1
|
Fieten H, Gill Y, Martin AJ, Concilli M, Dirksen K, van Steenbeek FG, Spee B, van den Ingh TSGAM, Martens ECCP, Festa P, Chesi G, van de Sluis B, Houwen RHJH, Watson AL, Aulchenko YS, Hodgkinson VL, Zhu S, Petris MJ, Polishchuk RS, Leegwater PAJ, Rothuizen J. The Menkes and Wilson disease genes counteract in copper toxicosis in Labrador retrievers: a new canine model for copper-metabolism disorders. Dis Model Mech 2016; 9:25-38. [PMID: 26747866 PMCID: PMC4728329 DOI: 10.1242/dmm.020263] [Citation(s) in RCA: 52] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
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. Summary: Labrador retrievers with hereditary copper toxicosis are a useful new model for copper-metabolism disorders.
Collapse
Affiliation(s)
- Hille Fieten
- Department of Clinical Sciences of Companion Animals, Faculty of Veterinary Medicine, Utrecht University, Yalelaan 104, 3584 CM Utrecht, The Netherlands
| | - Yadvinder Gill
- The WALTHAM Centre for Pet Nutrition, Waltham-on-the-Wolds, Melton Mowbray, Leicestershire, LE14 4RT, UK
| | - Alan J Martin
- The WALTHAM Centre for Pet Nutrition, Waltham-on-the-Wolds, Melton Mowbray, Leicestershire, LE14 4RT, UK
| | - Mafalda Concilli
- Telethon Institute of Genetics and Medicine (TIGEM), Via Campi Flegrei 34, 80078 Pozzuoli (NA), Italy
| | - Karen Dirksen
- Department of Clinical Sciences of Companion Animals, Faculty of Veterinary Medicine, Utrecht University, Yalelaan 104, 3584 CM Utrecht, The Netherlands
| | - Frank G van Steenbeek
- Department of Clinical Sciences of Companion Animals, Faculty of Veterinary Medicine, Utrecht University, Yalelaan 104, 3584 CM Utrecht, The Netherlands
| | - Bart Spee
- Department of Clinical Sciences of Companion Animals, Faculty of Veterinary Medicine, Utrecht University, Yalelaan 104, 3584 CM Utrecht, The Netherlands
| | | | - Ellen C C P Martens
- Department of Clinical Sciences of Companion Animals, Faculty of Veterinary Medicine, Utrecht University, Yalelaan 104, 3584 CM Utrecht, The Netherlands
| | - Paola Festa
- Telethon Institute of Genetics and Medicine (TIGEM), Via Campi Flegrei 34, 80078 Pozzuoli (NA), Italy
| | - Giancarlo Chesi
- Telethon Institute of Genetics and Medicine (TIGEM), Via Campi Flegrei 34, 80078 Pozzuoli (NA), Italy
| | - Bart van de Sluis
- Department of Pediatrics, Molecular Genetics Section, University of Groningen, University Medical Center, Antonius Deusinglaan 1, 9713 AV Groningen, The Netherlands
| | - Roderick H J H Houwen
- Department of Pediatric Gastroenterology, Wilhelmina Children's Hospital, University Medical Center, Lundlaan 6, 3584 EA Utrecht, The Netherlands
| | - Adrian L Watson
- The WALTHAM Centre for Pet Nutrition, Waltham-on-the-Wolds, Melton Mowbray, Leicestershire, LE14 4RT, UK
| | - Yurii S Aulchenko
- Novosibirsk State University, 630090 Novosibirsk, Russia Institute of Cytology and Genetics, 630090 Novosibirsk, Russia
| | - Victoria L Hodgkinson
- Department of Biochemistry, University of Missouri, Columbia, MO 65211, USA The Christopher S. Bond Life Science Center, University of Missouri, Columbia, MO 65211, USA
| | - Sha Zhu
- Department of Biochemistry, University of Missouri, Columbia, MO 65211, USA The Christopher S. Bond Life Science Center, University of Missouri, Columbia, MO 65211, USA
| | - Michael J Petris
- 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
| | - Roman S Polishchuk
- Telethon Institute of Genetics and Medicine (TIGEM), Via Campi Flegrei 34, 80078 Pozzuoli (NA), Italy
| | - Peter A J Leegwater
- Department of Clinical Sciences of Companion Animals, Faculty of Veterinary Medicine, Utrecht University, Yalelaan 104, 3584 CM Utrecht, The Netherlands
| | - Jan Rothuizen
- Department of Clinical Sciences of Companion Animals, Faculty of Veterinary Medicine, Utrecht University, Yalelaan 104, 3584 CM Utrecht, The Netherlands
| |
Collapse
|
2
|
Zhu S, Shanbhag V, Hodgkinson VL, Petris MJ. Multiple di-leucines in the ATP7A copper transporter are required for retrograde trafficking to the trans-Golgi network. Metallomics 2016; 8:993-1001. [PMID: 27337370 DOI: 10.1039/c6mt00093b] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
The ATP7A protein is a ubiquitous copper-transporting P-type ATPase that is mutated in the lethal pediatric disorder of copper metabolism, Menkes disease. The steady-state location of ATP7A is within the trans-Golgi network (TGN), where it delivers copper to copper-dependent enzymes within the secretory pathway. However, ATP7A constantly cycles between the TGN and the plasma membrane, and in the presence of high copper concentrations, the exocytic arm of this cycling pathway is enhanced to promote a steady-state distribution of ATP7A to post-Golgi vesicles and the plasma membrane. A single di-leucine endocytic motif within the cytosolic carboxy tail of ATP7A (1487LL) was previously shown to be essential for TGN localization by functioning in retrieval from the plasma membrane, however, the requirement of other di-leucine signals in this region has not been fully investigated. While there has been some success in identifying sequence elements within ATP7A required for trafficking and catalysis, progress has been hampered by the instability of the ATP7A cDNA in high-copy plasmids during replication in Escherichia coli. In this study, we find that the use of DNA synthesis to generate silent mutations across the majority of both mouse and human ATP7A open reading frames was sufficient to stabilize these genes in high-copy plasmids, thus permitting the generation of full-length expression constructs. Using the stabilized mouse Atp7a construct, we identify a second di-leucine motif in the carboxy tail of ATP7A (1459LL) as essential for steady-state localization in the TGN by functioning in endosome-to-TGN trafficking. Taken together, these findings demonstrate that multiple di-leucine signals are required for recycling ATP7A from the plasma membrane to the TGN and illustrate the utility of large-scale codon reassignment as a simple and effective approach to circumvent cDNA instability in high-copy plasmids.
Collapse
Affiliation(s)
- Sha Zhu
- Department of Biochemistry, University of Missouri, Columbia, MO 65211, USA
| | | | | | | |
Collapse
|
3
|
Hodgkinson VL, Zhu S, Wang Y, Ladomersky E, Nickelson K, Weisman GA, Lee J, Gitlin JD, Petris MJ. Autonomous requirements of the Menkes disease protein in the nervous system. Am J Physiol Cell Physiol 2015; 309:C660-8. [PMID: 26269458 DOI: 10.1152/ajpcell.00130.2015] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2015] [Accepted: 08/03/2015] [Indexed: 02/05/2023]
Abstract
Menkes disease is a fatal neurodegenerative disorder arising from a systemic copper deficiency caused by loss-of-function mutations in a ubiquitously expressed copper transporter, ATP7A. Although this disorder reveals an essential role for copper in the developing human nervous system, the role of ATP7A in the pathogenesis of signs and symptoms in affected patients, including severe mental retardation, ataxia, and excitotoxic seizures, remains unknown. To directly examine the role of ATP7A within the central nervous system, we generated Atp7a(Nes) mice, in which the Atp7a gene was specifically deleted within neural and glial cell precursors without impairing systemic copper homeostasis, and compared these mice with the mottled brindle (mo-br) mutant, a murine model of Menkes disease in which Atp7a is defective in all cells. Whereas mo-br mice displayed neurodegeneration, demyelination, and 100% mortality prior to weaning, the Atp7a(Nes) mice showed none of these phenotypes, exhibiting only mild sensorimotor deficits, increased anxiety, and susceptibility to NMDA-induced seizure. Our results indicate that the pathophysiology of severe neurological signs and symptoms in Menkes disease is the result of copper deficiency within the central nervous system secondary to impaired systemic copper homeostasis and does not arise from an intrinsic lack of ATP7A within the developing brain. Furthermore, the sensorimotor deficits, hypophagia, anxiety, and sensitivity to NMDA-induced seizure in the Atp7a(Nes) mice reveal unique autonomous requirements for ATP7A in the nervous system. Taken together, these data reveal essential roles for copper acquisition in the central nervous system in early development and suggest novel therapeutic approaches in affected patients.
Collapse
Affiliation(s)
- Victoria L Hodgkinson
- Department of Biochemistry, University of Missouri, Columbia, Missouri; Christopher S. Bond Life Science Center, University of Missouri, Columbia, Missouri
| | - Sha Zhu
- Department of Biochemistry, University of Missouri, Columbia, Missouri; Christopher S. Bond Life Science Center, University of Missouri, Columbia, Missouri
| | - Yanfang Wang
- Department of Nutrition and Exercise Physiology, University of Missouri, Columbia, Missouri; Christopher S. Bond Life Science Center, University of Missouri, Columbia, Missouri
| | - Erik Ladomersky
- Department of Biochemistry, University of Missouri, Columbia, Missouri; Christopher S. Bond Life Science Center, University of Missouri, Columbia, Missouri
| | - Karen Nickelson
- Department of Biochemistry, University of Missouri, Columbia, Missouri; Christopher S. Bond Life Science Center, University of Missouri, Columbia, Missouri
| | - Gary A Weisman
- Department of Biochemistry, University of Missouri, Columbia, Missouri; Christopher S. Bond Life Science Center, University of Missouri, Columbia, Missouri
| | - Jaekwon Lee
- Redox Biology Center, Department of Biochemistry, University of Nebraska, Lincoln, Nebraska; and
| | | | - Michael J Petris
- Department of Biochemistry, University of Missouri, Columbia, Missouri; Department of Nutrition and Exercise Physiology, University of Missouri, Columbia, Missouri; Christopher S. Bond Life Science Center, University of Missouri, Columbia, Missouri;
| |
Collapse
|
4
|
Hodgkinson VL, Dale JM, Garcia ML, Weisman GA, Lee J, Gitlin JD, Petris MJ. X-linked spinal muscular atrophy in mice caused by autonomous loss of ATP7A in the motor neuron. J Pathol 2015; 236:241-50. [PMID: 25639447 DOI: 10.1002/path.4511] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2014] [Revised: 01/23/2015] [Accepted: 01/27/2015] [Indexed: 11/07/2022]
Abstract
ATP7A is a copper-transporting P-type ATPase that is essential for cellular copper homeostasis. Loss-of-function mutations in the ATP7A gene result in Menkes disease, a fatal neurodegenerative disorder resulting in seizures, hypotonia and failure to thrive, due to systemic copper deficiency. Most recently, rare missense mutations in ATP7A that do not impact systemic copper homeostasis have been shown to cause X-linked spinal muscular atrophy type 3 (SMAX3), a distal hereditary motor neuropathy. An understanding of the mechanistic and pathophysiological basis of SMAX3 is currently lacking, in part because the disease-causing mutations have been shown to confer both loss- and gain-of-function properties to ATP7A, and because there is currently no animal model of the disease. In this study, the Atp7a gene was specifically deleted in the motor neurons of mice, resulting in a degenerative phenotype consistent with the clinical features in affected patients with SMAX3, including the progressive deterioration of gait, age-dependent muscle atrophy, denervation of neuromuscular junctions and a loss of motor neuron cell bodies. Taken together, these data reveal autonomous requirements for ATP7A that reveal essential roles for copper in the maintenance and function of the motor neuron, and suggest that SMAX3 is caused by a loss of ATP7A function that specifically impacts the spinal motor neuron.
Collapse
Affiliation(s)
- Victoria L Hodgkinson
- Department of Biochemistry, University of Missouri, Columbia, MO, USA.,Christopher S Bond Life Science Center, University of Missouri, Columbia, MO, USA
| | - Jeffery M Dale
- Department of Biological Sciences, University of Missouri, Columbia, MO, USA.,Christopher S Bond Life Science Center, University of Missouri, Columbia, MO, USA
| | - Michael L Garcia
- Department of Biological Sciences, University of Missouri, Columbia, MO, USA.,Christopher S Bond Life Science Center, University of Missouri, Columbia, MO, USA
| | - Gary A Weisman
- Department of Biochemistry, University of Missouri, Columbia, MO, USA.,Christopher S Bond Life Science Center, University of Missouri, Columbia, MO, USA
| | - Jaekwon Lee
- Redox Biology Center, University of Nebraska, Lincoln, NE, USA
| | | | - Michael J Petris
- Department of Biochemistry, University of Missouri, Columbia, MO, USA.,Department of Nutrition and Exercise Physiology, University of Missouri, Columbia, MO, USA.,Christopher S Bond Life Science Center, University of Missouri, Columbia, MO, USA
| |
Collapse
|