1. Enterophilin-1, a New Partner of Sorting Nexin 1, Decreases Cell Surface Epidermal Growth Factor Receptor
- Author
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Ronald Barbaras, Véronique Pons, Michel Nauze, Françoise Hullin-Matsuda, Ama Gassama-Diagne, Christine Pérès, Hugues Chap, Xavier Collet, and Bertrand Perret
- Subjects
Macromolecular Substances ,Endosome ,Cellular differentiation ,education ,Cell ,Vesicular Transport Proteins ,Endosomes ,Biology ,Kidney ,Biochemistry ,Two-Hybrid System Techniques ,otorhinolaryngologic diseases ,medicine ,Animals ,Humans ,ERBB3 ,Epidermal growth factor receptor ,Molecular Biology ,Gene Library ,Cell growth ,Membrane Proteins ,Cell Differentiation ,Cell Biology ,Molecular biology ,Endocytosis ,Cell biology ,ErbB Receptors ,Protein Transport ,Enterocytes ,medicine.anatomical_structure ,COS Cells ,biology.protein ,Enterocyte differentiation ,Caco-2 Cells ,Carrier Proteins ,Lysosomes ,A431 cells ,HeLa Cells - 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.
- Published
- 2003