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Trafficking of IgG by FcRn in Epithelial Polarized Cells
Author(s) -
Massol Ramiro Horacio,
Lencer Wayne
Publication year - 2009
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.23.1_supplement.686.2
Subject(s) - transcytosis , endocytosis , endosome , microbiology and biotechnology , chemistry , immunoglobulin g , neonatal fc receptor , intracellular , antibody , biology , immunology , cell , biochemistry
FcRn transports IgG and IgG‐opsonized antigens across polarized epithelial cells that line mucosal surfaces. IgG transport by FcRn is essential for IgG homeostasis, short‐term passive immunity and contributes to epithelial maintenance, inflammatory responses and host defense at mucosal surfaces. In this work we characterized some aspects of the endocytosis and intracellular trafficking of FcRn in epithelial polarized cells. We found that FcRn‐IgG complexes are internalized from either the apical or basolateral surface mainly via clathrin‐mediated endocytosis. These complexes are then transported into the recycling endosome (RE) after which a fraction of IgG is recycled back to the surface of origin or transcytosed to the opposite cell surface. A very small fraction of FcRn‐IgG complexes is delivered to late endosomes/lysosomes. Whereas the actin motor myosin Vb and the GTPase Rab25 regulate sorting of these complexes out of the RE specific for transcytosis, Rab11a regulates recycling to the basolateral membrane only. Finally, we found that IgG‐opsonized particles crosslink and divert FcRn from the typical transcytotic and recycling pathways into the degradative pathway. This unusual mode of transport of FcRn‐IgG‐particles to the lysosomes may be important for the initiation of antigen processing or for the neutralization of pathogenic microbes.