title: The Cbl-interacting protein TULA inhibits dynamin-dependent endocytosis.
abstract: The Cbl- and ubiquitin-interacting protein T-cell ubiquitin ligand (TULA) has been demonstrated to inhibit endocytosis and downregulation of ligand-activated EGF receptor (EGFR) by impairing Cbl-induced ubiquitination. We presently report that TULA additionally inhibited clathrin-dependent endocytosis in general, as both uptake of transferrin (Tf) and low-density lipoprotein (LDL) was inhibited. Additionally, endocytosis of the raft proteins CD59 and major histocompatibility complex class I (MHC-I), which we demonstrate were mainly endocytosed clathrin-independently, but dynamin-dependently, was blocked in cells overexpressing TULA. By contrast, the uptake of ricin, which is mainly endocytosed clathrin- and dynamin-independently, was not affected by overexpressed TULA. Consistently, TULA and dynamin co-immunoprecipitated and colocalized intracellularly, and upon overexpression of dynamin the TULA-mediated inhibitory effect on endocytosis of Tf, LDL, CD59 and MHC-I was counteracted. Overexpressed dynamin did not restore ubiquitination of the EGFR, and consistently dynamin did not rescue endocytosis of the EGFR in cells overexpressing TULA. We conclude that TULA inhibits both clathrin-dependent and clathrin-independent endocytic pathways by functionally sequestering dynamin via the SH3 domain of TULA binding proline-rich sequences in dynamin.
authors: Institute of Pathology, Faculty Division Rikshospitalet, University of Oslo, Rikshospitalet-Radiumhospitalet Medical Centre, 0027 Oslo, Norway.
authors: Vibeke
authors: V
authors: Bertelsen
authors: Kamilla
authors: K
authors: Breen
authors: Kirsten
authors: K
authors: Sandvig
authors: Espen
authors: E
authors: Stang
authors: Inger Helene
authors: IH
authors: Madshus
mesh_terms: D018957:CD59 Antigens / Q000378:metabolism; D002352:Carrier Proteins / Q000502:physiology*; D002966:Clathrin / Q000378:metabolism; D034281:Dynamins / Q000235:genetics / Q000378:metabolism*; D004705:Endocytosis; D004815:Epidermal Growth Factor / Q000502:physiology; D066246:ErbB Receptors / Q000378:metabolism; D006367:HeLa Cells; D015395:Histocompatibility Antigens Class I / Q000378:metabolism; D006801:Humans; D008077:Lipoproteins, LDL / Q000378:metabolism; D008565:Membrane Proteins; D009154:Mutation; D050721:Proto-Oncogene Proteins c-cbl / Q000378:metabolism*; D012276:Ricin / Q000378:metabolism; D014168:Transferrin / Q000378:metabolism; D025801:Ubiquitin / Q000378:metabolism; D018909:src Homology Domains
chemical_list: D018957:CD59 Antigens; C489394:CLIP4 protein, human; D002352:Carrier Proteins; D002966:Clathrin; D015395:Histocompatibility Antigens Class I; D008077:Lipoproteins, LDL; D008565:Membrane Proteins; D014168:Transferrin; D025801:Ubiquitin; D004815:Epidermal Growth Factor; D012276:Ricin; D050721:Proto-Oncogene Proteins c-cbl; D066246:ErbB Receptors; D034281:Dynamins