Ocadaic acid treatment causes tyrosine phosphorylation of caveolin-2 and induces internalization of caveolae in rat peritoneal macrophages

Anna L. Kiss, Erzsébet Botos, Ágnes Turi, Nándor Müllner

Research output: Article

17 Citations (Scopus)

Abstract

In this paper, we provide evidences that protein phosphatases could regulate the internalization cycle of caveolae in rat peritoneal cells. Ocadaic acid (OA) - a serine/threonine phosphatase inhibitor - was used in various concentrations (4 and 100nM) to study the internalization of horseradish peroxidase (HRP) in resident and elicited macrophages. We have found that OA in both concentrations has significantly decreased HRP uptake in resident and elicited cells. The results of our morphometrical analysis showed that in OA-treated cells, the number of surface-connected caveolae has been dramatically decreased. Simultaneously large, endosome-like vacuoles containing small vesicles appeared in the cytoplasm. The membrane of these small vesicles was labeled with anti-caveolin-1 antibody. Immunoprecipitation and Western blot analysis revealed that in OA-treated cells a ∼29 kDa protein identified as caveolin-2 in macrophages was phosphorylated on tyrosine residues. These data support the idea that there is a close correlation between the phosphorylation of caveolin-2 and endocytosis of caveolae: the tyrosine phosphorylation of this ∼29 kDa protein can drive caveolae to pinch off from the plasma membrane and causes accumulation of caveolae in a multivesicular body-like cellular compartment, which was never found to contain lysosomal enzymes. As a result of OA treatment caveolin-2 remains phosphorylated and the phosphorylation of these protein might inhibit the recycling of caveolae.

Original languageEnglish
Pages (from-to)707-715
Number of pages9
JournalMicron
Volume35
Issue number8
DOIs
Publication statusPublished - dec. 1 2004

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ASJC Scopus subject areas

  • Structural Biology
  • Materials Science(all)
  • Physics and Astronomy(all)
  • Cell Biology

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