title: Single-chain antibody-mediated intracellular retention of ErbB-2 impairs Neu differentiation factor and epidermal growth factor signaling.
abstract: ErbB-2 becomes rapidly phosphorylated and activated following treatment of many cell lines with epidermal growth factor (EGF) or Neu differentiation factor (NDF). However, these factors do not directly bind ErbB-2, and its activation is likely to be mediated via transmodulation by other members of the type I/EGF receptor (EGFR)-related family of receptor tyrosine kinases. The precise role of ErbB-2 in the transduction of the signals elicited by EGF and NDF is unclear. We have used a novel approach to study the role of ErbB-2 in signaling through this family of receptors. An ErbB-2-specific single-chain antibody, designed to prevent transit through the endoplasmic reticulum and cell surface localization of ErbB-2, has been expressed in T47D mammary carcinoma cells, which express all four known members of the EGFR family. We show that cell surface expression of ErbB-2 was selectively suppressed in these cells and that the activation of the mitogen-activated protein kinase pathway and p70/p85S6K, induction of c-fos expression, and stimulation of growth by NDF were dramatically impaired. Activation of mitogen-activated protein kinase and p70/p85S6K and induction of c-fos expression by EGF were also significantly reduced. We conclude that in T47D cells, ErbB-2 is a major NDF signal transducer and a potentiator of the EGF signal. Thus, our observations demonstrate that ErbB-2 plays a central role in the type I/EGFR-related family of receptors and that receptor transmodulation represents a crucial step in growth factor signaling.
authors.affiliation: Friedrich Miescher-Institut, Basel, Switzerland.
authors.forename: D
authors.initials: D
authors.lastname: Graus-Porta
authors.forename: R R
authors.initials: RR
authors.lastname: Beerli
authors.forename: N E
authors.initials: NE
authors.lastname: Hynes
mesh_terms: D000911:Antibodies, Monoclonal / Q000096:biosynthesis / Q000378:metabolism*; D001943:Breast Neoplasms; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000378:metabolism; D002455:Cell Division / Q000187:drug effects; D002460:Cell Line; D004789:Enzyme Activation; D004815:Epidermal Growth Factor / Q000494:pharmacology*; D066246:ErbB Receptors / Q000302:isolation & purification / Q000378:metabolism; D015870:Gene Expression; D016762:Genes, fos / Q000187:drug effects; D006023:Glycoproteins / Q000494:pharmacology*; D006801:Humans; D007143:Immunoglobulin Heavy Chains / Q000096:biosynthesis / Q000378:metabolism; D007147:Immunoglobulin Light Chains / Q000096:biosynthesis / Q000378:metabolism; D007135:Immunoglobulin Variable Region / Q000096:biosynthesis / Q000378:metabolism; D007700:Kinetics; D020880:Neuregulins; D010766:Phosphorylation; D019000:Phosphotyrosine; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D011505:Protein-Tyrosine Kinases / Q000378:metabolism*; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000378:metabolism*; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000378:metabolism / Q000494:pharmacology; D019893:Ribosomal Protein S6 Kinases; D015398:Signal Transduction; D014407:Tumor Cells, Cultured; D014443:Tyrosine / Q000031:analogs & derivatives / Q000032:analysis
chemical_list: D000911:Antibodies, Monoclonal; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D004815:Epidermal Growth Factor; D066246:ErbB Receptors; D006023:Glycoproteins; D007143:Immunoglobulin Heavy Chains; D007147:Immunoglobulin Light Chains; D007135:Immunoglobulin Variable Region; D020880:Neuregulins; D019000:Phosphotyrosine; D017346:Protein Serine-Threonine Kinases; D011505:Protein-Tyrosine Kinases; D018719:Erb-b2 Receptor Tyrosine Kinases; D011994:Recombinant Proteins; D019893:Ribosomal Protein S6 Kinases; D014443:Tyrosine