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Endosomal trafficking of the ligated FcvarepsilonRI receptor

Gul'nar V Fattakhova1, Madhan Masilamani, Sriram Narayanan

  • 1Receptor Cell Biology Section, Laboratory of Immunogenetics, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, MD 20852, United States.

Molecular Immunology
|October 24, 2008
PubMed

Insights

Internalized high-affinity IgE receptor (FcεRI) traffics through endosomes to lysosomes. Syk deficiency accelerates this FcεRI transport, suggesting Syk regulates FcεRI endosomal retention.

Area of Science:

  • Immunology
  • Cell Biology
  • Molecular Biology

Background:

  • Aggregation of the high-affinity IgE receptor (FcεRI) on mast cells triggers mediator release and receptor internalization.
  • The trafficking pathway of internalized FcεRI within the endosomal-lysosomal system remains largely uncharacterized.

Purpose of the Study:

  • To investigate the endosomal trafficking dynamics of aggregated FcεRI.
  • To determine the role of Syk kinase in FcεRI trafficking.

Main Methods:

  • Utilized RBL-2H3 cells, including Syk-deficient variants.
  • Employed immunofluorescence microscopy to track FcεRI localization with endosomal markers (EEA1, Rab5, Rab7).

Main Results:

  • Aggregated FcεRI localized to early endosomes (EEA1+) within 15 minutes post-ligation.
  • FcεRI appeared in late endosomes (Rab7+) and lysosomes at later time points.
  • FcεRI subunits (alpha and gamma) remained associated during trafficking.
  • Syk-deficient cells exhibited accelerated FcεRI transport to lysosomes.

Conclusions:

  • FcεRI undergoes time-dependent sorting within the endosomal-lysosomal network.
  • Syk kinase appears critical for regulating FcεRI trafficking and retention in endosomes.

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