title: The Deubiquitinase USP47 Stabilizes MAPK by Counteracting the Function of the N-end Rule ligase POE/UBR4 in Drosophila.
abstract: RAS-induced MAPK signaling is a central driver of the cell proliferation apparatus. Disruption of this pathway is widely observed in cancer and other pathologies. Consequently, considerable effort has been devoted to understanding the mechanistic aspects of RAS-MAPK signal transmission and regulation. While much information has been garnered on the steps leading up to the activation and inactivation of core pathway components, comparatively little is known on the mechanisms controlling their expression and turnover. We recently identified several factors that dictate Drosophila MAPK levels. Here, we describe the function of one of these, the deubiquitinase (DUB) USP47. We found that USP47 acts post-translationally to counteract a proteasome-mediated event that reduces MAPK half-life and thereby dampens signaling output. Using an RNAi-based genetic interaction screening strategy, we identified UBC6, POE/UBR4, and UFD4, respectively, as E2 and E3 enzymes that oppose USP47 activity. Further characterization of POE-associated factors uncovered KCMF1 as another key component modulating MAPK levels. Together, these results identify a novel protein degradation module that governs MAPK levels. Given the role of UBR4 as an N-recognin ubiquitin ligase, our findings suggest that RAS-MAPK signaling in Drosophila is controlled by the N-end rule pathway and that USP47 counteracts its activity.
authors.affiliation: Institute for Research in Immunology and Cancer, Laboratory of Intracellular Signaling, Université de Montréal, Montreal, Quebec, Canada.
authors.forename: Dariel
authors.identifier: 0000-0001-6987-5487
authors.initials: D
authors.lastname: Ashton-Beaucage
authors.affiliation: Institute for Research in Immunology and Cancer, Laboratory of Intracellular Signaling, Université de Montréal, Montreal, Quebec, Canada.
authors.forename: Caroline
authors.initials: C
authors.lastname: Lemieux
authors.affiliation: Institute for Research in Immunology and Cancer, Laboratory of Intracellular Signaling, Université de Montréal, Montreal, Quebec, Canada.
authors.forename: Christian M
authors.initials: CM
authors.lastname: Udell
authors.affiliation: Institute for Research in Immunology and Cancer, Laboratory of Intracellular Signaling, Université de Montréal, Montreal, Quebec, Canada.
authors.forename: Malha
authors.initials: M
authors.lastname: Sahmi
authors.affiliation: Institute for Research in Immunology and Cancer, Laboratory of Intracellular Signaling, Université de Montréal, Montreal, Quebec, Canada.
authors.forename: Samuel
authors.initials: S
authors.lastname: Rochette
authors.affiliation: Institute for Research in Immunology and Cancer, Laboratory of Intracellular Signaling, Université de Montréal, Montreal, Quebec, Canada.|Département de pathologie et de biologie cellulaire, Université de Montréal, Montreal, Quebec, Canada.
authors.forename: Marc
authors.initials: M
authors.lastname: Therrien
mesh_terms: D000818:Animals; D030801:Animals, Genetically Modified; D002148:Calmodulin-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D002460:Cell Line; D029721:Drosophila Proteins / Q000235:genetics / Q000378:metabolism*; D004331:Drosophila melanogaster / Q000166:cytology / Q000235:genetics / Q000378:metabolism*; D048049:Extracellular Signal-Regulated MAP Kinases / Q000235:genetics / Q000378:metabolism*; D007168:IMP Dehydrogenase / Q000235:genetics / Q000378:metabolism; D015151:Immunoblotting; D020935:MAP Kinase Signaling System / Q000235:genetics; D008954:Models, Biological; D009154:Mutation; D055550:Protein Stability; D034622:RNA Interference; D020133:Reverse Transcriptase Polymerase Chain Reaction; D044767:Ubiquitin-Protein Ligases / Q000235:genetics / Q000378:metabolism; D064570:Ubiquitin-Specific Proteases / Q000235:genetics / Q000378:metabolism*; D054875:Ubiquitination; D014921:Wings, Animal / Q000378:metabolism
chemical_list: D002148:Calmodulin-Binding Proteins; D029721:Drosophila Proteins; D007168:IMP Dehydrogenase; C000609465:ras protein, Drosophila; D044767:Ubiquitin-Protein Ligases; C115917:poe protein, Drosophila; D048049:Extracellular Signal-Regulated MAP Kinases; C086795:rl protein, Drosophila; C000603177:USP47 protein, Drosophila; D064570:Ubiquitin-Specific Proteases