title: AMBRA1 interplay with cullin E3 ubiquitin ligases regulates autophagy dynamics.
abstract: Autophagy maintains cellular homeostasis by degrading harmful or unnecessary intracellular components. How the autophagy response is induced rapidly and transiently remains largely unknown. We report that the E3 ubiquitin ligases Cullin-5 and Cullin-4 regulate the onset and termination of autophagy, respectively, by dynamically interacting with AMBRA1, a regulator of autophagy. Under normal conditions, Cullin-4 binding to AMBRA1 limits its protein abundance. Autophagy stimuli promote AMBRA1 stabilization by causing ULK1-dependent Cullin-4 release. Notably, Cullin-4/AMBRA1 dissociation is transient, and the re-established interaction triggers AMBRA1 degradation, terminating the autophagy response. Moreover, Cullin-4 inhibits the interaction between AMBRA1 and another Cullin E3 ligase. Indeed, upon Cullin-4 dissociation, AMBRA1 binds and inhibits Cullin-5, thus promoting the accumulation of the mTOR inhibitor DEPTOR. Through DEPTOR stabilization, AMBRA1 establishes a feedback loop that ensures the rapid onset of autophagy by enhancing mTOR inactivation. Our findings show that Cullin-mediated degradation of autophagy regulators temporally controls the autophagy response.
authors.affiliation: National Institute for Infectious Diseases "L. Spallanzani" IRCCS, 00149 Rome, Italy; Department of Biology, University of Rome "Tor Vergata," 00173 Rome, Italy.
authors.forename: Manuela
authors.initials: M
authors.lastname: Antonioli
authors.affiliation: National Institute for Infectious Diseases "L. Spallanzani" IRCCS, 00149 Rome, Italy; Department of Biology, University of Rome "Tor Vergata," 00173 Rome, Italy.
authors.forename: Federica
authors.initials: F
authors.lastname: Albiero
authors.affiliation: Dulbecco Telethon Institute at the Department of Biology, University of Rome "Tor Vergata," 00173 Rome, Italy; Laboratory of Molecular Neuroembryology, IRCCS Fondazione Santa Lucia, 00143 Rome, Italy.
authors.forename: Francesca
authors.initials: F
authors.lastname: Nazio
authors.affiliation: National Institute for Infectious Diseases "L. Spallanzani" IRCCS, 00149 Rome, Italy.
authors.forename: Tiziana
authors.initials: T
authors.lastname: Vescovo
authors.affiliation: National Institute for Infectious Diseases "L. Spallanzani" IRCCS, 00149 Rome, Italy.
authors.forename: Ariel Basulto
authors.initials: AB
authors.lastname: Perdomo
authors.affiliation: National Institute for Infectious Diseases "L. Spallanzani" IRCCS, 00149 Rome, Italy; Department of Biology, University of Rome "Tor Vergata," 00173 Rome, Italy.
authors.forename: Marco
authors.initials: M
authors.lastname: Corazzari
authors.affiliation: National Institute for Infectious Diseases "L. Spallanzani" IRCCS, 00149 Rome, Italy; Department of Biology, University of Rome "Tor Vergata," 00173 Rome, Italy.
authors.forename: Claudia
authors.initials: C
authors.lastname: Marsella
authors.affiliation: National Institute for Infectious Diseases "L. Spallanzani" IRCCS, 00149 Rome, Italy.
authors.forename: Pierluca
authors.initials: P
authors.lastname: Piselli
authors.affiliation: Department of Dermatology, University Freiburg Medical Center, 79104 Freiburg, Germany; ZBSA Center for Biological Systems Analysis, University of Freiburg, 79104 Freiburg, Germany.
authors.forename: Christine
authors.initials: C
authors.lastname: Gretzmeier
authors.affiliation: Department of Dermatology, University Freiburg Medical Center, 79104 Freiburg, Germany; ZBSA Center for Biological Systems Analysis, University of Freiburg, 79104 Freiburg, Germany.
authors.forename: Jörn
authors.initials: J
authors.lastname: Dengjel
authors.affiliation: Dulbecco Telethon Institute at the Department of Biology, University of Rome "Tor Vergata," 00173 Rome, Italy; Laboratory of Molecular Neuroembryology, IRCCS Fondazione Santa Lucia, 00143 Rome, Italy; Unit of Cell Stress and Survival, Danish Cancer Society Research Center, Strandboulevarden 49, 2100 Copenhagen Ø, Denmark.
authors.forename: Francesco
authors.initials: F
authors.lastname: Cecconi
authors.affiliation: National Institute for Infectious Diseases "L. Spallanzani" IRCCS, 00149 Rome, Italy; Department of Biology, University of Rome "Tor Vergata," 00173 Rome, Italy. Electronic address: mauro.piacentini@uniroma2.it.
authors.forename: Mauro
authors.initials: M
authors.lastname: Piacentini
authors.affiliation: National Institute for Infectious Diseases "L. Spallanzani" IRCCS, 00149 Rome, Italy; Department of Biological and Environmental Sciences and Technologies (DiSTeBA), University of Salento, Lecce 73100, Italy. Electronic address: gianmaria.fimia@inmi.it.
authors.forename: Gian Maria
authors.initials: GM
authors.lastname: Fimia
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000378:metabolism*; D000818:Animals; D001343:Autophagy; D016923:Cell Death; D044842:Cullin Proteins / Q000378:metabolism*; D005347:Fibroblasts / Q000378:metabolism; D018507:Gene Expression Regulation, Developmental; D057809:HEK293 Cells; D006801:Humans; D051379:Mice; D058570:TOR Serine-Threonine Kinases / Q000378:metabolism; D025801:Ubiquitin / Q000378:metabolism; D044767:Ubiquitin-Protein Ligases / Q000378:metabolism*
chemical_list: C553334:AMBRA1 protein, human; D048868:Adaptor Proteins, Signal Transducing; C521754:Ambra1 protein, mouse; C114234:CUL4A protein, human; C496871:CUL5 protein, human; C491940:Cul4a protein, mouse; D044842:Cullin Proteins; D025801:Ubiquitin; C531145:cullin5 protein, mouse; D044767:Ubiquitin-Protein Ligases; C546842:MTOR protein, human; C546843:mTOR protein, mouse; D058570:TOR Serine-Threonine Kinases