Neonatal Fc receptor mediates internalization of Fc in transfected human endothelial cells

Nancy A. Goebl, Clifford M. Babbey, Amita Datta-Mannan, Derrick R. Witcher, Victor J. Wroblewski, Kenneth Dunn

Research output: Contribution to journalArticle

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Abstract

The neonatal Fc receptor, FcRn mediates an endocytic salvage pathway that prevents degradation of IgG, thus contributing to the homeostasis of circulating IgG. Based on the low affinity of IgG for FcRn at neutral pH, internalization of IgG by endothelial cells is generally believed to occur via fluid-phase endocytosis. To investigate the role of FcRn in IgG internalization, we used quantitative confocal microscopy to characterize internalization of fluorescent Fc molecules by HULEC-5A lung microvascular endothelia transfected with GFP fusion proteins of human or mouse FcRn. In these studies, cells transfected with FcRn accumulated significantly more intracellular Fc than untransfected cells. Internalization of FcRn-binding forms of Fc was proportional to FcRn expression level, was enriched relative to dextran internalization in proportion to FcRn expression level, and was blocked by incubation with excess unlabeled Fc. Because we were unable to detect either surface expression of FcRn or surface binding of Fc, these results suggest that FcRn-dependent internalization of Fc may occur through sequestration of Fc by FcRn in early endosomes. These studies indicate that FcRn-dependent internalization of IgG may be important not only in cells taking up IgG from an extracellular acidic space, but also in endothelial cells participating in homeostatic regulation of circulating IgG levels.

Original languageEnglish
Pages (from-to)5490-5505
Number of pages16
JournalMolecular Biology of the Cell
Volume19
Issue number12
DOIs
StatePublished - Dec 2008

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Endothelial Cells
Immunoglobulin G
neonatal Fc receptors
Endosomes
Extracellular Space
Endocytosis
Dextrans
Confocal Microscopy
Endothelium
Homeostasis
Lung

ASJC Scopus subject areas

  • Molecular Biology
  • Cell Biology

Cite this

Neonatal Fc receptor mediates internalization of Fc in transfected human endothelial cells. / Goebl, Nancy A.; Babbey, Clifford M.; Datta-Mannan, Amita; Witcher, Derrick R.; Wroblewski, Victor J.; Dunn, Kenneth.

In: Molecular Biology of the Cell, Vol. 19, No. 12, 12.2008, p. 5490-5505.

Research output: Contribution to journalArticle

Goebl, NA, Babbey, CM, Datta-Mannan, A, Witcher, DR, Wroblewski, VJ & Dunn, K 2008, 'Neonatal Fc receptor mediates internalization of Fc in transfected human endothelial cells', Molecular Biology of the Cell, vol. 19, no. 12, pp. 5490-5505. https://doi.org/10.1091/mbc.E07-02-0101
Goebl, Nancy A. ; Babbey, Clifford M. ; Datta-Mannan, Amita ; Witcher, Derrick R. ; Wroblewski, Victor J. ; Dunn, Kenneth. / Neonatal Fc receptor mediates internalization of Fc in transfected human endothelial cells. In: Molecular Biology of the Cell. 2008 ; Vol. 19, No. 12. pp. 5490-5505.
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