title: Heterodimerization of endothelin-converting enzyme-1 isoforms regulates the subcellular distribution of this metalloprotease.
abstract: Endothelin-converting enzyme (ECE) is a membrane metalloprotease that generates endothelin from its direct precursor big endothelin. Four isoforms of ECE-1 are produced from a single gene through the use of alternate promoters. These isoforms share the same extracellular catalytic domain and contain unique cytosolic tails, which results in their specific subcellular targeting. We investigated the distribution of ECE-1 isoforms in transfected AtT-20 neuroendocrine cells. Whereas ECE-1a and 1c were present at the plasma membrane, ECE-1b and ECE-1d were retained inside the cells. We found that both intracellular isoforms were concentrated in the endosomal system: ECE-1d in recycling endosomes, and ECE-1b in late endosomes/multivesicular bodies. Leucine-based motifs were involved in the intracellular retention of these isoforms, and the targeting of ECE-1b to the degradation pathway required an additional signal in the N terminus. The concentration of ECE-1 isoforms in the endosomal system suggested new functions for these enzymes. Potential novel functions include redistribution of other isoforms through direct interaction. We have showed that ECE-1 isoforms could heterodimerize, and that in such heterodimers the ECE-1b targeting signal was dominant. Interaction of a plasma membrane isoform with ECE-1b resulted in its intracellular localization and decreased its extracellular activity. These data demonstrated that the targeting signals specific for ECE-1b constitute a regulatory domain per se that could modulate the localization and the activity of other isoforms.
authors.affiliation: INSERM U 36 Collège de France Paris, 75005 Paris, France. laurent.muller@college-de-france.fr
authors.forename: Laurent
authors.initials: L
authors.lastname: Muller
authors.forename: Alain
authors.initials: A
authors.lastname: Barret
authors.forename: Eric
authors.initials: E
authors.lastname: Etienne
authors.forename: Rina
authors.initials: R
authors.lastname: Meidan
authors.forename: Olivier
authors.initials: O
authors.lastname: Valdenaire
authors.forename: Pierre
authors.initials: P
authors.lastname: Corvol
authors.forename: Claude
authors.initials: C
authors.lastname: Tougard
mesh_terms: D000111:Acetylcysteine / Q000031:analogs & derivatives* / Q000494:pharmacology; D000595:Amino Acid Sequence; D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D016282:Aspartic Acid Endopeptidases / Q000235:genetics / Q000378:metabolism*; D002460:Cell Line / Q000187:drug effects; D019281:Dimerization; D034281:Dynamins / Q000235:genetics / Q000378:metabolism; D011992:Endosomes / Q000378:metabolism / Q000648:ultrastructure; D000072396:Endothelin-Converting Enzymes; D004791:Enzyme Inhibitors / Q000494:pharmacology; D007527:Isoenzymes / Q000235:genetics / Q000378:metabolism*; D018942:Macrolides; D008666:Metalloendopeptidases / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D010902:Pituitary Gland / Q000166:cytology; D017434:Protein Structure, Tertiary; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism
chemical_list: D000900:Anti-Bacterial Agents; D004791:Enzyme Inhibitors; D007527:Isoenzymes; D018942:Macrolides; D011993:Recombinant Fusion Proteins; C057620:bafilomycin A; C067713:lactacystin; D016282:Aspartic Acid Endopeptidases; D008666:Metalloendopeptidases; C000606925:Ece1 protein, mouse; D000072396:Endothelin-Converting Enzymes; D034281:Dynamins; D000111:Acetylcysteine