title: Mitochondrial cereblon functions as a Lon-type protease.
abstract: Lon protease plays a major role in the protein quality control system in mammalian cell mitochondria. It is present in the mitochondrial matrix, and degrades oxidized and misfolded proteins, thereby protecting the cell from various extracellular stresses, including oxidative stress. The intellectual disability-associated and thalidomide-binding protein cereblon (CRBN) contains a large, highly conserved Lon domain. However, whether CRBN has Lon protease-like function remains unknown. Here, we determined if CRBN has a protective function against oxidative stress, similar to Lon protease. We report that CRBN partially distributes in mitochondria, suggesting it has a mitochondrial function. To specify the mitochondrial role of CRBN, we mitochondrially expressed CRBN in human neuroblastoma SH-SY5Y cells. The resulting stable SH-SY5Y cell line showed no apparent effect on the mitochondrial functions of fusion, fission, and membrane potential. However, mitochondrially expressed CRBN exhibited protease activity, and was induced by oxidative stress. In addition, stably expressed cells exhibited suppressed neuronal cell death induced by hydrogen peroxide. These results suggest that CRBN functions specifically as a Lon-type protease in mitochondria.
authors.affiliation: Faculty of Science and Engineering, Waseda University, TWIns, 2-2 Wakamatsu, Shinjuku, Tokyo 162-8480, Japan.
authors.forename: Kosuke
authors.initials: K
authors.lastname: Kataoka
authors.affiliation: Faculty of Science and Engineering, Waseda University, TWIns, 2-2 Wakamatsu, Shinjuku, Tokyo 162-8480, Japan.
authors.forename: China
authors.initials: C
authors.lastname: Nakamura
authors.affiliation: Faculty of Science and Engineering, Waseda University, TWIns, 2-2 Wakamatsu, Shinjuku, Tokyo 162-8480, Japan.|Research Organization for Nano &Life Innovation, Waseda University, Japan.
authors.forename: Toru
authors.initials: T
authors.lastname: Asahi
authors.affiliation: Faculty of Science and Engineering, Waseda University, TWIns, 2-2 Wakamatsu, Shinjuku, Tokyo 162-8480, Japan.|Research Organization for Nano &Life Innovation, Waseda University, Japan.
authors.forename: Naoya
authors.initials: N
authors.lastname: Sawamura
mesh_terms: D048868:Adaptor Proteins, Signal Transducing; D016923:Cell Death; D002460:Cell Line; D006801:Humans; D053078:Membrane Potential, Mitochondrial; D008928:Mitochondria / Q000378:metabolism*; D018384:Oxidative Stress; D010447:Peptide Hydrolases / Q000378:metabolism*; D049070:Protease La / Q000378:metabolism*; D021382:Protein Sorting Signals; D044767:Ubiquitin-Protein Ligases
chemical_list: D048868:Adaptor Proteins, Signal Transducing; C502543:CRBN protein, human; D021382:Protein Sorting Signals; D044767:Ubiquitin-Protein Ligases; D010447:Peptide Hydrolases; D049070:Protease La