title: Lethal giant discs, a novel C2-domain protein, restricts notch activation during endocytosis.
abstract: The Notch signaling pathway plays a central role in animal growth and patterning, and its deregulation leads to many human diseases, including cancer. Mutations in the tumor suppressor lethal giant discs (lgd) induce strong Notch activation and hyperplastic overgrowth of Drosophila imaginal discs. However, the gene that encodes Lgd and its function in the Notch pathway have not yet been identified. Here, we report that Lgd is a novel, conserved C2-domain protein that regulates Notch receptor trafficking. Notch accumulates on early endosomes in lgd mutant cells and signals in a ligand-independent manner. This phenotype is similar to that seen when cells lose endosomal-pathway components such as Erupted and Vps25. Interestingly, Notch activation in lgd mutant cells requires the early endosomal component Hrs, indicating that Hrs is epistatic to Lgd. These data suggest that Lgd affects Notch trafficking between the actions of Hrs and the late endosomal component Vps25. Taken together, our data identify Lgd as a novel tumor-suppressor protein that regulates Notch signaling by targeting Notch for degradation or recycling.
authors.affiliation: Department of Biochemistry and Molecular Biology, University of Texas M.D. Anderson Cancer Center, Houston, Texas 77030, USA.
authors.forename: Jennifer L
authors.initials: JL
authors.lastname: Childress
authors.forename: Melih
authors.initials: M
authors.lastname: Acar
authors.forename: Chunyao
authors.initials: C
authors.lastname: Tao
authors.forename: Georg
authors.initials: G
authors.lastname: Halder
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D015153:Blotting, Western; D017931:DNA Primers; D004330:Drosophila / Q000235:genetics* / Q000502:physiology; D029721:Drosophila Proteins / Q000235:genetics* / Q000378:metabolism*; D004705:Endocytosis / Q000235:genetics* / Q000502:physiology; D056827:Endosomal Sorting Complexes Required for Transport; D007150:Immunohistochemistry; D008969:Molecular Sequence Data; D010750:Phosphoproteins / Q000378:metabolism; D051880:Receptors, Notch / Q000378:metabolism*; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D015398:Signal Transduction / Q000235:genetics*; D025521:Tumor Suppressor Proteins / Q000235:genetics* / Q000378:metabolism
chemical_list: D017931:DNA Primers; D029721:Drosophila Proteins; D056827:Endosomal Sorting Complexes Required for Transport; C497759:N protein, Drosophila; D010750:Phosphoproteins; D051880:Receptors, Notch; D025521:Tumor Suppressor Proteins; C096164:hepatocyte growth factor-regulated tyrosine kinase substrate; C515862:l(2)gd1 protein, Drosophila