Lipid raft-dependent FcεRI ubiquitination regulates receptor endocytosis through the action of ubiquitin binding adaptors

Rosa Molfetta, Francesca Gasparrini, Giovanna Peruzzi, Laura Vian, Mario Picolli, Luigi Frati, Angela Santoni, Rosella Paolini

Research output: Contribution to journalArticle

Abstract

The best characterized role for ubiquitination of membrane receptors is to negatively regulate signaling by targeting receptors for lysosomal degradation. The high affinity receptor for IgE (FcεRI) expressed on mast cells and basophils is rapidly ubiquitinated upon antigen stimulation. However, the nature and the role of this covalent modification are still largelly unknown. Here, we show that FcεRI subunits are preferentially ubiquitinated at multiple sites upon stimulation, and provide evidence for a role of ubiquitin as an internalization signal: under conditions of impaired receptor ubiquitination a decrease of receptor entry is observed by FACS analysis and fluorescence microscopy. We also used biochemical approaches combined with fluorescence microscopy, to demonstrate that receptor endocytosis requires the integrity of specific membrane domains, namely lipid rafts. Additionally, by RNA interference we demonstrate the involvement of ubiquitin-binding endocytic adaptors in FceRI internalization and sorting. Notably, the triple depletion of Eps15, Eps15R and Epsin1 negatively affects the early steps of Ag-induced receptor endocytosis, whereas Hrs depletion retains ubiquitinated receptors into early endosomes and partially prevents their sorting into lysosomes for degradation. Our results are compatible with a scenario in which the accumulation of engaged receptor subunits into lipid rafts is required for receptor ubiquitination, a prerequisite for efficient receptor internalization, sorting and delivery to a lysosomal compartment.

Original languageEnglish
Article numbere5604
JournalPLoS One
Volume4
Issue number5
DOIs
Publication statusPublished - May 19 2009

ASJC Scopus subject areas

  • Agricultural and Biological Sciences(all)
  • Biochemistry, Genetics and Molecular Biology(all)
  • Medicine(all)

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    Molfetta, R., Gasparrini, F., Peruzzi, G., Vian, L., Picolli, M., Frati, L., Santoni, A., & Paolini, R. (2009). Lipid raft-dependent FcεRI ubiquitination regulates receptor endocytosis through the action of ubiquitin binding adaptors. PLoS One, 4(5), [e5604]. https://doi.org/10.1371/journal.pone.0005604