Tauroursodeoxycholic acid protects rat hepatocytes from bile acid-induced apoptosis via activation of survival pathways

Authors

  • Marieke H. Schoemaker,

    1. Center for Liver, Digestive and Metabolic Diseases, Groningen University Institute for Drug Exploration, Groningen, The Netherlands
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  • Laura Conde de la Rosa,

    1. Center for Liver, Digestive and Metabolic Diseases, Groningen University Institute for Drug Exploration, Groningen, The Netherlands
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  • Manon Buist-Homan,

    1. Center for Liver, Digestive and Metabolic Diseases, Groningen University Institute for Drug Exploration, Groningen, The Netherlands
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  • Titia E. Vrenken,

    1. Center for Liver, Digestive and Metabolic Diseases, Groningen University Institute for Drug Exploration, Groningen, The Netherlands
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  • Rick Havinga,

    1. Center for Liver, Digestive and Metabolic Diseases, Groningen University Institute for Drug Exploration, Groningen, The Netherlands
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  • Klaas Poelstra,

    1. Center for Liver, Digestive and Metabolic Diseases, Groningen University Institute for Drug Exploration, Groningen, The Netherlands
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  • Hidde J. Haisma,

    1. Department of Therapeutic Gene Modulation, Groningen University Institute for Drug Exploration, Groningen, The Netherlands
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  • Peter L. M. Jansen,

    1. Center for Liver, Digestive and Metabolic Diseases, Groningen University Institute for Drug Exploration, Groningen, The Netherlands
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  • Han Moshage

    Corresponding author
    1. Center for Liver, Digestive and Metabolic Diseases, Groningen University Institute for Drug Exploration, Groningen, The Netherlands
    • Department of Gastroenterology and Hepatology, University Hospital Groningen, P.O. Box 30.001, 9700 RB, Groningen, The Netherlands
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    • fax: 31-50-3619306


  • Presented, in part, at the annual meeting of the American Association for the Study of Liver Diseases, Boston, 2002.

Abstract

Ursodeoxycholic acid (UDCA) is used in the treatment of cholestatic liver diseases, but its mechanism of action is not yet well defined. The aim of this study was to explore the protective mechanisms of the taurine-conjugate of UDCA (tauroursodeoxycholic acid [TUDCA]) against glycochenodeoxycholic acid (GCDCA)-induced apoptosis in primary cultures of rat hepatocytes. Hepatocytes were exposed to GCDCA, TUDCA, the glyco-conjugate of UDCA (GUDCA), and TCDCA. The phosphatidylinositol-3 kinase pathway (PI3K) and nuclear factor-κB were inhibited using LY 294002 and adenoviral overexpression of dominant-negative IκB, respectively. The role of p38 and extracellular signal-regulated protein kinase mitogen-activated protein kinase (MAPK) pathways were investigated using the inhibitors SB 203580 and U0 126 and Western blot analysis. Transcription was blocked by actinomycin-D. Apoptosis was determined by measuring caspase-3, -9, and -8 activity using fluorimetric enzyme detection, Western blot analysis, immunocytochemistry, and nuclear morphological analysis. Our results demonstrated that uptake of GCDCA is needed for apoptosis induction. TUDCA, but not TCDCA and GUDCA, rapidly inhibited, but did not delay, apoptosis at all time points tested. However, the protective effect of TUDCA was independent of its inhibition of caspase-8. Up to 6 hours of preincubation with TUDCA before addition of GCDCA clearly decreased GCDCA-induced apoptosis. At up to 1.5 hours after exposure with GCDCA, the addition of TUDCA was still protective. This protection was dependent on activation of p38, ERK MAPK, and PI3K pathways, but independent of competition on the cell membrane, NF-κB activation, and transcription. In conclusion, TUDCA contributes to the protection against GCDCA-induced mitochondria-controlled apoptosis by activating survival pathways. Supplemental material for this article can be found on the HEPATOLOGY website (http://interscience.wiley.com/jpages/0270-9139/supplmat/index.html). (HEPATOLOGY 2004;39:1563–1573.)

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