title: Endosomal accumulation of the activated epidermal growth factor receptor (EGFR) induces apoptosis.
abstract: Endocytosis positively and negatively regulates cell surface receptor signaling by temporally and spatially controlling interactions with downstream effectors. This process controls receptor-effector communication. However, the relationship between receptor endocytic trafficking and cell physiology is unclear. In MDA-MB-468 cells, cell surface EGF receptors (EGFRs) promote cell growth, whereas intracellular EGFRs induce apoptosis, making these cells an excellent model for studying the endocytic regulation of EGFR signaling. In addition, MDA-MB-468 cells have limited EGFR degradation following stimulation. Here, we report that in MDA-MB-468 cells the phosphorylated EGFR accumulates on the limiting membrane of the endosome with its carboxyl terminus oriented to the cytoplasm. To determine whether perturbation of EGFR trafficking is sufficient to cause apoptosis, we used pharmacological and biochemical strategies to disrupt EGFR endocytic trafficking in HeLa cells, which do not undergo EGF-dependent apoptosis. Manipulation of HeLa cells so that active EGF·EGFRs accumulate on the limiting membrane of endosomes reveals that receptor phosphorylation is sustained and leads to apoptosis. When EGF·EGFR complexes accumulated in the intraluminal vesicles of the late endosome, phosphorylation of the receptor was not sustained, nor did the cells undergo apoptosis. These data demonstrate that EGFR-mediated apoptosis is initiated by the activated EGFR from the limiting membrane of the endosome.
authors.affiliation: Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, 73106.
authors.forename: Jamie S
authors.initials: JS
authors.lastname: Rush
authors.affiliation: Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, 73106.
authors.forename: Leslie M
authors.initials: LM
authors.lastname: Quinalty
authors.affiliation: Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, 73106.
authors.forename: Luke
authors.initials: L
authors.lastname: Engelman
authors.affiliation: Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, 73106; Oklahoma Center for Neuroscience, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, 73106; Department of Pharmaceutical Sciences, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73106.
authors.forename: David M
authors.initials: DM
authors.lastname: Sherry
authors.affiliation: Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, 73106. Electronic address: brian-ceresa@ouhsc.edu.
authors.forename: Brian P
authors.initials: BP
authors.lastname: Ceresa
mesh_terms: D017209:Apoptosis / Q000187:drug effects / Q000235:genetics; D045744:Cell Line, Tumor; D004268:DNA-Binding Proteins / Q000172:deficiency / Q000235:genetics; D004705:Endocytosis / Q000187:drug effects / Q000235:genetics; D056827:Endosomal Sorting Complexes Required for Transport / Q000172:deficiency / Q000235:genetics; D011992:Endosomes / Q000187:drug effects / Q000378:metabolism*; D004815:Epidermal Growth Factor / Q000494:pharmacology; D066246:ErbB Receptors / Q000037:antagonists & inhibitors / Q000378:metabolism*; D055785:Gene Knockdown Techniques; D006367:HeLa Cells; D006801:Humans; D008985:Monensin / Q000494:pharmacology; D010766:Phosphorylation / Q000187:drug effects / Q000235:genetics; D014157:Transcription Factors / Q000172:deficiency / Q000235:genetics; D020691:rab GTP-Binding Proteins / Q000172:deficiency / Q000235:genetics; D000090802:rab7 GTP-Binding Proteins; D000099177:Tsg101 Protein
chemical_list: D004268:DNA-Binding Proteins; D056827:Endosomal Sorting Complexes Required for Transport; D004815:Epidermal Growth Factor; D066246:ErbB Receptors; D008985:Monensin; D014157:Transcription Factors; D020691:rab GTP-Binding Proteins; D000090802:rab7 GTP-Binding Proteins; D000099177:Tsg101 Protein
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