Role of the P-Type ATPases, ATP7A and ATP7B in brain copper homeostasis

Elements in trace amount with a significant role in human physiology: a tumor pathophysiological and diagnostic aspects

Cancer has a devastating impact globally regardless of gender, age, and community, which continues its severity to the population due to the lack of efficient strategy for the cancer diagnosis and treatment. According to the World Health Organisation report, one out of six people dies due to this deadly cancer and we need effective strategies to regulate it. In this context, trace element has a very hidden and unexplored role and require more attention from investigators. The variation in concentration of trace elements was observed during comparative studies on a cancer patient and a healthy person making them an effective target for cancer regulation. The percentage of trace elements present in the human body depends on environmental exposure, food habits, and habitats and could be instrumental in the early diagnosis of cancer. In this review, we have conducted inclusive analytics on trace elements associated with the various types of cancers and explored the several methods involved in their analysis. Further, intricacies in the correlation of trace elements with prominent cancers like prostate cancer, breast cancer, and leukaemia are represented in this review. This comprehensive information on trace elements proposes their role during cancer and as biomarkers in cancer diagnosis.

The physiological and pathophysiological roles of copper in the nervous system

Copper is a critical trace element in biological systems due the vast number of essential enzymes that require the metal as a cofactor, including cytochrome c oxidase, superoxide dismutase and dopamine-β-hydroxylase. Due its key role in oxidative metabolism, antioxidant defence and neurotransmitter synthesis, copper is particularly important for neuronal development and proper neuronal function. Moreover, increasing evidence suggests that copper also serves important functions in synaptic and network activity, the regulation of circadian rhythms, and arousal. However, it is important to note that because of copper's ability to redox cycle and generate reactive species, cellular levels of the metal must be tightly regulated to meet cellular needs while avoiding copper-induced oxidative stress. Therefore, it is essential that the intricate system of copper transporters, exporters, copper chaperones and copper trafficking proteins function properly and in coordinate fashion. Indeed, disorders of copper metabolism such as Menkes disease and Wilson disease, as well as diseases linked to dysfunction of copper-requiring enzymes, such as SOD1-linked amyotrophic lateral sclerosis, demonstrate the dramatic neurological consequences of altered copper homeostasis. In this review, we explore the physiological importance of copper in the nervous system as well as pathologies related to improper copper handling.

The Role of Copper Overload in Modulating Neuropsychiatric Symptoms

Copper is a transition metal essential for growth and development and indispensable for eukaryotic life. This metal is essential to neuronal function: its deficiency, as well as its overload have been associated with multiple neurodegenerative disorders such as Alzheimer's disease and Wilson's disease and psychiatric conditions such as schizophrenia, bipolar disorder, and major depressive disorders. Copper plays a fundamental role in the development and function of the human Central Nervous System (CNS), being a cofactor of multiple enzymes that play a key role in physiology during development. In this context, we thought it would be timely to summarize data on alterations in the metabolism of copper at the CNS level that might influence the development of neuropsychiatric symptoms. We present a non-systematic review with the study selection based on the authors' judgement to offer the reader a perspective on the most significant elements of neuropsychiatric symptoms in Wilson's disease. We highlight that Wilson's disease is characterized by marked heterogeneity in clinical presentation among patients with the same mutation. This should motivate more research efforts to disentangle the role of environmental factors in modulating the expression of genetic predisposition to this disorder.

STEAP2 promotes hepatocellular carcinoma progression via increased copper levels and stress-activated MAP kinase activity

Six Transmembrane Epithelial Antigen of Prostate 2 (STEAP2) belongs to a family of metalloreductases, which indirectly aid in uptake of iron and copper ions. Its role in hepatocellular carcinoma (HCC) remains to be characterized. Here, we report that STEAP2 expression was upregulated in HCC tumors compared with paired adjacent non-tumor tissues by RNA sequencing, RT-qPCR, Western blotting, and immunostaining. Public HCC datasets demonstrated upregulated STEAP2 expression in HCC and positive association with tumor grade. Transient and stable knockdown (KD) of STEAP2 in HCC cell lines abrogated their malignant phenotypes in vitro and in vivo, while STEAP2 overexpression showed opposite effects. STEAP2 KD in HCC cells led to significant alteration of genes associated with extracellular matrix organization, cell adhesion/chemotaxis, negative enrichment of an invasiveness signature gene set, and inhibition of cell migration/invasion. STEAP2 KD reduced intracellular copper levels and activation of stress-activated MAP kinases including p38 and JNK. Treatment with copper rescued the reduced HCC cell migration due to STEAP2 KD and activated p38 and JNK. Furthermore, treatment with p38 or JNK inhibitors significantly inhibited copper-mediated cell migration. Thus, STEAP2 plays a malignant-promoting role in HCC cells by driving migration/invasion via increased copper levels and MAP kinase activities. Our study uncovered a novel molecular mechanism contributing to HCC malignancy and a potential therapeutic target for HCC treatment.

Integrative analysis of bioinformatics and machine learning to identify cuprotosis-related biomarkers and immunological characteristics in heart failure

Backgrounds

Cuprotosis is a newly discovered programmed cell death by modulating tricarboxylic acid cycle. Emerging evidence showed that cuprotosis-related genes (CRGs) are implicated in the occurrence and progression of multiple diseases. However, the mechanism of cuprotosis in heart failure (HF) has not been investigated yet.

Methods

The HF microarray datasets GSE16499, GSE26887, GSE42955, GSE57338, GSE76701, and GSE79962 were downloaded from the Gene Expression Omnibus (GEO) database to identify differentially expressed CRGs between HF patients and nonfailing donors (NFDs). Four machine learning models were used to identify key CRGs features for HF diagnosis. The expression profiles of key CRGs were further validated in a merged GEO external validation dataset and human samples through quantitative reverse-transcription polymerase chain reaction (qRT-PCR). In addition, Gene Ontology (GO) function enrichment, Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment, and immune infiltration analysis were used to investigate potential biological functions of key CRGs.

Results

We discovered nine differentially expressed CRGs in heart tissues from HF patients and NFDs. With the aid of four machine learning algorithms, we identified three indicators of cuprotosis (DLAT, SLC31A1, and DLST) in HF, which showed good diagnostic properties. In addition, their differential expression between HF patients and NFDs was confirmed through qRT-PCR. Moreover, the results of enrichment analyses and immune infiltration exhibited that these diagnostic markers of CRGs were strongly correlated to energy metabolism and immune activity.

Conclusions

Our study discovered that cuprotosis was strongly related to the pathogenesis of HF, probably by regulating energy metabolism-associated and immune-associated signaling pathways.

Copper Metabolism and Cuproptosis: Molecular Mechanisms and Therapeutic Perspectives in Neurodegenerative Diseases

Copper is an essential trace element, and plays a vital role in numerous physiological processes within the human body. During normal metabolism, the human body maintains copper homeostasis. Copper deficiency or excess can adversely affect cellular function. Therefore, copper homeostasis is stringently regulated. Recent studies suggest that copper can trigger a specific form of cell death, namely, cuproptosis, which is triggered by excessive levels of intracellular copper. Cuproptosis induces the aggregation of mitochondrial lipoylated proteins, and the loss of iron-sulfur cluster proteins. In neurodegenerative diseases, the pathogenesis and progression of neurological disorders are linked to copper homeostasis. This review summarizes the advances in copper homeostasis and cuproptosis in the nervous system and neurodegenerative diseases. This offers research perspectives that provide new insights into the targeted treatment of neurodegenerative diseases based on cuproptosis.

Fluorescence-Based Proteoliposome Methods to Monitor Redox-Active Transition Metal Transmembrane Translocation by Metal Transporters

Transmembrane transition metal transporter proteins are central gatekeepers in selectively controlling vectorial metal cargo uptake and extrusion across cellular membranes in all living organisms, thus playing key roles in essential and toxic metal homeostasis. Biochemical characterization of transporter-mediated translocation events and transport kinetics of redox-active metals, such as iron and copper, is challenged by the complexity in generating reconstituted systems in which vectorial metal transport can be studied in real time. We present fluorescence-based proteoliposome methods to monitor redox-active metal transmembrane translocation upon reconstitution of purified metal transporters in artificial lipid bilayers. By encapsulating turn-on/-off iron or copper-dependent sensors in the proteoliposome lumen and conducting real-time transport assays using small unilamellar vesicles (SUVs), in which selected purified Fe(II) and Cu(I) transmembrane importer and exporter proteins have been reconstituted, we provide a platform to monitor metal translocation events across lipid bilayers in real time. The strategy is modular and expandable toward the study of different transporter families featuring diverse metal substrate selectivity and promiscuity.

Copper-transporting ATPases throughout the animal evolution - From clinics to basal neuron-less animals

Copper-transporting ATPases are a group of heavy metal-transporting proteins and which can be found in all living organisms. In animals, they are generally referred to as ATP7 proteins and are involved in many different physiological processes including the maintaining of copper homeostasis and the supply of copper to cuproenzymes. A single ATP7 gene is present in non-chordate animals while it is divided into ATP7A and ATP7B in chordates. In humans, dysfunction of ATP7 proteins can lead to severe genetic disorders, such as, Menkes disease and Wilson's disease, which are characterized by abnormal copper transport and accumulation, causing significant health complications. Therefore, there is a substantial amount of research on ATP7 genes and ATP7 proteins in humans and mice to understand pathophysiological conditions and find potential therapeutic interventions. Copper-transporting ATPases have also been investigated in some non-mammalian vertebrates, protostomes, single-cellular eukaryotes, prokaryotes, and archaea to gain useful evolutionary insights. However, ATP7 function in many animals has been somewhat neglected, particularly in non-bilaterians. Previous reviews on this topic only broadly summarized the available information on the function and evolution of ATP7 genes and ATP7 proteins and included only the classic vertebrate and invertebrate models. Given this, and the fact that a considerable amount of new information on this topic has been published in recent years, the present study was undertaken to provide an up-to-date, comprehensive summary of ATP7s/ATP7s and give new insights into their evolutionary relationships. Additionally, this work provides a framework for studying these genes and proteins in non-bilaterians. As early branching animals, they are important to understand the evolution of function of these proteins and their important role in copper homeostasis and neurotransmission.

Distribution of non-ceruloplasmin-bound copper after i.v. 64Cu injection studied with PET/CT in patients with Wilson disease

Background & Aims

In Wilson disease (WD), copper accumulation and increased non-ceruloplasmin-bound copper in plasma lead to liver and brain pathology. To better understand the fate of non-ceruloplasmin-bound copper, we used PET/CT to examine the whole-body distribution of intravenously injected 64-copper (64Cu).

Methods

Eight patients with WD, five heterozygotes, and nine healthy controls were examined by dynamic PET/CT for 90 min and static PET/CT up to 20 h after injection. We measured 64Cu activity in blood and tissue and quantified the kinetics by compartmental analysis.

Results

Initially, a large fraction of injected 64Cu was distributed to extrahepatic tissues, especially skeletal muscle. Thus, across groups, extrahepatic tissues accounted for 45-58% of the injected dose (%ID) after 10 min, and 45-55% after 1 h. Kinetic analysis showed rapid exchange of 64Cu between blood and muscle as well as adipose tissue, with 64Cu retention in a secondary compartment, possibly mitochondria. This way, muscle and adipose tissue may protect the brain from spikes in non-ceruloplasmin-bound copper. Tiny amounts of cerebral 64Cu were detected (0.2%ID after 90 min and 0.3%ID after 6 h), suggesting tight control of cerebral copper in accordance with a cerebral clearance that is 2-3-fold lower than in muscle. Compared to controls, patients with WD accumulated more hepatic copper 6-20 h after injection, and also renal copper at 6 h.

Conclusion

Non-ceruloplasmin-bound copper is initially distributed into a number of tissues before being redistributed slowly to the eliminating organ, the liver. Cerebral uptake of copper is extremely slow and likely highly regulated. Our findings provide new insights into the mechanisms of copper control.

Impact and implications

Maintaining non-ceruloplasmin-bound copper within the normal range is an important treatment goal in WD as this "free" copper is considered toxic to the liver and brain. We found that intravenously injected non-ceruloplasmin-bound copper quickly distributed to a number of tissues, especially skeletal muscle, subcutaneous fat, and the liver, while uptake into the brain was slow. This study offers new insights into the mechanisms of copper control, which may encourage further research into potential new treatment targets.

Clinical trial number

2016-001975-59.

Genetic diversity, tissue-specific expression, and functional analysis of the ATP7A gene in sheep

In humans, variation of the ATP7A gene may cause cranial exostosis, which is similar to "human horn," but the function of the ATP7A gene in sheep is still unknown. Tissue expression patterns and potential functional loci analysis of the ATP7A gene could help understand its function in sheep horn. In this study, we first identified tissue, sex, breed, and species-specific expression of the ATP7A gene in sheep based on the RNA-sequencing (RNA-seq) data. Second, the potential functional sites of the ATP7A gene were analyzed by using the whole genome sequencing (WGS) data of 99 sheep from 10 breeds. Last, the allele-specific expression of the ATP7A gene was explored. Our result showed the ATP7A gene has significantly higher expression in the big horn than in the small horn, and the ATP7A gene has high expression in the horn and skin, suggesting that this gene may be related to the horn. The PCA results show that the region around the ATP7A can distinguish horned and hornless groups to some extent, further indicating that the ATP7A may be related to horns. When compared with other species, we find seven ruminate specific amino acid sites of the ATP7A protein, which can be important to the ruminate horn. By analyzing WGS, we found 6 SNP sites with significant differences in frequency in horned and hornless populations, and most of these variants are present in the intron. But we still find some potential functional sites, including three missenses, three synonymous mutations, and four Indels. Finally, by combining the RNA-seq and WGS functional loci results, we find three mutations that showed allele-specific expression between big and small horns. This study shows that the ATP7A gene in sheep may be related to horn size, and several potential functional sites we identified here can be useful molecular markers for sheep horn breeding.

Identification of Cuproptosis Clusters and Integrative Analyses in Parkinson's Disease

Parkinson's disease (PD) is the second most common neurodegenerative disease; it mainly occurs in the elderly population. Cuproptosis is a newly discovered form of regulated cell death involved in the progression of various diseases. Combining multiple GEO datasets, we analyzed the expression profile and immunity of cuproptosis-related genes (CRGs) in PD. Dysregulated CRGs and differential immune responses were identified between PD and non-PD substantia nigra. Two CRG clusters were defined in PD. Immune analysis suggested that CRG cluster 1 was characterized by a high immune response. The enrichment analysis showed that CRG cluster 1 was significantly enriched in immune activation pathways, such as the Notch pathway and the JAK-STAT pathway. KIAA0319, AGTR1, and SLC18A2 were selected as core genes based on the LASSO analysis. We built a nomogram that can predict the occurrence of PD based on the core genes. Further analysis found that the core genes were significantly correlated with tyrosine hydroxylase activity. This study systematically evaluated the relationship between cuproptosis and PD and established a predictive model for assessing the risk of cuproptosis subtypes and the outcome of PD patients. This study provides a new understanding of PD-related molecular mechanisms and provides new insights into the treatment of PD.

Molecular Characterization of Indigenous Rhizobia from Kenyan Soils Nodulating with Common Beans

Kenya is the seventh most prominent producer of common beans globally and the second leading producer in East Africa. However, the annual national productivity is low due to insufficient quantities of vital nutrients and nitrogen in the soils. Rhizobia are symbiotic bacteria that fix nitrogen through their interaction with leguminous plants. Nevertheless, inoculating beans with commercial rhizobia inoculants results in sparse nodulation and low nitrogen supply to the host plants because these strains are poorly adapted to the local soils. Several studies describe native rhizobia with much better symbiotic capabilities than commercial strains, but only a few have conducted field studies. This study aimed to test the competence of new rhizobia strains that we isolated from Western Kenya soils and for which the symbiotic efficiency was successfully determined in greenhouse experiments. Furthermore, we present and analyze the whole-genome sequence for a promising candidate for agricultural application, which has high nitrogen fixation features and promotes common bean yields in field studies. Plants inoculated with the rhizobial isolate S3 or with a consortium of local isolates (COMB), including S3, produced a significantly higher number of seeds and seed dry weight when compared to uninoculated control plants at two study sites. The performance of plants inoculated with commercial isolate CIAT899 was not significantly different from uninoculated plants (p > 0.05), indicating tight competition from native rhizobia for nodule occupancy. Pangenome analysis and the overall genome-related indices showed that S3 is a member of R. phaseoli. However, synteny analysis revealed significant differences in the gene order, orientation, and copy numbers between S3 and the reference R. phaseoli. Isolate S3 is phylogenomically similar to R. phaseoli. However, it has undergone significant genome rearrangements (global mutagenesis) to adapt to harsh conditions in Kenyan soils. Its high nitrogen fixation ability shows optimal adaptation to Kenyan soils, and the strain can potentially replace nitrogenous fertilizer application. We recommend that extensive fieldwork in other parts of the country over a period of five years be performed on S3 to check on how the yield changes with varying whether conditions.

Lead exposure disturbs ATP7B-mediated copper export from brain barrier cells by inhibiting XIAP-regulated COMMD1 protein degradation

The brain barrier is an important structure for metal ion homeostasis. According to studies, lead (Pb) exposure disrupts the transportation of copper (Cu) through the brain barrier, which may cause impairment of the nervous system; however, the specific mechanism is unknown. The previous studies suggested the X-linked inhibitor of apoptosis (XIAP) is a sensor for cellular Cu level which mediate the degradation of the MURR1 domain-containing 1 (COMMD1) protein. XIAP/COMMD1 axis was thought to be an important regulator in Cu metabolism maintenance. In this study, the role of XIAP-regulated COMMD1 protein degradation in Pb-induced Cu disorders in brain barrier cells was investigated. Pb exposure significantly increased Cu levels in both cell types, according to atomic absorption technology testing. Western blotting and reverse transcription PCR (RT-PCR) showed that COMMD1 protein levels were significantly increased, whereas XIAP, ATP7A, and ATP7B protein levels were significantly decreased. However, there were no significant effects at the messenger RNA (mRNA) level (XIAP, ATP7A, and ATP7B). Pb-induced Cu accumulation and ATP7B expression were reduced when COMMD1 was knocked down by transient small interfering RNA (siRNA) transfection. In addition, transient plasmid transfection of XIAP before Pb exposure reduced Pb-induced Cu accumulation, increased COMMD1 protein levels, and decreased ATP7B levels. In conclusion, Pb exposure can reduce XIAP protein expression, increase COMMD1 protein levels, and specifically decrease ATP7B protein levels, resulting in Cu accumulation in brain barrier cells.

Construction of diagnostic prediction model for Wilson's disease

Background

Wilson's disease, also known as hepatolenticular degeneration, is a rare human autosomal recessive inherited disorder of copper metabolism. The clinical manifestations are diverse, and the diagnosis and treatment are often delayed. The purpose of this study is to establish a new predictive diagnostic model of Wilson's disease and evaluate its predictive efficacy by multivariate regression analysis of small trauma, good accuracy, low cost, and quantifiable serological indicators, in order to identify Wilson's disease early, improve the diagnosis rate, and clarify the treatment plan.

Methods

A retrospective analysis was performed on 127 patients with Wilson's disease admitted to the First People's Hospital of Yunnan Province from January 2003 to May 2022 as the experimental group and 73 patients with normal serological indicators who were not diagnosed with Wilson's disease. SPSS version 26.0 software was used for single factor screening and a multivariate binary logistic regression analysis to screen out independent factors. R version 4.1.0 software was used to establish an intuitive nomogram prediction model for the independent influencing factors included. The accuracy of the nomogram prediction model was evaluated and quantified by calculating the concordance index (C-index) and drawing the calibration curve. At the same time, the area under the curve (AUC) of the nomogram prediction model and the receiver operating characteristic (ROC) curve of the Leipzig score was calculated to compare the predictive ability of the nomogram model and the current Leipzig score for Wilson's disease.

Results

Alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (AKP), albumin (ALB), uric acid (UA), serum calcium (Ca), serum phosphorus (P), and hemoglobin (HGB) are closely related to the occurrence of Wilson's disease (p < 0.1). The prediction model of Wilson's disease contains seven independent predictors: ALT, AST, AKP, ALB, UA, Ca, and P. The AUC value of the prediction model was 0.971, and the C-index value was 0.972. The calibration curve was well fitted with the ideal curve. The nomogram prediction model had a good predictive effect on the occurrence of Wilson's disease; the ROC curve of Leipzig score was drawn, and the AUC value was calculated. The AUC of the Leipzig score was 0.969, indicating that the prediction model and the scoring system had predictive value, and the nomogram prediction model had a better predictive effect on the research objects of the center.

Conclusion

ALT, AST, AKP, ALB, UA, Ca, and P are independent predictors of Wilson's disease, and can be used as early predictors. Based on the nomogram prediction model, the optimal threshold was determined to be 0.698, which was an important reference index for judging Wilson's disease. Compared with the Leipzig score, the nomogram prediction model has a relatively high sensitivity and specificity and has a good clinical application value.

Clinical and genetic characterization of pediatric patients with Wilson's disease from Yunnan province where ethnic minorities gather

Background: Wilson's disease (WD) is an autosomal recessive disease that is caused by mutations in the ATP7B (a copper-transporting P-type ATPase) gene. The disease has a low prevalence and is characterized by a copper metabolism disorder. However, various characteristics of the disease are determined by race and geographic region. We aimed to discover novel ATP7B mutations in pediatric patients with WD from Yunnan province, where there is a high proportion of ethnic minorities. We also performed a comprehensive analysis of ATP7B mutations in the different ethnic groups found in Southwest China. Methods: We recruited 45 patients who had been clinically diagnosed with WD, from 44 unrelated families. Routine clinical examinations and laboratory evaluations were performed and details of age, gender, ethnic group and symptoms at onset were collected. Direct sequencing of the ATP7B gene was performed in 39 of the 45 patients and their families. Results: In this study, participants came from seven different ethnic groups in China: Han, Bai, Dai, Zhuang, Yi, Hui and Jingpo. Three out of ten patients from ethnic minorities presented with elevated transaminases, when compared to the majority of the Han patients. Forty distinct mutations (28 missense, six splicing, three non-sense, two frameshift and one mutation of uncertain significance) were identified in the 39 patients with WD. Four of the mutations were novel and the most frequent mutation was c.2333G > T (p.R778L, allelic frequency: 15.38%). Using the phenotype-genotype correlation analysis, patients from ethnic minorities were shown to be more likely to have homozygous mutations (p = 0.035) than Han patients. The patients who carried the c.2310C > G mutation had lower serum ceruloplasmin levels (p = 0.012). In patients with heterozygous mutations, c.3809A > G was significantly associated with ethnic minorities (p = 0.042). The frequency of a protein-truncating variant (PTV) in Han patients was 34.38% (11/32), while we did not find PTV in patients from ethnic minorities. Conclusion: This study revealed genetic defects in 39 pediatric patients with WD from Yunnan province. Four novel mutations were identified and have enriched the WD database. We characterized the genotypes and phenotypes in different minorities, which will enhance the current knowledge on the population genetics of WD in China.

Toxic effects and transcriptional responses in zebrafish liver cells following perfluorooctanoic acid exposure

As a typical type of persistent organic pollutant, perfluorooctanoic acid (PFOA) is pervasive in the environment. Multiple studies have found that PFOA has hepatotoxicity, but the mechanism remains poorly understood. In this study, the toxic effects of different concentrations of PFOA on zebrafish liver cells were systematically assessed by recording cell survival, ultrastructural observations, and transcriptome analyses. The results showed that the inhibition of cell viability and the massive accumulation of autophagic vacuoles were observed at 400 µM PFOA, while transcriptomic changes occurred with treatments of 1 and 400 µM PFOA. The transcription levels of 1055 (977 up- and 78 down-regulated genes) and 520 (446 up- and 74 down-regulated genes) genes were significantly changed after treatment with 1 and 400 µM PFOA, respectively. Based on Kyoto encyclopedia of genes and genomes (KEGG) enrichment analysis, significant expression changes were observed in autophagy, tight junction, signal transduction, immune system, endocrine system, and metabolism-related pathways, indicating that such processes were greatly affected by PFOA exposure. The findings of this study will provide a scientific basis for the toxic effects and potential toxic mechanisms of PFOA on zebrafish, and provide information for ecological risk assessments.

Chelation Combination-A Strategy to Mitigate the Neurotoxicity of Manganese, Iron, and Copper?

The chelating thiol dimercaptosuccinate (DMSA) and the traditional agent D-penicillamine (PSH) are effective in enhancing the urinary excretion of copper (Cu) and lead (Pb) in poisoned individuals. However, DMSA, PSH, EDTA (ethylenediamine tetraacetate), and deferoxamine (DFOA) are water-soluble agents with limited access to the central nervous system (CNS). Strategies for mobilization of metals such as manganese (Mn), iron (Fe), and Cu from brain deposits may require the combined use of two agents: one water-soluble agent to remove circulating metal into urine, in addition to an adjuvant shuttler to facilitate the brain-to-blood mobilization. The present review discusses the chemical basis of metal chelation and the ligand exchange of metal ions. To obtain increased excretion of Mn, Cu, and Fe, early experiences showed promising results for CaEDTA, PSH, and DFOA, respectively. Recent experiments have indicated that p-amino salicylate (PAS) plus CaEDTA may be a useful combination to remove Mn from binding sites in CNS, while the deferasirox-DFOA and the tetrathiomolybdate-DMSA combinations may be preferable to promote mobilization of Fe and Cu, respectively, from the CNS. Further research is requested to explore benefits of chelator combinations.

Association of cerebral spinal fluid copper imbalance in amyotrophic lateral sclerosis

A plethora of environmental risk factors has been persistently implicated in the pathogenesis of amyotrophic lateral sclerosis (ALS), including metal/metalloids. This study aimed to examine potential associations between cerebral spinal fluid (CSF) metal/metalloids and ALS risks. CSF concentrations of copper (Cu), nickel (Ni), mercury (Hg), arsenic (As), manganese (Mn), and iron (Fe) in ALS (spinal- and bulbar-onset) patients and controls were measured using inductively coupled plasma mass spectrometry (ICP-MS). Results from this study revealed marked differences between control, spinal-onset, and bulbar-onset groups. We report that Cu levels were lower in the ALS and spinal-onset groups compared to the control group. Ni level were higher in the spinal-onset group compared to the control and bulbar-onset groups. In addition, associations between CSF metal/metalloid levels with disease severity, sex, and serum triglycerides were also examined to broach the potential relevance of neurotoxic metal/metalloids in ALS disease heterogeneity.

The Role of Copper Homeostasis in Brain Disease

In the human body, copper is an important trace element and is a cofactor for several important enzymes involved in energy production, iron metabolism, neuropeptide activation, connective tissue synthesis, and neurotransmitter synthesis. Copper is also necessary for cellular processes, such as the regulation of intracellular signal transduction, catecholamine balance, myelination of neurons, and efficient synaptic transmission in the central nervous system. Copper is naturally present in some foods and is available as a dietary supplement. Only small amounts of copper are typically stored in the body and a large amount of copper is excreted through bile and urine. Given the critical role of copper in a breadth of cellular processes, local concentrations of copper and the cellular distribution of copper transporter proteins in the brain are important to maintain the steady state of the internal environment. The dysfunction of copper metabolism or regulatory pathways results in an imbalance in copper homeostasis in the brain, which can lead to a myriad of acute and chronic pathological effects on neurological function. It suggests a unique mechanism linking copper homeostasis and neuronal activation within the central nervous system. This article explores the relationship between impaired copper homeostasis and neuropathophysiological progress in brain diseases.

Disrupting Cu trafficking as a potential therapy for cancer

Copper ions play a crucial role in various cellular biological processes. However, these copper ions can also lead to toxicity when their concentration is not controlled by a sophisticated copper-trafficking system. Copper dys-homeostasis has been linked to a variety of diseases, including neurodegeneration and cancer. Therefore, manipulating Cu-trafficking to trigger selective cancer cell death may be a viable strategy with therapeutic benefit. By exploiting combined in silico and experimental strategies, we identified small peptides able to bind Atox1 and metal-binding domains 3-4 of ATP7B proteins. We found that these peptides reduced the proliferation of cancer cells owing to increased cellular copper ions concentration. These outcomes support the idea of harming copper trafficking as an opportunity for devising novel anti-cancer therapies.

Neuroimaging Correlates of Cognitive Deficits in Wilson's Disease

BACKGROUND

Cognitive impairment is common in neurological presentations of Wilson's disease (WD). Various domains can be affected, and subclinical deficits have been reported in patients with hepatic presentations. Associations with imaging abnormalities have not been systematically tested.

OBJECTIVE

The aim was to determine the neuroanatomical basis for cognitive deficits in WD.

METHODS

We performed a 16-item neuropsychological test battery and magnetic resonance brain imaging in 40 patients with WD. The scores for each test were compared between patients with neurological and hepatic presentations and with normative data. Associations with Unified Wilson's Disease Rating Scale neurological examination subscores were examined. Quantitative, whole-brain, multimodal imaging analyses were used to identify associations with neuroimaging abnormalities in chronically treated stable patients.

RESULTS

Abstract reasoning, executive function, processing speed, calculation, and visuospatial function scores were lower in patients with neurological presentations than in those with hepatic presentations and correlated with neurological examination subscores. Deficits in abstract reasoning and phonemic fluency were associated with lower putamen volumes even after controlling for neurological severity. About half of patients with hepatic presentations had poor performance in memory for faces, cognitive flexibility, or associative learning relative to normative data. These deficits were associated with widespread cortical atrophy and/or white matter diffusion abnormalities.

CONCLUSIONS

Subtle cognitive deficits in patients with seemingly hepatic presentations represent a distinct neurological phenotype associated with diffuse cortical and white matter pathology. This may precede the classical neurological phenotype characterized by movement disorders and executive dysfunction and be associated with basal ganglia damage. A binary phenotypic classification for WD may no longer be appropriate. © 2022 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Calcium and the Ca-ATPase SPCA1 modulate plasma membrane abundance of ZIP8 and ZIP14 to regulate Mn(II) uptake in brain microvascular endothelial cells

Manganese (II) accumulation in human brain microvascular endothelial cells is mediated by the metal-ion transporters ZRT IRT-like protein 8 (ZIP8) and ZRT IRT-like protein 14 (ZIP14). The plasma membrane occupancy of ZIP14, in particular, is increased in cells treated with Mn²⁺, lipopolysaccharide, or IL-6, but the mechanism of this regulation has not been elucidated. The calcium-transporting type 2C member 1 ATPase, SPCA1, is a Golgi-localized Ca²⁺-uptake transporter thought to support Golgi uptake of Mn²⁺ also. Here, we show using surface protein biotinylation, indirect immunofluorescence, and GFP-tagged proteins that cytoplasmic Ca²⁺ regulates ZIP8- and ZIP14-mediated manganese accumulation in human brain microvascular endothelial cells by increasing the plasma membrane localization of these transporters. We demonstrate that RNAi knockdown of SPCA1 expression results in an increase in cytoplasmic Ca²⁺ levels. In turn, we found increased cytoplasmic Ca²⁺ enhances membrane-localized ZIP8 and ZIP14 and a subsequent increase in ⁵⁴Mn²⁺ uptake. Furthermore, overexpression of WT SPCA1 or a gain-of-function mutant resulted in a decrease in cytoplasmic Ca²⁺ and ⁵⁴Mn²⁺ accumulation. While addition of Ca²⁺ positively regulated ZIP-mediated ⁵⁴Mn²⁺ uptake, we show chelation of Ca²⁺ diminished manganese transport. In conclusion, the modulation of ZIP8 and ZIP14 membrane cycling by cytoplasmic calcium is a novel finding and provides new insight into the regulation of the uptake of Mn²⁺ and other divalent metal ions–mediated ZIP metal transporters.

Polarized trafficking and copper transport activity of ATP7B: a mutational approach to establish genotype-phenotype correlation in Wilson disease

Mutation in ATP7B gene causes Wilson disease (WD) that is characterized by severe hepatic and neurological symptoms. ATP7B localizes at the trans-Golgi Network (TGN) transporting copper to copper-dependent enzymes and traffics in apically targeted vesicles upon intracellular copper elevation. To decode the cellular underpinnings of WD manifestation we investigated copper-responsive polarized trafficking and copper transport activity of fifteen WD causing point mutations in ATP7B. Amino-terminal mutations Gly85Val, Leu168Pro and Gly591Asp displayed TGN and sub-apical localization whereas, Leu492Ser mislocalized at the basolateral region. The actuator domain mutation Gly875Arg shows retention in the endoplasmic reticulum (ER), Ala874Val and Leu795Phe show partial targeting to TGN and post-Golgi vesicles. The Nucleotide-Binding Domain mutations His1069Gln and Leu1083Phe also display impaired targeting. The C-terminal mutations Leu1373Pro/Arg is arrested at ER but Ser1423Asn shows TGN localization. Transmembrane mutant Arg778Leu resides in ER and TGN while Arg969Gln is exclusively ER localized. Cellular Cu level does not alter the targeting of any of the studied mutations. Mutants that traffic to TGN exhibits biosynthetic function. Finally, we correlated cellular phenotypes with the clinical manifestation of the two most prevalent mutations; the early onset and more aggressive WD caused by Arg778Leu and the milder form of WD caused by mutation His1069Gln. This article is protected by copyright. All rights reserved.

Identification of a novel homozygous SCO2 variant in siblings with early-onset axonal Charcot-Marie-Tooth disease

The synthesis of cytochrome c oxidase 2 (SCO2) gene encodes for a mitochondrial located metallochaperone essential for the synthesis of the cytochrome c oxidase (COX) subunit 2. Recessive mutations in SCO2 have been reported in several cases with fatal infantile cardioencephalomyopathy with COX deficiency and in only four cases with axonal neuropathy. Here, we identified a homozygous pathogenic variant (c.361G>C; p.(Gly121Arg)) in SCO2 in two brothers with isolated axonal motor neuropathy. To address pathogenicity of the amino acid substitution, biochemical studies were performed and revealed increased level of the mutant SCO2-protein and a dysregulation of COX subunits in leukocytes and moreover unraveled decrease of proteins involved in the manifestation of neuropathies. Hence, our combined data strengthen the concept of SCO2 being causative for a very rare form of axonal neuropathy, expand its molecular genetic spectrum and provide first biochemical insights into the underlying pathophysiology. This article is protected by copyright. All rights reserved.

Golgi Metal Ion Homeostasis in Human Health and Diseases

The Golgi apparatus is a membrane organelle located in the center of the protein processing and trafficking pathway. It consists of sub-compartments with distinct biochemical compositions and functions. Main functions of the Golgi, including membrane trafficking, protein glycosylation, and sorting, require a well-maintained stable microenvironment in the sub-compartments of the Golgi, along with metal ion homeostasis. Metal ions, such as Ca²⁺, Mn²⁺, Zn²⁺, and Cu²⁺, are important cofactors of many Golgi resident glycosylation enzymes. The homeostasis of metal ions in the secretory pathway, which is required for proper function and stress response of the Golgi, is tightly regulated and maintained by transporters. Mutations in the transporters cause human diseases. Here we provide a review specifically focusing on the transporters that maintain Golgi metal ion homeostasis under physiological conditions and their alterations in diseases.

Comparative assessment of blood Metal/metalloid levels, clinical heterogeneity, and disease severity in amyotrophic lateral sclerosis patients

Amyotrophic lateral sclerosis is an unremitting neurodegenerative (ND) disease characterized by progressive and fatal loss of motor neuron function. While underlying mechanisms for ALS susceptibility are complex, current understanding suggests that interactions between age, genetic, and environmental factors may be the key. Environmental exposure to metal/metalloids has been implicated in various ND diseases including ALS, Alzheimer's Disease (AD), and Parkinson's Disease (PD). However, most of currently available population-based ALS studies in relation to metal exposure are based on individuals from European ancestry, while East Asian populations, especially cohorts from China, are less well-characterized. This study aims to examine the association between metal/metalloid levels and ALS onset by evaluating blood cadmium (Cd), lead (Pb), Cu, Zn, calcium (Ca), magnesium (Mg), and iron (Fe) levels in controls and sporadic ALS patients from North Western China. We report that Cu and Fe levels are found at higher levels in ALS patients compared to the controls. Spinal and bulbar onset patients show significant difference in Ca levels. Moreover, Cd, Pb, Cu, and Ca levels are positively correlated with high disease severity. Results from this study may provide new insights for understanding not only the role of metal/metalloids in ALS susceptibility, but also progression and forms of onset.

Bis-choline tetrathiomolybdate prevents copper-induced blood-brain barrier damage

The blood–brain barrier endothelial cell monolayer becomes permeable to elevated copper loosely bound to albumin, which can be avoided by a high-affinity copper chelator but not by D-penicillamine.

In Wilson disease, excessive copper accumulates in patients’ livers and may, upon serum leakage, severely affect the brain according to current viewpoints. Present remedies aim at avoiding copper toxicity by chelation, for example, by D-penicillamine (DPA) or bis-choline tetrathiomolybdate (ALXN1840), the latter with a very high copper affinity. Hence, ALXN1840 may potentially avoid neurological deterioration that frequently occurs upon DPA treatment. As the etiology of such worsening is unclear, we reasoned that copper loosely bound to albumin, that is, mimicking a potential liver copper leakage into blood, may damage cells that constitute the blood-brain barrier, which was found to be the case in an in vitro model using primary porcine brain capillary endothelial cells. Such blood–brain barrier damage was avoided by ALXN1840, plausibly due to firm protein embedding of the chelator bound copper, but not by DPA. Mitochondrial protection was observed, a prerequisite for blood–brain barrier integrity. Thus, high-affinity copper chelators may minimize such deterioration in the treatment of neurologic Wilson disease.

PLEKHA5, PLEKHA6, and PLEKHA7 bind to PDZD11 to target the Menkes ATPase ATP7A to the cell periphery and regulate copper homeostasis

Copper homeostasis is crucial for cellular physiology and development, and its dysregulation leads to disease. The Menkes ATPase ATP7A plays a key role in copper efflux, by trafficking from the Golgi to the plasma membrane upon cell exposure to elevated copper, but the mechanisms that target ATP7A to the cell periphery are poorly understood. PDZD11 interacts with the C-terminus of ATP7A, which contains sequences involved in ATP7A trafficking, but the role of PDZD11 in ATP7A localization is unknown. Here we identify PLEKHA5 and PLEKHA6 as new interactors of PDZD11 that bind to the PDZD11 N-terminus through their WW domains similarly to the junctional protein PLEKHA7. Using CRISPR-KO kidney epithelial cells, we show by immunofluorescence microscopy that WW-PLEKHAs (PLEKHA5, PLEKHA6, PLEKHA7) recruit PDZD11 to distinct plasma membrane localizations and that they are required for the efficient anterograde targeting of ATP7A to the cell periphery in elevated copper conditions. Pull-down experiments show that WW-PLEKHAs promote PDZD11 interaction with the C-terminus of ATP7A. However, WW-PLEKHAs and PDZD11 are not necessary for ATP7A Golgi localization in basal copper, ATP7A copper-induced exit from the Golgi, and ATP7A retrograde trafficking to the Golgi. Finally, measuring bioavailable and total cellular copper, metallothionein-1 expression, and cell viability shows that WW-PLEKHAs and PDZD11 are required for maintaining low intracellular copper levels when cells are exposed to elevated copper. These data indicate that WW-PLEKHAs-PDZD11 complexes regulate the localization and function of ATP7A to promote copper extrusion in elevated copper.

Dynamic and cell-specific transport networks for intracellular copper ions

Copper (Cu) homeostasis is essential for the development and function of many organisms. In humans, Cu misbalance causes serious pathologies and has been observed in a growing number of diseases. This Review focuses on mammalian Cu(I) transporters and highlights recent studies on regulation of intracellular Cu fluxes. Cu is used by essential metabolic enzymes for their activity. These enzymes are located in various intracellular compartments and outside cells. When cells differentiate, or their metabolic state is otherwise altered, the need for Cu in different cell compartments change, and Cu has to be redistributed to accommodate these changes. The Cu transporters SLC31A1 (CTR1), SLC31A2 (CTR2), ATP7A and ATP7B regulate Cu content in cellular compartments and maintain Cu homeostasis. Increasing numbers of regulatory proteins have been shown to contribute to multifaceted regulation of these Cu transporters. It is becoming abundantly clear that the Cu transport networks are dynamic and cell specific. The comparison of the Cu transport machinery in the liver and intestine illustrates the distinct composition and dissimilar regulatory response of their Cu transporters to changing Cu levels.

Wilson's disease: update on pathogenesis, biomarkers and treatments

Wilson's disease is an autosomal-recessive disorder of copper metabolism caused by mutations in ATP7B and associated with neurological, psychiatric, ophthalmological and hepatic manifestations. Decoppering treatments are used to prevent disease progression and reduce symptoms, but neurological outcomes remain mixed. In this article, we review the current understanding of pathogenesis, biomarkers and treatments for Wilson's disease from the neurological perspective, with a focus on recent advances. The genetic and molecular mechanisms associated with ATP7B dysfunction have been well characterised, but despite extensive efforts to identify genotype-phenotype correlations, the reason why only some patients develop neurological or psychiatric features remains unclear. We discuss pathological processes through which copper accumulation leads to neurodegeneration, such as mitochondrial dysfunction, the role of brain iron metabolism and the broader concept of selective neuronal vulnerability in Wilson's disease. Delayed diagnoses continue to be a major problem for patients with neurological presentations. We highlight limitations in our current approach to making a diagnosis and novel diagnostic biomarkers, including the potential for newborn screening programmes. We describe recent progress in developing imaging and wet (fluid) biomarkers for neurological involvement, including findings from quantitative MRI and other neuroimaging studies, and the development of a semiquantitative scoring system for assessing radiological severity. Finally, we cover the use of established and novel chelating agents, paradoxical neurological worsening, and progress developing targeted molecular and gene therapy for Wilson's disease, before discussing future directions for translational research.

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.

Role of zinc and copper ions in the pathogenetic mechanisms of traumatic brain injury and Alzheimer's disease

The disruption of homeostasis of zinc (Zn2+) and copper (Cu2+) ions in the central nervous system is involved in the pathogenesis of many neurodegenerative diseases, such as amyotrophic lateral sclerosis, Wilson's, Creutzfeldt-Jakob, Parkinson's, and Alzheimer's diseases (AD), and traumatic brain injury (TBI). The last two pathological conditions of the brain are the most common; moreover, it is possible that TBI is a risk factor for the development of AD. Disruptions of Zn2+ and Cu2+ homeostasis play an important role in the mechanisms of pathogenesis of both TBI and AD. This review attempts to summarize and systematize the currently available research data on this issue. The neurocytotoxicity of Cu2+ and Zn2+, the synergism of the toxic effect of calcium and Zn2+ ions on the mitochondria of neurons, and the interaction of Zn2+ and Cu2+ with β-amyloid (Abeta) and tau protein are considered.

Autism spectrum disorder: Trace elements imbalances and the pathogenesis and severity of autistic symptoms

The identification of biomarkers as diagnostic tools and predictors of response to treatment of neurological developmental disorders (NDD) such as schizophrenia (SZ), attention deficit hyperactivity disorder (ADHD), or autism spectrum disorder (ASD), still remains an important challenge for clinical medicine. Metallomic profiles of ASD patients cover, besides essential elements such as cobalt, chromium, copper, iron, manganese, molybdenum, zinc, selenium, also toxic metals burden of: aluminum, arsenic, mercury, lead, beryllium, nickel, cadmium. Performed studies indicate that children with ASD present a reduced ability of eliminating toxic metals, which leads to these metals' accumulation and aggravation of autistic symptoms. Extensive metallomic studies allow a better understanding of the importance of trace elements as environmental factors in the pathogenesis of ASD. Even though a mineral imbalance is a fact in ASD, we are still expecting relevant tests and the elaboration of reference levels of trace elements as potential biomarkers useful in diagnosis, prevention, and treatment of ASD.

Copper: An Intracellular Achilles' Heel Allowing the Targeting of Epigenetics, Kinase Pathways, and Cell Metabolism in Cancer Therapeutics

Copper is an essential transition metal frequently increased in cancer known to strongly influence essential cellular processes. Targeted therapy protocols utilizing both novel and repurposed drug agents initially demonstrate strong efficacy, before failing in advanced cancers as drug resistance develops and relapse occurs. Overcoming this limitation involves the development of strategies and protocols aimed at a wider targeting of the underlying molecular changes. Receptor Tyrosine Kinase signaling pathways, epigenetic mechanisms and cell metabolism are among the most common therapeutic targets, with molecular investigations increasingly demonstrating the strong influence each mechanism exerts on the others. Interestingly, all these mechanisms can be influenced by intracellular copper. We propose that copper chelating agents, already in clinical trial for multiple cancers, may simultaneously target these mechanisms across a wide variety of cancers, serving as an excellent candidate for targeted combination therapy. This review summarizes the known links between these mechanisms, copper, and copper chelation therapy.

A Comprehensive Analysis and Splicing Characterization of Naturally Occurring Synonymous Variants in the ATP7B Gene

Next-generation sequencing is effective for the molecular diagnosis of genetic diseases. However, the identification of the clinical significance of synonymous variants remains a challenge. Our previous study showed that some synonymous variants in ATP7B gene produced splicing disruptions, leading to Wilson disease (WD). To test the hypothesis that synonymous variants of ATP7B cause abnormal splicing by disrupting authentic splice sites or splicing regulatory elements, we used computational tools and minigene assays to characterize 253 naturally occurring ATP7B gene synonymous variants in this study. Human Splicing Finder (HSF) and ESE Finder 3.0 were used to predict the impact of these rare synonymous variants on pre-mRNA splicing. Then, we cloned 14 different wild-type Minigene_ATP7B_ex constructs for in vitro minigene assay, including 16 exons of ATP7B gene. After computational prediction, 85 candidate variants were selected to be introduced into the corresponding Minigene_ATP7B_ex constructs for splicing assays. Using this two-step procedure, we demonstrated that 11 synonymous variants in ExAc database (c.1620C>T, c.3888C>T, c.1554C>T, c.1677C>T, c.1830G>A, c.1875T>A, c.2826C>A, c.4098G>A, c.2994C>T, c.3243G>A, and c.3747G>A) disrupted RNA splicing in vitro, and two (c.1620C>T and c.3243G>A) of these caused a complete exon skipping. The results not only provided a reliable experimental basis for the genetic diagnosis of WD patients but also offered some new insights into the pathogenicity of synonymous variants in genetic diseases.

Markers of copper transport in the cingulum bundle in schizophrenia

Imaging and postmortem studies indicate that schizophrenia subjects exhibit abnormal connectivity in several white matter tracts, including the cingulum bundle. Copper chelators given to experimental animals damage myelin and myelin-producing oligodendrocytes, and the substantia nigra of schizophrenia subjects shows lower levels of copper, copper transporters, and copper-utilizing enzymes. This study aimed to elucidate the potential role of copper homeostasis in white matter pathology in schizophrenia. Protein levels of the copper transporters ATP7A and CTR1, and dysbindin-1, an upstream modulator of copper metabolism and schizophrenia susceptibility factor, were measured using Western blot analyses of the postmortem cingulum bundle of schizophrenia subjects (n=16) and matched controls (n=13). Additionally, the patient group was subdivided by treatment status: off- (n=8) or on-medication (n=8). Relationships between proteins from the current study were correlated among themselves and markers of axonal integrity previously measured in the same cohort. Schizophrenia subjects exhibited similar protein levels to controls, with no effect of antipsychotic treatment. The dysbindin-1A/1BC relationship was positive in controls and schizophrenia subjects; however, antipsychotic treatment appeared to reverse this relationship in a statistically different manner from that of controls and unmedicated subjects. The relationships between dysbindin-1A/neurofilament heavy and ATP7A/α-tubulin were positively correlated in the schizophrenia group that was significantly different from the lack of correlation in controls. Copper transporters and dysbindin-1 appear to be more significantly affected in the grey matter of schizophrenia subjects. However, the relationships among proteins in white matter may be more substantial and dependent on treatment status.

Plasma Neurofilament Light as a Biomarker of Neurological Involvement in Wilson's Disease

BACKGROUND

Outcomes are unpredictable for neurological presentations of Wilson's disease (WD). Dosing regimens for chelation therapy vary and monitoring depends on copper indices, which do not reflect end-organ damage.

OBJECTIVE

To identify a biomarker for neurological involvement in WD.

METHODS

Neuronal and glial-specific proteins were measured in plasma samples from 40 patients and 38 age-matched controls. Patients were divided into neurological or hepatic presentations and those with recent neurological presentations or deterioration associated with non-adherence were subcategorized as having active neurological disease. Unified WD Rating Scale scores and copper indices were recorded.

RESULTS

Unlike copper indices, neurofilament light (NfL) concentrations were higher in neurological than hepatic presentations. They were also higher in those with active neurological disease when controlling for severity and correlated with neurological examination subscores in stable patients.

CONCLUSION

NfL is a biomarker of neurological involvement with potential use in guiding chelation therapy and clinical trials for novel treatments. © 2020 University College London. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Retromer retrieves the Wilson disease protein ATP7B from endolysosomes in a copper-dependent manner

The Wilson disease protein, ATP7B maintains copper (herein referring to the Cu+ ion) homeostasis in the liver. ATP7B traffics from trans-Golgi network to endolysosomes to export excess copper. Regulation of ATP7B trafficking to and from endolysosomes is not well understood. We investigated the fate of ATP7B after copper export. At high copper levels, ATP7B traffics primarily to acidic, active hydrolase (cathepsin-B)-positive endolysosomes and, upon subsequent copper chelation, returns to the trans-Golgi network (TGN). At high copper, ATP7B colocalizes with endolysosomal markers and with a core member of retromer complex, VPS35. Knocking down VPS35 did not abrogate the copper export function of ATP7B or its copper-responsive anterograde trafficking to vesicles; rather upon subsequent copper chelation, ATP7B failed to relocalize to the TGN, which was rescued by overexpressing wild-type VPS35. Overexpressing mutants of the retromer complex-associated proteins Rab7A and COMMD1 yielded a similar non-recycling phenotype of ATP7B. At high copper, VPS35 and ATP7B are juxtaposed on the same endolysosome and form a large complex that is stabilized by in vivo photoamino acid labeling and UV-crosslinking. We demonstrate that retromer regulates endolysosome to TGN trafficking of copper transporter ATP7B in a manner that is dependent upon intracellular copper.

Abnormal Levels of Metal Micronutrients and Autism Spectrum Disorder: A Perspective Review

The aim of the present review is to summarize the prevalence of abnormal levels of various metal micronutrients including copper (Cu), iron (Fe), magnesium (Mg), zinc (Zn), and selenium (Se) in Autism Spectrum Disorder (ASD) using hair, nail and serum samples. A correlation of selected abnormal metal ions with known neurodevelopmental processes using Gene Ontology (GO) term was also conducted. Data included in this review are derived from ASD clinical studies performed globally. Metal ion disparity data is also analyzed and discussed based on gender (Male/Female) to establish any gender dependent correlation. Finally, a rational perspective and possible path to better understand the role of metal micronutrients in ASD is suggested.

Copper Dyshomeostasis in Neurodegenerative Diseases-Therapeutic Implications

Copper is one of the most abundant basic transition metals in the human body. It takes part in oxygen metabolism, collagen synthesis, and skin pigmentation, maintaining the integrity of blood vessels, as well as in iron homeostasis, antioxidant defense, and neurotransmitter synthesis. It may also be involved in cell signaling and may participate in modulation of membrane receptor-ligand interactions, control of kinase and related phosphatase functions, as well as many cellular pathways. Its role is also important in controlling gene expression in the nucleus. In the nervous system in particular, copper is involved in myelination, and by modulating synaptic activity as well as excitotoxic cell death and signaling cascades induced by neurotrophic factors, copper is important for various neuronal functions. Current data suggest that both excess copper levels and copper deficiency can be harmful, and careful homeostatic control is important. This knowledge opens up an important new area for potential therapeutic interventions based on copper supplementation or removal in neurodegenerative diseases including Wilson’s disease (WD), Menkes disease (MD), Alzheimer’s disease (AD), Parkinson’s disease (PD), and others. However, much remains to be discovered, in particular, how to regulate copper homeostasis to prevent neurodegeneration, when to chelate copper, and when to supplement it.

A complementary study approach unravels novel players in the pathoetiology of Hirschsprung disease

Hirschsprung disease (HSCR, OMIM 142623) involves congenital intestinal obstruction caused by dysfunction of neural crest cells and their progeny during enteric nervous system (ENS) development. HSCR is a multifactorial disorder; pathogenetic variants accounting for disease phenotype are identified only in a minority of cases, and the identification of novel disease-relevant genes remains challenging. In order to identify and to validate a potential disease-causing relevance of novel HSCR candidate genes, we established a complementary study approach, combining whole exome sequencing (WES) with transcriptome analysis of murine embryonic ENS-related tissues, literature and database searches, in silico network analyses, and functional readouts using candidate gene-specific genome-edited cell clones. WES datasets of two patients with HSCR and their non-affected parents were analysed, and four novel HSCR candidate genes could be identified: ATP7A, SREBF1, ABCD1 and PIAS2. Further rare variants in these genes were identified in additional HSCR patients, suggesting disease relevance. Transcriptomics revealed that these genes are expressed in embryonic and fetal gastrointestinal tissues. Knockout of these genes in neuronal cells demonstrated impaired cell differentiation, proliferation and/or survival. Our approach identified and validated candidate HSCR genes and provided further insight into the underlying pathomechanisms of HSCR.

Copper metabolism as a unique vulnerability in cancer

The last 25 years have witnessed tremendous progress in identifying and characterizing proteins that regulate the uptake, intracellular trafficking and export of copper. Although dietary copper is required in trace amounts, sufficient quantities of this metal are needed to sustain growth and development in humans and other mammals. However, copper is also a rate-limiting nutrient for the growth and proliferation of cancer cells. Oral copper chelators taken with food have been shown to confer anti-neoplastic and anti-metastatic benefits in animals and humans. Recent studies have begun to identify specific roles for copper in pathways of oncogenic signaling and resistance to anti-neoplastic drugs. Here, we review the general mechanisms of cellular copper homeostasis and discuss roles of copper in cancer progression, highlighting metabolic vulnerabilities that may be targetable in the development of anticancer therapies.

Activity-Based Sensing with a Metal-Directed Acyl Imidazole Strategy Reveals Cell Type-Dependent Pools of Labile Brain Copper

Copper is a required nutrient for life and particularly important to the brain and central nervous system. Indeed, copper redox activity is essential to maintaining normal physiological responses spanning neural signaling to metabolism, but at the same time copper misregulation is associated with inflammation and neurodegeneration. As such, chemical probes that can track dynamic changes in copper with spatial resolution, especially in loosely bound, labile forms, are valuable tools to identify and characterize its contributions to healthy and disease states. In this report, we present an activity-based sensing (ABS) strategy for copper detection in live cells that preserves spatial information by a copper-dependent bioconjugation reaction. Specifically, we designed copper-directed acyl imidazole dyes that operate through copper-mediated activation of acyl imidazole electrophiles for subsequent labeling of proximal proteins at sites of elevated labile copper to provide a permanent stain that resists washing and fixation. To showcase the utility of this new ABS platform, we sought to characterize labile copper pools in the three main cell types in the brain: neurons, astrocytes, and microglia. Exposure of each of these cell types to physiologically relevant stimuli shows distinct changes in labile copper pools. Neurons display translocation of labile copper from somatic cell bodies to peripheral processes upon activation, whereas astrocytes and microglia exhibit global decreases and increases in intracellular labile copper pools, respectively, after exposure to inflammatory stimuli. This work provides foundational information on cell type-dependent homeostasis of copper, an essential metal in the brain, as well as a starting point for the design of new activity-based probes for metals and other dynamic signaling and stress analytes in biology.

Neurodevelopmental disorders: Metallomics studies for the identification of potential biomarkers associated to diagnosis and treatment

BACKGROUND

Diagnosis and treatment of complex diseases such as Neurodevelopmental Disorders (NDDs) can be resolved through the identification of biomarkers. Metallomics (research on biometals) and metallomes (metalloproteins/metalloenzymes/chaperones) along with genomics, proteomics and metabolomics, can contribute to accelerate and improve this process.

AIM

This review focused on four NDDs pathologies (Schizophrenia, SZ; Attention Deficit Hyperactivity Disorder, ADHD; Autism, ADS; Epilepsy), and we reported, for the first time, different studies on the role played by the principal six essential trace elements (Cobalt, Co; Copper, Cu; Iron, Fe; Manganese, Mn; Selenium, Se; Zinc, Zn) that can influence diagnosis/treatment.

RESULTS

in light of the literature presented, based on meta-analyses, we suggest that Zn (glutamatergic neurotransmission, inflammation, neurodegeneration, autoimmunity alterations), could be a potential diagnostic biomarker associated to SZ. Moreover, considering the single association studies going in the same direction, increased Cu (catecholamine alterations, glucose intolerance, altered lipid metabolism/oxidative stress) and lower Fe (dopaminergic dysfunctions) levels were associated with a specific negative symptomatology. Lower Mn (lipid metabolism/oxidative stress alterations), and lower Se (metabolic syndrome) were linked to SZ. From the meta-analyses in ADHD, it is evidenced that Fe (and ferritin in particular), Mn, and Zn (oxidative stress dysfunctions) could be potential diagnostic biomarkers, mainly associated to severe hyperactive or inattentive symptoms; as well as Cu, Fe, Zn in ADS and Zn in Epilepsy. Fe, Zn and Mn levels seem to be influenced by antipsychotics treatment in SZ; Mn and Zn by methylphenidate treatment in ADHD; Cu and Zn by antiepileptic drugs in Epilepsy.

CONCLUSIONS

Although there is controversy and further studies are needed, this work summarizes the state of art of the literature on this topic. We claim to avoid underreporting the impact of essential trace elements in paving the way for biomarkers research for NDDs.

Agricultural Use of Copper and Its Link to Alzheimer's Disease

Copper is an essential nutrient for plants, animals, and humans because it is an indispensable component of several essential proteins and either lack or excess are harmful to human health. Recent studies revealed that the breakdown of the regulation of copper homeostasis could be associated with Alzheimer's disease (AD), the most common form of dementia. Copper accumulation occurs in human aging and is thought to increase the risk of AD for individuals with a susceptibility to copper exposure. This review reports that one of the leading causes of copper accumulation in the environment and the human food chain is its use in agriculture as a plant protection product against numerous diseases, especially in organic production. In the past two decades, some countries and the EU have invested in research to reduce the reliance on copper. However, no single alternative able to replace copper has been identified. We suggest that agroecological approaches are urgently needed to design crop protection strategies based on the complementary actions of the wide variety of crop protection tools for disease control.

The Effect of a Rat Diet Without Added Cu on Redox Status in Tissues and Epigenetic Changes in the Brain

The aim of the study was to determine whether feeding rats a diet without added Cu increases oxidation of macromolecules in tissues, as well as epigenetic changes in the brain. The rats were divided into two groups: the Cu-6.5 group which was fed a diet with a standard content of Cu in mineral mixture – 6.5 mg Cu from CuCO3 per kg of diet; and the Cu-0 group which was fed a diet with a mineral mix without Cu supplementation. At the end of the experiment the rats were weighed and blood samples were collected. Finally, the rats were euthanized and then the liver, small intestine, spleen, kidneys, heart, brain, lung, testes and leg muscles were removed and weighed. In the blood of Cu-0 rats the lower Cp activity and greater GPx and CAT activity than in Cu-6.5 rats were noticed. In the liver, lungs, heart and testes of Cu-0 rats, a decreased content of Cu were noticed. Application of Cu-0 diets resulted in increased LOOH level in the small intestine, liver, and heart, as well as increased MDA content in the liver, spleen, lungs, brain and testes. The Cu-0 treatment caused a decrease in SOD activity in the heart, lungs and testes of the rats and a decrease in CAT activity in the small intestine. In the brain and testes of rats from the Cu-0 treatment, lower content of GSH + GSSG was observed. The brain of rats from the Cu-0 treatment showed an increase in the level of PCs, 8-OHdG, Casp 8 and DNA methylation. The research has shown that a deficiency of Cu in the diet impairs the body’s antioxidant defences, which in turn leads to increased lipid oxidation in the liver, small intestinal wall, heart, spleen, lungs, brain and testes, as well as to oxidation of proteins and DNA in the brain. A deficiency of Cu in the diet also increases methylation of cytosine in the brain.

Subcellular Localization of Copper-Cellular Bioimaging with Focus on Neurological Disorders

As an essential trace element, copper plays a pivotal role in physiological body functions. In fact, dysregulated copper homeostasis has been clearly linked to neurological disorders including Wilson and Alzheimer’s disease. Such neurodegenerative diseases are associated with progressive loss of neurons and thus impaired brain functions. However, the underlying mechanisms are not fully understood. Characterization of the element species and their subcellular localization is of great importance to uncover cellular mechanisms. Recent research activities focus on the question of how copper contributes to the pathological findings. Cellular bioimaging of copper is an essential key to accomplish this objective. Besides information on the spatial distribution and chemical properties of copper, other essential trace elements can be localized in parallel. Highly sensitive and high spatial resolution techniques such as LA-ICP-MS, TEM-EDS, S-XRF and NanoSIMS are required for elemental mapping on subcellular level. This review summarizes state-of-the-art techniques in the field of bioimaging. Their strengths and limitations will be discussed with particular focus on potential applications for the elucidation of copper-related diseases. Based on such investigations, further information on cellular processes and mechanisms can be derived under physiological and pathological conditions. Bioimaging studies might enable the clarification of the role of copper in the context of neurodegenerative diseases and provide an important basis to develop therapeutic strategies for reduction or even prevention of copper-related disorders and their pathological consequences.

ATPase copper transporter A, negatively regulated by miR-148a-3p, contributes to cisplatin resistance in breast cancer cells

BACKGROUND

Breast cancer is the leading cause of death among women. Cisplatin is an effective drug for breast cancer, but resistance often develops during long term chemotherapy. While the mechanism of chemotherapy resistance is still not fully understood.

METHODS

Survival analyses of ATP7A and ATP7B were used to evaluate their effects on the development of Breast invasive carcinoma (BRCA). Immunostaining, flow cytometry, and IC50 assay were utilized to examine the effects of ATP7A-siRNA combined with cisplatin on apoptosis in breast cancer cells. Q-PCR, western blotting, and dual-luciferase assay were employed to confirm ATP7A is a novel target gene of miR-148a-3p.

RESULTS

In this current study, we identified knocking-down ATP7A could enhance cytotoxicity treatment of cisplatin in breast cancer cells. We also demonstrated miR-148a-3p overexpression in BRCA cells increased the sensitivity to cisplatin, and subsequently enhanced DNA damage and apoptosis. Moreover, we found ATP7A is a novel target gene of miR-148a-3p. In brief, our results showed miR-148a could accelerate chemotherapy induced-apoptosis in breast cancer cells by inhibiting ATP7A expression.

CONCLUSIONS

Our results highlight that inhibition of ATP7A is a potential strategy for targeting breast cancer resistant to cisplatin, and we provided an interesting method to compare the involvement of various genes in the assessment of cisplatin resistance.