title: CIN85 regulates ubiquitination and degradative endosomal sorting of the EGF receptor.
abstract: CIN85 has been demonstrated to interact with a number of proteins involved in endocytosis and intracellular sorting. However, the exact functional role of CIN85 in endocytosis remains unclear. We have investigated whether CIN85 plays a role in EGF-induced EGF receptor (EGFR) internalization, as previously suggested, or whether CIN85 is rather involved in endosomal sorting of the EGFR. When over-expressing a dominant negative interfering CIN85 mutant consisting of three SH3 domains only, we found that internalization of EGF was inhibited. However, when knocking down CIN85 by RNAi, the EGF-EGFR uptake appeared similar to in control cells. Furthermore, in CIN85 depleted cells, EGF-induced ubiquitination of the EGFR was decreased, and degradation of EGF-EGFR complexes was delayed. Our data further demonstrated that depletion of CIN85 increased the recycling of EGF, suggesting that CIN85 plays a role in endosomal sorting of the ubiquitinated EGFR. Our data also demonstrated that CIN85 was constitutively associated with Hrs, and this strengthens the hypothesis of a functional role of CIN85 in endosomal EGFR sorting.
authors.affiliation: Institute of Pathology, Faculty of Medicine, University of Oslo, Oslo, Norway.
authors.forename: Sissel Beate
authors.initials: SB
authors.lastname: Rønning
authors.forename: Nina Marie
authors.initials: NM
authors.lastname: Pedersen
authors.forename: Inger Helene
authors.initials: IH
authors.lastname: Madshus
authors.forename: Espen
authors.initials: E
authors.lastname: Stang
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000378:metabolism*; D002478:Cells, Cultured; D011992:Endosomes / Q000378:metabolism*; D004815:Epidermal Growth Factor / Q000378:metabolism; D066246:ErbB Receptors / Q000378:metabolism*; D006367:HeLa Cells; D006801:Humans; D011994:Recombinant Proteins / Q000378:metabolism; D054875:Ubiquitination
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D011994:Recombinant Proteins; C433810:SH3KBP1 protein, human; D004815:Epidermal Growth Factor; D066246:ErbB Receptors