Lateral propagation of EGF signaling after local stimulation is dependent on receptor density.
We analyzed lateral propagation of epidermal growth factor (EGF) signaling in single live COS cells following local stimulation, achieved by the use of laminar flows containing rhodamine-labeled EGF. The spatiotemporal pattern of EGF signaling was visualized by fluorescent indicators for Ras activation and tyrosine phosphorylation. Contrary to the findings in previous reports, both signals were localized to the stimulated regions in control COS cells expressing EGF receptor at the basal level. However, the signals spread over the entire cell when EGF receptors were overexpressed or when receptor/ligand endocytosis was blocked. We thus present evidence that ligand-independent propagation of EGF signaling occurs only when the receptor density on the plasma membrane is high, such as in carcinoma cells.
Laboratory for Cell Function and Dynamics, Advanced Technology Development Center, Brain Science Institute, RIKEN, 2-1 Hirosawa, Wako-city, Saitama 351-0198, Japan.
Asako
A
Sawano
Shuichi
S
Takayama
Michiyuki
M
Matsuda
Atsushi
A
Miyawaki
D000818:Animals; D001426:Bacterial Proteins / Q000096:biosynthesis / Q000235:genetics; D019556:COS Cells; D002277:Carcinoma / Q000378:metabolism*; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism*; D015194:Diffusion Chambers, Culture / Q000379:methods; D004305:Dose-Response Relationship, Drug; D004705:Endocytosis / Q000187:drug effects / Q000502:physiology*; D004815:Epidermal Growth Factor / Q000037:antagonists & inhibitors / Q000378:metabolism*; D066246:ErbB Receptors / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D005057:Eukaryotic Cells / Q000166:cytology / Q000378:metabolism*; D020558:GTP Phosphohydrolases; D005786:Gene Expression Regulation / Q000187:drug effects / Q000502:physiology; D049452:Green Fluorescent Proteins; D006801:Humans; D007202:Indicators and Reagents; D008164:Luminescent Proteins / Q000096:biosynthesis / Q000235:genetics; D046911:Macromolecular Substances; D010766:Phosphorylation; D015800:Protozoan Proteins / Q000096:biosynthesis / Q000187:drug effects; D011994:Recombinant Proteins; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology*; D014407:Tumor Cells, Cultured; D014443:Tyrosine / Q000378:metabolism; D018631:ras Proteins / Q000096:biosynthesis / Q000187:drug effects
D001426:Bacterial Proteins; D007202:Indicators and Reagents; D008164:Luminescent Proteins; D046911:Macromolecular Substances; D015800:Protozoan Proteins; D011994:Recombinant Proteins; C065352:rhoptry associated protein, Plasmodium; C054562:yellow fluorescent protein, Bacteria; D049452:Green Fluorescent Proteins; D014443:Tyrosine; D004815:Epidermal Growth Factor; D066246:ErbB Receptors; C430804:Raichu-Ras protein; D020558:GTP Phosphohydrolases; D018631:ras Proteins