The copper chaperone for superoxide dismutase

Cross talk between SOD1 and the mitochondrial UPR in cancer and neurodegeneration

The mitochondrial unfolded protein response (UPR^mt) is rapidly gaining attention. While the CHOP (ATF4/5) axis of the UPR^mt was the first to be described, other axes have subsequently been reported. Validation of this complex pathway in C. elegans has been extensively studied. However, validation of the UPR^mt in mouse models of disease known to implicate mitochondrial reprogramming or dysfunction, such as cancer and neurodegeneration, respectively, is only beginning to emerge. This review summarizes recent findings and highlights the major role of the superoxide dismutase SOD1 in the communication between the mitochondria and the nucleus in these settings. While SOD1 has mostly been studied in the context of familial amyotrophic lateral sclerosis (fALS), recent studies suggest that SOD1 may be a potentially important mediator of the UPR^mt and converge to emphasize an increasingly vital role of SOD1 as a therapeutic target in cancer.

Redox Mechanisms in Neurodegeneration: From Disease Outcomes to Therapeutic Opportunities

SIGNIFICANCE

Once considered to be mere by-products of metabolism, reactive oxygen, nitrogen and sulfur species are now recognized to play important roles in diverse cellular processes such as response to pathogens and regulation of cellular differentiation. It is becoming increasingly evident that redox imbalance can impact several signaling pathways. For instance, disturbances of redox regulation in the brain mediate neurodegeneration and alter normal cytoprotective responses to stress. Very often small disturbances in redox signaling processes, which are reversible, precede damage in neurodegeneration. Recent Advances: The identification of redox-regulated processes, such as regulation of biochemical pathways involved in the maintenance of redox homeostasis in the brain has provided deeper insights into mechanisms of neuroprotection and neurodegeneration. Recent studies have also identified several post-translational modifications involving reactive cysteine residues, such as nitrosylation and sulfhydration, which fine-tune redox regulation. Thus, the study of mechanisms via which cell death occurs in several neurodegenerative disorders, reveal several similarities and dissimilarities. Here, we review redox regulated events that are disrupted in neurodegenerative disorders and whose modulation affords therapeutic opportunities.

CRITICAL ISSUES

Although accumulating evidence suggests that redox imbalance plays a significant role in progression of several neurodegenerative diseases, precise understanding of redox regulated events is lacking. Probes and methodologies that can precisely detect and quantify in vivo levels of reactive oxygen, nitrogen and sulfur species are not available.

FUTURE DIRECTIONS

Due to the importance of redox control in physiologic processes, organisms have evolved multiple pathways to counteract redox imbalance and maintain homeostasis. Cells and tissues address stress by harnessing an array of both endogenous and exogenous redox active substances. Targeting these pathways can help mitigate symptoms associated with neurodegeneration and may provide avenues for novel therapeutics. Antioxid. Redox Signal. 30, 1450-1499.

Molecular recognition and maturation of SOD1 by its evolutionarily destabilised cognate chaperone hCCS

Superoxide dismutase-1 (SOD1) maturation comprises a string of posttranslational modifications which transform the nascent peptide into a stable and active enzyme. The successive folding, metal ion binding, and disulphide acquisition steps in this pathway can be catalysed through a direct interaction with the copper chaperone for SOD1 (CCS). This process confers enzymatic activity and reduces access to noncanonical, aggregation-prone states. Here, we present the functional mechanisms of human copper chaperone for SOD1 (hCCS)-catalysed SOD1 activation based on crystal structures of reaction precursors, intermediates, and products. Molecular recognition of immature SOD1 by hCCS is driven by several interface interactions, which provide an extended surface upon which SOD1 folds. Induced-fit complexation is reliant on the structural plasticity of the immature SOD1 disulphide sub-loop, a characteristic which contributes to misfolding and aggregation in neurodegenerative disease. Complexation specifically stabilises the SOD1 disulphide sub-loop, priming it and the active site for copper transfer, while delaying disulphide formation and complex dissociation. Critically, a single destabilising amino acid substitution within the hCCS interface reduces hCCS homodimer affinity, creating a pool of hCCS available to interact with immature SOD1. hCCS substrate specificity, segregation between solvent and biological membranes, and interaction transience are direct results of this substitution. In this way, hCCS-catalysed SOD1 maturation is finessed to minimise copper wastage and reduce production of potentially toxic SOD1 species.

Transcriptomics of Epichloë-Grass Symbioses in Host Vegetative and Reproductive Stages

Epichloë species are fungal symbionts (endophytes) of cool-season grasses that transmit vertically via inflorescence primordia (IP), ovaries (OV), and ultimately, embryos. Epichloë coenophiala, an endophyte of tall fescue (Schedonorus arundinaceus), provides multiple protective benefits to the grass. We conducted transcriptome analysis of the tall fescue-E. coenophiala symbiosis, comparing IP, OV, vegetative pseudostems (PS), and the lemma and palea (LP) (bracts) of the young floret. Transcriptomes of host OV and PS exhibited almost no significant differences attributable to endophyte presence or absence. Comparison of endophyte gene expression in different plant parts revealed numerous differentially expressed genes (DEGs). The 150 endophyte DEGs significantly higher in PS over OV included genes for alkaloid biosynthesis and sugar or amino acid transport. The 277 endophyte DEGs significantly higher in OV over PS included genes for protein chaperones (including most heat-shock proteins), trehalose synthesis complex, a bax inhibitor-1 protein homolog, the CLC chloride ion channel, catalase, and superoxide dismutase. Similar trends were apparent in the Brachypodium sylvaticum-Epichloë sylvatica symbiosis. Gene expression profiles in tall fescue IP and LP indicated that the endophyte transcriptome shift began early in host floral development. We discuss possible roles of the endophyte DEGs in colonization of reproductive grass tissues.

Blockage of SLC31A1-dependent copper absorption increases pancreatic cancer cell autophagy to resist cell death

Objectives

Clinical observations have demonstrated that copper levels elevate in several cancer types, and copper deprivation is shown to inhibit tumour angiogenesis and growth in both animal models and preclinical trials. However, the content of copper in pancreatic duct adenocarcinoma (PDAC) and whether it is a potential therapy target is still unknown.

Materials and Methods

The levels of copper in PDAC specimens were detected by ICP‐MS assays. Copper depletion in Panc‐1 or MiaPaCa‐2 cells was conducted via copper transporter 1 (SLC31A1) interference and copper chelator tetrathiomolybdate (TM) treatment. The effects of copper deprivation on cancer cells were evaluated by cell proliferation, migration, invasion, colony formation and cell apoptosis. The mechanism of copper deprivation‐caused cancer cell quiescence was resolved through mitochondrial dysfunction tests and autophagy studies. The tumour‐suppression experiments under the condition of copper block and/or autophagy inhibition were performed both in vitro and in xenografted mice.

Results

SLC31A1‐dependent copper levels are correlated with the malignant degree of pancreatic cancer. Blocking copper absorption could inhibit pancreatic cancer progression but did not increase cell death. We found that copper deprivation increased mitochondrial ROS level and decreased ATP level, which rendered cancer cells in a dormant state. Strikingly, copper deprivation caused an increase in autophagy to resist death of pancreatic cancer cells. Simultaneous treatment with TM and autophagy inhibitor CQ increased cell death of cancer cells in vitro and retarded cancer growth in vivo.

Conclusions

These findings reveal that copper deprivation‐caused cell dormancy and the increase in autophagy is a reason for the poor clinical outcome obtained from copper depletion therapies for cancers. Therefore, the combination of autophagy inhibition and copper depletion is potentially a novel strategy for the treatment of pancreatic cancer and other copper‐dependent malignant tumours.

The Role of Copper Homeostasis at the Host-Pathogen Axis: From Bacteria to Fungi

Copper is an essential trace element participating in many vital biological processes, however it becomes a toxic agent when in excess. Thus, precise and tight regulation of copper homeostasis processes, including transport, delivery, storage, detoxification, and efflux machineries, is important, ensuring that only the amount needed to sustain basic biological functions and simultaneously prevent copper toxicity in the cell is maintained. Numerous exciting studies have revealed that copper plays an indispensable role at the microbial pathogen-host axis for entities ranging from pathogenic bacteria to deadly fungal species. Analyses of copper homeostases in bacteria and fungi extensively demonstrate that copper is utilized by the host immune system as an anti-microbial agent. The expression of copper efflux and detoxification from microbial pathogens is induced to counteract the host's copper bombardment, which in turn disrupts these machineries, resulting in the attenuation of microbial survival in host tissue. We hereby review the latest work in copper homeostases in pathogenic bacteria and fungi and focus on the maintenance of a copper balance at the pathogen-host interaction axis.

The yeast copper chaperone for copper-zinc superoxide dismutase (CCS1) is a multifunctional chaperone promoting all levels of SOD1 maturation

Copper (Cu) is essential for the survival of aerobic organisms through its interaction with molecular oxygen (O₂). However, Cu's chemical properties also make it toxic, requiring specific cellular mechanisms for Cu uptake and handling, mediated by Cu chaperones. CCS1, the budding yeast (S. cerevisiae) Cu chaperone for Cu-zinc (Zn) superoxide dismutase (SOD1) activates by directly promoting both Cu delivery and disulfide formation in SOD1. The complete mechanistic details of this transaction along with recently proposed molecular chaperone-like functions for CCS1 remain undefined. Here, we present combined structural, spectroscopic, kinetic, and thermodynamic data that suggest a multifunctional chaperoning role(s) for CCS1 during SOD1 activation. We observed that CCS1 preferentially binds a completely immature form of SOD1 and that the SOD1·CCS1 interaction promotes high-affinity Zn(II) binding in SOD1. Conserved aromatic residues within the CCS1 C-terminal domain are integral in these processes. Previously, we have shown that CCS1 delivers Cu(I) to an entry site at the SOD1·CCS1 interface upon binding. We show here that Cu(I) is transferred from CCS1 to the entry site and then to the SOD1 active site by a thermodynamically driven affinity gradient. We also noted that efficient transfer from the entry site to the active site is entirely dependent upon the oxidation of the conserved intrasubunit disulfide bond in SOD1. Our results herein provide a solid foundation for proposing a complete molecular mechanism for CCS1 activity and reclassification as a first-of-its-kind "dual chaperone."

Genome-wide identification, characterization, and expression analysis of superoxide dismutase (SOD) genes in foxtail millet (Setaria italica L.)

Superoxide dismutases (SODs) play important roles in plant growth, development, and response to abiotic stresses. Despite SOD gene families have been identified in various plant species, little is known in foxtail millet (Setaria italica L.). In this study, a systematic analysis of SOD gene family was performed in foxtail millet and the expression pattern of SOD genes in response to abiotic stressors was analyzed at the whole-genomic level. Eight SOD genes were identified in foxtail millet, including 4 Cu/ZnSODs, 3 FeSODs, and 1 MnSOD. These SiSODs are unevenly distributed across 5 of the 9 chromosomes. Phylogenetic analysis showed that SOD proteins could be divided into two major categories (Cu/ZnSODs and Fe-MnSODs), containing seven subgroups, from foxtail millet and other plant species. SOD genes have conserved motif and exon/intron composition in the same subgroup among Setaria italica, Setaria viridis, and Oryza sativa. Additionally, many cis-elements that respond to different stressors were distributed at different densities in the promoters of 8 SiSODs. The expression patterns of SiSODs in different tissues and different abiotic stressors indicated that the SiSODs may play important roles in reactive oxygen species scavenging, caused by various stressors in foxtail millet. This study provides a foundation for the further cloning and functional verification of the SOD gene family response to environmental stimuli in foxtail millet.

Lack of superoxide dismutase in a rad51 mutant exacerbates genomic instability and oxidative stress-mediated cytotoxicity in Saccharomyces cerevisiae

A genetic analysis of synthetic lethal interactions in yeast revealed that the mutation of SOD1, encoding an antioxidant enzyme that scavenges superoxide anion radical, impaired the growth of a set of mutants defective in homologous recombination (HR) pathway. Hence, SOD1 inhibition has been proposed as a promising approach for the selective killing of HR-deficient cancer cells. However, we show that the deletion of RAD51 and SOD1 is not synthetic lethal but displays considerably slow growth and synergistic sensitivity to both reactive oxygen species (ROS)- and DNA double-strand break (DSB)-generating drugs in the budding yeast Saccharomyces cerevisiae. The function of Sod1 in regard to Rad51 is dependent on Ccs1, a copper chaperone for Sod1. Sod1 deficiency aggravates genomic instability in conjunction with the absence of Rad51 by inducing DSBs and an elevated mutation frequency. Inversely, lack of Rad51 causes a Sod1 deficiency-derived increase of intracellular ROS levels. Taken together, our results indicate that there is a significant and specific crosstalk between two major cellular damage response pathways, ROS signaling and DSB repair, for cell survival.

Unraveling the cause of white striping in broilers using metabolomics

White striping (WS) is a major problem affecting the broiler industry. Fillets affected by this myopathy present pathologies that compromise the quality of the meat, and most importantly, make the fillets more prone to rejection by the consumer. The exact etiology is still unknown, which is why a metabolomics analysis was performed on breast samples of broilers. The overall objective was to identify biological pathways involved in the pathogenesis of WS. The analysis was performed on a total of 51 muscle samples and distinction was made between normal (n = 19), moderately affected (n = 24) and severely affected (n = 8) breast fillets. Samples were analyzed using gas chromatographic mass spectral analysis and liquid chromatography quadrupole time-of-flight mass spectrometry. Data were subsequently standardized, normalized and analyzed using various multivariate statistical procedures. Metabolomics allowed for the identification of several pathways that were altered in white striped breast fillets. The tricarboxylic acid cycle exhibited opposing directionalities. This is described in literature as the backflux and enables the TCA cycle to produce high-energy phosphates through matrix-level phosphorylation and, therefore, produce energy under conditions of hypoxia. Mitochondrial fatty acid oxidation was limited due to disturbances in especially cis-5–14:1 carnitine (log2 FC of 2, P < 0.01). Because of this, accumulation of harmful fatty acids took place, especially long-chain ones, which damages cell structures. Conversion of arginine to citrulline increased presumably to produce nitric oxide, which enhances blood flow under conditions of hypoxia. Nitric oxide however also increases oxidative damage. Increases in taurine (log2 FC of 1.2, P < 0.05) suggests stabilization of the sarcolemma under hypoxic conditions. Lastly, organic osmolytes (sorbitol, taurine, and alanine) increased (P < 0.05) in severely affected birds; likely this disrupts cell volume maintenance. Based on the results of this study, hypoxia was the most likely cause/initiator of WS in broilers. We speculate that birds suffering from WS have a vascular support system in muscle that is borderline adequate to support growth, but triggers like activity results in local hypoxia that damages tissue.

Metal cofactors trafficking and assembly in the cell: a molecular view

Metal ions are essential cofactors required by the proteome of organisms from any kingdom of life to correctly exert their functions. Dedicated cellular import, transport and homeostasis systems assure that the needed metal ion is correctly delivered and inserted into the target proteins and avoid the presence of free metal ions in the cell, preventing oxidative damaging. Among metal ions, in eukaryotic organisms copper and iron are required by proteins involved in absolutely essential functions, such as respiration, oxidative stress protection, catalysis, gene expression regulation. Copper and iron binding proteins are localized in essentially all cellular compartments. Copper is physiologically present mainly as individual metal ion. Iron can be present both as individual metal ion or as part of cofactors, such as hemes and iron-sulfur (Fe-S) clusters. Both metal ions are characterized by the ability to cycle between different oxidation states, which enable them to catalyze redox reactions and to participate in electron transfer processes. Here we describe in detail the main processes responsible for the trafficking of copper and iron sulfur clusters, with particular interest for the structural aspects of the maturation of copper and iron-sulfur-binding proteins.

Identification of a novel zinc-binding protein, C1orf123, as an interactor with a heavy metal-associated domain

Heavy metal-associated (HMA) domains bind metal ions at its Cys-x-x-Cys (CxxC) motif and constitute an intracellular network for trafficking of metal ions for utilization and detoxification. We thus expect that novel metalloproteins can be identified by screening proteins interacting with a HMA domain. In this study, we performed yeast two-hybrid screening of the human proteome and found an uncharacterized protein encoded as open reading frame 123 in chromosome 1 (C1orf123) that can interact specifically with the HMA domain of a copper chaperone for superoxide dismutase (CCS^dI). Our X-ray structural analysis of C1orf123 further revealed that it binds a Zn²⁺ ion in a tetrahedral coordination with four thiolate groups from two conserved CxxC motifs. For the interaction between C1orf123 and CCS^dI, the CxxC motifs in both C1orf123 and CCS^dI were required, implying metal-mediated interaction through the CxxC motifs. Notably, C1orf123 did not interact with several other HMA domains containing CxxC motifs, supporting high specificity in the interaction between C1orf123 and CCS^dI. Based upon these results, we further discuss functional and structural significance of the interaction between C1orf123 and CCS.

A copper transcription factor, AfMac1, regulates both iron and copper homeostasis in the opportunistic fungal pathogen Aspergillus fumigatus

Although iron and copper are co-ordinately regulated in living cells, the homeostatic effects of each of these metals on the other remain unknown. Here, we show the function of AfMac1, a transcriptional activator of the copper and iron regulons of Aspergillus fumigatus, on the interaction between iron and copper. In addition to the copper-specific AfMac1-binding motif 5'-TGTGCTCA-3' found in the promoter region of ctrC, the iron-specific AfMac1-binding motif 5'-AT(C/G)NN(A/T)T(A/C)-3' was identified in the iron regulon but not in the copper regulon by ChIP sequence analysis. Furthermore, mutation of the AfMac1-binding motif of sit1 eliminated AfMac1-mediated sit1 up-regulation. Interestingly, the regulation of gene expression in the iron regulon by AfMac1 was not affected by copper and vice versa AfMac1 localized to the nucleus under iron- or copper-depleted conditions, and AfMac1 was mostly detected in the cytoplasm under iron- or copper-replete conditions. Taken together, these results suggest that A. fumigatus independently regulates iron and copper homeostasis in a manner that involves AfMac1 and mutual interactions.

Low Doses of Polyethylene Glycol Coated Iron Oxide Nanoparticles Cause Significant Elemental Changes within Main Organs

The main goal of this study was to evaluate the elemental changes occurring in the main rat organs (kidneys, spleen, heart, brain) as a result of polyethylene glycol-coated magnetic iron oxide nanoparticles (PEG-IONPs) administration. For this purpose, 24 animals were divided into four equinumerous groups, and the three of them were intravenously injected with PEG-IONPs dispersed in 15% solution of mannitol in dose of 0.03 mg of Fe per 1 kg of body weight. The organs were collected 2 h, 24 h and 7 days passing from NPs administration, respectively, for the 2H, 24H, and 7D experimental groups. The forth group of animals, namely control group, was injected with 1 mL of physiological saline solution. For the analysis of subtle elemental changes occurring in the organs after nanoparticles injection, highly sensitive method of total reflection X-ray fluorescence spectroscopy was used. Obtained results showed that administration of even such low doses of PEG-IONPs may lead to statistically significant changes in the accumulation of selected elements within kidneys and heart. Two hours and 7 days from NPs injection, the Fe level in kidneys was higher compared to that of control rats. Elevated levels of Cu, possibly associated with systemic action of ceruloplasmine enzyme, were found within kidneys in 24H and 7D groups, while in heart the similar observation was done only for 24H group. The levels of Ca and Zn increased in kidneys and heart during the first 2 h from the injection and were again elevated in these organs 7 days later. The abnormalities in Ca and Zn accumulations occurring exactly in the same manner may suggest that these elements may interplay either in the mechanisms responsible for the detoxification of the PEG-IONPs or pathological processes occurring as a result of their action.

Low Ctr1p, due to lack of Sco1p results in lowered cisplatin uptake and mediates insensitivity of rho0 yeast to cisplatin

Copper and cisplatin share copper transporter 1 (Ctr1) for cellular import. Copper depletion increases sensitivity of wild type yeast to cisplatin, whereas mitochondrial DNA-deficient rho0 cells are resistant to cisplatin. In the current study, we sought to determine whether copper deprivation modulates sensitivity of rho0 yeast to cisplatin. Yeast cultures grown in low copper medium and exposed to bathocuproine disulfonic acid resulted in significant reduction of intracellular copper. We report here that low copper medium rendered wild type hypersensitive to cisplatin, but failed to sensitize rho0 yeast to cisplatin. Wild type yeast grown in low copper medium exhibited ~2.0 fold enhanced cytotoxicity in survival and colony-forming ability compared to copper adequate wild type cells. The effect of copper restriction on cisplatin sensitivity was associated with upregulation of copper transporter 1 mRNA as well as protein, facilitating enhanced uptake and accumulation of cisplatin. Rho0 yeast also showed increased copper transporter 1 mRNA upon copper restriction, but failed to increase corresponding protein. Loss of synthesis of cytochrome coxidase 1 protein (Sco1) in rho0 cells deregulated copper transporter 1, impaired Pt uptake and lowered cytotoxicity, despite lowered glutathione levels. Sco1Δ mutants exhibited low copper transporter 1, reduced Pt accumulation suggesting that Sco1 mediated regulation of copper transporter 1 is responsible for altered sensitivity to cisplatin. Rho0 cells demonstrated loss of Sco1, resulting in copper deficiency by lowering copper transporter 1 abundance, via mechanism involving increased turnover due to ubiquitination. These findings reveal that a Sco1-dependent mitochondrial signal regulates cellular cisplatin import and cytotoxicity.

Evaluation of lipid peroxidation and the level of some elements in rat erythrocytes during separate and combined vanadium and magnesium administration

The impact of vanadium (V) and magnesium (Mg) as sodium metavanadate (SMV, 0.125 mg V/ml) and magnesium sulfate (MS, 0.06 mg Mg/ml) on lipid peroxidation (LPO) and selected elements in the rat erythrocytes (RBCs) was investigated. Relationships between some indices determined in RBC were also studied. SMV alone (Group II) elevated the malondialdehyde level (MDA_RBC) (by 95% and 60%), compared with the control (Group I) and MS-supplemented rats (Group III), respectively, reduced the concentration of Cu_RBC (by 23.5%), in comparison with Group I, but did not change the levels of Na_RBC, K_RBC, and Ca_RBC, whereas MS alone (Group III) only reduced the Cu_RBC concentration (by 22%), compared with Group I. The SMV + MS combination (Group IV) reduced and elevated the Cu_RBC (by 24%) and Ca_RBC (by 111%) concentrations, respectively, in comparison with Groups I and III, and these changes were induced by the V-Mg antagonistic and synergistic interaction, respectively. The combined SMV + MS effect also enhanced the MDA_RBC level, compared with Groups I (by 79%) and III (by 47%) and slightly limited its concentration, compared with Group II, which, in turn, resulted from the distinct trend toward the V-Mg antagonistic interaction. We can conclude that V (as SMV) is able to stimulate LPO in rat RBCs and that V-Mg interactive effects are involved in changes in Cu_RBC, Ca_RBC, and MDA_RBC. Further studies are needed to elucidate the exact mechanisms of the V-Mg antagonistic/synergistic interactions and to provide insight into the biochemical mechanisms of changes in rats suffering from anemia [1], characterized by a disrupted antioxidant barrier in RBCs [2] and an intensified free radical process in these cells.

In-Cell NMR in Human Cells: Direct Protein Expression Allows Structural Studies of Protein Folding and Maturation

Cellular structural biology methods are needed to characterize biological processes at atomic resolution in the physiological environment of the cell. Toward this goal, solution in-cell NMR is a powerful approach because it provides structural and dynamic data on macromolecules inside living cells. Several approaches have been developed for in-cell NMR in cultured human cells, which are needed to study processes related to human diseases that rely on the delivery of exogenous macromolecules to the cells. Such strategies, however, may not be applicable to proteins that are sensitive to the external environment or prone to aggregate and can introduce artifacts during protein purification or delivery. As a complementary approach, direct protein expression for in-cell NMR in human cells was developed. This strategy is especially useful when studying processes like protein folding, maturation, and post-translational modification, starting right after protein synthesis. Compared with the protein expression techniques in mammalian cells commonly used in cellular biology, the low sensitivity of NMR requires higher protein levels. Among the cell lines used for high-yield protein expression, the HEK293T cell line was chosen, as it can be efficiently transfected with a cost-effective reagent. A vector originally designed for secreted proteins allows high-level cytosolic protein expression. For isotopic labeling, commercially available or homemade labeled media are employed. Uniform or amino acid type-selective labeling strategies are possible. Protein expression can be targeted to specific organelles (e.g., mitochondria), allowing for in organello NMR applications. A variant of the approach was developed that allows the sequential expression of two or more proteins, with only one selectively labeled. Protein expression in HEK293T cells was applied to recapitulate the maturation steps of intracellular superoxide dismutase 1 (SOD1) and to study the effect of mutations linked to familial amyotrophic lateral sclerosis (fALS) by in-cell NMR. Intracellular wild-type SOD1 spontaneously binds zinc, while it needs the copper chaperone for superoxide dismutase (CCS) for copper delivery and disulfide bond formation. Some fALS-linked mutations impair zinc binding and cause SOD1 to irreversibly unfold, likely forming the precursor of cytotoxic aggregates. The SOD-like domain of CCS acts as a molecular chaperone toward mutant SOD1, stabilizing its folding and allowing zinc binding and correct maturation. Changes in protein redox state distributions can also be investigated by in-cell NMR. Mitochondrial proteins require the redox-regulating partners glutaredoxin 1 (Grx1) and thioredoxin (Trx) to remain in the reduced, import-competent state in the cytosol, whereas SOD1 requires CCS for disulfide bond formation. In both cases, the proteins do not equilibrate with the cytosolic redox pool. Cysteine oxidation in response to oxidative stress can also be monitored. In the near future, in-cell NMR in human cells will likely benefit from technological advancements in NMR hardware, the development of bioreactor systems for increased sample lifetime, the application of paramagnetic NMR to obtain structural restraints, and advanced tools for genome engineering and should be increasingly integrated with advanced cellular imaging techniques.

The mitochondrial metallochaperone SCO1 maintains CTR1 at the plasma membrane to preserve copper homeostasis in the murine heart

SCO1 is a ubiquitously expressed, mitochondrial protein with essential roles in cytochrome c oxidase (COX) assembly and the regulation of copper homeostasis. SCO1 patients present with severe forms of early onset disease, and ultimately succumb from liver, heart or brain failure. However, the inherent susceptibility of these tissues to SCO1 mutations and the clinical heterogeneity observed across SCO1 pedigrees remain poorly understood phenomena. To further address this issue, we generated Sco1hrt/hrt and Sco1stm/stm mice in which Sco1 was specifically deleted in heart and striated muscle, respectively. Lethality was observed in both models due to a combined COX and copper deficiency that resulted in a dilated cardiomyopathy. Left ventricular dilation and loss of heart function was preceded by a temporal decrease in COX activity and copper levels in the longer-lived Sco1stm/stm mice. Interestingly, the reduction in copper content of Sco1stm/stm cardiomyocytes was due to the mislocalisation of CTR1, the high affinity transporter that imports copper into the cell. CTR1 was similarly mislocalized to the cytosol in the heart of knockin mice carrying a homozygous G115S substitution in Sco1, which in humans causes a hypertrophic cardiomyopathy. Our current findings in the heart are in marked contrast to our prior observations in the liver, where Sco1 deletion results in a near complete absence of CTR1 protein. These data collectively argue that mutations perturbing SCO1 function have tissue-specific consequences for the machinery that ultimately governs copper homeostasis, and further establish the importance of aberrant mitochondrial signaling to the etiology of copper handling disorders.

Quantifying the Interaction between Copper-Zinc Superoxide Dismutase (Sod1) and its Copper Chaperone (Ccs1)

Immature copper-zinc superoxide dismutase (Sod1) is activated by its copper chaperone (Ccs1). Ccs1 delivers a single copper ion and catalyzes oxidation of an intra-subunit disulfide bond within each Sod1 monomer through a mechanistically ambiguous process. Here, we use residue specific fluorescent labeling of immature Sod1 to quantitate the thermodynamics of the Sod1•Ccs1 interaction while determining a more complete view of Ccs1 function. Ccs1 preferentially binds a completely immature form of Sod1 that is metal deficient and disulfide reduced (E, E-Sod1^SH). However, binding induces structural changes that promote high-affinity zinc binding by the Ccs1-bound Sod1 molecule. This adds further support to the notion that Ccs1 likely plays dual chaperoning roles during the Sod1 maturation process. Further analysis reveals that in addition to the copper-dependent roles during Sod1 activation, the N- and C-terminal domains of Ccs1 also have synergistic roles in securing both Sod1 recognition and its own active conformation. These results provide new and measurable analyses of the molecular determinants guiding Ccs1-mediated Sod1 activation.

Comparison of proteomic profiles in the ovary of Sterlet sturgeon (Acipenser ruthenus) during vitellogenic stages

One of the challenges of sturgeon aquaculture is that sturgeon takes an extended amount of time to reach sexual maturity. The pattern of the protein expression in relation to the late maturity of sturgeon can help to better understand changes in sexual maturity. 17β-estradiol (E2), testosterone (T) and vitellogenin (Vtg) levels were examined at all stages of sexual maturation in Sterlet sturgeon (Acipenser ruthenus). Two-dimensional gel electrophoresis and mass spectrometry analysis were used to show the pattern of the ovarian proteins. The T levels increased from the previtellogenic to the postvitellogenic stages (P < 0.05) and Vtg showed a decremental pattern in pre- and postvitellogenic, and atresia (not significantly). The analysis showed 900 protein spots, 19 of which were successfully identified and had significant differences between the previtellogenic and the vitellogenic groups (P < 0.05). Among the identified proteins, 40% involved in cell defense (heat shock protein, Glutathione peroxidase, natural killer enhancing factor, peroxiredoxin-2), 30% in transcription and translation (constitutive photomorphogenesis 9 and Ybx2), 20% in metabolism and energy production (triose-phosphate isomerase (TPI)) and 10% in transport (glycolipid transfer protein). In the vitellogenic stage, the proteins were related to metabolism and energy production (TPI, ES1, creatin kinase, enolase, nucleoside diphosphate kinase, 50%), cell defense (thioredoxin and dislophid isomerase, 20%) and transport (fatty acid binding protein, 10%). Our findings show changes in protein expression pattern from cell defense to metabolism during egg development.

Copper Acquisition and Utilization in Fungi

Fungal cells colonize and proliferate in distinct niches, from soil and plants to diverse tissues in human hosts. Consequently, fungi are challenged with the goal of obtaining nutrients while simultaneously elaborating robust regulatory mechanisms to cope with a range of availability of nutrients, from scarcity to excess. Copper is essential for life but also potentially toxic. In this review we describe the sophisticated homeostatic mechanisms by which fungi acquire, utilize, and control this biochemically versatile trace element. Fungal pathogens, which can occupy distinct host tissues that have their own intrinsic requirements for copper homeostasis, have evolved mechanisms to acquire copper to successfully colonize the host, disseminate to other tissues, and combat host copper bombardment mechanisms that would otherwise mitigate virulence.

SOD1 Phosphorylation by mTORC1 Couples Nutrient Sensing and Redox Regulation

Nutrients are not only organic compounds fueling bioenergetics and biosynthesis, but also key chemical signals controlling growth and metabolism. Nutrients enormously impact the production of reactive oxygen species (ROS), which play essential roles in normal physiology and diseases. How nutrient signaling is integrated with redox regulation is an interesting, but not fully understood, question. Herein, we report that superoxide dismutase 1 (SOD1) is a conserved component of the mechanistic target of rapamycin complex 1 (mTORC1) nutrient signaling. mTORC1 regulates SOD1 activity through reversible phosphorylation at S39 in yeast and T40 in humans in response to nutrients, which moderates ROS level and prevents oxidative DNA damage. We further show that SOD1 activation enhances cancer cell survival and tumor formation in the ischemic tumor microenvironment and protects against the chemotherapeutic agent cisplatin. Collectively, these findings identify a conserved mechanism by which eukaryotes dynamically regulate redox homeostasis in response to changing nutrient conditions.

Cellular copper homeostasis: current concepts on its interplay with glutathione homeostasis and its implication in physiology and human diseases

Copper is a trace element essential for almost all living organisms. But the level of intracellular copper needs to be tightly regulated. Dysregulation of cellular copper homeostasis leading to various diseases demonstrates the importance of this tight regulation. Copper homeostasis is regulated not only within the cell but also within individual intracellular compartments. Inactivation of export machinery results in excess copper being redistributed into various intracellular organelles. Recent evidence suggests the involvement of glutathione in playing an important role in regulating copper entry and intracellular copper homeostasis. Therefore interplay of both homeostases might play an important role within the cell. Similar to copper, glutathione balance is tightly regulated within individual cellular compartments. This review explores the existing literature on the role of glutathione in regulating cellular copper homeostasis. On the one hand, interplay of glutathione and copper homeostasis performs an important role in normal physiological processes, for example neuronal differentiation. On the other hand, perturbation of the interplay might play a key role in the pathogenesis of copper homeostasis disorders.

Effects of maturation on the conformational free-energy landscape of SOD1

Amyotrophic lateral sclerosis (ALS) is a devastating fatal syndrome characterized by very rapid degeneration of motor neurons. A leading hypothesis is that ALS is caused by toxic protein misfolding and aggregation, as also occurs in many other neurodegenerative disorders, such as prion, Alzheimer's, Parkinson's, and Huntington's diseases. A prominent cause of familial ALS is mutations in the protein superoxide dismutase (SOD1), which promote the formation of misfolded SOD1 conformers that are prone to aberrant interactions both with each other and with other cellular components. We have shown previously that immature SOD1, lacking bound Cu and Zn metal ions and the intrasubunit disulfide bond (apoSOD1^2SH), has a rugged free-energy surface (FES) and exchanges with four other conformations (excited states) that have millisecond lifetimes and sparse populations on the order of a few percent. Here, we examine further states of SOD1 along its maturation pathway, as well as those off-pathway resulting from metal loss that have been observed in proteinaceous inclusions. Metallation and disulfide bond formation lead to structural transformations including local ordering of the electrostatic loop and native dimerization that are observed in rare conformers of apoSOD1^2SH; thus, SOD1 maturation may occur via a population-switch mechanism whereby posttranslational modifications select for preexisting structures on the FES. Metallation and oxidation of SOD1 stabilize the native, mature conformation and decrease the number of detected excited conformational states, suggesting that it is the immature forms of the protein that contribute to misfolded conformations in vivo rather than the highly stable enzymatically active dimer.

Oxidative Stress Response Tips the Balance in Aspergillus terreus Amphotericin B Resistance

In this study, we characterize the impact of antioxidative enzymes in amphotericin B (AmB)-resistant (ATR) and rare AmB-susceptible (ATS) clinical Aspergillus terreus isolates. We elucidate expression profiles of superoxide dismutase (SOD)- and catalase (CAT)-encoding genes, enzymatic activities of SODs, and superoxide anion production and signaling pathways involved in the oxidative stress response (OSR) in ATS and ATR strains under AmB treatment conditions. We show that ATR strains possess almost doubled basal SOD activity compared to that of ATS strains and that ATR strains exhibit an enhanced OSR, with significantly higher sod2 mRNA levels and significantly increased cat transcripts in ATR strains upon AmB treatment. In particular, inhibition of SOD and CAT proteins renders resistant isolates considerably susceptible to the drug in vitro In conclusion, this study shows that SODs and CATs are crucial for AmB resistance in A. terreus and that targeting the OSR might offer new treatment perspectives for resistant species.

Recent findings on the physiological function of DJ-1: Beyond Parkinson's disease

Several mutations in the gene coding for DJ-1 have been associated with early onset forms of parkinsonism. In spite of the massive effort spent by the scientific community in understanding the physiological role of DJ-1, a consensus on what DJ-1 actually does within the cells has not been reached, with several diverse functions proposed. At present, the most accepted function for DJ-1 is a neuronal protective role against oxidative stress. However, how exactly this function is exerted by DJ-1 is not clear. In recent years, novel molecular mechanisms have been suggested that may account for the antioxidant properties of DJ-1. In this review, we critically analyse the experimental evidence, including some very recent findings, supporting the purported neuroprotective role of DJ-1 through different mechanisms linked to oxidative stress handling, as well as the relevance of these processes in the context of Parkinson's disease.

Functional characterization of the copper transcription factor AfMac1 from Aspergillus fumigatus

Although copper functions as a cofactor in many physiological processes, copper overload leads to harmful effects in living cells. Thus, copper homeostasis is tightly regulated. However, detailed copper metabolic pathways have not yet been identified in filamentous fungi. In this report, we investigated the copper transcription factor AfMac1 ( Aspergillus fumigatusMac1 homolog) and identified its regulatory mechanism in A. fumigatus AfMac1 has domains homologous to the DNA-binding and copper-binding domains of Mac1 from Saccharomyces cerevisiae, and AfMac1 efficiently complemented Mac1 in S. cerevisiae Expression of Afmac1 resulted in CTR1 up-regulation, and mutation of the DNA-binding domain of Afmac1 failed to activate CTR1 expression in S. cerevisiae The Afmac1 deletion strain of A. fumigatus failed to grow in copper-limited media, and its growth was restored by introducing ctrC We found that AfMac1 specifically bound to the promoter region of ctrC based on EMSA. The AfMac1-binding motif 5'-TGTGCTCA-3' was identified from the promoter region of ctrC, and the addition of mutant ctrC lacking the AfMac1-binding motif failed to up-regulate ctrC in A. fumigatus Furthermore, deletion of Afmac1 significantly reduced strain virulence and activated conidial killing activity by neutrophils and macrophages. Taken together, these results suggest that AfMac1 is a copper transcription factor that regulates cellular copper homeostasis in A. fumigatus.

Insights into the mechanisms of copper dyshomeostasis in amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis (ALS) is a severe neuromuscular disease characterised by a progressive loss of motor neurons that usually results in paralysis and death within 2 to 5 years after disease onset. The pathophysiological mechanisms involved in ALS remain largely unknown and to date there is no effective treatment for this disease. Here, we review clinical and experimental evidence suggesting that dysregulation of copper homeostasis in the central nervous system is a crucial underlying event in motor neuron degeneration and ALS pathophysiology. We also review and discuss novel approaches seeking to target copper delivery to treat ALS. These novel approaches may be clinically relevant not only for ALS but also for other neurological disorders with abnormal copper homeostasis, such as Parkinson's, Huntington's and Prion diseases.

Copper-zinc superoxide dismutase is activated through a sulfenic acid intermediate at a copper ion entry site

Metallochaperones are a diverse family of trafficking molecules that provide metal ions to protein targets for use as cofactors. The copper chaperone for superoxide dismutase (Ccs1) activates immature copper-zinc superoxide dismutase (Sod1) by delivering copper and facilitating the oxidation of the Sod1 intramolecular disulfide bond. Here, we present structural, spectroscopic, and cell-based data supporting a novel copper-induced mechanism for Sod1 activation. Ccs1 binding exposes an electropositive cavity and proposed "entry site" for copper ion delivery on immature Sod1. Copper-mediated sulfenylation leads to a sulfenic acid intermediate that eventually resolves to form the Sod1 disulfide bond with concomitant release of copper into the Sod1 active site. Sod1 is the predominant disulfide bond-requiring enzyme in the cytoplasm, and this copper-induced mechanism of disulfide bond formation obviates the need for a thiol/disulfide oxidoreductase in that compartment.

Gene expression patterns in the progression of canine copper-associated chronic hepatitis

Copper is an essential trace element, but can become toxic when present in abundance. The severe effects of copper-metabolism imbalance are illustrated by the inherited disorders Wilson disease and Menkes disease. The Labrador retriever dog breed is a novel non-rodent model for copper-storage disorders carrying mutations in genes known to be involved in copper transport. Besides disease initiation and progression of copper accumulation, the molecular mechanisms and pathways involved in progression towards copper-associated chronic hepatitis still remain unclear. Using expression levels of targeted candidate genes as well as transcriptome micro-arrays in liver tissue of Labrador retrievers in different stages of copper-associated hepatitis, pathways involved in progression of the disease were studied. At the initial phase of increased hepatic copper levels, transcriptomic alterations in livers mainly revealed enrichment for cell adhesion, developmental, inflammatory, and cytoskeleton pathways. Upregulation of targeted MT1A and COMMD1 mRNA shows the liver's first response to rising intrahepatic copper concentrations. In livers with copper-associated hepatitis mainly an activation of inflammatory pathways is detected. Once the hepatitis is in the chronic stage, transcriptional differences are found in cell adhesion adaptations and cytoskeleton remodelling. In view of the high similarities in copper-associated hepatopathies between men and dog extrapolation of these dog data into human biomedicine seems feasible.

Structure and Synaptic Function of Metal Binding to the Amyloid Precursor Protein and its Proteolytic Fragments

Alzheimer’s disease (AD) is ultimately linked to the amyloid precursor protein (APP). However, current research reveals an important synaptic function of APP and APP-like proteins (APLP1 and 2). In this context various neurotrophic and neuroprotective functions have been reported for the APP proteolytic fragments sAPPα, sAPPβ and the monomeric amyloid-beta peptide (Aβ). APP is a metalloprotein and binds copper and zinc ions. Synaptic activity correlates with a release of these ions into the synaptic cleft and dysregulation of their homeostasis is linked to different neurodegenerative diseases. Metal binding to APP or its fragments affects its structure and its proteolytic cleavage and therefore its physiological function at the synapse. Here, we summarize the current data supporting this hypothesis and provide a model of how these different mechanisms might be intertwined with each other.

S-acylation of SOD1, CCS, and a stable SOD1-CCS heterodimer in human spinal cords from ALS and non-ALS subjects

Previously, we found that human Cu, Zn-superoxide dismutase (SOD1) is S-acylated (palmitoylated) in vitro and in amyotrophic lateral sclerosis (ALS) mouse models, and that S-acylation increased for ALS-causing SOD1 mutants relative to wild type. Here, we use the acyl resin-assisted capture (acyl-RAC) assay to demonstrate S-acylation of SOD1 in human post-mortem spinal cord homogenates from ALS and non-ALS subjects. Acyl-RAC further revealed that endogenous copper chaperone for SOD1 (CCS) is S-acylated in both human and mouse spinal cords, and in vitro in HEK293 cells. SOD1 and CCS formed a highly stable heterodimer in human spinal cord homogenates that was resistant to dissociation by boiling, denaturants, or reducing agents and was not observed in vitro unless both SOD1 and CCS were overexpressed. Cysteine mutations that attenuate SOD1 maturation prevented the SOD1-CCS heterodimer formation. The degree of S-acylation was highest for SOD1-CCS heterodimers, intermediate for CCS monomers, and lowest for SOD1 monomers. Given that S-acylation facilitates anchoring of soluble proteins to cell membranes, our findings suggest that S-acylation and membrane localization may play an important role in CCS-mediated SOD1 maturation. Furthermore, the highly stable S-acylated SOD1-CCS heterodimer may serve as a long-lived maturation intermediate in human spinal cord.

Oxygen-dependent activation of Cu,Zn-superoxide dismutase-1

Copper zinc superoxide dismutase (Sod1) is a critical enzyme in limiting reactive oxygen species in both the cytosol and the mitochondrial intermembrane space.

Copper and Alzheimer's Disease

Alzheimer's disease (AD) is the most common form of adult neurode-generation and is characterised by progressive loss of cognitive function leading to death. The neuropathological hallmarks include extracellular amyloid plaque accumulation in affected regions of the brain, formation of intraneuronal neurofibrillary tangles, chronic neuroinflammation, oxidative stress, and abnormal biometal homeostasis. Of the latter, major changes in copper (Cu) levels and localisation have been identified in AD brain, with accumulation of Cu in amyloid deposits, together with deficiency of Cu in some brain regions. The amyloid precursor protein (APP) and the amyloid beta (Aβ) peptide both have Cu binding sites, and interaction with Cu can lead to potentially neurotoxic outcomes through generation of reactive oxygen species. In addition, AD patients have systemic changes to Cu metabolism, and altered Cu may also affect neuroinflammatory outcomes in AD. Although we still have much to learn about Cu homeostasis in AD patients and its role in disease aetiopathology, therapeutic approaches for regulating Cu levels and interactions with Cu-binding proteins in the brain are currently being developed. This review will examine how Cu is associated with pathological changes in the AD brain and how these may be targeted for therapeutic intervention.

Molecular features of copper binding proteins involved in copper homeostasis

Copper has a wide and important role in biological systems, determining conformation and activity of many metalloproteins and enzymes, such as cytochrome oxidase and superoxide dismutase . Furthermore, due to its possible reactivity with nonspecific proteins and toxic effects, elaborate systems of absorption, concentration buffering, delivery to specific protein sites and elimination, require a complex system including small carriers, chaperones and active transporters. The P-type copper ATPases ATP7A and ATP7B provide an important system for acquisition, active transport, distribution and elimination of copper. Relevance of copper metabolism to human diseases and therapy is already known. It is quite certain that further studies will reveal detailed and useful information on biochemical mechanisms and relevance to diseases. © 2016 IUBMB Life, 69(4):211-217, 2017.

Erythrocyte copper chaperone for superoxide dismutase and superoxide dismutase as biomarkers for hepatic copper concentrations in Labrador retrievers

Hereditary hepatic copper accumulation in Labrador retrievers leads to hepatitis with fibrosis and eventually cirrhosis. The development of a non-invasive blood-based biomarker for copper status in dogs could be helpful in identifying dogs at risk and to monitor copper concentrations during treatment. In this study, two cellular copper metabolism proteins, Cu/Zn superoxide dismutase (SOD1) and its chaperone (copper chaperone for SOD1, CCS) were measured in erythrocytes and tested for association with hepatic copper concentrations in 15 Labrador retrievers with normal or increased hepatic copper concentrations. Antibodies against CCS and SOD1 were applicable for use in canine specimens. This was demonstrated by the loss of immune-reactive bands for CCS and SOD1 in siRNA treated canine bile duct epithelial cells. Erythrocyte CCS and CCS/SOD1 ratios were decreased 2.37 (P <0.001) and 3.29 (P <0.001) fold in the high copper group compared to the normal copper group. Erythrocyte CCS and CCS/SOD1 ratio are potential new biomarkers for hepatic copper concentrations in Labrador retrievers and could facilitate early diagnosis and treatment monitoring for copper-associated hepatitis in dogs.

In Absence of the Cellular Prion Protein, Alterations in Copper Metabolism and Copper-Dependent Oxidase Activity Affect Iron Distribution

Essential elements as copper and iron modulate a wide range of physiological functions. Their metabolism is strictly regulated by cellular pathways, since dysregulation of metal homeostasis is responsible for many detrimental effects. Neurodegenerative disorders such as Alzheimer's disease, Parkinson's disease and prion diseases are characterized by alterations of metal ions. These neurodegenerative maladies involve proteins that bind metals and mediate their metabolism through not well-defined mechanisms. Prion protein, for instance, interacts with divalent cations via multiple metal-binding sites and it modulates several metal-dependent physiological functions, such as S-nitrosylation of NMDA receptors. In this work we focused on the effect of prion protein absence on copper and iron metabolism during development and adulthood. In particular, we investigated copper and iron functional values in serum and several organs such as liver, spleen, total brain and isolated hippocampus. Our results show that iron content is diminished in prion protein-null mouse serum, while it accumulates in liver and spleen. Our data suggest that these alterations can be due to impairments in copper-dependent cerulopalsmin activity which is known to affect iron mobilization. In prion protein-null mouse total brain and hippocampus, metal ion content shows a fluctuating trend, suggesting the presence of homeostatic compensatory mechanisms. However, copper and iron functional values are likely altered also in these two organs, as indicated by the modulation of metal-binding protein expression levels. Altogether, these results reveal that the absence of the cellular prion protein impairs copper metabolism and copper-dependent oxidase activity, with ensuing alteration of iron mobilization from cellular storage compartments.

Changes in intracellular copper concentration and copper-regulating gene expression after PC12 differentiation into neurons

It is suspected that some neurodegenerative diseases are a result of the disturbance of copper (Cu) homeostasis, although it remains unclear whether the disturbance of Cu homeostasis has aberrant effects on neurons. Herein, we investigated Cu metabolism specifically in neurons in terms of changes in the intracellular Cu concentration and the expression of Cu-regulating genes, such as Cu transporters and metallothioneins (MTs), before and after the differentiation of rat pheochromocytoma cells (PC12 cells) into neurons. After the differentiation, Cu and Zn imaging with fluorescent probes revealed an increase in intracellular Cu concentration. The concentrations of other essential metals, which were determined by an inductively coupled plasma mass spectrometer, were not altered. The mRNA expression of the Cu influx transporter, Ctr1, was decreased after the differentiation, and the differentiated cells acquired tolerance to Cu and cisplatin, another substrate of Ctr1. In addition, the expression of MT-3, a brain-specific isoform, was increased, contrary to the decreased expression of MT-1 and MT-2. Taken together, the differentiation of PC12 cells into neurons induced MT-3 expression, thereby resulting in intracellular Cu accumulation. The decrease in Ctr1 expression was assumed to be a response aimed at abolishing the physiological accumulation of Cu after the differentiation.

Effects of Dietary Copper-Methionine on Matrix Metalloproteinase-2 in the Lungs of Cold-Stressed Broilers as an Animal Model for Pulmonary Hypertension

The objective of the present study was to investigate the effects of different levels of copper (as supplemental copper-methionine) on ascites incidence and matrix metalloproteinase-2 (MMP-2) changes in the lungs of cold-stressed broilers. For this purpose, 480 1-day-old Ross 308 broiler chickens were randomly assigned to six treatments. Treatments consisted of two ambient temperatures (thermoneutral and cold stress) each combined with 0, 100, and 200 mg supplemental copper/kg as copper-methionine in a 2 × 3 factorial arrangement in a completely randomized design with four replicates. Ascites was diagnosed based on abdominal and pericardial fluid accumulation at 45 days of age. Fourty-eight broilers were killed at 38 and 45 days of age, and their lungs were collected for biological analysis. Results showed that MMP-2 increased in the lungs of ascitic broilers and that copper-methionine supplementation significantly reduced MMP-2 in cold-stressed broiler chickens. Treatments did not affect tissue inhibitor of metalloproteinase-2 (TIMP-2) at 38 and 45 days of age, and no difference was observed between 100 and 200 mg/kg copper-methionine treatments. In conclusion, copper-methionine at higher than conventional levels of supplementation decreased ascites incidence in low temperature through reduced MMP-2 concentration. Further research is warranted to investigate the effect of copper on MMP-2 concentrations in other tissues with high oxygen demand.

Thioether Coordination Chemistry for Molecular Imaging of Copper in Biological Systems

Copper is an essential element in biological systems. Its potent redox activity renders it necessary for life, but at the same time, misregulation of its cellular pools can lead to oxidative stress implicated in aging and various disease states. Copper is commonly thought of as a static cofactor buried in protein active sites; however, evidence of a more loosely bound, labile pool of copper has emerged. To help identify and understand new roles for dynamic copper pools in biology, we have developed selective molecular imaging agents for this metal, drawing inspiration from both biological binding motifs and synthetic model complexes that reveal thioether coordination as a general design strategy for selective and sensitive copper recognition. In this review, we summarize some contributions, primarily from our own laboratory, on fluorescence- and magnetic resonance-based molecular-imaging probes for studying copper in living systems using thioether coordination chemistry.

Copper dyshomoeostasis in Parkinson's disease: implications for pathogenesis and indications for novel therapeutics

Copper is a biometal essential for normal brain development and function, thus copper deficiency or excess results in central nervous system disease. Well-characterized disorders of disrupted copper homoeostasis with neuronal degeneration include Menkes disease and Wilson's disease but a large body of evidence also implicates disrupted copper pathways in other neurodegenerative disorders, including Parkinson's disease, Alzheimer's disease, Amyotrophic lateral sclerosis, Huntington's disease and prion diseases. In this short review we critically evaluate the data regarding changes in systemic and brain copper levels in Parkinson's disease, where alterations in brain copper are associated with regional neuronal cell death and disease pathology. We review copper regulating mechanisms in the human brain and the effects of dysfunction within these systems. We then examine the evidence for a role for copper in pathogenic processes in Parkinson's disease and consider reports of diverse copper-modulating strategies in in vitro and in vivo models of this disorder. Copper-modulating therapies are currently advancing through clinical trials for Alzheimer's and Huntington's disease and may also hold promise as disease modifying agents in Parkinson's disease.

Transcriptome analysis of copper homeostasis genes reveals coordinated upregulation of SLC31A1,SCO1, and COX11 in colorectal cancer

Copper homeostasis and distribution is strictly regulated by a network of transporters and intracellular chaperones encoded by a group of genes collectively known as copper homeostasis genes (CHGs). In this work, analysis of The Cancer Genome Atlas database for somatic point mutations in colorectal cancer revealed that inactivating mutations are absent or extremely rare in CHGs. Using oligonucleotide microarrays, we found a strong increase in mRNA levels of the membrane copper transporter 1 protein [CTR1; encoded by the solute carrier family 31 member 1 gene (SLC31A1 gene)] in our series of colorectal carcinoma samples. CTR1 is the main copper influx transporter and changes in its expression are able to induce modifications of cellular copper accumulation. The increased SLC31A1 mRNA level is accompanied by a parallel increase in transcript levels for copper efflux pump ATP7A, copper metabolism Murr1 domain containing 1 (COMMD1), the cytochrome C oxidase assembly factors [synthesis of cytochrome c oxidase 1 (SCO1) and cytochrome c oxidase copper chaperone 11 (COX11)], the cupric reductase six transmembrane epithelial antigen of the prostate (STEAP3), and the metal‐regulatory transcription factors (MTF1, MTF2) and specificity protein 1 (SP1). The significant correlation between SLC31A1,SCO1, and COX11 mRNA levels suggests that this transcriptional upregulation might be part of a coordinated program of gene regulation. Transcript‐level upregulation of SLC31A1,SCO1, and COX11 was also confirmed by the analysis of different colon carcinoma cell lines (Caco‐2, HT116, HT29) and cancer cell lines of different tissue origin (MCF7, PC3). Finally, exon‐level expression analysis of SLC31A1 reveals differential expression of alternative transcripts in colorectal cancer and normal colonic mucosa.

Roles of vacuolar H+-ATPase in the oxidative stress response of Candida glabrata

Vacuolar H(+)-ATPase (V-ATPase) is responsible for the acidification of eukaryotic intracellular compartments and plays an important role in oxidative stress response (OSR), but its molecular bases are largely unknown. Here, we investigated how V-ATPase is involved in the OSR by using a strain lacking VPH2, which encodes an assembly factor of V-ATPase, in the pathogenic fungus Candida glabrata The loss of Vph2 resulted in increased H2O2 sensitivity and intracellular reactive oxygen species (ROS) level independently of mitochondrial functions. The Δvph2 mutant also displayed growth defects under alkaline conditions accompanied by the accumulation of intracellular ROS and these phenotypes were recovered in the presence of the ROS scavenger N-acetyl-l-cysteine. Both expression and activity levels of mitochondrial manganese superoxide dismutase (Sod2) and catalase (Cta1) were decreased in the Δvph2 mutant. Phenotypic analyses of strains lacking and overexpressing these genes revealed that Sod2 and Cta1 play a predominant role in endogenous and exogenous OSR, respectively. Furthermore, supplementation of copper and iron restored the expression of SOD2 specifically in the Δvph2 mutant, suggesting that the homeostasis of intracellular cupper and iron levels maintained by V-ATPase was important for the Sod2-mediated OSR. This report demonstrates novel roles of V-ATPase in the OSR in C. glabrata.