The recycling and transcytotic pathways for IgG transport by FcRn are distinct and display an inherent polarity

J Cell Biol. 2009 May 18;185(4):673-84. doi: 10.1083/jcb.200809122.

Abstract

The Fc receptor FcRn traffics immunoglobulin G (IgG) in both directions across polarized epithelial cells that line mucosal surfaces, contributing to host defense. We show that FcRn traffics IgG from either apical or basolateral membranes into the recycling endosome (RE), after which the actin motor myosin Vb and the GTPase Rab25 regulate a sorting step that specifies transcytosis without affecting recycling. Another regulatory component of the RE, Rab11a, is dispensable for transcytosis, but regulates recycling to the basolateral membrane only. None of these proteins affect FcRn trafficking away from lysosomes. Thus, FcRn transcytotic and recycling sorting steps are distinct. These results are consistent with a single structurally and functionally heterogeneous RE compartment that traffics FcRn to both cell surfaces while discriminating between recycling and transcytosis pathways polarized in their direction of transport.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cell Compartmentation
  • Cell Line
  • Cell Membrane / metabolism
  • Cell Polarity*
  • Dogs
  • Endosomes / metabolism
  • Humans
  • Immunoglobulin G / metabolism*
  • Myosin Heavy Chains / physiology
  • Myosin Type V / physiology
  • Protein Transport*
  • Receptors, Fc / metabolism*
  • rab GTP-Binding Proteins / physiology

Substances

  • Immunoglobulin G
  • MYO5B protein, human
  • Rab25 protein, human
  • Receptors, Fc
  • Myosin Type V
  • rab11 protein
  • Myosin Heavy Chains
  • rab GTP-Binding Proteins