title: Cathepsin Protease Controls Copper and Cisplatin Accumulation via Cleavage of the Ctr1 Metal-binding Ectodomain.
abstract: Copper is an essential metal ion for embryonic development, iron acquisition, cardiac function, neuropeptide biogenesis, and other critical physiological processes. Ctr1 is a high affinity Cu(+) transporter on the plasma membrane and endosomes that exists as a full-length protein and a truncated form of Ctr1 lacking the methionine- and histidine-rich metal-binding ectodomain, and it exhibits reduced Cu(+) transport activity. Here, we identify the cathepsin L/B endolysosomal proteases functioning in a direct and rate-limiting step in the Ctr1 ectodomain cleavage. Cells and mice lacking cathepsin L accumulate full-length Ctr1 and hyper-accumulate copper. As Ctr1 also transports the chemotherapeutic drug cisplatin via direct binding to the ectodomain, we demonstrate that the combination of cisplatin with a cathepsin L/B inhibitor enhances cisplatin uptake and cell killing. These studies identify a new processing event and the key protease that cleaves the Ctr1 metal-binding ectodomain, which functions to regulate cellular Cu(+) and cisplatin acquisition.
authors.affiliation: Department of Pharmacology and Cancer Biology, Duke University School of Medicine, Durham, North Carolina 27710. Electronic address: helena.ohrvik@imbim.uu.se.
authors.forename: Helena
authors.initials: H
authors.lastname: Öhrvik
authors.affiliation: Department of Pharmacology and Cancer Biology, Duke University School of Medicine, Durham, North Carolina 27710.
authors.forename: Brandon
authors.initials: B
authors.lastname: Logeman
authors.affiliation: Department of Biochemistry and Molecular and Structural Biology, Jozef Stefan Institute, SI-1000 Ljubljana, Slovenia; Faculty of Chemistry and Chemical Technology, University of Ljubljana, SI-1000 Ljubljana, Slovenia.
authors.forename: Boris
authors.initials: B
authors.lastname: Turk
authors.affiliation: Institute of Molecular Medicine and Cell Research, Medical Faculty, Freiburg 79104 Germany; BIOSS Centre for Biological Signalling Studies, University of Freiburg, Freiburg 79104 Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Reinheckel
authors.affiliation: Department of Pharmacology and Cancer Biology, Duke University School of Medicine, Durham, North Carolina 27710; Department of Biochemistry, Duke University School of Medicine, Durham, North Carolina 27710; Department of Molecular Genetics and Microbiology, Duke University School of Medicine, Durham, North Carolina 27710. Electronic address: dennis.thiele@duke.edu.
authors.forename: Dennis J
authors.initials: DJ
authors.lastname: Thiele
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002403:Cathepsins / Q000378:metabolism*; D027682:Cation Transport Proteins / Q000378:metabolism*; D002460:Cell Line; D002945:Cisplatin / Q000378:metabolism*; D003300:Copper / Q000378:metabolism*; D000079923:Copper Transporter 1; D006801:Humans; D051379:Mice; D018345:Mice, Knockout; D059748:Proteolysis; D017386:Sequence Homology, Amino Acid
chemical_list: D027682:Cation Transport Proteins; D000079923:Copper Transporter 1; C490077:Slc31a1 protein, mouse; D003300:Copper; D002403:Cathepsins; D002945:Cisplatin
keywords: anti-cancer drug; cathepsin; cisplatin; copper transport; cysteine protease; intracellular processing; metal homeostasis; protein processing