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EGF‐Induced Activation of the EGF Receptor Does Not Trigger Mobilization of Caveolae
Author(s) -
Kazazic Maja,
Roepstorff Kirstine,
Johannessen Lene E.,
Pedersen Nina M.,
van Deurs Bo,
Stang Espen,
Madshus Inger H.
Publication year - 2006
Publication title -
traffic
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.677
H-Index - 130
eISSN - 1600-0854
pISSN - 1398-9219
DOI - 10.1111/j.1600-0854.2006.00487.x
Subject(s) - caveolae , endocytosis , immunoelectron microscopy , microbiology and biotechnology , biology , clathrin , hela , internalization , caveolin 1 , receptor , caveolin , cell , biochemistry , signal transduction , immunology , antibody
Caveolae‐dependent endocytosis has recently been proposed in the uptake of EGF receptor (EGFR) at high concentrations of ligand. Consistently, upon incubation of HEp2 and HeLa cells with methyl‐β‐cyclodextrin, we observed a small inhibitory effect on endocytosis of ligated EGFR in HEp2 cells. However, immunoelectron microscopy showed the same relative amount of bound EGF localizing to caveolae on incubation with high and low concentrations of EGF, not supporting rapid recruitment of EGFR to caveolae. Live‐cell microscopy furthermore demonstrated that incubating HEp2 cells with high concentrations of EGF did not increase the mobility of caveolae. By RNA‐interference‐mediated knockdown of clathrin heavy chain in HEp2 and HeLa cells, we found that endocytosis of EGFR was efficiently inhibited both at high and low concentrations of EGF. Our results show that caveolae are not involved in endocytosis of EGF‐bound EGFR to any significant degree and that high concentrations of EGF do not further mobilize caveolae.