Presenilin promotes dietary copper uptake

Muscle Psn gene combined with exercise contribute to healthy aging of skeletal muscle and lifespan by adaptively regulating Sirt1/PGC-1α and arm pathway

The Presenilin (Psn) gene is closely related to aging, but it is still unclear the role of Psn genes in skeletal muscle. Here, the Psn-UAS/Mhc-GAL4 system in Drosophila was used to regulate muscle Psn overexpression(MPO) and muscle Psn knockdown(MPK). Drosophila were subjected to endurance exercise from 4 weeks to 5 weeks old. The results showed that MPO and exercise significantly increased climbing speed, climbing endurance, lifespan, muscle SOD activity, Psn expression, Sirt1 expression, PGC-1α expression, and armadillo (arm) expression in aged Drosophila, and they significantly decreased muscle malondialdehyde levels. Interestingly, when the Psn gene is knockdown by 0.78 times, the PGC-1α expression and arm expression were also down-regulated, but the exercise capacity and lifespan were increased. Furthermore, exercise combined with MPO further improved the exercise capacity and lifespan. MPK combined with exercise further improves the exercise capacity and lifespan. Thus, current results confirmed that the muscle Psn gene was a vital gene that contributed to the healthy aging of skeletal muscle since whether it was overexpressed or knocked down, the aging progress of skeletal muscle structure and function was slowed down by regulating the activity homeostasis of Sirt1/PGC-1α pathway and Psn/arm pathway. Exercise enhanced the function of the Psn gene to delay skeletal muscle aging by up regulating the activity of the Sirt1/PGC-1α pathway and Psn/arm pathway.

Patient-Derived Blood-Brain Barrier Model for Screening Copper Bis(thiosemicarbazone) Complexes as Potential Therapeutics in Alzheimer's Disease

Alzheimer's disease (AD) is the most prevalent cause of dementia characterized by a progressive cognitive decline. Addressing neuroinflammation represents a promising therapeutic avenue to treat AD; however, the development of effective antineuroinflammatory compounds is often hindered by their limited blood-brain barrier (BBB) permeability. Consequently, there is an urgent need for accurate, preclinical AD patient-specific BBB models to facilitate the early identification of immunomodulatory drugs capable of efficiently crossing the human AD BBB. This study presents a unique approach to BBB drug permeability screening as it utilizes the familial AD patient-derived induced brain endothelial-like cell (iBEC)-based model, which exhibits increased disease relevance and serves as an improved BBB drug permeability assessment tool when compared to traditionally employed in vitro models. To demonstrate its utility as a small molecule drug candidate screening platform, we investigated the effects of diacetylbis(N(4)-methylthiosemicarbazonato)copper(II) (CuII(atsm)) and a library of metal bis(thiosemicarbazone) complexes─a class of compounds exhibiting antineuroinflammatory therapeutic potential in neurodegenerative disorders. By evaluating the toxicity, cellular accumulation, and permeability of those compounds in the AD patient-derived iBEC, we have identified 3,4-hexanedione bis(N(4)-methylthiosemicarbazonato)copper(II) (CuII(dtsm)) as a candidate with good transport across the AD BBB. Furthermore, we have developed a multiplex approach where AD patient-derived iBEC were combined with immune modulators TNFα and IFNγ to establish an in vitro model representing the characteristic neuroinflammatory phenotype at the patient's BBB. Here, we observed that treatment with CuII(dtsm) not only reduced the expression of proinflammatory cytokine genes but also reversed the detrimental effects of TNFα and IFNγ on the integrity and function of the AD iBEC monolayer. This suggests a novel pathway through which copper bis(thiosemicarbazone) complexes may exert neurotherapeutic effects on AD by mitigating BBB neuroinflammation and related BBB integrity impairment. Together, the presented model provides an effective and easily scalable in vitro BBB platform for screening AD drug candidates. Its improved translational potential makes it a valuable tool for advancing the development of metal-based compounds aimed at modulating neuroinflammation in AD.

Whole-exome sequencing reveals PSEN1 and ATP7B combined variants as a possible cause of early-onset Lewy body dementia: a case study of genotype-phenotype correlation

Dementia with Lewy bodies is a neurodegenerative disease, sharing features with Parkinson's and Alzheimer's diseases. We report a case of a patient dementia with Lewy bodies carrying combined PSEN1 and ATP7B mutations. A man developed dementia with Lewy bodies starting at the age of 60 years. CSF biomarkers were of Alzheimer's disease and DaTSCAN was abnormal. Whole-exome sequencing revealed a heterozygous p.Ile408Thr PSEN1 variant and a homozygous p.Arg616Trp ATP7B variant. This case reinstates the need of considering ATP7B mutations when evaluating a patient with parkinsonism and supports p.Ile408Thr as a pathogenic PSEN1 variant.

Probable Reasons for Neuron Copper Deficiency in the Brain of Patients with Alzheimer’s Disease: The Complex Role of Amyloid

Alzheimer’s disease is a progressive neurodegenerative disorder that eventually leads the affected patients to die. The appearance of senile plaques in the brains of Alzheimer’s patients is known as a main symptom of this disease. The plaques consist of different components, and according to numerous reports, their main components include beta-amyloid peptide and transition metals such as copper. In this disease, metal dyshomeostasis leads the number of copper ions to simultaneously increase in the plaques and decrease in neurons. Copper ions are essential for proper brain functioning, and one of the possible mechanisms of neuronal death in Alzheimer’s disease is the copper depletion of neurons. However, the reason for the copper depletion is as yet unknown. Based on the available evidence, we suggest two possible reasons: the first is copper released from neurons (along with beta-amyloid peptides), which is deposited outside the neurons, and the second is the uptake of copper ions by activated microglia.

Copper in tumors and the use of copper-based compounds in cancer treatment

Copper homeostasis is strictly regulated by protein transporters and chaperones, to allow its correct distribution and avoid uncontrolled redox reactions. Several studies address copper as involved in cancer development and spreading (epithelial to mesenchymal transition, angiogenesis). However, being endogenous and displaying a tremendous potential to generate free radicals, copper is a perfect candidate, once opportunely complexed, to be used as a drug in cancer therapy with low adverse effects. Copper ions can be modulated by the organic counterpart, after complexed to their metalcore, either in redox potential or geometry and consequently reactivity. During the last four decades, many copper complexes were studied regarding their reactivity toward cancer cells, and many of them could be a drug choice for phase II and III in cancer therapy. Also, there is promising evidence of using ⁶⁴Cu in nanoparticles as radiopharmaceuticals for both positron emission tomography (PET) imaging and treatment of hypoxic tumors. However, few compounds have gone beyond testing in animal models, and none of them got the status of a drug for cancer chemotherapy. The main challenge is their solubility in physiological buffers and their different and non-predictable mechanism of action. Moreover, it is difficult to rationalize a structure-based activity for drug design and delivery. In this review, we describe the role of copper in cancer, the effects of copper-complexes on tumor cell death mechanisms, and point to the new copper complexes applicable as drugs, suggesting that they may represent at least one component of a multi-action combination in cancer therapy.

The essential elements of Alzheimer's disease

Treatments for Alzheimer’s disease (AD) directed against the prominent amyloid plaque neuropathology are yet to be proved effective despite many phase 3 clinical trials. There are several other neurochemical abnormalities that occur in the AD brain that warrant renewed emphasis as potential therapeutic targets for this disease. Among those are the elementomic signatures of iron, copper, zinc, and selenium. Here, we review these essential elements of AD for their broad potential to contribute to Alzheimer’s pathophysiology, and we also highlight more recent attempts to translate these findings into therapeutics. A reinspection of large bodies of discovery in the AD field, such as this, may inspire new thinking about pathogenesis and therapeutic targets.

Copper Toxicity Links to Pathogenesis of Alzheimer's Disease and Therapeutics Approaches

Alzheimer's disease (AD) is an irreversible, age-related progressive neurological disorder, and the most common type of dementia in aged people. Neuropathological lesions of AD are neurofibrillary tangles (NFTs), and senile plaques comprise the accumulated amyloid-beta (Aβ), loaded with metal ions including Cu, Fe, or Zn. Some reports have identified metal dyshomeostasis as a neurotoxic factor of AD, among which Cu ions seem to be a central cationic metal in the formation of plaque and soluble oligomers, and have an essential role in the AD pathology. Cu-Aβ complex catalyzes the generation of reactive oxygen species (ROS) and results in oxidative damage. Several studies have indicated that oxidative stress plays a crucial role in the pathogenesis of AD. The connection of copper levels in AD is still ambiguous, as some researches indicate a Cu deficiency, while others show its higher content in AD, and therefore there is a need to increase and decrease its levels in animal models, respectively, to study which one is the cause. For more than twenty years, many in vitro studies have been devoted to identifying metals' roles in Aβ accumulation, oxidative damage, and neurotoxicity. Towards the end, a short review of the modern therapeutic approach in chelation therapy, with the main focus on Cu ions, is discussed. Despite the lack of strong proofs of clinical advantage so far, the conjecture that using a therapeutic metal chelator is an effective strategy for AD remains popular. However, some recent reports of genetic-regulating copper transporters in AD models have shed light on treating this refractory disease. This review aims to succinctly present a better understanding of Cu ions' current status in several AD features, and some conflicting reports are present herein.

Traditional Chinese Medicine for Alzheimer's Disease and Other Cognitive Impairment: A Review

Cognitive impairment (CI) refers to the dysfunction of memory, language, visual space, execution, calculation, understanding, and judgment in one or more aspects. With global aging, CI will become prevalent worldwide. At present, there is no effective cure for CI. However, Nobel laureate Tu Youyou's research on artemisinin has inspired Chinese researchers to focus on traditional Chinese herbs (TCHs) for the treatment of CI. Traditional Chinese Medicine (TCM) has led to a theory for an independent CI system. The pathogenesis of such impairment involves deficiency, phlegm, and stagnation and involves a range of organs, including the brain, kidneys, heart, liver, and spleen. Our current understanding of the etiology and pathogenesis of this condition has led to the realization that TCHs can improve cognitive dysfunction. Clinical research has shown that TCHs can improve the neuropsychological scale score of patients, the TCM symptom score, and the patient's quality of life. Research has also suggested that TCHs can retard Aβ deposits and tauopathy, regulate the metabolism of cholinergic neurotransmitters, and so on. However, due to their complexity, little is known of the safety and efficacy of TCHs in patients with CI. It is likely that we will be able to identify the precise mechanisms associated with the action of TCHs in such patients due to the integration of multiple technologies. This paper summarizes the pharmacokinetics, curative effect, and mechanisms of action of traditional Chinese herbs in order to provide a scientific basis for the improvement of cognitive dysfunction by TCHs.

Genetic Disorders Associated with Metal Metabolism

Genetic disorders associated with metal metabolism form a large group of disorders and mostly result from defects in the proteins/enzymes involved in nutrient metabolism and energy production. These defects can affect different metabolic pathways and cause mild to severe disorders related to metal metabolism. Some disorders have moderate to severe clinical consequences. In severe cases, these elements accumulate in different tissues and organs, particularly the brain. As they are toxic and interfere with normal biological functions, the severity of the disorder increases. However, the human body requires a very small amount of these elements, and a deficiency of or increase in these elements can cause different genetic disorders to occur. Some of the metals discussed in the present review are copper, iron, manganese, zinc, and selenium. These elements may play a key role in the pathology and physiology of the nervous system.

Biometals as Potential Predictors of the Neurodegenerative Decline in Alzheimer's Disease

Alzheimer’s Disease (AD) is a debilitating neurodegenerative disease that is diagnosed by gradual memory loss and certain cognitive impairments involving attention, reasoning, and language. Most of the research on Alzheimer’s disease focuses on the correlation of its neuropathological changes in the neurofibrillary tangles caused by hyper-phosphorylated tau protein and β-amyloid plaques with respect to cognitive impairment. Its pathology, however, remains incompletely understood. Currently, research has demonstrated that environmental factors such as biometals play a crucial role in exacerbating AD progression. The present review examines the role of metals in AD progression and how metal dyshomeostasis attributes to AD pathogenesis. 

It was found that certain metals possess both beneficial and harmful properties in terms of AD progression. Depending upon the concentration of the metal of interest, copper, zinc, iron, and selenium have general beneficial properties. However, when present in excess, they can lead to oxidative stress and hyperphosphorylation of tau protein, amongst other harmful effects, while calcium and magnesium were seen to have beneficial effects by regulating biometal uptake. 

In this review, we have provided evidential studies that focus on the involvement of certain metals in antioxidant pathways leading to the formation of reactive species indicative of neurodegeneration.

Non-coding RNA influences in dementia

Dementia is a complex clinical syndrome characterised by progressive decline in cognitive function. It usually presents itself as impairment in memory, loss of judgement, abstract thinking and other disturbances that are severe enough to interfere with activities of daily living. It has long been considered as one of the major challenges at present posing an ever-increasing demand on global health and social care systems. Of all the different forms of dementia, Alzheimer's disease (AD) is the most common. The term non-coding RNA (ncRNA) refers to RNA sequences which do not have the ability to be translated into proteins and therefore mainly fall within the realm of the recently acknowledged ‘dark matter’ of the genome. This genomic dark matter encompasses a whole spectrum of differing ncRNA families such as microRNAs (miRNAs), long non-coding RNAs (lncRNAs), PIWI-interacting RNAs (piRNAs), transfer RNAs (tRNAs), small nuclear RNAs (snoRNAs) and circular RNAs (circRNAs), to name but a few. Consequently, due to the widespread influences of miRNAs and lncRNAs across all disease pathways, it is of critical importance for researchers in the field of dementia to focus their attention on possible ncRNA-induced pathogeneses, with the ultimate goal of identifying novel diagnostic procedures and drug targets, together with the development of novel therapies to control such a devastating mental condition in the patient population.

Presenilins as Drug Targets for Alzheimer's Disease-Recent Insights from Cell Biology and Electrophysiology as Novel Opportunities in Drug Development

A major cause underlying familial Alzheimer's disease (AD) are mutations in presenilin proteins, presenilin 1 (PS1) and presenilin 2 (PS2). Presenilins are components of the γ-secretase complex which, when mutated, can affect amyloid precursor protein (APP) processing to toxic forms of amyloid beta (Aβ). Consequently, presenilins have been the target of numerous and varied research efforts to develop therapeutic strategies for AD. The presenilin 1 gene harbors the largest number of AD-causing mutations resulting in the late onset familial form of AD. As a result, the majority of efforts for drug development focused on PS1 and Aβ. Soon after the discovery of the major involvement of PS1 and PS2 in γ-secretase activity, it became clear that neuronal signaling, particularly calcium ion (Ca²⁺) signaling, is regulated by presenilins and impacted by mutations in presenilin genes. Intracellular Ca²⁺ signaling not only controls the activity of neurons, but also gene expression patterns, structural functionality of the cytoskeleton, synaptic connectivity and viability. Here, we will briefly review the role of presenilins in γ-secretase activity, then focus on the regulation of Ca²⁺ signaling, oxidative stress, and cellular viability by presenilins within the context of AD and discuss the relevance of presenilins in AD drug development efforts.

Role of Copper in the Onset of Alzheimer's Disease Compared to Other Metals

Alzheimer's disease (AD) is a neurodegenerative disorder that is characterized by amyloid plaques in patients' brain tissue. The plaques are mainly made of β-amyloid peptides and trace elements including Zn2+, Cu2+, and Fe2+. Some studies have shown that AD can be considered a type of metal dyshomeostasis. Among metal ions involved in plaques, numerous studies have focused on copper ions, which seem to be one of the main cationic elements in plaque formation. The involvement of copper in AD is controversial, as some studies show a copper deficiency in AD, and consequently a need to enhance copper levels, while other data point to copper overload and therefore a need to reduce copper levels. In this paper, the role of copper ions in AD and some contradictory reports are reviewed and discussed.

Copper and Zinc Homeostasis: Lessons from Drosophila melanogaster

Maintenance of metal homeostasis is crucial for many different enzymatic activities and in turn for cell function and survival. In addition, cells display detoxification and protective mechanisms against toxic accumulation of metals. Perturbation of any of these processes normally leads to cellular dysfunction and finally to cell death. In the last years, loss of metal regulation has been described as a common pathological feature in many human neurodegenerative diseases. However, in most cases, it is still a matter of debate whether such dyshomeostasis is a primary or a secondary downstream defect. In this review, we will summarize and critically evaluate the contribution of Drosophila to model human diseases that involve altered metabolism of metals or in which metal dyshomeostasis influence their pathobiology. As a prerequisite to use Drosophila as a model, we will recapitulate and describe the main features of core genes involved in copper and zinc metabolism that are conserved between mammals and flies. Drosophila presents some unique strengths to be at the forefront of neurobiological studies. The number of genetic tools, the possibility to easily test genetic interactions in vivo and the feasibility to perform unbiased genetic and pharmacological screens are some of the most prominent advantages of the fruitfly. In this work, we will pay special attention to the most important results reported in fly models to unveil the role of copper and zinc in cellular degeneration and their influence in the development and progression of human neurodegenerative pathologies such as Parkinson's disease, Alzheimer's disease, Huntington's disease, Friedreich's Ataxia or Menkes, and Wilson's diseases. Finally, we show how these studies performed in the fly have allowed to give further insight into the influence of copper and zinc in the molecular and cellular causes and consequences underlying these diseases as well as the discovery of new therapeutic strategies, which had not yet been described in other model systems.

Drosophila melanogaster Models of Metal-Related Human Diseases and Metal Toxicity

Iron, copper and zinc are transition metals essential for life because they are required in a multitude of biological processes. Organisms have evolved to acquire metals from nutrition and to maintain adequate levels of each metal to avoid damaging effects associated with its deficiency, excess or misplacement. Interestingly, the main components of metal homeostatic pathways are conserved, with many orthologues of the human metal-related genes having been identified and characterized in Drosophila melanogaster. Drosophila has gained appreciation as a useful model for studying human diseases, including those caused by mutations in pathways controlling cellular metal homeostasis. Flies have many advantages in the laboratory, such as a short life cycle, easy handling and inexpensive maintenance. Furthermore, they can be raised in a large number. In addition, flies are greatly appreciated because they offer a considerable number of genetic tools to address some of the unresolved questions concerning disease pathology, which in turn could contribute to our understanding of the metal metabolism and homeostasis. This review recapitulates the metabolism of the principal transition metals, namely iron, zinc and copper, in Drosophila and the utility of this organism as an experimental model to explore the role of metal dyshomeostasis in different human diseases. Finally, a summary of the contribution of Drosophila as a model for testing metal toxicity is provided.

Metallo-pathways to Alzheimer's disease: lessons from genetic disorders of copper trafficking

Copper is an essential metal ion that provides catalytic function to numerous enzymes and also regulates neurotransmission and intracellular signaling. Conversely, a deficiency or excess of copper can cause chronic disease in humans. Menkes and Wilson disease are two rare heritable disorders of copper transport that are characterized by copper deficiency and copper overload, respectively. Changes to copper status are also a common feature of several neurodegenerative disorders including Alzheimer's disease (AD), Parkinson's disease (PD) and Amyotrophic lateral sclerosis (ALS). In the case of AD, which is characterized by brain copper depletion, changes in the distribution of copper has been linked with various aspects of the disease process; protein aggregation, defective protein degradation, oxidative stress, inflammation and mitochondrial dysfunction. Although AD is a multifactorial disease that is likely caused by a breakdown in multiple cellular pathways, copper and other metal ions such as iron and zinc play a central role in many of these cellular processes. Pioneering work by researchers who have studied relatively rare copper transport diseases has shed light on potential metal ion related disease mechanisms in other forms of neurodegeneration such as AD.

Spatial memory deficits in a mouse model of late-onset Alzheimer's disease are caused by zinc supplementation and correlate with amyloid-beta levels

Much of the research in Alzheimer’s disease (AD) that uses mouse models focuses on the early-onset form of the disease, which accounts for less than 5% of cases. In contrast, this study used a late-onset AD model to examine the interaction between increased dietary zinc (Zn) and the apolipoprotein E (ApoE) gene. ApoE ε4 is overrepresented in late-onset AD and enhances Zn binding to amyloid-β (Aβ). This study sought to determine if elevated dietary Zn would impair spatial memory in CRND8 mice (CRND8), as well as mice who carry both the mutated human amyloid precursor protein (APP) and ApoE ε4 genes (CRND8/E4). Mice were provided with either lab tap water or water enhanced with 10 ppm Zn (ZnCO₃) for 4 months. At 6 months of age, spatial memory was measured by the Barnes maze. CRND8 mice exhibited significant memory deficits compared to WT mice, as shown by an increased latency to reach the escape box. For the CRND8/E4, but not the CRND8 mice, those given Zn water made significantly more errors than those on lab water. During the probe trial for the WT group, those on Zn water spent significantly less time in the target quadrant than those on lab water. These data suggest that increased dietary Zn can significantly impair spatial memory in CRND8/E4. WT mice given Zn water were also impaired on the 24-h probe trial when compared to lab water WTs. Within the CRND8/E4 group only, levels of soluble Aβ were significantly correlated with average primary latencies. Within the Zn-treated CRND8/E4 group, there was a significant correlation between insoluble Aβ and average primary errors. Levels of the zinc transporter 3, ZnT3, were negatively correlated with soluble Aβ (p < 0.01). These findings are particularly relevant because increased intake of dietary supplements, such as Zn, are common in the elderly—a population already at risk for AD. Given the effects observed in the CRND8/E4 mice, ApoE status should be taken into consideration when evaluating the efficacy of therapies targeting metals.

What can flies tell us about copper homeostasis?

Copper (Cu) is an essential redox active metal that is potentially toxic in excess. Multicellular organisms acquire Cu from the diet and must regulate uptake, storage, distribution and export of Cu at both the cellular and organismal levels. Systemic Cu deficiency can be fatal, as seen in Menkes disease patients. Conversely Cu toxicity occurs in patients with Wilson disease. Cu dyshomeostasis has also been implicated in neurodegenerative disorders such as Alzheimer's disease. Over the last decade, the fly Drosophila melanogaster has become an important model organism for the elucidation of eukaryotic Cu regulatory mechanisms. Gene discovery approaches with Drosophila have identified novel genes with conserved protein functions relevant to Cu homeostasis in humans. This review focuses on our current understanding of Cu uptake, distribution and export in Drosophila and the implications for mammals.

Copper and copper proteins in Parkinson's disease

Copper is a transition metal that has been linked to pathological and beneficial effects in neurodegenerative diseases. In Parkinson's disease, free copper is related to increased oxidative stress, alpha-synuclein oligomerization, and Lewy body formation. Decreased copper along with increased iron has been found in substantia nigra and caudate nucleus of Parkinson's disease patients. Copper influences iron content in the brain through ferroxidase ceruloplasmin activity; therefore decreased protein-bound copper in brain may enhance iron accumulation and the associated oxidative stress. The function of other copper-binding proteins such as Cu/Zn-SOD and metallothioneins is also beneficial to prevent neurodegeneration. Copper may regulate neurotransmission since it is released after neuronal stimulus and the metal is able to modulate the function of NMDA and GABA A receptors. Some of the proteins involved in copper transport are the transporters CTR1, ATP7A, and ATP7B and the chaperone ATOX1. There is limited information about the role of those biomolecules in the pathophysiology of Parkinson's disease; for instance, it is known that CTR1 is decreased in substantia nigra pars compacta in Parkinson's disease and that a mutation in ATP7B could be associated with Parkinson's disease. Regarding copper-related therapies, copper supplementation can represent a plausible alternative, while copper chelation may even aggravate the pathology.