Characterization of E-cadherin endocytosis in isolated MCF-7 and chinese hamster ovary cells: the initial fate of unbound E-cadherin.
The endocytosis of E-cadherin has recently emerged as an important determinant of cadherin function with the potential to participate in remodeling adhesive contacts. In this study we focused on the initial fate of E-cadherin when it predominantly exists free on the cell surface prior to adhesive binding or incorporation into junctions. Surface-labeling techniques were used to define the endocytic itinerary of E-cadherin in MCF-7 cells and in Chinese hamster ovary cells stably expressing human E-cadherin. We found that in this experimental system E-cadherin entered a transferrin-negative compartment before transport to the early endosomal compartment, where it merged with classical clathrin-mediated uptake pathways. E-cadherin endocytosis was inhibited by mutant dynamin, but not by an Eps15 mutant that effectively blocked transferrin internalization. Furthermore, sustained signaling by the ARF6 GTPase appeared to trap endocytosed E-cadherin in large peripheral structures. We conclude that in isolated cells unbound E-cadherin on the cell surface is predominantly endocytosed by a clathrin-independent pathway resembling macropinocytotic internalization, which then fuses with the early endosomal system. Taken with earlier reports, this suggests the possibility that multiple pathways exist for E-cadherin entry into cells that are likely to reflect cell context and regulation.
Paterson
Andrew D
AD
School for Biomedical Science, The University of Queensland, St. Lucia, Brisbane, Australia 4072.
Parton
Robert G
RG
Ferguson
Charles
C
Stow
Jennifer L
JL
Yap
Alpha S
AS
D000089982:ADP-Ribosylation Factor 6; D020727:ADP-Ribosylation Factors / Q000378:metabolism; D000818:Animals; D001943:Breast Neoplasms; D016466:CHO Cells; D015820:Cadherins / Q000378:metabolism*; D002451:Cell Compartmentation / Q000502:physiology; D002966:Clathrin / Q000378:metabolism; D006224:Cricetinae; D004705:Endocytosis / Q000502:physiology*; D011992:Endosomes / Q000378:metabolism; D020558:GTP Phosphohydrolases / Q000378:metabolism; D006801:Humans; D008565:Membrane Proteins / Q000378:metabolism; D016253:Microscopy, Immunoelectron; D014407:Tumor Cells, Cultured / Q000378:metabolism / Q000648:ultrastructure
D000089982:ADP-Ribosylation Factor 6; D015820:Cadherins; D002966:Clathrin; D008565:Membrane Proteins; D020558:GTP Phosphohydrolases; D020727:ADP-Ribosylation Factors; C000715348:ARF6 protein, human