title: Quantum dot ligands provide new insights into erbB/HER receptor-mediated signal transduction.
abstract: The erbB/HER family of transmembrane receptor tyrosine kinases (RTKs) mediate cellular responses to epidermal growth factor (EGF) and related ligands. We have imaged the early stages of RTK-dependent signaling in living cells using: (i) stable expression of erbB1/2/3 fused with visible fluorescent proteins (VFPs), (ii) fluorescent quantum dots (QDs) bearing epidermal growth factor (EGF-QD) and (iii) continuous confocal laser scanning microscopy and flow cytometry. Here we demonstrate that EGF-QDs are highly specific and potent in the binding and activation of the EGF receptor (erbB1), being rapidly internalized into endosomes that exhibit active trafficking and extensive fusion. EGF-QDs bound to erbB1 expressed on filopodia revealed a previously unreported mechanism of retrograde transport to the cell body. When erbB2-monomeric yellow fluorescent protein (mYFP) or erbB3-monomeric Citrine (mCitrine) were coexpressed with erbB1, the rates and extent of endocytosis of EGF-QD and the RTK-VFP demonstrated that erbB2 but not erbB3 heterodimerizes with erbB1 after EGF stimulation, thereby modulating EGF-induced signaling. QD-ligands will find widespread use in basic research and biotechnological developments.
authors.affiliation: Department of Molecular Biology, Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, D-37077 Göttingen, Germany. dlidke@gwdg.de
authors.forename: Diane S
authors.initials: DS
authors.lastname: Lidke
authors.forename: Peter
authors.initials: P
authors.lastname: Nagy
authors.forename: Rainer
authors.initials: R
authors.lastname: Heintzmann
authors.forename: Donna J
authors.initials: DJ
authors.lastname: Arndt-Jovin
authors.forename: Janine N
authors.initials: JN
authors.lastname: Post
authors.forename: Hernan E
authors.initials: HE
authors.lastname: Grecco
authors.forename: Elizabeth A
authors.initials: EA
authors.lastname: Jares-Erijman
authors.forename: Thomas M
authors.initials: TM
authors.lastname: Jovin
mesh_terms: D000818:Animals; D002462:Cell Membrane / Q000378:metabolism*; D006224:Cricetinae; D011992:Endosomes / Q000378:metabolism / Q000648:ultrastructure; D004815:Epidermal Growth Factor / Q000378:metabolism; D006801:Humans; D009038:Motion; D018739:Oncogene Proteins v-erbB / Q000378:metabolism; D011485:Protein Binding; D025941:Protein Interaction Mapping / Q000379:methods*; D021381:Protein Transport / Q000502:physiology*; D045663:Quantum Dots; D011956:Receptors, Cell Surface / Q000378:metabolism*; D015398:Signal Transduction / Q000502:physiology*; D013050:Spectrometry, Fluorescence / Q000379:methods*
chemical_list: D018739:Oncogene Proteins v-erbB; D011956:Receptors, Cell Surface; D004815:Epidermal Growth Factor