatocytes efficiently (>90%) converted and secreted 100 μM D(4)CA to D(4)TCA and D(4)GCA. The relative amounts of D(4)TCA and D(4)GCA produced were dependent on the presence of glycine or taurine in the medium. Treatment of D(4)CA-exposed hepatocytes with 30-150 μg/mL digitonin led to the complete release of D(4)CA, D(4)GCA, and glyceraldehyde 3-phosphate dehydrogenase (GAPDH) (cytosolic marker). Full release of D(4)TCA, catalase, and BAAT was only observed at 500 μg/mL digitonin, indicating the presence of D(4)TCA in membrane-enclosed organelles. D(4)TCA was detected in fractions of purified peroxisomes, which did not contain D(4)CA and D(4)GCA. Conclusion: We established a novel assay to study conjugation and intra- and transcellular transport of bile salts. Using this assay, we show that cholic acid shuttles through peroxisomes for taurine-conjugation. |
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Authors:
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Krzysztof P Rembacz; Jannes Woudenberg; Mark Hoekstra; Elles Z Jonkers; Fiona A J van den Heuvel; Manon Buist-Homan; Titia E Woudenberg-Vrenken; Jana Rohacova; M Luisa Marin; Miguel A Miranda; Han Moshage; Frans Stellaard; Klaas Nico Faber |
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Publication Detail:
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Type: Journal Article; Research Support, Non-U.S. Gov't Date: 2010-11-03 |
Journal Detail:
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Title: Hepatology (Baltimore, Md.) Volume: 52 ISSN: 1527-3350 ISO Abbreviation: Hepatology Publication Date: 2010 Dec |
Date Detail:
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Created Date: 2010-11-24 Completed Date: 2011-01-10 Revised Date: - |
Medline Journal Info:
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Nlm Unique ID: 8302946 Medline TA: Hepatology Country: United States |
Other Details:
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Languages: eng Pagination: 2167-76 Citation Subset: IM |
Copyright Information:
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Copyright © 2010 American Association for the Study of Liver Diseases. |
Affiliation:
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Department of Gastroenterology and Hepatology, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands. |
Export Citation:
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| MeSH Terms | |
Descriptor/Qualifier:
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Acyltransferases
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metabolism* Animals Apoptosis / drug effects Bile Acids and Salts / metabolism* Cells, Cultured Cholates / metabolism Chromatography, Liquid Digitonin / pharmacology Hepatocytes / metabolism* Male Peroxisomes / drug effects, metabolism* Rats Rats, Wistar Tandem Mass Spectrometry Taurine / metabolism* |
| Chemical | |
Reg. No./Substance:
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0/Bile Acids and Salts; 0/Cholates; 107-35-7/Taurine; 11024-24-1/Digitonin; EC 2.3.-/Acyltransferases; EC 2.3.1.-/bile acid-CoA amino acid N-acyltransferase |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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