title: Copper(II) ions affect the gating dynamics of the 20S proteasome: a molecular and in cell study.
abstract: Due to their altered metabolism cancer cells are more sensitive to proteasome inhibition or changes of copper levels than normal cells. Thus, the development of copper complexes endowed with proteasome inhibition features has emerged as a promising anticancer strategy. However, limited information is available about the exact mechanism by which copper inhibits proteasome. Here we show that Cu(II) ions simultaneously inhibit the three peptidase activities of isolated 20S proteasomes with potencies (IC50) in the micromolar range. Cu(II) ions, in cell-free conditions, neither catalyze red-ox reactions nor disrupt the assembly of the 20S proteasome but, rather, promote conformational changes associated to impaired channel gating. Notably, HeLa cells grown in a Cu(II)-supplemented medium exhibit decreased proteasome activity. This effect, however, was attenuated in the presence of an antioxidant. Our results suggest that if, on one hand, Cu(II)-inhibited 20S activities may be associated to conformational changes that favor the closed state of the core particle, on the other hand the complex effect induced by Cu(II) ions in cancer cells is the result of several concurring events including ROS-mediated proteasome flooding, and disassembly of the 26S proteasome into its 20S and 19S components.
authors.affiliation: Istituto di Biostrutture e Bioimmagini - CNR Sede di Catania, Via P. Gaifami, 9- 95126 Catania, Italy.
authors.forename: Anna Maria
authors.initials: AM
authors.lastname: Santoro
authors.affiliation: Istituto di Biostrutture e Bioimmagini - CNR Sede di Catania, Via P. Gaifami, 9- 95126 Catania, Italy.|Fondazione RiMed, Via Bandiera 11, 90133, Palermo, Italy.
authors.forename: Irene
authors.initials: I
authors.lastname: Monaco
authors.affiliation: Istituto di Biostrutture e Bioimmagini - CNR Sede di Catania, Via P. Gaifami, 9- 95126 Catania, Italy.
authors.forename: Francesco
authors.initials: F
authors.lastname: Attanasio
authors.affiliation: Istituto di Biostrutture e Bioimmagini - CNR Sede di Catania, Via P. Gaifami, 9- 95126 Catania, Italy.
authors.forename: Valeria
authors.initials: V
authors.lastname: Lanza
authors.affiliation: Istituto di Biostrutture e Bioimmagini - CNR Sede di Catania, Via P. Gaifami, 9- 95126 Catania, Italy.
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Pappalardo
authors.affiliation: Istituto di Biostrutture e Bioimmagini - CNR Sede di Catania, Via P. Gaifami, 9- 95126 Catania, Italy.
authors.forename: Marianna Flora
authors.initials: MF
authors.lastname: Tomasello
authors.affiliation: Dipartimento di Scienze Chimiche, Università di Catania, Viale Andrea Doria 6, 95125 Catania, Italy.
authors.forename: Alessandra
authors.initials: A
authors.lastname: Cunsolo
authors.affiliation: Istituto di Biostrutture e Bioimmagini - CNR Sede di Catania, Via P. Gaifami, 9- 95126 Catania, Italy.|Dipartimento di Scienze Chimiche, Università di Catania, Viale Andrea Doria 6, 95125 Catania, Italy.
authors.forename: Enrico
authors.initials: E
authors.lastname: Rizzarelli
authors.affiliation: IRCCS-Istituto di Ricerche Farmacologiche "Mario Negri", Via Giuseppe La Masa 19, 20156, Milano, Italy.
authors.forename: Ada
authors.initials: A
authors.lastname: De Luigi
authors.affiliation: IRCCS-Istituto di Ricerche Farmacologiche "Mario Negri", Via Giuseppe La Masa 19, 20156, Milano, Italy.
authors.forename: Mario
authors.initials: M
authors.lastname: Salmona
authors.affiliation: Istituto di Biostrutture e Bioimmagini - CNR Sede di Catania, Via P. Gaifami, 9- 95126 Catania, Italy.
authors.forename: Danilo
authors.initials: D
authors.lastname: Milardi
mesh_terms: D003300:Copper / Q000494:pharmacology*; D006367:HeLa Cells; D006801:Humans; D020128:Inhibitory Concentration 50; D015640:Ion Channel Gating / Q000187:drug effects*; D007477:Ions; D009154:Mutation / Q000235:genetics; D046988:Proteasome Endopeptidase Complex / Q000378:metabolism*; D061988:Proteasome Inhibitors / Q000494:pharmacology; D017382:Reactive Oxygen Species / Q000378:metabolism; D013050:Spectrometry, Fluorescence; D014364:Tryptophan / Q000378:metabolism; D015032:Zinc / Q000494:pharmacology
chemical_list: D007477:Ions; D061988:Proteasome Inhibitors; D017382:Reactive Oxygen Species; D003300:Copper; D014364:Tryptophan; D046988:Proteasome Endopeptidase Complex; C061553:ATP dependent 26S protease; D015032:Zinc