title: Notch signaling from the endosome requires a conserved dileucine motif.
abstract: Notch signaling is reliant on γ-secretase-mediated processing, although the subcellular location where γ-secretase cleaves Notch to initiate signaling remains unresolved. Accumulating evidence demonstrates that Notch signaling is modulated by endocytosis and endosomal transport. In this study, we investigated the relationship between Notch transport itinerary and signaling capacity. In doing so, we discovered a highly conserved dileucine sorting signal encoded within the cytoplasmic tail that directs Notch to the limiting membrane of the lysosome for signaling. Mutating the dileucine motif led to receptor accumulation in cation-dependent mannose-phosphate receptor-positive tubular early endosomes and a reduction in Notch signaling capacity. Moreover, truncated receptor forms that mimic activated Notch were readily cleaved by γ-secretase within the endosome; however, the cleavage product was proteasome-sensitive and failed to contribute to robust signaling. Collectively these results indicate that Notch signaling from the lysosome limiting membrane is conserved and that receptor targeting to this compartment is an active process. Moreover, the data support a model in which Notch signaling in mammalian systems is initiated from either the plasma membrane or lysosome, but not the early endosome.
authors.affiliation: Department of Genetics, Cell Biology, and Development, University of Minnesota, Minneapolis, MN 55455, USA.
authors.forename: Li
authors.initials: L
authors.lastname: Zheng
authors.forename: Cosmo A
authors.initials: CA
authors.lastname: Saunders
authors.forename: Erika B
authors.initials: EB
authors.lastname: Sorensen
authors.forename: Nicole C
authors.initials: NC
authors.lastname: Waxmonsky
authors.forename: Sean D
authors.initials: SD
authors.lastname: Conner
mesh_terms: D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D053829:Amyloid Precursor Protein Secretases / Q000378:metabolism; D000818:Animals; D017124:Conserved Sequence; D004151:Dipeptides / Q000737:chemistry / Q000235:genetics; D011992:Endosomes / Q000378:metabolism*; D006367:HeLa Cells; D006801:Humans; D008247:Lysosomes / Q000378:metabolism; D051379:Mice; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D021382:Protein Sorting Signals; D021381:Protein Transport; D051881:Receptor, Notch1 / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction; D020696:rab5 GTP-Binding Proteins / Q000378:metabolism
chemical_list: D004151:Dipeptides; C497761:NOTCH1 protein, human; D021382:Protein Sorting Signals; D051881:Receptor, Notch1; C038361:leucylleucine; D053829:Amyloid Precursor Protein Secretases; D020696:rab5 GTP-Binding Proteins