title: The Menkes and Wilson disease genes counteract in copper toxicosis in Labrador retrievers: a new canine model for copper-metabolism disorders.
abstract: The deleterious effects of a disrupted copper metabolism are illustrated by hereditary diseases caused by mutations in the genes coding for the copper transporters ATP7A and ATP7B. Menkes disease, involving ATP7A, is a fatal neurodegenerative disorder of copper deficiency. Mutations in ATP7B lead to Wilson disease, which is characterized by a predominantly hepatic copper accumulation. The low incidence and the phenotypic variability of human copper toxicosis hamper identification of causal genes or modifier genes involved in the disease pathogenesis. The Labrador retriever was recently characterized as a new canine model for copper toxicosis. Purebred dogs have reduced genetic variability, which facilitates identification of genes involved in complex heritable traits that might influence phenotype in both humans and dogs. We performed a genome-wide association study in 235 Labrador retrievers and identified two chromosome regions containing ATP7A and ATP7B that were associated with variation in hepatic copper levels. DNA sequence analysis identified missense mutations in each gene. The amino acid substitution ATP7B:p.Arg1453Gln was associated with copper accumulation, whereas the amino acid substitution ATP7A:p.Thr327Ile partly protected against copper accumulation. Confocal microscopy indicated that aberrant copper metabolism upon expression of the ATP7B variant occurred because of mis-localization of the protein in the endoplasmic reticulum. Dermal fibroblasts derived from ATP7A:p.Thr327Ile dogs showed copper accumulation and delayed excretion. We identified the Labrador retriever as the first natural, non-rodent model for ATP7B-associated copper toxicosis. Attenuation of copper accumulation by the ATP7A mutation sheds an interesting light on the interplay of copper transporters in body copper homeostasis and warrants a thorough investigation of ATP7A as a modifier gene in copper-metabolism disorders. The identification of two new functional variants in ATP7A and ATP7B contributes to the biological understanding of protein function, with relevance for future development of therapy.
authors.affiliation: Department of Clinical Sciences of Companion Animals, Faculty of Veterinary Medicine, Utrecht University, Yalelaan 104, 3584 CM Utrecht, The Netherlands h.fieten@uu.nl.
authors.forename: Hille
authors.initials: H
authors.lastname: Fieten
authors.affiliation: The WALTHAM Centre for Pet Nutrition, Waltham-on-the-Wolds, Melton Mowbray, Leicestershire, LE14 4RT, UK.
authors.forename: Yadvinder
authors.initials: Y
authors.lastname: Gill
authors.affiliation: The WALTHAM Centre for Pet Nutrition, Waltham-on-the-Wolds, Melton Mowbray, Leicestershire, LE14 4RT, UK.
authors.forename: Alan J
authors.initials: AJ
authors.lastname: Martin
authors.affiliation: Telethon Institute of Genetics and Medicine (TIGEM), Via Campi Flegrei 34, 80078 Pozzuoli (NA), Italy.
authors.forename: Mafalda
authors.initials: M
authors.lastname: Concilli
authors.affiliation: Department of Clinical Sciences of Companion Animals, Faculty of Veterinary Medicine, Utrecht University, Yalelaan 104, 3584 CM Utrecht, The Netherlands.
authors.forename: Karen
authors.initials: K
authors.lastname: Dirksen
authors.affiliation: Department of Clinical Sciences of Companion Animals, Faculty of Veterinary Medicine, Utrecht University, Yalelaan 104, 3584 CM Utrecht, The Netherlands.
authors.forename: Frank G
authors.initials: FG
authors.lastname: van Steenbeek
authors.affiliation: Department of Clinical Sciences of Companion Animals, Faculty of Veterinary Medicine, Utrecht University, Yalelaan 104, 3584 CM Utrecht, The Netherlands.
authors.forename: Bart
authors.initials: B
authors.lastname: Spee
authors.affiliation: TCCI Consultancy BV, Cicerolaan 1, 3584 AJ Utrecht, The Netherlands.
authors.forename: Ted S G A M
authors.initials: TS
authors.lastname: van den Ingh
authors.affiliation: Department of Clinical Sciences of Companion Animals, Faculty of Veterinary Medicine, Utrecht University, Yalelaan 104, 3584 CM Utrecht, The Netherlands.
authors.forename: Ellen C C P
authors.initials: EC
authors.lastname: Martens
authors.affiliation: Telethon Institute of Genetics and Medicine (TIGEM), Via Campi Flegrei 34, 80078 Pozzuoli (NA), Italy.
authors.forename: Paola
authors.initials: P
authors.lastname: Festa
authors.affiliation: Telethon Institute of Genetics and Medicine (TIGEM), Via Campi Flegrei 34, 80078 Pozzuoli (NA), Italy.
authors.forename: Giancarlo
authors.initials: G
authors.lastname: Chesi
authors.affiliation: Department of Pediatrics, Molecular Genetics Section, University of Groningen, University Medical Center, Antonius Deusinglaan 1, 9713 AV Groningen, The Netherlands.
authors.forename: Bart
authors.initials: B
authors.lastname: van de Sluis
authors.affiliation: Department of Pediatric Gastroenterology, Wilhelmina Children's Hospital, University Medical Center, Lundlaan 6, 3584 EA Utrecht, The Netherlands.
authors.forename: Roderick H J H
authors.initials: RH
authors.lastname: Houwen
authors.affiliation: The WALTHAM Centre for Pet Nutrition, Waltham-on-the-Wolds, Melton Mowbray, Leicestershire, LE14 4RT, UK.
authors.forename: Adrian L
authors.initials: AL
authors.lastname: Watson
authors.affiliation: Novosibirsk State University, 630090 Novosibirsk, Russia Institute of Cytology and Genetics, 630090 Novosibirsk, Russia.
authors.forename: Yurii S
authors.initials: YS
authors.lastname: Aulchenko
authors.affiliation: Department of Biochemistry, University of Missouri, Columbia, MO 65211, USA The Christopher S. Bond Life Science Center, University of Missouri, Columbia, MO 65211, USA.
authors.forename: Victoria L
authors.initials: VL
authors.lastname: Hodgkinson
authors.affiliation: Department of Biochemistry, University of Missouri, Columbia, MO 65211, USA The Christopher S. Bond Life Science Center, University of Missouri, Columbia, MO 65211, USA.
authors.forename: Sha
authors.initials: S
authors.lastname: Zhu
authors.affiliation: Department of Biochemistry, University of Missouri, Columbia, MO 65211, USA The Christopher S. Bond Life Science Center, University of Missouri, Columbia, MO 65211, USA Nutrition and Exercise Physiology, University of Missouri, Columbia, MO 65211, USA.
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Petris
authors.affiliation: Telethon Institute of Genetics and Medicine (TIGEM), Via Campi Flegrei 34, 80078 Pozzuoli (NA), Italy.
authors.forename: Roman S
authors.initials: RS
authors.lastname: Polishchuk
authors.affiliation: Department of Clinical Sciences of Companion Animals, Faculty of Veterinary Medicine, Utrecht University, Yalelaan 104, 3584 CM Utrecht, The Netherlands.
authors.forename: Peter A J
authors.initials: PA
authors.lastname: Leegwater
authors.affiliation: Department of Clinical Sciences of Companion Animals, Faculty of Veterinary Medicine, Utrecht University, Yalelaan 104, 3584 CM Utrecht, The Netherlands.
authors.forename: Jan
authors.initials: J
authors.lastname: Rothuizen
mesh_terms: D000251:Adenosine Triphosphatases / Q000235:genetics*; D000595:Amino Acid Sequence; D000818:Animals; D027682:Cation Transport Proteins / Q000235:genetics*; D003300:Copper / Q000633:toxicity*; D000073840:Copper-Transporting ATPases; D004195:Disease Models, Animal; D004285:Dogs; D004721:Endoplasmic Reticulum / Q000378:metabolism; D005260:Female; D014644:Genetic Variation; D055106:Genome-Wide Association Study; D005838:Genotype; D056945:Hep G2 Cells; D006527:Hepatolenticular Degeneration / Q000235:genetics*; D006801:Humans; D008099:Liver / Q000378:metabolism; D008297:Male; D007706:Menkes Kinky Hair Syndrome / Q000235:genetics*; D008969:Molecular Sequence Data; D020125:Mutation, Missense; D010641:Phenotype; D017434:Protein Structure, Tertiary; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid
chemical_list: D027682:Cation Transport Proteins; D003300:Copper; D000251:Adenosine Triphosphatases; C081184:ATP7A protein, human; C000612464:ATP7B protein, human; D000073840:Copper-Transporting ATPases
keywords: ATP7A; ATP7B; Dog; Liver