title: Enterophilin-1, a new partner of sorting nexin 1, decreases cell surface epidermal growth factor receptor.
abstract: We previously described enterophilin-1 (Ent-1), a new intestinal protein bearing an extended leucine zipper and a B30.2 domain. Ent-1 expression is associated with growth arrest and enterocyte differentiation. To investigate the importance of Ent-1 in the differentiation, we performed a yeast two-hybrid screening. We identified sorting nexin 1 (SNX1) as a novel partner of Ent-1 and confirmed the specificity of interaction by co-immunoprecipitation experiments in mammalian cells. SNX1 is associated with endosomal membranes and triggers the endosome-to-lysosome pathway of epidermal growth factor receptor (EGFR). We observe by immunofluorescence microscopy that Ent-1 and SNX1 are co-localized on vesicular and tubulovesicular structures, which are different from early endosome antigen 1-containing endosomes. By gel filtration chromatography, we show that Ent-1 and SNX1 co-eluted in macromolecular complexes containing part of EGFR. Furthermore, overexpressed Ent-1 decreases cell surface EGFR. Ent-1 and SNX1 co-overexpression strongly extends EGFR diminution, indicating a synergetic effect of both proteins on cell surface EGFR removal. Interestingly, the increase of endogenous Ent-1 expression correlates with the decrease of EGFR during spontaneous differentiation of Caco-2 cells. We thus propose a role of Ent-1 in the trafficking of EGFR to down-regulate intestinal mitogenic signals, highlighting the mechanisms of cell growth arrest associated with enterocytic differentiation.
authors.affiliation: Institut Fédératif de Recherche Claude de Préval, IFR 30, Université Paul Sabatier, and Centre Hospitalo-Universitaire de Toulouse, INSERM Unité 563, Department of Lipoproteins and Lipid Mediators, Hôpital Purpan, F31059 Toulouse Cedex, France.
authors.forename: Véronique
authors.initials: V
authors.lastname: Pons
authors.forename: Françoise
authors.initials: F
authors.lastname: Hullin-Matsuda
authors.forename: Michel
authors.initials: M
authors.lastname: Nauze
authors.forename: Ronald
authors.initials: R
authors.lastname: Barbaras
authors.forename: Christine
authors.initials: C
authors.lastname: Pérès
authors.forename: Xavier
authors.initials: X
authors.lastname: Collet
authors.forename: Bertrand
authors.initials: B
authors.lastname: Perret
authors.forename: Hugues
authors.initials: H
authors.lastname: Chap
authors.forename: Ama
authors.initials: A
authors.lastname: Gassama-Diagne
mesh_terms: D000818:Animals; D019556:COS Cells; D018938:Caco-2 Cells; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D002454:Cell Differentiation; D004705:Endocytosis / Q000502:physiology*; D011992:Endosomes / Q000378:metabolism; D020895:Enterocytes / Q000166:cytology / Q000378:metabolism; D066246:ErbB Receptors / Q000378:metabolism*; D015723:Gene Library; D006367:HeLa Cells; D006801:Humans; D007668:Kidney / Q000166:cytology; D008247:Lysosomes / Q000378:metabolism; D046911:Macromolecular Substances; D008565:Membrane Proteins / Q000378:metabolism; D021381:Protein Transport / Q000502:physiology; D020798:Two-Hybrid System Techniques; D033921:Vesicular Transport Proteins
chemical_list: D002352:Carrier Proteins; D046911:Macromolecular Substances; D008565:Membrane Proteins; D033921:Vesicular Transport Proteins; C429554:enterophilin-1; D066246:ErbB Receptors