Cholangiocytes exhibit dynamic, actin-dependent apical membrane turnover

R. Brian Doctor, Rolf Dahl, Laura Fouassier, Gordan Kilic, J. Gregory Fitz

Research output: Contribution to journalArticle

32 Scopus citations

Abstract

The present studies of cholangiocytes used complementary histological, biochemical, and electrophysiological methods to identify a dense population of subapical vesicles, quantify the rates of vesicular trafficking, and assess the contribution of the actin cytoskeleton to membrane trafficking. FM 1-43 fluorescence measured significant basal rates of total exocytosis (1.33 ± 0.16% plasma membrane/min) in isolated cholangiocytes and apical exocytosis in cholangiocyte monolayers. Cell surface area remained unchanged, indicating that there was a concurrent, equivalent rate of endocytosis. FM 1-43 washout studies showed that 36% of the endocytosed membrane was recycled to the plasma membrane. 8-(4-Chlorophenylthio)adenosine 3′,5′-cyclic monophosphate (CPT-cAMP; cAMP analog) increased exocytosis by 71 ± 31%, whereas the Rp diastereomer of adenosine 3′,5′-cyclic monophosphothioate (Rp-cAMPS; protein kinase A inhibitor) diminished basal exocytosis by 53 ± 11%. A dense population of 140-nm subapical vesicles arose, in part, from apical membrane endocytosis. Phalloidin staining showed that a sub-population of the endocytosed vesicles was encapsulated by F-actin. Furthermore, membrane trafficking was inhibited by disrupting the actin cytoskeleton with cytochalasin D (51 ± 13% of control) or jasplakinolide (58 ± 9% of control). These studies indicate that there is a high rate of vesicular trafficking at the apical membrane of cholangiocytes and suggest that both cAMP and the actin cytoskeleton contribute importantly to these events.

Original languageEnglish (US)
Pages (from-to)C1042-C1052
JournalAmerican Journal of Physiology - Cell Physiology
Volume282
Issue number5 51-5
DOIs
StatePublished - 2002

Keywords

  • Endocytosis
  • Exocytosis
  • Vesicular trafficking

ASJC Scopus subject areas

  • Physiology
  • Cell Biology

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