Ethanol selectively impairs clathrin-mediated internalization in polarized hepatic cells

David J. Fernandez, Benita L. McVicker, Dean J. Tuma, Pamela L. Tuma

Research output: Contribution to journalArticle

9 Scopus citations

Abstract

Although alcoholic liver disease is clinically well-described, the molecular basis for alcohol-induced hepatotoxicity is not well understood. Previously, we determined that the clathrin-mediated internalization of asialoglycoprotein receptor was impaired in ethanol-treated WIF-B cells whereas the internalization of a glycophosphatidylinositol-anchored protein thought to be endocytosed via a caveolae/raft-mediated pathway was not changed suggesting that clathrin-mediated endocytosis is selectively impaired by ethanol. To test this possibility, we examined the internalization of a panel of proteins and compounds internalized by different mechanisms in control and ethanol-treated WIF-B cells. We determined that the internalization of markers known to be internalized via clathrin-mediated mechanisms was impaired. In contrast, the internalization of markers for caveolae/raft-mediated endocytosis, fluid phase internalization or non-vesicle-mediated uptake was not impaired in ethanol-treated cells. We further determined that clathrin heavy chain accumulated at the basolateral surface in small puncta in ethanol-treated cells while there was decreased dynamin-2 membrane association. Interestingly, the internalization of resident apical proteins that lack any known internalization signals was also disrupted by ethanol suggesting that these proteins are internalized via clathrin-mediated mechanisms. This conclusion is consistent with our findings that dominant negative dynamin-2 overexpression impaired internalization of known clathrin markers and single spanning apical residents, but not of markers of fluid phase or raft-mediated internalization. Together these results indicate that ethanol exposure selectively impairs hepatic clathrin-mediated internalization by preventing vesicle fission from the plasma membrane.

Original languageEnglish (US)
Pages (from-to)648-655
Number of pages8
JournalBiochemical Pharmacology
Volume78
Issue number6
DOIs
StatePublished - Sep 15 2009

Keywords

  • Clathrin
  • Dynamin-2
  • Endocytosis
  • Ethanol
  • Liver injury
  • WIF-B cells

ASJC Scopus subject areas

  • Biochemistry
  • Pharmacology

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