title: A ligand-inducible anaplastic lymphoma kinase chimera is endocytosis impaired.
abstract: Ligand-induced membrane trafficking of the anaplastic lymphoma kinase (ALK) was studied using a chimeric receptor in which the extracellular and transmembrane domain of ALK was substituted for the corresponding regions of epidermal growth factor receptor (EGFR). Wild-type EGFR, EGFR/ALK and an EGFR/ALK kinase negative mutant were independently expressed in mouse NR6 fibroblasts. The capacity of EGFR/ALK to mediate [125I]-EGF internalization, receptor degradation and downregulation, which has never been previously described, was assayed. The rate of [125I]-EGF-induced internalization mediated by the cytoplasmic domain of ALK was reduced several fold compared with the wild-type EGFR. The low rate of EGF internalization promoted by EGFR/ALK correlated with an impaired degradation and downregulation of the receptor and indicate that ALK is not subject to traditional mechanisms used to regulate receptor tyrosine kinase function. Accordingly, ALK-activated intracellular domain does not associate in vivo with c-cbl and does not undergo ligand-mediated ubiquitination. The current study provides new insight into the function and regulation of ALK suggesting that the relative long membrane residence of activated ALK might confers a more potent and prolonged signaling activity. Indeed NR6-EGFR/ALK cells exhibited a approximately 3-fold increase in a maximal mitogenic response than NR6-EGFR.
authors.affiliation: Laboratory of Cellular and Molecular Biology, Institute of Clinical Medicine, University of Ancona, Via Tronto 10/A, 60020 Ancona, Italy.
authors.forename: Michela
authors.initials: M
authors.lastname: Serresi
authors.forename: Gina
authors.initials: G
authors.lastname: Piccinini
authors.forename: Elisa
authors.initials: E
authors.lastname: Pierpaoli
authors.forename: Francesca
authors.initials: F
authors.lastname: Fazioli
mesh_terms: D019943:Amino Acid Substitution; D000077548:Anaplastic Lymphoma Kinase; D000818:Animals; D001120:Arginine / Q000378:metabolism; D015536:Down-Regulation; D004705:Endocytosis; D004790:Enzyme Induction; D066246:ErbB Receptors / Q000235:genetics / Q000378:metabolism; D005347:Fibroblasts / Q000378:metabolism; D007700:Kinetics; D008024:Ligands; D051379:Mice; D016297:Mutagenesis, Site-Directed; D041681:NIH 3T3 Cells; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D011505:Protein-Tyrosine Kinases / Q000096:biosynthesis* / Q000737:chemistry / Q000378:metabolism; D020794:Receptor Protein-Tyrosine Kinases; D011993:Recombinant Fusion Proteins / Q000378:metabolism*
chemical_list: D008024:Ligands; D011993:Recombinant Fusion Proteins; D001120:Arginine; C000626174:Alk protein, mouse; D000077548:Anaplastic Lymphoma Kinase; D066246:ErbB Receptors; D011505:Protein-Tyrosine Kinases; D020794:Receptor Protein-Tyrosine Kinases