Acute ligand-independent Src activation mimics low EGF-induced EGFR surface signalling and redistribution into recycling endosomes.
Src, a non-receptor tyrosine kinase, is a key signal transduction partner of epidermal growth factor (EGF) receptor (EGFR). In human breast cancer, EGFR and Src are frequently over-expressed and/or over-activated. Although reciprocal activation is documented, mechanisms underlying Src:EGFR interactions are incompletely understood. We here exploited ts/v-Src thermo-activation in MDCK monolayers to test whether acute Src activation impacts on signalling and trafficking of non-liganded EGFR. We found that thermo-activation caused rapid Src recruitment to the plasma membrane, concomitant association with EGFR, and its phosphorylation at Y845 and Y1173 predominantly at the cell surface. Like low EGF concentrations, activated Src (i) decreased EGF surface binding without affecting the total EGFR pool; (ii) triggered EGFR endocytosis via clathrin-coated vesicles; (iii) and led to its sequestration in perinuclear/recycling endosomes with avoidance of multivesicular bodies and lysosomal degradation. Combined Src activation and EGF were synergistic for EGFR-Y845 and -Y1173 phosphorylation at some endosomes. We conclude that acute effects of Src in MDCK cells may mimic those of low EGF on EGFR activation and redistribution. Src:EGFR interactions may be sufficient to trigger EGFR activation and might contribute to its local signalling, without requiring either soluble extracellular signal or receptor over-expression.
Medts
T
T
Université catholique de Louvain and de Duve Institute (ICP), CELL Unit, UCL-75.41, avenue Hippocrate, 75, 1200 Brussels, Belgium.
de Diesbach
P
P
Cominelli
A
A
N'Kuli
F
F
Tyteca
D
D
Courtoy
P J
PJ
D000818:Animals; D002462:Cell Membrane / Q000187:drug effects / Q000201:enzymology*; D002465:Cell Movement / Q000187:drug effects; D002467:Cell Nucleus / Q000187:drug effects / Q000378:metabolism; D022163:Clathrin-Coated Vesicles / Q000378:metabolism; D004285:Dogs; D004705:Endocytosis / Q000187:drug effects*; D011992:Endosomes / Q000187:drug effects / Q000201:enzymology*; D004789:Enzyme Activation / Q000187:drug effects; D004815:Epidermal Growth Factor / Q000494:pharmacology*; D004847:Epithelial Cells / Q000166:cytology / Q000187:drug effects / Q000201:enzymology; D066246:ErbB Receptors / Q000378:metabolism*; D022001:Focal Adhesions / Q000187:drug effects / Q000378:metabolism; D006801:Humans; D042541:Intracellular Space / Q000187:drug effects / Q000378:metabolism; D008024:Ligands; D010766:Phosphorylation / Q000187:drug effects; D011485:Protein Binding / Q000187:drug effects; D021381:Protein Transport / Q000187:drug effects; D015398:Signal Transduction / Q000187:drug effects*; D020695:rab4 GTP-Binding Proteins / Q000378:metabolism; D019061:src-Family Kinases / Q000378:metabolism*
D008024:Ligands; D004815:Epidermal Growth Factor; D066246:ErbB Receptors; D019061:src-Family Kinases; D020695:rab4 GTP-Binding Proteins