Copper Transporter ATP7A Research Articles

Elesclomol alleviates Menkes pathology and mortality by escorting Cu to cuproenzymes in mice.

Loss-of-function mutations in the copper (Cu) transporter ATP7A cause Menkes disease. Menkes is an infantile, fatal, hereditary copper-deficiency disorder that is characterized by progressive neurological injury culminating in death, typically by 3 years of age. Severe copper deficiency leads to multiple pathologies, including impaired energy generation caused by cytochrome c oxidase dysfunction in the mitochondria. Here we report that the small molecule elesclomol escorted copper to the mitochondria and increased cytochrome c oxidase levels in the brain. Through this mechanism, elesclomol prevented detrimental neurodegenerative changes and improved the survival of the mottled-brindled mouse-a murine model of severe Menkes disease. Thus, elesclomol holds promise for the treatment of Menkes and associated disorders of hereditary copper deficiency.

Elesclomol rescues Menkes disease mice

Biomedicine Menkes disease results from loss-of-function mutations in the P-type copper-transporting adenosine triphosphatase ATP7A. Children diagnosed with Menkes present with connective tissue abnormalities and neurodegenerative changes that result in death caused by severe copper deficiency, typically before 3 years of age. In the brain, lack of copper impairs cytochrome c oxidase (complex IV) in the electron transport chain, which leads to progressive neurological injury in Menkes patients. No treatment exists for Menkes disease because of the difficulty in supplying the brain with copper using traditional hydrophilic copper complexes such as copper histidine. Guthrie et al. developed a treatment involving the drug elesclomol that successfully alleviated disease symptoms in a mouse model of Menkes disease (see the Perspective by Lutsenko). Science , this issue p. [620][1]; see also p. [584][2] [1]: /lookup/doi/10.1126/science.aaz8899 [2]: /lookup/doi/10.1126/science.abb6662

Copper induce zebrafish retinal developmental defects via triggering stresses and apoptosis

BackgroundThe disorder of copper homeostasis is linked with disease and developmental defects, and excess copper_nanoparticles (CuNPs) and ion (Cu2+) will induce developmental malformation and disease in organisms. However, little knowledge is available regarding its potential regulation mechanisms, and little study links excess copper with retinal developmental malformation and disease.MethodsEmbryos were stressed with copper (CuNPs and Cu2+), and cell proliferation and apoptosis assays, reactive oxygen species (ROS) and endoplasmic reticulum (ER) signaling detections, and genetic mutants cox17−/− and atp7a−/− application, were used to evaluate copper induced retinal developmental malformation and the underlying genetic and biological regulating mechanisms.ResultsCopper reduced retinal cells and down-regulated expression of retinal genes, damaged the structures of ER and mitochondria in retinal cells, up-regulated unfold protein responses (UPR) and ROS, and increased apoptosis in copper-stressed retinal cells. The copper induced retinal defects could be significantly neutralized by ROS scavengers reduced Glutathione (GSH) & N-acetylcysteine (NAC) and ER stress inhibitor 4- phenylbutyric acid (PBA). Blocking the transportation of copper to mitochondria, or to trans-Golgi network and to be exported into plasma, by deleting gene cox17 or atp7a, could alleviate retinal developmental defects in embryos under copper stresses.ConclusionsThis is probably the first report to reveal that copper nanoparticles and ions induce retinal developmental defects via upregulating UPR and ROS, leading to apoptosis in zebrafish embryonic retinal cells. Integrated function of copper transporter (Cox17 and Atp7a) is necessary for copper induced retinal defects.Graphical abstract

The expression of copper transporters associated with the ototoxicity induced by platinum-based chemotherapeutic agents

BackgroundAntitumor agents based on platinum have gained a well-established place in the treatment of several forms of cancer. Their efficiency is hampered by serious toxic effects against healthy tissues as well. Ototoxicity is a serious side effect leading to hearing impairment and represents an important issue affecting the patients’ quality of life. The currently used platinum chemotherapeutics exert different toxicity towards cochlear cells. The aim of our study was to answer some questions regarding the differential uptake and cellular pharmacodynamics of Cisplatin (CDDP), Carboplatin (CBDCA) and Oxaliplatin (L-OHP) in the HEI-OC1 cochlear cell line. MethodsWe studied the expression of copper transporters CTR1, ATP7A and ATP7B which are presumably involved in the uptake, cellular transport and efflux of platinum compounds by immunofluorescence microscopy and flow-cytometry. The cellular uptake of the compounds was evaluated through the determination of intracellular platinum concentration by atomic absorption spectroscopy. The effects of the treatment of HEI-OC1 cells with platinum compounds were also evaluated: cytotoxicity with the Cell Titer Blue viability test, formation of reactive oxygen species with 2′,7’ –dichlorofluorescein diacetate, genotoxicity with the comet assay and apoptosis with the cleaved PARP ELISA test. ResultsCTR1, ATP7A and ATP7B were all expressed by HEI-OC1 cells. The treatment with the platinum compounds led to a modulation of their expression, manifested in a differential platinum uptake. Treatment with Cisplatin led to the highest intracellular concentration of platinum compared to Oxaliplatin and Carboplatin at the same dose. Treatment with CuSO4 reduced platinum uptake of all the compounds, significantly in the case of Cisplatin and Carboplatin. CDDP was the most cytotoxic against HEI-OC1 cells, with an IC50 = 65.79 μM, compared to 611.7 μM for L-OHP and 882.9 μM for CBDCA, at the same molar concentration. The production of ROS was the most intense after CDDP, followed by L-OHP and CBDCA. In the comet assay, at the 100 μM concentration, L-OHP and CBDCA induced DNA adducts while CDDP induced adducts as well as DNA strand breaks. CBDCA and L-OHP lead to a significant increase of cleaved PARP at 24h (p < 0.001), suggesting an important apoptotic process induced by these compounds at the used concentrations. ConclusionsThe results obtained in the current study suggest that the modulation of copper transporters locally may represent a new strategy against platinum drugs ototoxicity.

Single-cell tracking demonstrates copper chaperone Atox1 to be required for breast cancer cell migration

Copper ions are needed for several hallmarks of cancer. However, the involved pathways, mechanisms, and copper-binding proteins are mostly unknown. We recently found that cytoplasmic Antioxidant 1 copper chaperone (Atox1), which is up-regulated in breast cancer, is localized at the lamellipodia edges of aggressive breast cancer cells. To reveal molecular insights into a putative role in cell migration, we here investigated breast cancer cell (MDA-MB-231) migration by video microscopy as a function of Atox1. Tracking of hundreds of individual cells (per condition) over a 9-h time series revealed that cell migration velocity and directionality are significantly reduced upon Atox1 silencing in the cells. Because silencing of the copper transporter ATP7A also reduced cell migration, these proteins appear to be on the same pathway, suggesting that their well-known copper transport activity is involved. In-cell proximity ligation assays demonstrated that Atox1, ATP7A, and the proenzyme of lysyl oxidase (LOX; copper-loaded via ATP7A) are all in close proximity and that LOX activity is reduced upon Atox1 silencing in the cells. Since LOX is an established player in cancer cell migration, our results imply that Atox1 mediates breast cancer cell migration via coordinated copper transport in the ATP7A-LOX axis. Because individual cell migration is an early step in breast cancer metastasis, Atox1 levels in tumor cells may be a predictive measure of metastasis potential and serve as a biomarker for copper depletion therapy.

Association of the canine ATP7A and ATP7B with hepatic copper accumulation in Dobermann dogs.

BackgroundHepatic copper accumulation causes chronic hepatitis in dogs. Mutations in the copper transporters ATP7A and ATP7B were, respectively, associated with attenuation and enhancement of hepatic copper concentrations in Labrador Retrievers. There is a predisposition of Dobermanns to hepatitis with increased hepatic copper concentrations.ObjectivesTo investigate whether the ATP7A:c.980C>T and ATP7B:c.4358G>A mutations identified in Labrador Retrievers were associated with hepatic copper concentrations in Dobermanns.AnimalsDobermanns from the Netherlands (n = 122) and the United States (n = 78).MethodsIn this retrospective study, mutations in ATP7A and ATP7B were investigated as risk factors for hepatic copper accumulation in Dobermanns. Liver biopsies of 200 Dobermanns were evaluated by histochemical copper staining, quantitative copper measurement, or both modalities. ATP7A and ATP7B genotypes were obtained by Kompetitive Allele Specific PCR. A linear regression model was used to investigate an association between genotype and hepatic copper concentrations.ResultsThe ATP7A:c.980C>T was identified in both Dutch (2 heterozygous individuals) and American Dobermanns. In the American cohort, the minor allele frequency of the mutation was low (.081) and a possible effect on hepatic copper concentrations could not be established from this data set. A significant association of the ATP7B:c.4358G>A variant with increased hepatic copper concentrations in Dobermanns was observed.Conclusions and Clinical ImportanceThe ATP7B:c.4358G>A variant could be a contributor to hepatic copper accumulation underlying the risk of development of copper‐associated hepatitis in breeds other than the Labrador Retriever.

ATP7A delivers copper to the lysyl oxidase family of enzymes and promotes tumorigenesis and metastasis

Lysyl oxidase (LOX) and LOX-like (LOXL) proteins are copper-dependent metalloenzymes with well-documented roles in tumor metastasis and fibrotic diseases. The mechanism by which copper is delivered to these enzymes is poorly understood. In this study, we demonstrate that the copper transporter ATP7A is necessary for the activity of LOX and LOXL enzymes. Silencing of ATP7A inhibited LOX activity in the 4T1 mammary carcinoma cell line, resulting in a loss of LOX-dependent mechanisms of metastasis, including the phosphorylation of focal adhesion kinase and myeloid cell recruitment to the lungs, in an orthotopic mouse model of breast cancer. ATP7A silencing was also found to attenuate LOX activity and metastasis of Lewis lung carcinoma cells in mice. Meta-analysis of breast cancer patients found that high ATP7A expression was significantly correlated with reduced survival. Taken together, these results identify ATP7A as a therapeutic target for blocking LOX- and LOXL-dependent malignancies.

Impaired copper transport in schizophrenia results in a copper-deficient brain state: A new side to the dysbindin story

Objectives: Several schizophrenia brain regions exhibit decreased dysbindin. Dysbindin modulates copper transport crucial for myelination, monoamine metabolism and cellular homeostasis. Schizophrenia patients (SZP) exhibit increased plasma copper, while copper-decreasing agents produce schizophrenia-like behavioural and pathological abnormalities. Therefore, we sought to determine dysbindin and copper transporter protein expression and copper content in SZP.Methods: We studied the copper-rich substantia nigra (SN) using Western blot and inductively-coupled plasma mass spectrometry. We characterised specific protein domains of copper transporters ATP7A, CTR1, ATP7B and dysbindin isoforms 1 A and 1B/C in SZP (n = 15) and matched controls (n = 11), and SN copper content in SZP (n = 14) and matched controls (n = 11). As a preliminary investigation, we compared medicated (ON; n = 11) versus unmedicated SZP (OFF; n = 4).Results: SZP exhibited increased C terminus, but not N terminus, ATP7A. SZP expressed less transmembrane CTR1 and dysbindin 1B/C than controls. ON exhibited increased C terminus ATP7A protein versus controls. OFF exhibited less N terminus ATP7A protein than controls and ON, suggesting medication-induced rescue of the ATP7A N terminus. SZP exhibited less SN copper content than controls.Conclusions: These results provide the first evidence of disrupted copper transport in schizophrenia SN that appears to result in a copper-deficient state. Furthermore, copper homeostasis may be modulated by specific dysbindin isoforms and antipsychotic treatment.

Copper transporter ATP7A interacts with IQGAP1, a Rac1 binding scaffolding protein: role in PDGF-induced VSMC migration and vascular remodeling.

Vascular smooth muscle cell (VSMC) migration contributes to neointimal formation after vascular injury. We previously demonstrated that copper (Cu) transporter ATP7A is involved in platelet-derived growth factor (PDGF)-induced VSMC migration in a Cu- and Rac1-dependent manner. The underlying mechanism is still unknown. Here we show that ATP7A interacts with IQGAP1, a Rac1 and receptor tyrosine kinase binding scaffolding proteins, which mediates PDGF-induced VSMC migration and vascular remodeling. In cultured rat aortic SMCs, PDGF stimulation rapidly promoted ATP7A association with IQGAP1 and Rac1 and their translocation to the lipid rafts and leading edge. Cotransfection assay revealed that ATP7A directly bound to NH2-terminal domain of IQGAP1. Functionally, either ATP7A or IQGAP1 depletion using siRNA significantly inhibited PDGF-induced VSMC migration without additive effects, suggesting that IQGAP1 and ATP7A are in the same axis to promote migration. Furthermore, IQGAP1 siRNA blocked PDGF-induced ATP7A association with Rac1 as well as its translocation to leading edge, while PDGF-induced IQGAP1 translocation was not affected by ATP7A siRNA or Cu chelator. Overexpression of mutant IQGAP1 lacking a Rac1 binding site prevented PDGF-induced translocation of Rac1, but not ATP7A, to the leading edge, thereby inhibiting lamellipodia formation and VSMC migration. In vivo, ATP7A colocalized with IQGAP1 at neointimal VSMCs in a mice wire injury model, while neointimal formation and extracellular matrix deposition induced by vascular injury were inhibited in ATP7A mutant mice with reduced Cu transporter function. In summary, IQGAP1 functions as ATP7A and Rac1 binding scaffolding protein to organize PDGF-dependent ATP7A translocation to the lamellipodial leading edge, thereby promoting VSMC migration and vascular remodeling.

Copper regulates rest-activity cycles through the locus coeruleus-norepinephrine system.

The unusually high demand for metals in the brain along with insufficient understanding of how their dysregulation contributes to neurological diseases motivates the study of how inorganic chemistry influences neural circuitry. We now report that the transition metal copper is essential for regulating rest–activity cycles and arousal. Copper imaging and gene expression analysis in zebrafish identifies the locus coeruleus-norepinephrine (LC-NE) system, a vertebrate-specific neuromodulatory circuit critical for regulating sleep, arousal, attention, memory and emotion, as a copper-enriched unit with high levels of copper transporters CTR1 and ATP7A and the copper enzyme dopamine beta-hydroxylase (DBH) that produces NE. Copper deficiency induced by genetic disruption of ATP7A, which loads copper into DBH, lowers NE levels and hinders LC function as manifested by disruption in rest–activity modulation. Moreover, LC dysfunction caused by copper deficiency from ATP7A disruption can be rescued by restoring synaptic levels of NE, establishing a molecular CTR1-ATP7A-DBH-NE axis for copper-dependent LC function.

Interaction between the AAA ATPase p97/VCP and a concealed UBX domain in the copper transporter ATP7A is associated with motor neuron degeneration

The copper-transporting ATPase ATP7A contains eight transmembrane domains and is required for normal human copper homeostasis. Mutations in the ATP7A gene may lead to infantile-onset cerebral degeneration (Menkes disease); occipital horn syndrome (OHS), a related but much milder illness; or an adult-onset isolated distal motor neuropathy. The ATP7A missense mutation T994I is located in the sixth transmembrane domain of ATP7A, represents one of the variants associated with the latter phenotype, and is associated with an abnormal interaction with p97/valosin-containing protein (VCP), a hexameric AAA ATPase (ATPase associated with diverse cellular activities) with multiple biological functions. In this study, we further characterized this interaction and discovered a concealed UBX domain in the third lumenal loop of ATP7A, between its fifth and sixth transmembrane domains. We show that the T994I substitution results in conformational exposure of the UBX domain, which then binds the N-terminal domain of p97/VCP. We also show that this abnormal interaction occurs at or near the cell plasma membrane. The UBX domain has a conserved hydrophobic FP (Phe-Pro) motif, and substitution with di-alanine abrogated the interaction and restored the proper intracellular localization of ATP7A in the trans-Golgi network. Using protein MS, we identified potential coordinating components of the ATP7AT994I-p97 complex, including NSFL1 cofactor (NSF1C or p47) that may be relevant to the pathophysiology and clinical effects associated with ATP7AT994I Our study represents the first report of p97/VCP binding to a UBX domain that is not normally exposed, resulting in an aberrant protein-protein interaction leading to motor neuron degeneration.

Akt2 (Protein Kinase B Beta) Stabilizes ATP7A, a Copper Transporter for Extracellular Superoxide Dismutase, in Vascular Smooth Muscle: Novel Mechanism to Limit Endothelial Dysfunction in Type 2 Diabetes Mellitus.

Copper transporter ATP7A (copper-transporting/ATPase) is required for full activation of SOD3 (extracellular superoxide dismutase), which is secreted from vascular smooth muscle cells (VSMCs) and anchors to endothelial cell surface to preserve endothelial function by scavenging extracellular superoxide. We reported that ATP7A protein expression and SOD3 activity are decreased in insulin-deficient type 1 diabetes mellitus vessels, thereby, inducing superoxide-mediated endothelial dysfunction, which are rescued by insulin treatment. However, it is unknown regarding the mechanism by which insulin increases ATP7A expression in VSMCs and whether ATP7A downregulation is observed in T2DM (type2 diabetes mellitus) mice and human in which insulin-Akt (protein kinase B) pathway is selectively impaired. Here we show that ATP7A protein is markedly downregulated in vessels isolated from T2DM patients, as well as those from high-fat diet-induced or db/db T2DM mice. Akt2 (protein kinase B beta) activated by insulin promotes ATP7A stabilization via preventing ubiquitination/degradation as well as translocation to plasma membrane in VSMCs, which contributes to activation of SOD3 that protects against T2DM-induced endothelial dysfunction. Downregulation of ATP7A in T2DM vessels is restored by constitutive active Akt or PTP1B-/- (protein-tyrosine phosphatase 1B-deficient) T2DM mice, which enhance insulin-Akt signaling. Immunoprecipitation, in vitro kinase assay, and mass spectrometry analysis reveal that insulin stimulates Akt2 binding to ATP7A to induce phosphorylation at Ser1424/1463/1466. Furthermore, SOD3 activity is reduced in Akt2-/- vessels or VSMCs, which is rescued by ATP7A overexpression. Akt2 plays a critical role in ATP7A protein stabilization and translocation to plasma membrane in VSMCs, which contributes to full activation of vascular SOD3 that protects against endothelial dysfunction in T2DM.

Effect of Structural Modifications to Glyoxal-bis(thiosemicarbazonato)copper(II) Complexes on Cellular Copper Uptake, Copper-Mediated ATP7A Trafficking, and P-Glycoprotein Mediated Efflux.

Bis(thiosemicarbazonato)copper(II) complexes are of interest as potential therapeutics for cancer and neurodegenerative diseases as well as imaging agents for positron emission tomography (PET). The cellular uptake of six bis(thiosemcarbazonato)copper(II)complexes derived from glyoxal, with different functional groups Cu(gtsx) where x = different functional groups, was investigated in SKOV-3, HEK293, and HEK293 P-gp cell lines. Treatment of the cells with the copper complexes increased intracellular copper and increased levels of p-ERK due to activation of the Ras-Raf-MEK-ERK pathway. Treatment of SKOV-3 cells with low concentrations (μM) of two of the copper complexes led to trafficking of the endogenous copper transporter ATP7A from the Golgi network to the cell membrane. Experiments in HEK293 and HEK293-P-gp cells suggest that Cu(gtsm) and Cu(gtse) are substrates for the P-gp efflux protein but the complex with a pyrrolidine functional group, Cu(gtspyr), is not. A PET experiment in mice showed that [64Cu]Cu(gtspyr) has reasonable brain uptake but high liver uptake.

A CRISPR screen identifies a pathway required for paraquat-induced cell death.

Paraquat, a herbicide linked to Parkinson’s disease, generates reactive oxygen species (ROS) to cause cell death. Because the source of paraquat-induced ROS production remains unknown, we conducted a CRISPR-based positive selection screen to identify metabolic genes essential for paraquat-induced cell death. Our screen uncovered three genes, POR (cytochrome P450 oxidoreductase), ATP7A (copper transporter), and SLC45A4 (sucrose transporter), required for paraquat–induced cell death. Furthermore, our results revealed POR as the source of paraquat-induced ROS production. Thus, our study highlights the use of functional genomic screens to uncover redox biology.

Host and Pathogen Copper-Transporting P-Type ATPases Function Antagonistically during Salmonella Infection

Copper is an essential yet potentially toxic trace element that is required by all aerobic organisms. A key regulator of copper homeostasis in mammalian cells is the copper-transporting P-type ATPase ATP7A, which mediates copper transport from the cytoplasm into the secretory pathway, as well as copper export across the plasma membrane. Previous studies have shown that ATP7A-dependent copper transport is required for killing phagocytosed Escherichia coli in a cultured macrophage cell line. In this investigation, we expanded on these studies by generating Atp7aLysMcre mice, in which the Atp7a gene was specifically deleted in cells of the myeloid lineage, including macrophages. Primary macrophages isolated from Atp7aLysMcre mice exhibit decreased copper transport into phagosomal compartments and a reduced ability to kill Salmonella enterica serovar Typhimurium compared to that of macrophages isolated from wild-type mice. The Atp7aLysMcre mice were also more susceptible to systemic infection by S Typhimurium than wild-type mice. Deletion of the S Typhimurium copper exporters, CopA and GolT, was found to decrease infection in wild-type mice but not in the Atp7aLysMcre mice. These studies suggest that ATP7A-dependent copper transport into the phagosome mediates host defense against S Typhimurium, which is counteracted by copper export from the bacteria via CopA and GolT. These findings reveal unique and opposing functions for copper transporters of the host and pathogen during infection.

Abstract 5806: Exploring the role of copper-dependent lysyl oxidase (LOX) in metastatic growth

Abstract Copper is an enzymatic cofactor required for cellular respiration, iron homeostasis, melanogenesis, neurotransmitter biosynthesis, and connective tissue formation. Copper deficiency in humans is evidenced by Menkes disease, a lethal pediatric disorder caused by mutations in the ATP7A copper transporter. ATP7A, a ubiquitously expressed copper transporting P-type ATPase, transports copper from the cytoplasm into the Golgi complex to supply copper to secreted copper-dependent enzymes. Additionally, ATP7A functions to export copper from cells to avoid copper toxicity. Aberrant copper metabolism is characteristic of many cancers. Copper-chelating drugs such as tetrathiomolybdate or penicillamine have been shown to have anti-angiogenic and anti-neoplastic activity. Copper also appears to be rate limiting for mitogenic signaling pathways necessary for tumor growth such as RAS/RAF/MAPK signaling. The requirement for lysyl oxidase (LOX) proteins in tumor metastasis is further illustrative of copper’s role in cancer biology. Copper-dependent LOX proteins catalyze the oxidation of lysine residues within collagen and/or elastin, stabilizing crosslinks between these fibrous proteins during the formation or remodeling of the extracellular matrix. While research implicates a direct role for LOX proteins in many types of cancer, the use of copper chelators or other strategies to starve LOX enzymes of copper as a therapeutic strategy has been largely overlooked. LOX family members acquire copper in the secretory pathway via the ATP7A protein. Consistent with this requirement, LOX activity is reduced in cultured fibroblasts derived from patients with Menkes disease that lack functional ATP7A protein. As the cancer promoting properties of LOX enzymes have been shown to require catalytic activity, we hypothesize that blocking the ATP7A protein could be a powerful approach to inhibit LOX-dependent pro-tumorigenic and pro-metastatic pathways. In this study, we have found that genetic ablation of ATP7A using CRISPR/Cas9 inhibits the tumorigenic and metastatic potential of a multiple cancer cell lines in vivo. These findings could be attributed to a variety of copper functions or those of copper-dependent enzymes, such as LOX. In this study, we investigate the role of copper-dependent enzymes, such as LOX, using in vitro and in vivo methods. While others have implicated lysyl oxidase secreted by cancer cells in tumorigenesis and metastasis, the contributions of lysyl oxidase at the metastatic site have not been evaluated. Here, I describe a novel conditional mouse model that we use to explore this question. Citation Format: Kimberly Jasmer-McDonald, Michael Petris, Vinit Shanbhag, Nikita Gudekar. Exploring the role of copper-dependent lysyl oxidase (LOX) in metastatic growth [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 5806. doi:10.1158/1538-7445.AM2017-5806

The interactome of the copper transporter ATP7A belongs to a network of neurodevelopmental and neurodegeneration factors.

Genetic and environmental factors, such as metals, interact to determine neurological traits. We reasoned that interactomes of molecules handling metals in neurons should include novel metal homeostasis pathways. We focused on copper and its transporter ATP7A because ATP7A null mutations cause neurodegeneration. We performed ATP7A immunoaffinity chromatography and identified 541 proteins co-isolating with ATP7A. The ATP7A interactome concentrated gene products implicated in neurodegeneration and neurodevelopmental disorders, including subunits of the Golgi-localized conserved oligomeric Golgi (COG) complex. COG null cells possess altered content and subcellular localization of ATP7A and CTR1 (SLC31A1), the transporter required for copper uptake, as well as decreased total cellular copper, and impaired copper-dependent metabolic responses. Changes in the expression of ATP7A and COG subunits in Drosophila neurons altered synapse development in larvae and copper-induced mortality of adult flies. We conclude that the ATP7A interactome encompasses a novel COG-dependent mechanism to specify neuronal development and survival.

Dynamics of the metal binding domains and regulation of the human copper transporters ATP7B and ATP7A.

Copper transporters ATP7A and ATP7B regulate copper levels in the human cells and deliver copper to the biosynthetic pathways. ATP7A and ATP7B belong to the P-type ATPases and share much of the domain architecture and the mechanism of ATP hydrolysis with the other, well-studied, enzymes of this type. A unique structural feature of the copper ATPases is the chain of six cytosolic metal-binding domains (MBDs), which are believed to be involved in copper-dependent regulation of the activity and intracellular localization of these enzymes. Although the structures of all the MBDs have been solved, the mechanism of copper-dependent regulation of ATP7B and ATP7A, the roles of individual MBDs, and the relationship between the regulatory and catalytic copper binding are still unknown. We describe the structure and dynamics of the MBDs, review the current knowledge about their functional roles and propose a mechanism of regulation of ATP7B by copper-dependent changes in the dynamics and conformation of the MBD chain. Transient interactions between the MBDs, rather than transitions between distinct static conformations are likely to form the structural basis of regulation of the ATP-dependent copper transporters in human cells. © 2016 IUBMB Life, 69(4):226-235, 2017.

SA100. Abnormalities in Copper Transporters ATP7A and CTR1 in Postmortem Substantia Nigra in Schizophrenia

SA100. Abnormalities in Copper Transporters ATP7A and CTR1 in Postmortem Substantia Nigra in Schizophrenia

Copper therapy reduces intravascular hemolysis and derepresses ferroportin in mice with mosaic mutation (Atp7amo-ms): An implication for copper-mediated regulation of the Slc40a1 gene expression

Mosaic mutant mice displaying functional dysfunction of Atp7a copper transporter (the Menkes ATPase) are an established animal model of Menkes disease and constitute a convenient tool for investigating connections between copper and iron metabolisms. This model allows to explore changes in iron metabolism in suckling mutant mice suffering from systemic copper deficiency as well as in young and adult ones undergone copper therapy, which reduces lethal effect of the Atp7a gene mutation. Our recent study demonstrated that 14-day-old mosaic mutant males display blood cell abnormalities associated with intravascular hemolysis, and show disturbances in the functioning of the hepcidin-ferroportin regulatory axis, which controls systemic iron homeostasis. We thus aimed to check whether copper supplementation recovers mutants from hemolytic insult and rebalance systemic iron regulation. Copper supplementation of 14-day-old mosaic mutants resulted in the reestablishment of hematological status, attenuation of hepicidin and concomitant induction of the iron exporter ferroportin/Slc40a1 expression in the liver, down-regulated in untreated mutants. Interestingly, treatment of wild-type males with copper, induced hepcidin-independent up-regulation of ferroportin protein level in hepatic macrophages in both young and adult (6-month-old) animals. Stimulatory effect of copper on ferroportin mRNA and protein levels was confirmed in bone marrow-derived macrophages isolated from both wild-type and mosaic mutant males. Our study indicates that copper is an important player in the regulation of the Slc40a1 gene expression.