Copper transport protein (Ctr1) levels in mice are tissue specific and dependent on copper status

Copper homeostasis and neurodegenerative diseases

Copper, one of the most prolific transition metals in the body, is required for normal brain physiological activity and allows various functions to work normally through its range of concentrations. Copper homeostasis is meticulously maintained through a complex network of copper-dependent proteins, including copper transporters (CTR1 and CTR2), the two copper ion transporters the Cu -transporting ATPase 1 (ATP7A) and Cu-transporting beta (ATP7B), and the three copper chaperones ATOX1, CCS, and COX17. Disruptions in copper homeostasis can lead to either the deficiency or accumulation of copper in brain tissue. Emerging evidence suggests that abnormal copper metabolism or copper binding to various proteins, including ceruloplasmin and metallothionein, is involved in the pathogenesis of neurodegenerative disorders. However, the exact mechanisms underlying these processes are not known. Copper is a potent oxidant that increases reactive oxygen species production and promotes oxidative stress. Elevated reactive oxygen species levels may further compromise mitochondrial integrity and cause mitochondrial dysfunction. Reactive oxygen species serve as key signaling molecules in copper-induced neuroinflammation, with elevated levels activating several critical inflammatory pathways. Additionally, copper can bind aberrantly to several neuronal proteins, including alpha-synuclein, tau, superoxide dismutase 1, and huntingtin, thereby inducing neurotoxicity and ultimately cell death. This study focuses on the latest literature evaluating the role of copper in neurodegenerative diseases, with a particular focus on copper-containing metalloenzymes and copper-binding proteins in the regulation of copper homeostasis and their involvement in neurodegenerative disease pathogenesis. By synthesizing the current findings on the functions of copper in oxidative stress, neuroinflammation, mitochondrial dysfunction, and protein misfolding, we aim to elucidate the mechanisms by which copper contributes to a wide range of hereditary and neuronal disorders, such as Wilson's disease, Menkes' disease, Alzheimer's disease, Parkinson's disease, amyotrophic lateral sclerosis, Huntington's disease, and multiple sclerosis. Potential clinically significant therapeutic targets, including superoxide dismutase 1, D-penicillamine, and 5,7-dichloro-2-[(dimethylamino)methyl]-8-hydroxyquinoline, along with their associated therapeutic agents, are further discussed. Ultimately, we collate evidence that copper homeostasis may function in the underlying etiology of several neurodegenerative diseases and offer novel insights into the potential prevention and treatment of these diseases based on copper homeostasis.

Mammalian copper homeostasis: physiological roles and molecular mechanisms

In the past decade, evidence for the numerous roles of copper (Cu) in mammalian physiology has grown exponentially. The discoveries of Cu involvement in cell signaling, autophagy, cell motility, differentiation, and regulated cell death (cuproptosis) have markedly extended the list of already known functions of Cu, such as a cofactor of essential metabolic enzymes, a protein structural component, and a regulator of protein trafficking. Novel and unexpected functions of Cu transporting proteins and enzymes have been identified, and new disorders of Cu homeostasis have been described. Significant progress has been made in the mechanistic studies of two classic disorders of Cu metabolism, Menkes disease and Wilson's disease, which paved the way for novel approaches to their treatment. The discovery of cuproptosis and the role of Cu in cell metastatic growth have markedly increased interest in targeting Cu homeostatic pathways to treat cancer. In this review, we summarize the established concepts in the field of mammalian Cu physiology and discuss how new discoveries of the past decade expand and modify these concepts. The roles of Cu in brain metabolism and in cell functional speciation and a recently discovered regulated cell death have attracted significant attention and are highlighted in this review.

Copper homeostasis and cuproptosis in central nervous system diseases

Copper (Cu), an indispensable micronutrient for the sustenance of living organisms, contributes significantly to a vast array of fundamental metabolic processes. The human body maintains a relatively low concentration of copper, which is mostly found in the bones, liver, and brain. Despite its low concentration, Cu plays a crucial role as an indispensable element in the progression and pathogenesis of central nervous system (CNS) diseases. Extensive studies have been conducted in recent years on copper homeostasis and copper-induced cell death in CNS disorders, including glioma, Alzheimer's disease, Amyotrophic lateral sclerosis, Huntington's disease, and stroke. Cuproptosis, a novel copper-induced cell death pathway distinct from apoptosis, necrosis, pyroptosis, and ferroptosis, has been identified as potentially intricately linked to the pathogenic mechanisms underlying various CNS diseases. Therefore, a systematic review of copper homeostasis and cuproptosis and their relationship with CNS disorders could deepen our understanding of the pathogenesis of these diseases. In addition, it may provide new insights and strategies for the treatment of CNS disorders.

Impact of liver diseases and pharmacological interactions on the transportome involved in hepatic drug disposition

The liver plays a pivotal role in drug disposition owing to the expression of transporters accounting for the uptake at the sinusoidal membrane and the efflux across the basolateral and canalicular membranes of hepatocytes of many different compounds. Moreover, intracellular mechanisms of phases I and II biotransformation generate, in general, inactive compounds that are more polar and easier to eliminate into bile or refluxed back toward the blood for their elimination by the kidneys, which becomes crucial when the biliary route is hampered. The set of transporters expressed at a given time, i.e., the so-called transportome, is encoded by genes belonging to two gene superfamilies named Solute Carriers (SLC) and ATP-Binding Cassette (ABC), which account mainly, but not exclusively, for the uptake and efflux of endogenous substances and xenobiotics, which include many different drugs. Besides the existence of genetic variants, which determines a marked interindividual heterogeneity regarding liver drug disposition among patients, prevalent diseases, such as cirrhosis, non-alcoholic steatohepatitis, primary sclerosing cholangitis, primary biliary cirrhosis, viral hepatitis, hepatocellular carcinoma, cholangiocarcinoma, and several cholestatic liver diseases, can alter the transportome and hence affect the pharmacokinetics of drugs used to treat these patients. Moreover, hepatic drug transporters are involved in many drug-drug interactions (DDI) that challenge the safety of using a combination of agents handled by these proteins. Updated information on these questions has been organized in this article by superfamilies and families of members of the transportome involved in hepatic drug disposition.

Cuproptosis: Mechanisms, biological significance, and advances in disease treatment-A systematic review

BACKGROUND

Copper is an essential trace element for biological systems, as it plays a critical role in the activity of various enzymes and metabolic processes. However, the dysregulation of copper homeostasis is closely associated with the onset and progression of numerous diseases. In recent years, copper-induced cell death, a novel form of cellular demise, has garnered significant attention. This process is characterized by the abnormal accumulation of intracellular copper ions, leading to cellular dysfunction and eventual cell death. Copper toxicity occurs through the interaction of copper with acylated enzymes in the tricarboxylic acid (TCA) cycle. This interaction results in subsequent protein aggregation, causing proteotoxic stress and ultimately resulting in cell death. Despite the promise of these findings, the detailed mechanisms and broader implications of cuproptosis remain underexplored. Therefore, our study aimed to investigate the role of copper in cell death and autophagy, focusing on the molecular mechanisms of cuproptosis. We also aimed to discuss recent advancements in copper-related research across various diseases and tumors, providing insights for future studies and potential therapeutic applications.

MAIN BODY

This review delves into the biological significance of copper metabolism and the molecular mechanisms underlying copper-induced cell death. Furthermore, we discuss the role of copper toxicity in the pathogenesis of various diseases, emphasizing recent advancements in the field of oncology. Additionally, we explore the therapeutic potential of targeting copper toxicity.

CONCLUSION

The study highlights the need for further research to explore alternative pathways of copper-induced cell death, detailed mechanisms of cuproptosis, and biomarkers for copper poisoning. Future research should focus on exploring the molecular mechanisms of cuproptosis, developing new therapeutic strategies, and verifying their safety and efficacy in clinical trials.

Cuproptosis and Cu: a new paradigm in cellular death and their role in non-cancerous diseases

Cuproptosis, a newly characterized form of regulated cell death driven by copper accumulation, has emerged as a significant mechanism underlying various non-cancerous diseases. This review delves into the complex interplay between copper metabolism and the pathogenesis of conditions such as Wilson's disease (WD), neurodegenerative disorders, and cardiovascular pathologies. We examine the molecular mechanisms by which copper dysregulation induces cuproptosis, highlighting the pivotal roles of key copper transporters and enzymes. Additionally, we evaluate the therapeutic potential of copper chelation strategies, which have shown promise in experimental models by mitigating copper-induced cellular damage and restoring physiological homeostasis. Through a comprehensive synthesis of recent advancements and current knowledge, this review underscores the necessity of further research to translate these findings into clinical applications. The ultimate goal is to harness the therapeutic potential of targeting cuproptosis, thereby improving disease management and patient outcomes in non-cancerous conditions associated with copper dysregulation.

Cuproptosis in cancers: Function and implications from bench to bedside

Copper, an indispensable micronutrient, is implicated in numerous vital biological processes and is essential for all physiological activities. Recently, the discovery of a novel type of copper-dependent cell death, known as cuproptosis, has shed light on its role in cancer development. Extensive research is currently underway to unravel the mechanisms underlying cuproptosis and its correlation with various cancer types. In this review, we summarize the findings regarding the roles and mechanisms of cuproptosis in various cancer types, including colorectal cancer, lung cancer, gastric cancer, breast cancer, liver cancer and cutaneous melanoma. Furthermore, the effects of copper-related agents such as copper chelators and copper ionophores on cell proliferation, apoptosis, angiogenesis, tumor immunity, and chemotherapy resistance have been explored in cancer preclinical and clinical trials. These insights provide promising avenues for the development of prospective anticancer drugs aimed at inducing cuproptosis.

Empirically derived formulae for calculation of age- and region-related levels of iron, copper and zinc in the adult C57BL/6 mouse brain

Metal dyshomeostasis is associated with neurodegenerative disorders, cancers and vascular disease. We report the effects of age (range: 3 to 18 months) on regional copper, iron and zinc levels in the brain of the C57BL/6 mouse, a widely used inbred strain with a permissive background allowing maximal expression of mutations in models that recapitulate these disorders. We present formulae that can be used to determine regional brain metal concentrations in the C57BL/6 mouse at any age in the range of three to eighteen months of life. Copper levels in the C57BL/6 mouse adult brain were highest in the striatum and cerebellum and increased with age, excepting the cortex and hippocampus. Regional iron levels increased linearly with age in all brain regions, while regional zinc concentrations became more homogeneous with age. Knockdown of the copper transporter Ctr1 reduced brain copper, but not iron or zinc, concentrations in a regionally-dependent manner. These findings demonstrate biometals in the brain change with age in a regionally-dependent manner. These data and associated formulae have implications for improving design and interpretation of a wide variety of studies in the C57BL/6 mouse.

Dynamic Regulation of Intracellular Labile Cu(I)/Cu(II) Cycle in Microalgae Chlamydomonas reinhardtii: Disrupting the Balance by Cu Stress

The labile metal pool involved in intracellular trafficking and homeostasis is the portion susceptible to environmental stress. Herein, we visualized the different intracellular distributions of labile Cu(I) and Cu(II) pools in the alga Chlamydomonas reinhardtii. We first demonstrated that labile Cu(I) predominantly accumulated in the granules within the cytoplasmic matrix, whereas the labile Cu(II) pool primarily localized in the pyrenoid and chloroplast. The cell cycle played an integral role in balancing the labile Cu(I)/Cu(II) pools. Specifically, the labile Cu(II) pool primarily accumulated during the SM phase following cell division, while the labile Cu(I) pool dynamically changed during the G phase as cell size increased. Notably, the labile Cu(II) pool in algae at the SM stage exhibited heightened sensitivity to environmental Cu stress. Exogenous Cu stress disrupted the intracellular labile Cu(I)/Cu(II) cycle and balance, causing a shift toward the labile Cu(II) pool. Our proteomic analysis further identified a putative cupric reductase, potentially capable of reducing Cu(II) to Cu(I), and four putative multicopper oxidases, potentially capable of oxidizing Cu(I) to Cu(II), which may be involved in the conversion between the labile Cu(I) pool and labile Cu(II) pool. Our study elucidated a dynamic cycle of the intracellular labile Cu(I)/Cu(II) pools, which were accessible and responsive to environmental changes.

Copper homeostasis and cuproptosis in atherosclerosis: metabolism, mechanisms and potential therapeutic strategies

Copper is an essential micronutrient that plays a pivotal role in numerous physiological processes in virtually all cell types. Nevertheless, the dysregulation of copper homeostasis, whether towards excess or deficiency, can lead to pathological alterations, such as atherosclerosis. With the advent of the concept of copper-induced cell death, termed cuproptosis, researchers have increasingly focused on the potential role of copper dyshomeostasis in atherosclerosis. In this review, we provide a broad overview of cellular and systemic copper metabolism. We then summarize the evidence linking copper dyshomeostasis to atherosclerosis and elucidate the potential mechanisms underlying atherosclerosis development in terms of both copper excess and copper deficiency. Furthermore, we discuss the evidence for and mechanisms of cuproptosis, discuss its interactions with other modes of cell death, and highlight the role of cuproptosis-related mitochondrial dysfunction in atherosclerosis. Finally, we explore the therapeutic strategy of targeting this novel form of cell death, aiming to provide some insights for the management of atherosclerosis.

Copper in Gynecological Diseases

Copper (Cu) is an essential micronutrient for the correct development of eukaryotic organisms. This metal plays a key role in many cellular and physiological activities, including enzymatic activity, oxygen transport, and cell signaling. Although the redox activity of Cu is crucial for enzymatic reactions, this property also makes it potentially toxic when found at high levels. Due to this dual action of Cu, highly regulated mechanisms are necessary to prevent both the deficiency and the accumulation of this metal since its dyshomeostasis may favor the development of multiple diseases, such as Menkes' and Wilson's diseases, neurodegenerative diseases, diabetes mellitus, and cancer. As the relationship between Cu and cancer has been the most studied, we analyze how this metal can affect three fundamental processes for tumor progression: cell proliferation, angiogenesis, and metastasis. Gynecological diseases are characterized by high prevalence, morbidity, and mortality, depending on the case, and mainly include benign and malignant tumors. The cellular processes that promote their progression are affected by Cu, and the mechanisms that occur may be similar. We analyze the crosstalk between Cu deregulation and gynecological diseases, focusing on therapeutic strategies derived from this metal.

Novel insights into anticancer mechanisms of elesclomol: More than a prooxidant drug

As an essential micronutrient for humans, the metabolism of copper is fine-tuned by evolutionarily conserved homeostatic mechanisms. Copper toxicity occurs when its concentration exceeds a certain threshold, which has been exploited in the development of copper ionophores, such as elesclomol, for anticancer treatment. Elesclomol has garnered recognition as a potent anticancer drug and has been evaluated in numerous clinical trials. However, the mechanisms underlying elesclomol-induced cell death remain obscure. The discovery of cuproptosis, a novel form of cell death triggered by the targeted accumulation of copper in mitochondria, redefines the significance of elesclomol in cancer therapy. Here, we provide an overview of copper homeostasis and its associated pathological disorders, especially copper metabolism in carcinogenesis. We summarize our current knowledge of the tumor suppressive mechanisms of elesclomol, with emphasis on cuproptosis. Finally, we discuss the strategies that may contribute to better application of elesclomol in cancer therapy.

Copper in hepatocellular carcinoma： A double-edged sword with therapeutic potentials

Copper is a necessary cofactor vital for maintaining biological functions, as well as participating in the development of cancer. A plethora of studies have demonstrated that copper is a double-edged sword, presenting both benefits and detriments to tumors. The liver is a metabolically active organ, and an imbalance of copper homeostasis can result in deleterious consequences to the liver. Hepatocellular carcinoma (HCC), the most common primary liver cancer, is a highly aggressive malignancy with limited viable therapeutic options. As research advances, the focus has shifted towards the relationships between copper and HCC. Innovatively, cuproplasia and cuproptosis have been proposed to depict copper-related cellular growth and death, providing new insights for HCC treatment. By summarizing the constantly elucidated molecular connections, this review discusses the mechanisms of copper in the pathogenesis, progression, and potential therapeutics of HCC. Additionally, we aim to tentatively provide a theoretical foundation and gospel for HCC patients.

Wilson disease complicated by Crohn disease: A case report and literature review

RATIONAL

Wilson disease (WD), also known as hepatolenticular degeneration, is an autosomal-recessive hereditary disease with abnormal copper metabolism. Crohn disease (CD) is a chronic inflammatory gastrointestinal disease, which belongs to inflammatory bowel disease, all segments of the gastrointestinal tract can be affected, especially the terminal ileum and colon, accompanied by extraintestinal manifestations and related immune disorders. WD complicated by ulcerative colitis has been reported before, but WD complicated by CD has not been reported so far.

PATIENT CONCERNS AND DIAGNOSIS

We presented the first report of a young patient with WD complicated by CD, who was admitted to the hospital because of repeated low fever, elevated C-reactive protein for 3 years, and anal fistula for 6 months.

INTERVENTIONS AND OUTCOMES

In this complicated disease, Ustekinumab is safe and effective.

LESSONS

We conclude that copper metabolism and oxidative stress play important roles in WD and CD.

Properties of recombinant extracellular N-terminal domain of human high-affinity copper transporter 1 (hNdCTR1) and its interactions with Cu(II) and Ag(I) ions

High-affinity copper transporter 1 (CTR1) is a key link in the transfer of copper (Cu) from the extracellular environment to the cell. Violation in the control system of its expression, or mutations in this gene, cause a global copper imbalance. However, the mechanism of copper transfer via CTR1 remains unclear. It has been shown that transformed bacteria synthesizing the fused GB1-NdCTR become resistant to toxic silver ions. According to UV-Vis spectrophotometry and isothermal titration calorimetry, electrophoretically pure GB1-NdCTR specifically and reversibly binds copper and silver ions, and binding is associated with aggregation. Purified NdCTR1 forms SDS-resistant oligomers. The link between nontrivial properties of NdCTR1 and copper import mechanism from extracellular space, as well as potential chelating properties of NdCTR1, are discussed.

The Combined Administration of Vitamin C and Copper Induces a Systemic Oxidative Stress and Kidney Injury

Vitamin C (ascorbic acid; AA) and copper (Cu²⁺) are well used supplements with many health-promoting actions. However, when they are used in combination, the Fenton reaction occurs, leading to the formation of highly reactive hydroxyl radicals. Given that kidney is vulnerable to many toxicants including free radicals, we speculated that the in vivo administration of AA plus Cu²⁺ may cause oxidative kidney injury. The purpose of this study was to address this possibility. Mice were administered with AA and Cu²⁺, alone or in combination, via oral gavage once a day for various periods. Changes in the systemic oxidative status, as well renal structure and functions, were examined. The administration of AA plus Cu²⁺ elevated protein oxidation in serum, intestine, bladder, and kidney, as evidenced by the increased sulfenic acid formation and decreased level of free sulfhydryl groups (-SH). The systemic oxidative stress induced by AA plus Cu²⁺ was associated with a significant loss of renal function and structure, as indicated by the increased blood urea nitrogen (BUN), creatinine and urinary proteins, as well as glomerular and tubular cell injury. These effects of AA and Cu²⁺ were only observed when used in combination, and could be entirely prevented by thiol antioxidant NAC. Further analysis using cultured renal tubular epithelial cells revealed that AA plus Cu²⁺ caused cellular protein oxidation and cell death, which could be abolished by NAC and catalase. Moreover, coincubation of AA and Cu²⁺ led to H₂O₂ production. Collectively, our study revealed that a combined administration of AA and Cu²⁺ resulted in systemic oxidative stress and renal cell injury. As health-promoting supplements, AA and Cu²⁺ should not be used together.

Copper homeostasis and cuproptosis in health and disease

As an essential micronutrient, copper is required for a wide range of physiological processes in virtually all cell types. Because the accumulation of intracellular copper can induce oxidative stress and perturbing cellular function, copper homeostasis is tightly regulated. Recent studies identified a novel copper-dependent form of cell death called cuproptosis, which is distinct from all other known pathways underlying cell death. Cuproptosis occurs via copper binding to lipoylated enzymes in the tricarboxylic acid (TCA) cycle, which leads to subsequent protein aggregation, proteotoxic stress, and ultimately cell death. Here, we summarize our current knowledge regarding copper metabolism, copper-related disease, the characteristics of cuproptosis, and the mechanisms that regulate cuproptosis. In addition, we discuss the implications of cuproptosis in the pathogenesis of various disease conditions, including Wilson's disease, neurodegenerative diseases, and cancer, and we discuss the therapeutic potential of targeting cuproptosis.

Decreased Expression of the Slc31a1 Gene and Cytoplasmic Relocalization of Membrane CTR1 Protein in Renal Epithelial Cells: A Potent Protective Mechanism against Copper Nephrotoxicity in a Mouse Model of Menkes Disease

Kidneys play an especial role in copper redistribution in the organism. The epithelial cells of proximal tubules perform the functions of both copper uptake from the primary urine and release to the blood. These cells are equipped on their apical and basal membrane with copper transporters CTR1 and ATP7A. Mosaic mutant mice displaying a functional dysfunction of ATP7A are an established model of Menkes disease. These mice exhibit systemic copper deficiency despite renal copper overload, enhanced by copper therapy, which is indispensable for their life span extension. The aim of this study was to analyze the expression of Slc31a1 and Slc31a2 genes (encoding CTR1/CTR2 proteins) and the cellular localization of the CTR1 protein in suckling, young and adult mosaic mutants. Our results indicate that in the kidney of both intact and copper-injected 14-day-old mutants showing high renal copper content, CTR1 mRNA level is not up-regulated compared to wild-type mice given a copper injection. The expression of the Slc31a1 gene in 45-day-old mice is even reduced compared with intact wild-type animals. In suckling and young copper-injected mutants, the CTR1 protein is relocalized from the apical membrane to the cytoplasm of epithelial cells of proximal tubules, the process which prevents copper transport from the primary urine and, thus, protects cells against copper toxicity.

Copper Modulates Adult Neurogenesis in Brain Subventricular Zone

The subventricular zone (SVZ) in lateral ventricles is the largest neurogenic region in adult brain containing high amounts of copper (Cu). This study aims to define the role of Cu in adult neurogenesis by chelating labile Cu ions using a well-established Cu chelator D-Penicillamine (D-Pen). A neurosphere model derived from adult mouse SVZ tissues was established and characterized for its functionality with regards to neural stem/progenitor cells (NSPCs). Applying D-Pen in cultured neurospheres significantly reduced intracellular Cu levels and reversed the Cu-induced suppression of NSPC’s differentiation and migration. An in vivo intracerebroventricular (ICV) infusion model was subsequently established to infuse D-Pen directly into the lateral ventricle. Metal analyses revealed a selective reduction of Cu in SVZ by 13.1% (p = 0.19) and 21.4% (p < 0.05) following D-Pen infusions at low (0.075 μg/h) and high (0.75 μg/h) doses for 28 days, respectively, compared to saline-infused controls. Immunohistochemical studies revealed that the 7-day, low-dose D-Pen infusion significantly increased Ki67(+)/Nestin(+) cell counts in SVZ by 28% (p < 0.05). Quantification of BrdU(+)/doublecortin (DCX)(+) newborn neuroblasts in the rostral migration stream (RMS) and olfactory bulb (OB) further revealed that the short-term, low-dose D-Pen infusion, as compared with saline-infused controls, resulted in more newborn neuroblasts in OB, while the high-dose D-Pen infusion showed fewer newborn neuroblasts in OB but with more arrested in the RMS. Long-term (28-day) infusion revealed similar outcomes. The qPCR data from neurosphere experiments revealed altered expressions of mRNAs encoding key proteins known to regulate SVZ adult neurogenesis, including, but not limited to, Shh, Dlx2, and Slit1, in response to the changed Cu level in neurospheres. Further immunohistochemical data indicated that Cu chelation also altered the expression of high-affinity copper uptake protein 1 (CTR1) and metallothionein-3 (MT3) in the SVZ as well as CTR1 in the choroid plexus, a tissue regulating brain Cu homeostasis. Taken together, this study provides first-hand evidence that a high Cu level in SVZ appears likely to maintain the stability of adult neurogenesis in this neurogenic zone.

Exposure of metal toxicity in Alzheimer's disease: An extensive review

Metals serve important roles in the human body, including the maintenance of cell structure and the regulation of gene expression, the antioxidant response, and neurotransmission. High metal uptake in the nervous system is harmful because it can cause oxidative stress, disrupt mitochondrial function, and impair the activity of various enzymes. Metal accumulation can cause lifelong deterioration, including severe neurological problems. There is a strong association between accidental metal exposure and various neurodegenerative disorders, including Alzheimer's disease (AD), the most common form of dementia that causes degeneration in the aged. Chronic exposure to various metals is a well-known environmental risk factor that has become more widespread due to the rapid pace at which human activities are releasing large amounts of metals into the environment. Consequently, humans are exposed to both biometals and heavy metals, affecting metal homeostasis at molecular and biological levels. This review highlights how these metals affect brain physiology and immunity and their roles in creating harmful proteins such as β-amyloid and tau in AD. In addition, we address findings that confirm the disruption of immune-related pathways as a significant toxicity mechanism through which metals may contribute to AD.

Effects of Fructose and Stress on Rat Renal Copper Metabolism and Antioxidant Enzymes Function

The effects of a fructose-rich diet and chronic stress on copper metabolism in the kidneys are still understudied. We investigated whether fructose and/or chronic unpredictable stress modulate copper metabolism in a way that affects redox homeostasis, thus contributing to progression of metabolic disturbances in the kidney. We determined protein level of copper transporters, chaperones, and cuproenzymes including cytochrome c oxidase, as well as antioxidant enzymes function in the kidneys of male Wistar rats subjected to 20% liquid fructose supplementation and/or chronic stress. Liquid fructose supplementation increased level of copper chaperone of superoxide dismutase and decreased metallothionein level, while rendering the level of copper importer and copper chaperones involved in copper delivery to mitochondria and trans Golgi network unaffected. Stress had no effect on renal copper metabolism. The activity and expression of renal antioxidant enzymes remained unaltered in all experimental groups. In conclusion, fructose, independently of stress, decreased renal copper level, and modulated renal copper metabolism as to preserve vital cellular function including mitochondrial energy production and antioxidative defense, at the expense of intracellular copper storage.

Review: Bioavailability of trace elements in farm animals: definition and practical considerations for improved assessment of efficacy and safety

Currently, the authorisation procedure of trace elements as feed additives in the European Union according to Regulation (EC) No. 1831/2003 does not consider the bioavailability of trace element sources. This manuscript provides framework conditions for in vivo experiments that aim to estimate differences in the relative bioavailability between supplements of essential trace elements. Framework conditions encompass necessary technical information on the test substance, the experimental design and diet composition as well as the suitability of status parameters that allow for relative comparisons of regression variables. This manuscript evolves recommendations for researchers to conduct solid and reliable experiments on the matter as well as decision makers to interpret the value of studies submitted with authorisation applications regarding a certain trace element supplement.

The Protective Effect of Rheum Ribes L., and Quercetin on Protein Carbonyl Levels Against Carbon Tetrachloride-Induced Liver and Kidney Damage in the Rats

Objective: Carbonyl formation between various oxidative modifications of amino acids in proteins can be an early sign of protein oxidation. Methods: The 2,4-dinitrophenylhydrazine (DNPH) method is the most reliable method widely used to measure carbonyl levels in proteins. In this study, the effect of Rheum ribes L. (Rr) and quercetin on proteın carbonyl, trace elements (Fe, Cu, Zn) and mineral (P) levels against carbon tetrachloride (CCl4) mediated liver and kidney damage was investigated. For this purpose, 56 Wistar albino female rats weighing 200 ± 220 g were used. Groups were designed as: controls, 0.3 ml DMSO, 1 ml/kg olive oil, 1 ml/kg CCl4, 100 mg/kg Rr, 100 mg/kg quercetin, 100 mg/kg Rr+1 ml/kg CCl4 and 100 mg/kg quercetin+1 ml/kg CCl4 groups. Results: Statistical analysis showed that in the CCl4 group was significantly higher than the control, olive oil, Rr., and quercetin groups in the PCO levels (p

Effect of Maternal Catalase Supplementation on Reproductive Performance, Antioxidant Activity and Mineral Transport in Sows and Piglets

This experiment was conducted to investigate the effects of maternal catalase (CAT) supplementation on reproductive performance, antioxidant enzyme activities, mineral transport, and mRNA expression of related genes in sows and offspring. A total of 40 pregnant sows at 95 days of gestation with similar parity (3−5 parities) and back-fat thickness were assigned randomly and equally into the control (CON) group (fed a basal diet) and CAT group (fed a basal diet supplemented with 660 mg/kg CAT; CAT activity, 280 U/g). The reproductive performance was recorded, and the placenta and blood samples of sows and neonatal piglets, as well as the jejunum and ileum samples from neonatal boars (eight replicates per group), were collected. Results showed that dietary supplementation with CAT significantly decreased the intrauterine growth restriction (IUGR) rate and increased the activity of serum CAT in neonatal piglets and umbilical cords (p < 0.05). In addition, CAT supplementation tended to improve total antioxidant capacity (T-AOC) levels in the maternal serum (p = 0.089) and umbilical cords of piglets (p = 0.051). The serum calcium (Ca), manganese (Mn), and zinc (Zn) of farrowing sows and Mn concentration in the umbilical cord, and serum Ca, magnesium (Mg), copper (Cu), and Mn of neonatal piglets were significantly increased (p < 0.05) in the CAT group. CAT supplementation downregulated mRNA expression of TRPV6 and CTR1 (p < 0.05), Cu/Zn SOD (p = 0.086) in the placenta and tended to increase the mRNA expression of the glutathione peroxidase 1 (GPX1) (p = 0.084), glutathione peroxidase 4 (GPX4) (p = 0.063), and CAT (p = 0.052) genes in the ileum of piglets. These results showed that the maternal CAT supplementation improved fetal growth by decreasing the IUGR rate, and modulated antioxidant activity, as well as mineral elements in the pregnant sows and their piglets.

Brain copper clearance by the blood-cerebrospinal fluid-barrier: Effects of lead exposure

Lead (Pb) is a heavy metal commonly found in the environment and is known to have neurotoxic, hematological, and other toxic effects. It has been reported that Pb exposure can disturb metal regulation in the blood-cerebrospinal fluid-barrier (BCB). Copper (Cu) plays a key role in maintaining normal brain function and can accumulate in the brain after Pb exposure. However, the mechanism by which Pb affects Cu levels in the brain is still unknown. This study investigated Cu clearance by the BCB in the central nervous system (CNS) of Sprague-Dawley rats after Pb exposure by focusing on the Cu transporter protein CTR1/ATP7A. Inductively coupled plasma mass spectrometry (ICP-MS) was used to examine how heavy metal levels change in the hippocampus, cortex, and cerebrospinal fluid (CSF) after Pb exposure. Ventriculo-cisternal perfusion measurements suggested that the ability of the BCB to deliver Cu from the CSF to the blood decreased after Pb exposure. The presence of excess Cu in the choroid plexus led to CTR1/ATP7A shifting toward the apical microvilli facing the CSF after Pb exposure. We further evaluated microstructure of the choroid plexus by transmission electron microscopy, revealing altered mitochondrial morphology with decreased microvilli after Pb exposure. Conclusively, exposure to Pb alters the cellular structure of the BCB and its Cu clearance function, which can cause further brain damage.

High glucose induced inflammation is inhibited by copper chelation via rescuing mitochondrial fusion protein 2 in retinal pigment epithelial cells

Altered trace element homeostasis is associated with diabetic complications, and studies have shown elevated copper levels in the serum of individuals with type 1 & 2 diabetes. Copper chelation has been shown to be beneficial by preventing or reversing diabetic organ damage and developing as a new treatment strategy for treating diabetic complications. Diabetic retinopathy is the major vision-threatening complication of diabetes. Recent studies have reported copper to be elevated in the serum of patients with diabetic retinopathy. Here in this study, we attempt to unravel the role of copper chelator penicillamine in retinal pigment epithelial cells exposed to high glucose (HG) and copper as a model for diabetic retinopathy. We have found that high glucose by itself and along with copper alters the mitochondrial morphology, reduces the expression of the mitochondrial fusion protein 2 (MFN2), and induces endoplasmic reticulum (ER) stress and inflammation. Copper chelation with penicillamine reduced all these changes in mitochondria, thereby rescuing the cells from mitochondrial damage and inflammation.

Age-dependent decline of copper clearance at the blood-cerebrospinal fluid barrier

The homeostasis of copper (Cu) in the central nervous system is regulated by the blood-brain barrier and blood-cerebrospinal (CSF) barrier (BCB) in the choroid plexus. While proteins responsible for Cu uptake, release, storage and intracellular trafficking exist in the choroid plexus, the influence of age on Cu clearance from the CSF via the choroid plexus and how Cu transporting proteins contribute to the process are unelucidated. This study was designed to test the hypothesis that the aging process diminishes Cu clearance from the CSF of rats by disrupting Cu transporting proteins in the choroid plexus. Data from ventriculo-cisternal perfusion experiments demonstrated greater ⁶⁴Cu radioactivity in the CSF effluents of older rats (18 months) compared to younger (1 month) and adult (2 months) rats, suggesting much slower removal of Cu by the choroid plexus in old animals. Studies utilizing qPCR and immunofluorescence revealed an age-specific expression pattern of Cu transporting proteins in the choroid plexus. Moreover, proteomic analyses unraveled age-specific proteomes in the choroid plexus with distinct pathway differences, particularly associated with extracellular matrix and neurodevelopment between young and old animals. Taken together, these findings support an age-dependent deterioration in CSF Cu clearance, which appears to be associated with altered subcellular distribution of Cu transporting proteins and proteomes in the choroid plexus.

Crossroads between membrane trafficking machinery and copper homeostasis in the nerve system

Imbalanced copper homeostasis and perturbation of membrane trafficking are two common symptoms that have been associated with the pathogenesis of neurodegenerative and neurodevelopmental diseases. Accumulating evidence from biophysical, cellular and in vivo studies suggest that membrane trafficking orchestrates both copper homeostasis and neural functions-however, a systematic review of how copper homeostasis and membrane trafficking interplays in neurons remains lacking. Here, we summarize current knowledge of the general trafficking itineraries for copper transporters and highlight several critical membrane trafficking regulators in maintaining copper homeostasis. We discuss how membrane trafficking regulators may alter copper transporter distribution in different membrane compartments to regulate intracellular copper homeostasis. Using Parkinson's disease and MEDNIK as examples, we further elaborate how misregulated trafficking regulators may interplay parallelly or synergistically with copper dyshomeostasis in devastating pathogenesis in neurodegenerative diseases. Finally, we explore multiple unsolved questions and highlight the existing challenges to understand how copper homeostasis is modulated through membrane trafficking.

Determination of Renal Distribution of Zinc, Copper, Iron, and Platinum in Mouse Kidney Using LA-ICP-MS

The main dose-limiting side effect of cisplatin is nephrotoxicity. The utilization of cisplatin is an issue of balancing tumour toxicity versus platinum-induced nephrotoxicity. In this study, we focused on intraorgan distribution of common essential trace elements zinc, copper, and iron in healthy mouse kidneys and distribution of platinum after cisplatin treatment. Renal distribution in 12 nontreated Nu-Nu mice (males) was assessed by laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). Furthermore, 9 Nu-Nu mice were treated with cisplatin. The order of elements concentration in kidneys was as follows: Fe > Zn > Cu. All three metals showed the higher concentrations at the cortex and medulla (28.60, 3.35, and 93.83 μg/g for Zn, Cu, and Fe, respectively) and lower concentration at the pelvis and the urinary tract (20.20, 1.93, and 62.48 μg/g for Zn, Cu, and Fe, respectively). No statistically significant difference between cortex and medulla was observed for these elements. After platinum treatment, the concentration of platinum in kidneys was enhanced more than 60-times, p < 0.001. Platinum significantly showed the highest accumulation in cortex (2.11 μg/g) with a gradient distribution. Platinum was less accumulated in medulla and pelvis than in cortex, and the lowest accumulation occurred in the urinary tract (1.13 μg/g). Image processing has been successfully utilized to colocalize metal distribution using LA-ICP-MS and histological samples images.

Systemic Copper Disorders Influence the Olfactory Function in Adult Rats: Roles of Altered Adult Neurogenesis and Neurochemical Imbalance

Disrupted systemic copper (Cu) homeostasis underlies neurodegenerative diseases with early symptoms including olfactory dysfunction. This study investigated the impact of Cu dyshomeostasis on olfactory function, adult neurogenesis, and neurochemical balance. Models of Cu deficiency (CuD) and Cu overload (CuO) were established by feeding adult rats with Cu-restricted diets plus ip. injection of a Cu chelator (ammonium tetrathiomolybdate) and excess Cu, respectively. CuD reduced Cu levels in the olfactory bulb (OB), subventricular zone (SVZ), rostral migratory stream (RMS), and striatum, while CuO increased Cu levels in these areas. The buried pellet test revealed both CuD and CuO prolonged the latency to uncover food. CuD increased neural proliferation and stem cells in the SVZ and newly differentiated neurons in the OB, whereas CuO caused opposite alterations, suggesting a "switch"-type function of Cu in regulating adult neurogenesis. CuO increased GABA in the OB, while both CuD and CuO reduced DOPAC, HVA, 5-HT and the DA turnover rate in olfactory-associated brain regions. Altered mRNA expression of Cu transport and storage proteins in tested brain areas were observed under both conditions. Together, results support an association between systemic Cu dyshomeostasis and olfactory dysfunction. Specifically, altered adult neurogenesis along the SVZ-RMS-OB pathway and neurochemical imbalance could be the factors that may contribute to olfactory dysfunction.

Copper biodistribution after acute systemic administration of copper gluconate to rats

Neurodegenerative disorders have been linked to the decrease of copper concentrations in different regions of the brain. Therefore, intake of micronutrient supplements could be a therapeutic alternative. Since the copper distribution profile has not been elucidated yet, the aim of this study was to characterize and to analyze the concentration profile of a single administration of copper gluconate to rats by two routes of administration. Male Wistar rats were divided into three groups. The control group received vehicle (n = 5), and the experimental groups received 79.5 mg/kg of copper orally (n = 4-6) or 0.64 mg/kg of copper intravenously. (n = 3-4). Blood, striatum, midbrain and liver samples were collected at different times. Copper concentrations were assessed using atomic absorption spectrophotometry. Copper concentration in samples from the control group were considered as baseline. The highest copper concentration in plasma was observed at 1.5 h after oral administration, while copper was quickly compartmentalized within the first hour after intravenous administration. The striatum evidenced a maximum metal concentration at 0.25 h for both routes of administration, however, the midbrain did not show any change. The highest concentration of the metal was held by the liver. The use of copper salts as replacement therapy should consider its rapid and discrete accumulation into the brain and the rapid and massive distribution of the metal into the liver for both oral and intravenous routes. Development of controlled-release pharmaceutical formulations may overcome the problems that the liver accumulation may imply, particularly, for hepatic copper toxicity.

Comparisons of segment-specific toxicity of platinum-based agents and cadmium using S1, S2, and S3 cells derived from mouse kidney proximal tubules

Renal toxicants such as cisplatin and cadmium cause segment-specific damages in kidney proximal tubules. Recently, we established an in vitro experimental system for evaluating segment-specific toxicity and transport of chemicals using immortalized S1, S2, and S3 cells derived from the S1, S2, and S3 regions of mouse kidney proximal tubules. In the present study, we examined the toxicity and accumulation of cisplatin, carboplatin, oxaliplatin, and cadmium in S1, S2, and S3 cells. We found that not only cisplatin but also carboplatin and oxaliplatin exhibited higher lethal toxicity in S3 cells than in S1 and S2 cells. At sublethal doses, cisplatin showed delayed induction of Kim-1 and clusterin on days 3 and 6, which may reflect the latent renal toxicity of cisplatin in vivo. The high sensitivities of S3 cells to the platinum-based agents were not due to the high accumulation of Pt in S3 cells. Exposure to cadmium resulted in similar toxicity among these cells, suggesting that S3 cells were not sensitive to any renal toxicants. Thus, the utilization of S1, S2, and S3 cells may provide a useful tool for the in vitro evaluation of the proximal tubule segment-specific toxicity of chemicals.

"Metal elements and pesticides as risk factors for Parkinson's disease - A review"

Essential metals including iron (Fe) and manganese (Mn) with known physiological functions in human body play an important role in cell homeostasis. Excessive exposure to these essential as well as non-essential metals including mercury (Hg) and Aluminum (Al) may contribute to pathological conditions, including PD. Each metal could be toxic through specific pathways. Epidemiological evidences from occupational and ecological studies besides various in vivo and in vitro studies have revealed the possible pathogenic role and neurotoxicity of different metals. Pesticides are substances that aim to mitigate the harm done by pests to plants and crops, and are extensively used to boost agricultural production. This review provides an outline of our current knowledge on the possible association between metals and PD. We have discussed the potential association between these two, furthermore the chemical properties, biological and toxicological aspects as well as possible mechanisms of Fe, Mn, Cu, Zn, Al, Ca, Pb, Hg and Zn in PD pathogenesis. In addition, we review recent evidence on deregulated microRNAs upon pesticide exposure and possible role of deregulated miRNA and pesticides to PD pathogenesis.

Changes in mammalian copper homeostasis during microbial infection

Animals carefully control homeostasis of Cu, a metal that is both potentially toxic and an essential nutrient. During infection, various shifts in Cu homeostasis can ensue. In mice infected with Candida albicans, serum Cu progressively rises and at late stages of infection, liver Cu rises, while kidney Cu declines. The basis for these changes in Cu homeostasis was poorly understood. We report here that the progressive rise in serum Cu is attributable to liver production of the multicopper oxidase ceruloplasmin (Cp). Through studies using Cp-/- mice, we find this elevated Cp helps recover serum Fe levels at late stages of infection, consistent with a role for Cp in loading transferrin with Fe. Cp also accounts for the elevation in liver Cu seen during infection, but not for the fluctuations in kidney Cu. The Cu exporting ATPase ATP7B is one candidate for kidney Cu control, but we find no change in the pattern of kidney Cu loss during infection of Atp7b-/- mice, implying alternative mechanisms. To test whether fungal infiltration of kidney tissue was required for kidney Cu loss, we explored other paradigms of infection. Infection with the intravascular malaria parasite Plasmodium berghei caused a rise in serum Cu and decrease in kidney Cu similar to that seen with C. albicans. Thus, dynamics in kidney Cu homeostasis appear to be a common feature among vastly different infection paradigms. The implications for such Cu homeostasis control in immunity are discussed.

Molecular Regulation of Copper Homeostasis in the Male Gonad during the Process of Spermatogenesis

Owing to its redox properties, copper is a cofactor of enzymes that catalyze reactions in fundamental metabolic processes. However, copper-oxygen interaction, which is a source of toxic oxygen radicals generated by the Fenton reaction, makes copper a doubled-edged-sword in an oxygen environment. Among the microelements influencing male fertility, copper plays a special role because both copper deficiency and overload in the gonads worsen spermatozoa quality and disturb reproductive function in mammals. Male gametes are produced during spermatogenesis, a multi-step process that consumes large amounts of oxygen. Germ cells containing a high amount of unsaturated fatty acids in their membranes are particularly vulnerable to excess copper-mediated oxidative stress. In addition, an appropriate copper level is necessary to initiate meiosis in premeiotic germ cells. The balance between essential and toxic copper concentrations in germ cells at different stages of spermatogenesis and in Sertoli cells that support their development is handled by a network of copper importers, chaperones, recipient proteins, and exporters. Here, we describe coordinated regulation/functioning of copper-binding proteins expressed in germ and Sertoli cells with special emphasis on copper transporters, copper transporting ATPases, and SOD1, a copper-dependent antioxidant enzyme. These and other proteins assure copper bioavailability in germ cells and protection against copper toxicity.

Copper(II) Binding by the Earliest Vertebrate Gonadotropin-Releasing Hormone, the Type II Isoform, Suggests an Ancient Role for the Metal

In vertebrate reproductive biology copper can influence peptide and protein function both in the pituitary and in the gonads. In the pituitary, copper binds to the key reproductive peptides gonadotropin-releasing hormone I (GnRH-I) and neurokinin B, to modify their structure and function, and in the male gonads, copper plays a role in testosterone production, sperm morphology and, thus, fertility. In addition to GnRH-I, most vertebrates express a second isoform, GnRH-II. GnRH-II can promote testosterone release in some species and has other non-reproductive roles. The primary sequence of GnRH-II has remained largely invariant over millennia, and it is considered the ancestral GnRH peptide in vertebrates. In this work, we use a range of spectroscopic techniques to show that, like GnRH-I, GnRH-II can bind copper. Phylogenetic analysis shows that the proposed copper-binding ligands are retained in GnRH-II peptides from all vertebrates, suggesting that copper-binding is an ancient feature of GnRH peptides.

Phase I study of metformin in combination with carboplatin/paclitaxel chemotherapy in patients with advanced epithelial ovarian cancer

Background Metformin use is associated with reduced cancer risk in epidemiological studies and has preclinical anti-cancer activity in ovarian cancer models. The primary objective of this phase I study was to determine the recommended phase II dose (RP2D) of metformin in combination with carboplatin/paclitaxel in patients with ovarian cancer. Secondary objectives were to describe safety and pharmacokinetics. Methods In this single-center trial the RP2D of metformin in combination with carboplatin area under the concentration-time curve (AUC) 6 and paclitaxel 175 mg/m2 every 3 weeks (q3w) in patients with advanced epithelial ovarian cancer was determined using a 3 + 3 escalation rule at three fixed dose levels: 500 mg three times daily (tds), 850 mg tds and 1000 mg tds. Metformin was commenced on day 3 of cycle 1 and continued until 3 weeks after the last chemotherapy administration. The RP2D was defined as the dose level at which 0 of 3 or ≤ 1 of 6 evaluable subjects experienced a metformin-related dose-limiting toxicity (DLT). Safety was assessed according to CTCAE v4.0. Plasma and serum samples for pharmacokinetic (PK) analyses were collected during treatment cycles 1 and 2. Results Fifteen patients with epithelial ovarian cancer and an indication for neo-adjuvant (n = 5) or palliative (n = 10) treatment were included. No DLTs were observed. Three patients discontinued study treatment during cycle 1 for other reasons than DLT. Six patients were treated at the RP2D of metformin 1000 mg tds. The most frequent low-grade toxicities were anemia, hypomagnesemia and diarrhea. Grade 3 adverse events (AEs) occurred in ten patients, most common were leucopenia (n = 4), thrombocytopenia (n = 3) and increased GGT (n = 3). There were no grade 4 AEs. Metformin increased the platinum (Pt) AUC (Δ22%, p = 0.013) and decreased the Pt clearance (Δ-28%, p = 0.013). Metformin plasma levels were all within the therapeutic range for diabetic patients (0.1-4 mg/L). Conclusion The RP2D of metformin in combination with carboplatin and paclitaxel in advanced ovarian cancer is 1000 mg tds. This is higher than the RP2D reported for combination with targeted agents. A potential PK interaction of metformin with carboplatin was identified.

Molecular machinery providing copper bioavailability for spermatozoa along the epididymial tubule in mouse

Progressive functional maturation of spermatozoa is completed during the transit of these cells through the epididymis, a tubule structure connecting a testicle to a vas deferens. Epididymal epithelial cells by means of their secretory and absorptive functions determine a highly specialized luminal microenvironment containing multiple organic and inorganic components. The latter include copper ions, which due to their redox properties are indispensable for critical homeostatic processes occurring in spermatozoa floating in different part of epididymis but can be potentially toxic. Main purpose of our study was to determine epididymal region-dependent expression and localization of copper transporters ensuring a tight control of copper concentration in epididymal fluid. We also aimed at identifying proteins responsible for copper uptake by spermatozoa and verifying whether this process is coordinated with copper supply to superoxide dismutase 1 (SOD1), a copper-dependent antioxidant enzyme. Our study identifies two ATPases-ATP7A, ATP7B and Slc31a1, major copper importers/exporters depending on their differential expression on epididymal polarized epithelial cells of the caput, corpus, and cauda. Next, ceruloplasmin seems to be a chief protein transporting copper in the epididymal fluid and providing this biometal to spermatozoa. The entry of copper to germ cells is mediated by Slc31a1 and is correlated with both expressions of copper chaperone for superoxide dismutase (CCS), copper chaperone directly providing copper ions to SOD1 and with the expression and activity of the latter. Our results outline a network of cooperating copper binding proteins expressed in epididymal epithelium and in spermatozoa that orchestrate bioavailability of this microelement for gametes and protect them against copper toxicity.

Combining elevated temperature with waterborne copper: Impacts on the energy metabolism of the killifish Poecilia vivipara

We have previously demonstrated in a companion work that acclimation to 28 °C potentiated waterborne copper (Cu) toxic effects in Poecilia vivipara through oxidative stress-related processes. In the present study, we hypothesized that these results were related to kinetic metabolic adjustments in enzymes from aerobic and anaerobic pathways. To test this, P. vivipara was acclimated to two temperatures (22 °C or 28 °C) for three weeks and then exposed to Cu (control, 9 or 20 μg/L) for 96 h. The activity of enzymes from glycolysis (pyruvate kinase [PK] and lactate dehydrogenase [LDH]), Krebs cycle (citrate synthase [CS]) and the electron transport chain system (ETS) were assessed in gills, liver and muscle. Interactive effects were only seen for hepatic LDH activity, as both metal exposure and heat stress, combined or not, inhibited this enzyme, showing a suppression in anaerobic pathways. Conversely, a Cu main effect was present in the liver, expressed as an elevation in ETS activity, showing an enhancement in hepatic aerobic metabolism likely related with the very energy-demanding process of metal detoxification. Moreover, this study shows that P. vivipara has a remarkable ability to compensate heat stress in terms of energy metabolism, as we could not observe acclimation temperature effects for most of the cases. Nonetheless, a tissue-dependent effect of elevated temperature was observed, as we could observe an inhibition in muscular CS activity. Finally, it is concluded that kinetic adjustments in terms of the energy metabolism are not related with the temperature-dependent elevation of Cu toxicity in P. vivipara as we previously hypothesized.

Chronic Copper Exposure Induces Hypospermatogenesis in Mice by Increasing Apoptosis Without Affecting Testosterone Secretion

Chronic copper exposure impaired spermatogenesis in adult male mice. The aim of this study was to determine whether chronic copper exposure can induce apoptosis of testicular cell and hypospermatogenesis via disturbing testosterone synthesis in adult male mice. In the present study, sixty CD-1 male mice were randomly divided into four groups, and were continuously administered for 8 weeks by oral gavage with copper sulfate at a dose of 0, 25, 100, and 150 mg/kg/day, respectively. We determined the content of serum and testicular copper, testicular coefficient, testicular histopathology, sperm count and motility, the mRNA and protein levels of Caspase-3, Bax, and Bcl-2, Leydig cell count, testosterone content, testosterone synthetase, and testosterone synthesis-related genes. The results showed that the copper levels in serum increased in a dose-dependent manner, and the copper levels in testes were significantly related to serum copper levels. Male mice given copper sulfate 100 and 150 dosage groups showed significant decreased in sperm motility and sperm number as well as increased in testes damage, and there was no significant change in testicular coefficient in the four groups. The mRNA levels of Bcl-2 decreased and Caspase-3 increased in 150 dosage group, and Bax increased in two higher dosage groups. Meanwhile, Caspase-3 and Bax proteins increased in 150 dosage group, and Bcl-2 protein decreased in three copper treatment groups. Nevertheless, there were no differences on the levels of testosterone content and testosterone synthetase of 3β-HSD, 17β-HSD, 17α-Hyd, and 20α-Hyd, mRNA levels of Cyp11a1, Cyp17a1, and Star, and quantity of Leydig cells in four groups. Overall, these data showed that chronic copper exposure led to copper residues in the testes, and the doses of 100 and 150 mg/kg/day copper sulfate may induce hypospermatogenesis by increasing apoptosis without affecting testosterone secretion.

Effects of Organic Copper on Growth Performance and Oxidative Stress in Mice

Copper (Cu) has been used as a feed additive for many years. However, high Cu amounts can cause oxidative stress and adversely affect animal performance. Such negative effects may depend on the amounts and forms of Cu. In the present study, the effects of inorganic Cu (CuSO₄) and organic Cu (chelate-Cu) present in mice feed on daily growth rate and Cu deposition in the liver, kidneys, spleen, brain, and serum were assessed in addition to the oxidative stress levels in the liver and brain. Organic Cu at a concentration of 15 mg/kg significantly enhanced daily growth rate in mice, whereas Cu deposition in the livers was significantly lower than that in the inorganic Cu group. Glutathione peroxidase activity in the liver of the mice fed with organic Cu significantly improved, whereas malondialdehyde levels in the brain and liver were significantly lower than that in the inorganic Cu group. The different effects of organic Cu and inorganic Cu provide key evidence supporting the use of organic Cu in animal feeds.

Reduced Neutrophil Extracellular Trap (NET) Formation During Systemic Inflammation in Mice With Menkes Disease and Wilson Disease: Copper Requirement for NET Release

Neutrophil extracellular traps (NETs) contribute to pathological disorders, and their release was directly linked to numerous diseases. With intravital microscopy (IVM), we showed previously that NETs also contribute to the pathology of systemic inflammation and are strongly deposited in liver sinusoids. Over a decade since NET discovery, still not much is known about the metabolic or microenvironmental aspects of their formation. Copper is a vital trace element essential for many biological processes, albeit its excess is potentially cytotoxic; thus, copper levels are tightly controlled by factors such as copper transporting ATPases, ATP7A, and ATP7B. By employing IVM, we studied the impact of copper on NET formation during endotoxemia in liver vasculature on two mice models of copper excess or deficiency, Wilson (ATP7B mutants) and Menkes (ATP7A mutants) diseases, respectively. Here, we show that respective ATP7 mutations lead to diminished NET release during systemic inflammation despite unaltered intrinsic capacity of neutrophils to cast NETs as tested ex vivo. In Menkes disease mice, the in vivo effect is mostly due to diminished neutrophil infiltration of the liver as unmutated mice with a subchronic copper deficiency release even more NETs than their controls during endotoxemia, whereas in Wilson disease mice, excess copper directly diminishes the capacity to release NETs, and this was further confirmed by ex vivo studies on isolated neutrophils co-cultured with exogenous copper and a copper-chelating agent. Taken together, the study extends our understanding on how microenvironmental factors affect NET release by showing that copper is not a prerequisite for NET release but its excess affects the trap casting by neutrophils.

High-precision isotopic analysis of serum and whole blood Cu, Fe and Zn to assess possible homeostasis alterations due to bariatric surgery

Bariatric surgery is an effective procedure to achieve weight loss in obese patients. However, homeostasis of essential metals may be disrupted as the main absorption site is bypassed. In this study, we determined Cu, Fe and Zn isotopic compositions in paired serum and whole blood samples of patients who underwent Roux-en-Y gastric bypass (RYGB) surgery for evaluation of longitudinal changes and their potential relation to mineral element concentrations and relevant clinical parameters used for monitoring the patient's condition. Samples from eight patients were collected pre-surgery and at 3, 6 and 12 months post-surgery. Multi-collector inductively coupled plasma-mass spectrometry (MC-ICP-MS) was used for high-precision isotope ratio measurements. Alterations in metal homeostasis related to bariatric surgery were reflected in the serum and whole blood Cu, Fe and Zn isotopic compositions. The serum and whole blood Cu became isotopically lighter (lower δ⁶⁵Cu values) after bariatric surgery, reaching statistical significance at 6 months post-surgery (p < 0.05). The difference between the serum and the whole blood Zn isotopic composition increased after surgery, reaching significance from 6 months post-surgery onwards (p < 0.05). Those changes in Cu, Fe and Zn isotopic compositions were not accompanied by similar changes in their respective concentrations, making isotopic analysis more sensitive to physiological changes than elemental content. Furthermore, the Zn isotopic composition correlates with blood glycaemic and lipid parameters, while the Fe isotopic composition correlates with glycaemic parameters. Graphical Abstract.

Energy metabolism enzymes inhibition by the combined effects of increasing temperature and copper exposure in the coral Mussismilia harttii

The combined effects of exposure to increasing temperature and copper (Cu) concentrations were evaluated in the zooxanthellate scleractinian coral Mussismilia harttii. Endpoints analyzed included activity of enzymes involved in glycolysis (pyruvate kinase, PK; lactate dehydrogenase, LDH), Krebs cycle (citrate synthase, CS; isocitrate dehydrogenase; IDH), electron transport chain (electron transport system, ETS) and pentose phosphate pathway (glucose-6-phosphate dehydrogenase, G6PDH). Coral polyps were kept under control conditions (25.0 ± 0.1 °C; 2.9 ± 0.7 μg/L Cu) or exposed to combined treatments of increasing temperature (26.6 ± 0.1 °C and 27.3 ± 0.1 °C) and concentrations of dissolved Cu (5.4 ± 0.9 and 8.6 ± 0.3 μg/L) for 4 and 12 days using a mesocosm system. PK activity was not affected by stressors. LDH, CS, IDH, ETS and G6PDH activities were temporally inhibited by stressors alone. CS, ETS and G6PDH activities remained inhibited by the combination of stressors after 12 days. Furthermore, all combinations between increasing temperature and exposure Cu were synergistic after prolonged exposure. Taken together, stressors applied alone led to temporary inhibitory effects on energy metabolism enzymes of the coral M. harttii, however, prolonged exposure reveals strong deleterious effects over the metabolism of corals due to the combination of stressors. The present study is the first one to give insights into the combined effects of increasing temperature and Cu exposure in the energy metabolism enzymes of a scleractinian coral. Findings suggest that moderate Cu contamination in future increasing temperature scenarios can be worrying for aerobic and oxidative metabolism of M. harttii.

Potential role of serotonin as a biological reductant associated with copper transportation

Serotonin (5-HT) is a neurotransmitter that is derived from tryptophan. Owing to a hydroxyl group attached to the indole nucleus, 5-HT exhibits a considerably higher redox activity than tryptophan. To gain insight into the biological relevance of the redox activity of 5-HT, the effect of Cu(I)-binding ligands on the 5-HT-mediated copper reduction was investigated. The d-d transition band of Cu(II) complexed with glycine [Cu(II)-Gly₂] was not affected by addition of 5-HT alone but was diminished when a thioether-containing compound coexists with 5-HT. Concomitant with disappearance of the d-d transition band of Cu(II)-Gly₂, the π-π* transition band of 5-hydroxyindole of 5-HT exhibits a red-shift which is consistently explained by oxidation of 5-HT and subsequent formation of a dimeric species. The redox reactions between 5-HT and copper are also accelerated by a peptide composed of a methionine (Met)-rich region in the extracellular domain of an integral membrane protein, copper transporter 1 (Ctr1). Since Ctr1 transports copper across the plasma membrane with specificity for Cu(I), reduction of extracellular Cu(II) to Cu(I) is required for copper uptake by Ctr1. Metalloreductases that can donate Cu(I) for Ctr1 have been identified in yeast but not yet been found in mammals. The results of this study indicate that the Met-rich region in the N-terminal extracellular domain of Ctr1 promotes the 5-HT-mediated Cu(II) reduction in order to acquire Cu(I) via a non-enzymatic process.

Life-time exposure to waterborne copper III: Effects on the energy metabolism of the killifish Poecilia vivipara

Copper ions (Cu) are essential to life maintenance, nonetheless, elevated concentrations can be hazardous. Acute and sub-chronic toxic effects of this metal are well known and are usually related to enzymatic inhibition, elevated ROS production and dysfunction of energy metabolism. Despite that, chronic studies are extremely rare. Therefore, the aim of this study was to assess the effects of chronic exposure to 5, 9 and 20 μg/L Cu (28 ad 345 days) on the energy metabolism and survival of the killifish Poecilia vivipara. To accomplish that, we evaluated the activity of enzymes related to aerobic (pyruvate kinase (PK); citrate synthase (CS)) and anaerobic metabolism (lactate dehydrogenase (LDH)) in whole-body (28 days) or in gills, liver and muscle (345 days) of exposed fish. Additionally, whole-body oxygen consumption was evaluated in fish exposed for 28 days and hepatic and muscular expression of genes involved in mitochondrial metabolism (cox I, II and III and atp5a1) was assessed in animals exposed for 345 days. Finally, final survival was evaluated. Following 28 days, Cu did not affect survival neither enzyme activities. However, increased whole-body oxygen consumption was observed in comparison to control condition. After 345 days, 76.8%, 63.9%, 60.9% and 0% survival were observed for control, 5, 9 and 20 μg/L groups, respectively. Animals exposed to 5 and 9 μg/L had a significant reduction in branchial and muscular LDH activity and in hepatic PK activity. Also, exposure to 9 μg/L significantly increased hepatic CS activity. For gene expression, Cu down-regulated muscular cox II (9 μg/L) and III (5 and 9 μg/L), and up-regulated hepatic atp5a1 (9 μg/L). Findings reported in the present study indicate that chronic exposure to Cu induces tissue-specific responses in key aspects of the energetic metabolism. In gills and muscle, Cu leads to reduced energy production through inhibition of anaerobic pathways and mitochondrial respiratory chain. This effect is paralleled by an increased ATP consumption in the liver, characterized by the augmented CS activity and atp5a1 expression. Finally, reduced PK activity indicate that oxidative stress may be involved with the observed outcomes.

Localization of Free and Bound Metal Species through X-Ray Synchrotron Fluorescence Microscopy in the Rodent Brain and Their Relation to Behavior

Biometals in the brain, such as zinc, copper, and iron, are often discussed in cases of neurological disorders; however, these metals also have important regulatory functions and mediate cell signaling and plasticity. With the use of synchrotron X-ray fluorescence, our lab localized total, both bound and free, levels of zinc, copper, and iron in a cross section of one hemisphere of a rat brain, which also showed differing metal distributions in different regions within the hippocampus, the site in the brain known to be crucial for certain types of memory. This review discusses the several roles of these metals in brain regions with an emphasis on hippocampal cell signaling, based on spatial mapping obtained from X-ray fluorescence microscopy. We also discuss the localization of these metals and emphasize different cell types and receptors in regions with metal accumulation, as well as the potential relationship between this physiology and behavior.

Cuprous binding promotes interaction of copper transport protein hCTR1 with cell membranes

Cu(i) binding promotes the interaction of hCTR1 with cell membranes, which could initiate the cellular uptake of copper ions.