title: Differential membrane compartmentalization of Ret by PTB-adaptor engagement.
abstract: Glial cell line-derived neurotrophic factor family ligands act through the receptor tyrosine kinase Ret, which plays important roles during embryonic development for cell differentiation, survival, and migration. Ret signaling is markedly affected by compartmentalization of receptor complexes into membrane subdomains. Ret can propagate biochemical signaling from within concentrates in cholesterol-rich membrane microdomains or lipid rafts, or outside such regions, but the mechanisms for, and consequences of, Ret translocation between these membrane compartments remain largely unclear. Here we investigate the interaction of Shc and Frs2 phosphotyrosine-binding domain-containing adaptor molecules with Ret and their function in redistributing Ret to specialized membrane compartments. We found that engagement of Ret with the Frs2 adaptor results in an enrichment of Ret in lipid rafts and that signal transduction pathways and chemotaxis responses depend on the integrity of such rafts. The competing Shc adaptor did not promote Ret translocation to equivalent domains, and Shc-mediated effects were less affected by disruption of lipid rafts. However, by expressing a chimeric Shc protein that localizes to lipid rafts, we showed that biochemical signaling downstream of Ret resembled that of Ret signaling via Frs2. We have identified a previously unknown mechanism in which phosphotyrosine-binding domain-containing adaptors, by means of relocating Ret receptor complexes to lipid rafts, segregate diverse signaling and cellular functions mediated by Ret. These results reveal the existence of a novel mechanism that could, by subcellular relocation of Ret, work to amplify ligand gradients during chemotaxis.
authors: Division of Molecular Neurobiology, Department of Medical Biochemistry and Biophysics, Karolinska Institute, Stockholm, Sweden.
authors: T K
authors: TK
authors: Lundgren
authors: Moritz
authors: M
authors: Luebke
authors: Anna
authors: A
authors: Stenqvist
authors: Patrik
authors: P
authors: Ernfors
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000378:metabolism; D002451:Cell Compartmentation / Q000502:physiology; D002458:Cell Fractionation; D045744:Cell Line, Tumor; D002462:Cell Membrane / Q000378:metabolism / Q000502:physiology*; D002465:Cell Movement; D020552:Comet Assay; D003902:Detergents / Q000494:pharmacology; D051100:Glial Cell Line-Derived Neurotrophic Factor / Q000235:genetics / Q000378:metabolism / Q000502:physiology; D049452:Green Fluorescent Proteins / Q000378:metabolism; D006801:Humans; D021962:Membrane Microdomains / Q000378:metabolism / Q000502:physiology*; D008565:Membrane Proteins / Q000378:metabolism; D009154:Mutation; D009447:Neuroblastoma / Q000473:pathology; D010766:Phosphorylation; D011485:Protein Binding; D051096:Proto-Oncogene Proteins c-ret / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D011994:Recombinant Proteins / Q000378:metabolism; D055765:Shc Signaling Adaptor Proteins; D015398:Signal Transduction; D000071425:Src Homology 2 Domain-Containing, Transforming Protein 1; D013347:Subcellular Fractions / Q000187:drug effects / Q000378:metabolism; D014162:Transfection; D047392:beta-Cyclodextrins / Q000494:pharmacology
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D003902:Detergents; C106534:FRS2 protein, human; D051100:Glial Cell Line-Derived Neurotrophic Factor; D008565:Membrane Proteins; D011994:Recombinant Proteins; C528024:SHC1 protein, human; D055765:Shc Signaling Adaptor Proteins; D000071425:Src Homology 2 Domain-Containing, Transforming Protein 1; D047392:beta-Cyclodextrins; C108732:methyl-beta-cyclodextrin; D049452:Green Fluorescent Proteins; D051096:Proto-Oncogene Proteins c-ret