Ceruloplasmin oxidation, a feature of Parkinson's disease CSF, inhibits ferroxidase activity and promotes cellular iron retention

Ceruloplasmin administration in the preclinical mouse model of aceruloplasminemia reveals a sex-related variation in biodistribution

Mutations in the ceruloplasmin (CP) gene are responsible for the rare genetic disease aceruloplasminemia characterized by iron accumulation in different organs, including the brain. We previously reported that administration of purified CP in the CP-deficient (cpKO) mouse model of the disease, was therapeutically effective. Here we evaluated the bioavailability of the therapeutic protein in different organs of the cpKO mouse. The distribution of administered radiolabelled-[64Cu]-CP was assessed in brain and peripheral tissues in vivo and ex vivo. The uptake of [64Cu]-CP in cpKO mice varied according to animal sex and age, with a higher accumulation in the cerebellum and liver of males at 6 months of age, while higher levels were observed in the same organs in females at 10 months. Sex-specific variations in the uptake of radiolabelled-CP were genotype-associated, by comparison with wild type mice. Based on these findings, we assessed sex effects on the therapeutic efficacy of the CP-replacement therapy previously performed. Multivariate analysis confirmed that the therapeutic effect was present for both sexes, and this was more pronounced in males than females. Therefore, sex-related variation in CP tissue bioavailability point to the possibility of sex-specific therapeutic regimens in the design of future CP-replacement therapies for aceruloplasminemia.

Reduced protein carbonylation on hormone therapy is associated with improved fibrinolysis in postmenopausal women: the impact of PAI-1 and TAFI activity

Hormone therapy (HT) has been reported to reduce protein carbonylation (PC) in postmenopausal women, in whom fibrinolysis is impaired. We investigated whether PC affects fibrinolysis and if HT modulates this effect. We enrolled 150 women aged 55.5 ± 4.7 years in a randomized interventional open-label study, including 50 on standard oral HT, 50 on ultra-low-dose HT, and 50 controls. PC, along with global fibrinolysis (clot lysis time, CLT), fibrinolysis proteins, and prothrombotic markers were determined at baseline and at 24 weeks. Patients with the baseline top quartile PC (> 2.07 nM/mg protein) had 10.3% longer CLT, higher activity (but not antigen) of TAFI (+ 19.9%) and PAI-1 (+ 68.1%) compared to the remainder. No differences were observed in thrombin generation, factor VIII, plasminogen or α2-antiplasmin. On-treatment PC decreased by 16.4% (p < 0.0001), without differences related to the type of HT, compared to baseline and by 30% compared to controls, in whom PC and fibrinolysis markers remained unchanged. Patients with PC > 2.07 nM/mg had shortened CLT during HT compared to baseline, along with lower PAI-1 (-69%) and TAFI (-26%) activity. In this subgroup CLT was 5.8% shorter compared to controls with the highest PC. In postmenopausal women with increased PC, HT was accompanied by PC reduction and faster clot lysis together with decreased PAI-1 and TAFI activity.

The role of iron transporters and regulators in Alzheimer's disease and Parkinson's disease: Pathophysiological insights and therapeutic prospects

Brain iron homeostasis plays a vital role in maintaining brain development and controlling neuronal function under physiological conditions. Many studies have shown that the imbalance of brain iron homeostasis is closely related to the pathogenesis of neurodegenerative diseases (NDs), such as Alzheimer's disease (AD) and Parkinson's disease (PD). Recent advances have revealed the importance of iron transporters and regulatory molecules in the pathogenesis and treatment of NDs. This review summarizes the research progress on brain iron overload and the aberrant expression of several key iron transporters and regulators in AD and PD, emphasizes the pathological roles of these molecules in the pathogenesis of AD and PD, and highlights the therapeutic prospects of targeting these iron transporters and regulators to restore brain iron homeostasis in the treatment of AD and PD. A comprehensive understanding of the pathophysiological roles of iron, iron transporters and regulators, and their regulations in NDs may provide new therapeutic avenues for more targeted neurotherapeutic strategies for treating these diseases.

Identification of SYNJ1 in a Complex Case of Juvenile Parkinsonism Using a Multiomics Approach

This study aimed to elucidate the genetic causes underlying the juvenile parkinsonism (JP) diagnosed in a girl with several family members diagnosed with spinocerebellar ataxia type 2 (SCA2). To achieve this, whole-exome sequencing, analysis of CAG repeats, RNA sequencing analysis on fibroblasts, and metabolite identification were performed. As a result, a homozygous missense mutation SNP T>C (rs2254562) in synaptojamin 1 (SYNJ1), which has been implicated in the regulation of membrane trafficking in the synaptic vesicles, was identified. Additionally, we observed overexpression of L1 cell adhesion molecule (L1CAM), Cdc37, GPX1, and GPX4 and lower expression of ceruloplasmin in the patient compared to the control. We also found changes in sphingolipid, inositol, and inositol phosphate metabolism. These findings help to clarify the mechanisms of JP and suggest that the etiology of JP in the patient may be multifactorial. This is the first report of the rs2254562 mutation in the SYNJ gene identified in a JP patient with seizures and cognitive impairment.

Tumor associated macrophages transfer ceruloplasmin mRNA to fibrosarcoma cells and protect them from ferroptosis

Solid tumors are characterized by hypoxic areas, which are prone for macrophage infiltration. Once infiltrated, macrophages polarize to tumor associated macrophages (TAM) to support tumor progression. Therefore, the crosstalk between TAMs and tumor cells is of current interest for the development of novel therapeutic strategies. These may comprise induction of an iron- and lipid peroxidation-dependent form of cell death, known as ferroptosis. To study the macrophage - tumor cell crosstalk we polarized primary human macrophages towards a TAM-like phenotype, co-cultured them with HT1080 fibrosarcoma cells, and analyzed the tumor cell response to ferroptosis induction. In TAMs the expression of ceruloplasmin mRNA increased, which was driven by hypoxia inducible factor 2 and signal transducer and activator of transcription 1. Subsequently, ceruloplasmin mRNA was transferred from TAMs to HT1080 cells via extracellular vesicles. In tumor cells, mRNA was translated into protein to protect HT1080 cells from RSL3-induced ferroptosis. Mechanistically this was based on reduced iron abundance and lipid peroxidation. Interestingly, in naïve macrophages also hypoxia induced ceruloplasmin under hypoxia and a co-culture of HT1080 cells with hypoxic macrophages recapitulated the protective effect observed in TAM co-cultures. In conclusion, TAMs provoke tumor cells to release iron and thereby protect them from lipid peroxidation/ferroptosis.

Cerebrospinal fluid protein biomarkers in Parkinson's disease

Proteomic profiling is an effective way to identify biomarkers for Parkinson's disease (PD). Cerebrospinal fluid (CSF) has direct connectivity with the brain and could be a source of finding biomarkers and their clinical implications. Comparative proteomic profiling has shown that a group of differentially displayed proteins exist. The studies performed using conventional and classical tools also supported the occurrence of these proteins. Many studies have highlighted the potential of CSF proteomic profiling for biomarker identification and their clinical applications. Some of these proteins are useful for disease diagnosis and prediction. Proteomic profiling of CSF also has immense potential to distinguish PD from similar neurodegenerative disorders. A few protein biomarkers help in fundamental knowledge generation and clinical interpretation. However, the specific biomarker of PD is not yet known. The use of proteomic approaches in clinical settings is also rare. A large-scale, multi-centric, multi-population and multi-continental study using multiple proteomic tools is warranted. Such a study can provide valuable, comprehensive and reliable information for a better understanding of PD and the development of specific biomarkers. The current article sheds light on the role of CSF proteomic profiling in identifying biomarkers of PD and their clinical implications. The article also explains the achievements, obstacles and hopes for future directions of this approach.

Lipid dysmetabolism in ceruloplasmin-deficient mice revealed both in vivo and ex vivo by MRI, MRS and NMR analyses

Ceruloplasmin (Cp) is a ferroxidase that plays a role in cellular iron homeostasis and is mainly expressed in the liver and secreted into the blood. Cp is also produced by adipose tissue, which releases it as an adipokine. Although a dysfunctional interaction of iron with the metabolism of lipids has been associated with several metabolic diseases, the role of Cp in adipose tissue metabolism and in the interplay between hepatocytes and adipocytes has been poorly investigated. We previously found that Cp-deficient (CpKO) mice become overweight and demonstrate adipose tissue accumulation together with liver steatosis during aging, suggestive of lipid dysmetabolism. In the present study, we investigated the lipid alterations which occur during aging in adipose tissue and liver of CpKO and wild-type mice both in vivo and ex vivo. During aging of CpKO mice, we observed adipose tissue accumulation and liver lipid deposition, both of which are associated with macrophage infiltration. Liver lipid deposition was characterized by accumulation of triglycerides, fatty acids and ω-3 fatty acids, as well as by a switch from unsaturated to saturated fatty acids, which is characteristic of lipid storage. Liver steatosis was preceded by iron deposition and macrophage infiltration, and this was observed to be already occurring in younger CpKO mice. The accumulation of ω-3 fatty acids, which can only be acquired through diet, was associated with body weight increase in CpKO mice despite food intake being equal to that of wild-type mice, thus underlining the alterations in lipid metabolism/catabolism in Cp-deficient animals.

Ferroptosis in Neurological Disease

Iron accumulation in the CNS occurs in many neurological disorders. It can contribute to neuropathology as iron is a redox-active metal that can generate free radicals. The reasons for the iron buildup in these conditions are varied and depend on which aspects of iron influx, efflux, or sequestration that help maintain iron homeostasis are dysregulated. Iron was shown recently to induce cell death and damage via lipid peroxidation under conditions in which there is deficient glutathione-dependent antioxidant defense. This form of cell death is called ferroptosis. Iron chelation has had limited success in the treatment of neurological disease. There is therefore much interest in ferroptosis as it potentially offers new drugs that could be more effective in reducing iron-mediated lipid peroxidation within the lipid-rich environment of the CNS. In this review, we focus on the molecular mechanisms that induce ferroptosis. We also address how iron enters and leaves the CNS, as well as the evidence for ferroptosis in several neurological disorders. Finally, we highlight biomarkers of ferroptosis and potential therapeutic strategies.

Abnormalities in Copper Status Associated with an Elevated Risk of Parkinson's Phenotype Development

In the last 15 years, among the many reasons given for the development of idiopathic forms of Parkinson's disease (PD), copper imbalance has been identified as a factor, and PD is often referred to as a copper-mediated disorder. More than 640 papers have been devoted to the relationship between PD and copper status in the blood, which include the following markers: total copper concentration, enzymatic ceruloplasmin (Cp) concentration, Cp protein level, and non-ceruloplasmin copper level. Most studies measure only one of these markers. Therefore, the existence of a correlation between copper status and the development of PD is still debated. Based on data from the published literature, meta-analysis, and our own research, it is clear that there is a connection between the development of PD symptoms and the number of copper atoms, which are weakly associated with the ceruloplasmin molecule. In this work, the link between the risk of developing PD and various inborn errors related to copper metabolism, leading to decreased levels of oxidase ceruloplasmin in the circulation and cerebrospinal fluid, is discussed.

Ceruloplasmin-Deficient Mice Show Dysregulation of Lipid Metabolism in Liver and Adipose Tissue Reduced by a Protein Replacement

Ceruloplasmin is a ferroxidase that plays a role in iron homeostasis; its deficiency fosters inter alia iron accumulation in the liver, which expresses the soluble form of the protein secreted into the bloodstream. Ceruloplasmin is also secreted by the adipose tissue, but its role in adipocytes has been poorly investigated. We hypothesized that ceruloplasmin might have a role in iron/lipid interplay. We investigated iron/lipid dysmetabolism in the liver and adipose tissue of the ceruloplasmin-deficient mouse (CpKO) model of aceruloplasminemia and evaluated the effectiveness of ceruloplasmin replacement. We found that CpKO mice were overweight, showing adipose tissue accumulation, liver iron deposition and steatosis. In the adipose tissue of CpKO mice, iron homeostasis was not altered. Conversely, the levels of adiponectin and leptin adipokines behaved opposite to the wild-type. Increased macrophage infiltration was observed in adipose tissue and liver of CpKO mice, indicating tissue inflammation. The treatment of CpKO mice with ceruloplasmin limited liver iron accumulation and steatosis without normalizing the expression of iron homeostasis-related proteins. In the CpKO mice, the protein replacement limited macrophage infiltration in both adipose and hepatic tissues reduced the level of serum triglycerides, and partially recovered adipokines levels in the adipose tissue. These results underline the link between iron and lipid dysmetabolism in ceruloplasmin-deficient mice, suggesting that ceruloplasmin in adipose tissue has an anti-inflammatory role rather than a role in iron homeostasis. Furthermore, these data also indicate that ceruloplasmin replacement therapy may be effective at a systemic level.

Free Radicals and Oxidative Stress: Signaling Mechanisms, Redox Basis for Human Diseases, and Cell Cycle Regulation

Free radicals contain one or more unpaired electrons in their valence shell, thus making them unstable, short-lived, and highly reactive species. Excessive generation of these free radicals ultimately leads to oxidative stress causing oxidation and damage to significant macromolecules in the living system and essentially disrupting signal transduction pathways and antioxidants equilibrium. At lower concentrations, ROS serves as "second messengers," influencing many physiological processes in the cell. However, higher concentrations beyond cell capacity cause oxidative stress, contributing to human pathologies such as diabetes, cancer, Parkinson's disease, cardiovascular diseases, cataract, asthma, hypertension, atherosclerosis, arthritis, and Alzheimer's disease. Signaling pathways such as NF-κB, MAPKs, PI3K/Akt/ mTOR, and Keap1-Nrf2- ARE modulate the detrimental effects of oxidative stress by increasing the expression of cellular antioxidant defenses, phase II detoxification enzymes, and decreased production of ROS. Free radicals such as H2O2 are indeed needed for the advancement of the cell cycle as these molecules influence DNA, proteins, and enzymes in the cell cycle pathway. In the course of cell cycle progression, the cellular redox environment becomes more oxidized, moving from the G1 phase, becoming higher in G2/M and moderate in the S phase. Signals in the form of an increase in cellular pro-oxidant levels are required, and these signals are often terminated by a rise in the amount of antioxidants and MnSOD with a decrease in the level of cyclin D1 proteins. Therefore, understanding the mechanism of cell cycle redox regulation will help in the therapy of many diseases.

Dysregulation of Iron Homeostasis in the Central Nervous System and the Role of Ferroptosis in Neurodegenerative Disorders

Significance: Iron accumulation occurs in the central nervous system (CNS) in a variety of neurological conditions as diverse as spinal cord injury, stroke, multiple sclerosis, Parkinson's disease, and others. Iron is a redox-active metal that gives rise to damaging free radicals if its intracellular levels are not controlled or if it is not properly sequestered within cells. The accumulation of iron occurs due to dysregulation of mechanisms that control cellular iron homeostasis. Recent Advances: The molecular mechanisms that regulate cellular iron homeostasis have been revealed in much detail in the past three decades, and new advances continue to be made. Understanding which aspects of iron homeostasis are dysregulated in different conditions will provide insights into the causes of iron accumulation and iron-mediated tissue damage. Recent advances in iron-dependent lipid peroxidation leading to cell death, called ferroptosis, has provided useful insights that are highly relevant for the lipid-rich environment of the CNS. Critical Issues: This review examines the mechanisms that control normal cellular iron homeostasis, the dysregulation of these mechanisms in neurological disorders, and more recent work on how iron can induce tissue damage via ferroptosis. Future Directions: Quick and reliable tests are needed to determine if and when ferroptosis contributes to the pathogenesis of neurological disorders. In addition, there is need to develop better druggable agents to scavenge lipid radicals and reduce CNS damage for neurological conditions for which there are currently few effective treatments. Antioxid. Redox Signal. 37, 150-170.

Iron Metabolism in Aging and Age-Related Diseases

Iron is a trace metal element necessary to maintain life and is also involved in a variety of biological processes. Aging refers to the natural life process in which the physiological functions of the various systems, organs, and tissues decline, affected by genetic and environmental factors. Therefore, it is imperative to investigate the relationship between iron metabolism and aging-related diseases, including neurodegenerative diseases. During aging, the accumulation of nonheme iron destroys the stability of the intracellular environment. The destruction of iron homeostasis can induce cell damage by producing hydroxyl free radicals, leading to mitochondrial dysfunction, brain aging, and even organismal aging. In this review, we have briefly summarized the role of the metabolic process of iron in the body, then discussed recent developments of iron metabolism in aging and age-related neurodegenerative diseases, and finally, explored some iron chelators as treatment strategies for those disorders. Understanding the roles of iron metabolism in aging and neurodegenerative diseases will fill the knowledge gap in the field. This review could provide new insights into the research on iron metabolism and age-related neurodegenerative diseases.

Quantitative evaluation of brain iron accumulation in different stages of Parkinson's disease

BACKGROUND AND PURPOSE

Excessive brain iron deposition is involved in Parkinson's disease (PD) pathogenesis. However, the correlation of iron accumulation in various brain nuclei is not well-established in different stages of the disease. This cross-sectional study aims to evaluate quantitative susceptibility mapping (QSM) as an imaging technique to measure brain iron accumulation in PD patients in different stages compared to healthy controls.

METHODS

Ninety-six PD patients grouped by their Hoehn and Yahr (H&Y) stages and 31 healthy controls were included in this analysis. The magnetic susceptibility values of the substantia nigra (SN), red nucleus (RN), caudate, putamen, and globus pallidus were obtained and compared.

RESULTS

Iron level was increased in the SN of PD patients in all stages versus controls (p < .001), with no significant difference within stages. Iron in the RN was significantly increased in stage II versus controls (p = .013) and combined stages III and IV versus controls (p < .001). The iron levels in caudate, putamen, and globus pallidus were not different between any groups.

CONCLUSIONS

Our data suggest iron accumulation occurs early in the disease course and only in the SN and RN of these patients. This is a large cross-sectional study of brain iron deposition in PD patients according to H&Y staging. Prospective studies are warranted to further validate QSM as a method to follow brain iron, which could serve as a disease biomarker and a therapeutic target.

An Unrecognized Fundamental Relationship between Neurotransmitters: Glutamate Protects against Catecholamine Oxidation

Neurotransmitter catecholamines (dopamine, epinephrine, and norepinephrine) are liable to undergo oxidation, which copper is deeply involved in. Catecholamine oxidation-derived neurotoxicity is recognized as a pivotal pathological mechanism in neurodegenerative diseases. Glutamate, as an excitatory neurotransmitter, is enriched in the brain at extremely high concentrations. However, the chemical biology relationship of these two classes of neurotransmitters remains largely unknown. In the present study, we assessed the influences of glutamate on the autoxidation of catecholamines, the copper- and copper-containing ceruloplasmin-mediated oxidation of catecholamines, the catecholamine-induced formation of quinoprotein, catecholamine/copper-induced hydroxyl radicals, and DNA damage in vitro. The results demonstrate that glutamate, at a physiologically achievable molar ratio of glutamate/catecholamines, has a pronounced inhibitory effect on catecholamine oxidation, catecholamine oxidation-evoked hydroxyl radicals, quinoprotein, and DNA damage. The protective mechanism of glutamate against catecholamine oxidation could be attributed to its restriction of the redox activity of copper via chelation. This previously unrecognized link between glutamate, catecholamines, and copper suggests that neurodegenerative disorders may occur and develop once the built-in equilibrium is disrupted and brings new insight into developing more effective prevention and treatment strategies for neurodegenerative diseases.

Oxidized/deamidated-ceruloplasmin dysregulates choroid plexus epithelial cells functionality and barrier properties via RGD-recognizing integrin binding

Choroid plexus epithelial cells (CPEpiCs) determine the composition of cerebrospinal fluid (CSF) and constitute the blood-CSF barrier (BCSFB), functions that are altered in neurodegenerative diseases. In Parkinson's disease (PD) the pathological environment oxidizes and deamidates the ceruloplasmin, a CSF-resident ferroxidase, which undergoes a gain of RGD-recognizing integrin binding property, that may result in signal transduction. We investigated the effects that oxidized/deamidated ceruloplasmin (Cp-ox/de) may exert on CPEpiCs functions. Through RGD-recognizing integrins binding, Cp-ox/de mediates CPEpiCs adhesion and intracellular signaling, resulting in cell proliferation inhibition and alteration of the secretome profile in terms of proteins related to cell-extracellular matrix interaction. Oxidative conditions, comparable to those found in the CSF of PD patients, induced CPEpiCs barrier leakage, allowing Cp-ox/de to cross it, transducing integrins-mediated signal that further worsens BCSFB integrity. This mechanism might contribute to PD pathological processes altering CSF composition and aggravating the already compromised BCSFB function.

Ceruloplasmin Deamidation in Neurodegeneration: From Loss to Gain of Function

Neurodegenerative disorders can induce modifications of several proteins; one of which is ceruloplasmin (Cp), a ferroxidase enzyme found modified in the cerebrospinal fluid (CSF) of neurodegenerative diseases patients. Cp modifications are caused by the oxidation induced by the pathological environment and are usually associated with activity loss. Together with oxidation, deamidation of Cp was found in the CSF from Alzheimer’s and Parkinson’s disease patients. Protein deamidation is a process characterized by asparagine residues conversion in either aspartate or isoaspartate, depending on protein sequence/structure and cellular environment. Cp deamidation occurs at two Asparagine-Glycine-Arginine (NGR)-motifs which, once deamidated to isoAspartate-Glycine-Arginine (isoDGR), bind integrins, a family of receptors mediating cell adhesion. Therefore, on the one hand, Cp modifications lead to loss of enzymatic activity, while on the other hand, these alterations confer gain of function to Cp. In fact, deamidated Cp binds to integrins and triggers intracellular signaling on choroid plexus epithelial cells, changing cell functioning. Working in concert with the oxidative environment, Cp deamidation could reach different target cells in the brain, altering their physiology and causing detrimental effects, which might contribute to the pathological mechanism.

Oxidative Stress in Parkinson's Disease: Potential Benefits of Antioxidant Supplementation

Parkinson's disease (PD) occurs in approximately 1% of the population over 65 years of age and has become increasingly more common with advances in age. The number of individuals older than 60 years has been increasing in modern societies, as well as life expectancy in developing countries; therefore, PD may pose an impact on the economic, social, and health structures of these countries. Oxidative stress is highlighted as an important factor in the genesis of PD, involving several enzymes and signaling molecules in the underlying mechanisms of the disease. This review presents updated data on the involvement of oxidative stress in the disease, as well as the use of antioxidant supplements in its therapy.

Ceruloplasmin oxidized and deamidated by Parkinson's disease cerebrospinal fluid induces epithelial cells proliferation arrest and apoptosis

In Parkinson's disease, the ferroxidase ceruloplasmin (Cp) is oxidized and deamidated by the pathological cerebrospinal fluid (CSF) environment. These modifications promote the gain of integrin binding properties, fostered by the deamidation of two NGR-motifs present in the Cp sequence that convert into the isoDGR-motif. Through isoDGR/integrin binding, the oxidized/deamidated-Cp (Cp-ox/de) mediates cell adhesion and transduces an intracellular signal in epithelial cells that seems to be addressed to regulate cell cycle, proliferation and cytoskeletal re-arrangement. However, the effect fostered on cells by integrins engagement via Cp-ox/de is not known. We found that in HaCaT epithelial cells, the incubation with Cp-ox/de resulted in proliferation inhibition mediated by isoDGR, cell cycle arrest and apoptosis induction. Similar proliferation inhibition was induced by treatment with purified Cp previously incubated in the CSF from Parkinson's disease patients, but not by Cp incubated in the CSF from healthy subjects. In human primary choroid plexus epithelial cells, a possible in vivo target of Cp-ox/de generated in pathological CSFs, we found that Cp-ox/de mediated cell adhesion via isoDGR/integrins binding and transduced an intracellular signal, which resulted in cell proliferation inhibition. Thus, the generation of Cp-ox/de in pathological CSFs and the consequent apoptosis induction of epithelial cells facing the liquor, might represent a novel mechanism that contributes to neurodegeneration.

Therapeutic strategies for Parkinson's disease: promising agents in early clinical development

INTRODUCTION

To date, no drug has demonstrated clinically indisputable neuroprotective efficacy in Parkinson's disease (PD). We also have no effective symptomatic treatment for disabling symptoms such as balance problems, and dementia, and we need to improve the efficacy and safety profile of drugs currently used in the management of motor complications.

AREAS COVERED

We examine the agents which appear to have most therapeutic promise based on concepts, feasibility in a reasonable time frame, and available clinical data and place an emphasis on disease-modifying treatments. PUBMED and Clinicaltrials.gov databases were searched for Phase I and II randomized trials for symptomatic or disease-modifying treatments considering only studies that began since 2010 or that were completed after 2015, up to 30 April 2020.

EXPERT OPINION

Encouraging progress has been made in our understanding of molecular pathways. We find passive immunization approaches against α-synuclein, LRRK2 kinase inhibitors, and treatment that can increase GCase activity, which have shown some efficacy on both GBA-mutated and non-mutated PD patients. The recognition of non-dopaminergic impairment and the prominent role of non-motor symptoms have prompted the development of trials on compounds that could tackle different neurotransmitter systems. Future approaches will encompass more personalized medicine strategies based on molecular signatures and non-motor phenotypes.

Cerebrospinal fluid ceruloplasmin levels predict cognitive decline and brain atrophy in people with underlying β-amyloid pathology

OBJECTIVES

The mechanisms leading to neurodegeneration in Alzheimer's disease (AD) may involve oxidative stress and neuroinflammation. Ceruloplasmin (Cp) is a circulating protein that intersects both these pathways, since its expression is increased during the acute phase response, and the protein acts to lower pro-oxidant iron in cells. Since the role of Cp in AD, and its potential for use as a biomarker is not established, we investigated CSF Cp and its association with longitudinal outcome measures related to AD.

METHODS

This was an observational study of 268 people from the Alzheimer's Disease Neuroimaging (ADNI) cohort. Subjects were classified clinically as having AD, mild cognitive impairment (MCI) or were cognitively normal (CN), and were also classified as being positive for β-amyloid using established thresholds in the CSF t-tau/Aβ42 ratio. Subjects underwent cognitive tests and MRI studies every 6 months for 2 years, then yearly thereafter for up to 6 years.

RESULTS

At baseline, CSF Cp was not associated with clinical or pathological diagnosis, but we found an unexpected association between CSF Cp and levels of CSF apolipoprotein E. In longitudinal analysis, high level of CSF Cp was associated with accelerated cognitive decline (as assessed by ADAS-Cog, CDR-SB, and MMSE) and ventricular volume enlargement in people classified as MCI and who had underlying β-amyloid pathology.

CONCLUSION

These results raise new questions into the role of Cp in neuroinflammation, oxidative stress, and APOE pathways involved in AD, and reveal the potential for this protein to be used as a biomarker in disease prognostication.

[The role of ferroptosis in chronic diseases]

Recently, ferroptosis, an iron-dependent novel type of cell death, has been characterized as an excessive accumulation of lipid peroxides and reactive oxygen species. Emerging studies demonstrate that ferroptosis not only plays an important role in the pathogenesis and progression of chronic diseases, but also functions differently in the different disease context. Notably, it is shown that activation of ferroptosis could potently inhibit tumor growth and increase sensitivity to chemotherapy and immunotherapy in various cancer settings. As a result, the development of more efficacious ferroptosis agonists remains the mainstay of ferroptosis-targeting strategy for cancer therapeutics. By contrast, in non-cancerous chronic diseases, including cardiovascular & cerebrovascular diseases and neurodegenerative diseases, ferroptosis functions as a risk factor to promote these diseases progression through triggering or accelerating tissue injury. As a matter of fact, blocking ferroptosis has been demonstrated to effectively prevent ischemia-reperfusion heart disease in preclinical animal models. Therefore, it is a promising field to develope potent ferroptosis inhibitors for preventing and treating cardiovascular & cerebrovascular diseases and neurodegenerative diseases. In this article, we summarize the most recent progress on ferroptosis in chronic diseases, and draw attention to the possible clinical impact of this recently emerged ferroptosis modalities.

Assessment of copper, iron, zinc and manganese status and speciation in patients with Parkinson's disease: A pilot study

BACKGROUND

The objective of this pilot study was to assess iron (Fe), copper (Cu), zinc (Zn), and manganese (Mn) status (hair, serum, and urine) and speciation (serum) in Parkinson's disease (PD) patients.

METHODS

A pilot study involving a total of 27 subjects (13 PD patients, 14 controls) was performed. Serum, urine, and hair metal content was assessed using ICP-MS. Speciation analysis of Cu, Zn, Fe, and Mn was performed using a hybrid HPLC-ICP-MS system.

RESULTS

Group comparisons did not reveal any significant group difference in serum Cu, Zn, Fe, and Mn total metal level between PD patients and controls. Speciation analysis revealed a significant decrease in Cu/ceruloplasmin copper in association with elevation of low-molecular weight species (amino acids)-bound copper. It is proposed that in PD, binding of Cu(II) ions to ceruloplasmin is reduced and free copper ions coordinate with low molecular weight ligands. The level of Mn-albumin complexes in PD patients was more than 4-fold higher as compared to the respective value in the control group. The observed difference may be considered as a marker of redistribution between high and low molecular weight ligands.

CONCLUSIONS

Metal speciation is significantly affected in serum of PD-patients. These findings are indicative of the potential role of metal metabolism and PD pathogenesis, although the exact mechanisms of such associations require further detailed studies.

Mitophagy and iron: two actors sharing the stage in age-associated neuronal pathologies

Aging is characterized by the deterioration of different cellular and organismal structures and functions. A typical hallmark of the aging process is the accumulation of dysfunctional mitochondria and excess iron, leading to a vicious cycle that promotes cell and tissue damage, which ultimately contribute to organismal aging. Accordingly, altered mitochondrial quality control pathways such as mitochondrial autophagy (mitophagy) as well as altered iron homeostasis, with consequent iron overload, can accelerate the aging process and the development and progression of different age-associated disorders. In this review we first briefly introduce the aging process and summarize molecular mechanisms regulating mitophagy and iron homeostasis. We then provide an overview on how dysfunction of these two processes impact on aging and age-associated neurodegenerative disorders with a focus on Alzheimer's disease, Parkinson's disease and Amyotrophic Lateral Sclerosis. Finally, we summarize some recent evidence showing mechanistic links between iron metabolism and mitophagy and speculate on how regulating the crosstalk between the two processes may provide protective effects against aging and age-associated neuronal pathologies.

Wild-type Cu/Zn-superoxide dismutase is misfolded in cerebrospinal fluid of sporadic amyotrophic lateral sclerosis

Background

A subset of familial forms of amyotrophic lateral sclerosis (ALS) are caused by mutations in the gene coding Cu/Zn-superoxide dismutase (SOD1). Mutant SOD1 proteins are susceptible to misfolding and abnormally accumulated in spinal cord, which is most severely affected in ALS. It, however, remains quite controversial whether misfolding of wild-type SOD1 is involved in more prevalent sporadic ALS (sALS) cases without SOD1 mutations.

Methods

Cerebrospinal fluid (CSF) from patients including sALS as well as several other neurodegenerative diseases and non-neurodegenerative diseases was examined with an immunoprecipitation assay and a sandwich ELISA using antibodies specifically recognizing misfolded SOD1.

Results

We found that wild-type SOD1 was misfolded in CSF from all sALS cases examined in this study. The misfolded SOD1 was also detected in CSF from a subset of Parkinson’s disease and progressive supranuclear palsy, albeit with smaller amounts than those in sALS. Furthermore, the CSF samples containing the misfolded SOD1 exhibited significant toxicity toward motor neuron-like NSC-34 cells, which was ameliorated by removal of the misfolded wild-type SOD1 with immunoprecipitation.

Conclusions

Taken together, we propose that misfolding of wild-type SOD1 in CSF is a common pathological process of ALS cases regardless of SOD1 mutations.

Proteomics in Human Parkinson's Disease: Present Scenario and Future Directions

Parkinson's disease (PD) is an age-related, threatening neurodegenerative disorder with no reliable treatment till date. Identification of specific and reliable biomarker is a major challenge for disease diagnosis and designing effective therapeutic strategy against it. PD pathology at molecular level involves abnormal expression and function of several proteins, including alpha-synuclein. These proteins affect the normal functioning of neurons through various post-translational modifications and interaction with other cellular components. The role of protein anomalies during PD pathogenesis can be better understood by the application of proteomics approach. A number of proteomic studies conducted on brain tissue, blood, and cerebrospinal fluid of PD patients have identified a wide array of protein alterations underlying disease pathogenesis. However, these studies are limited by the types of brain regions or biofluids utilized in the research. For a complete understanding of PD mechanism and discovery of reliable protein biomarkers, it is essential to analyze the proteome of different PD-associated brain regions and easily accessible biofluids such as saliva and urine. The present review summarizes the major advances in the field of PD research in humans utilizing proteomic techniques. Moreover, potential samples for proteomic analysis and limitations associated with the analyses of different types of samples have also been discussed.

Does Ceruloplasmin Defend Against Neurodegenerative Diseases?

Ceruloplasmin (CP) is the major copper transport protein in plasma, mainly produced by the liver. Glyco-sylphosphatidylinositol-linked CP (GPI-CP) is the predominant form expressed in astrocytes of the brain. A growing body of evidence has demonstrated that CP is an essential protein in the body with multiple functions such as regulating the home-ostasis of copper and iron ions, ferroxidase activity, oxidizing organic amines, and preventing the formation of free radicals. In addition, as an acute-phase protein, CP is induced during inflammation and infection. The fact that patients with genetic disorder aceruloplasminemia do not suffer from tissue copper deficiency, but rather from disruptions in iron metabolism shows essential roles of CP in iron metabolism rather than copper. Furthermore, abnormal metabolism of metal ions and ox-idative stress are found in other neurodegenerative diseases, such as Wilson’s disease, Alzheimer’s disease and Parkinson’s disease. Brain iron accumulation and decreased activity of CP have been shown to be associated with neurodegeneration. We hypothesize that CP may play a protective role in neurodegenerative diseases. However, whether iron accumulation is a cause or a result of neurodegeneration remains unclear. Further research on molecular mechanisms is required before a con-sensus can be reached regarding a neuroprotective role for CP in neurodegeneration. This review article summarizes the main physiological functions of CP and the current knowledge of its role in neurodegenerative diseases.

Lower detectability of non-invasive prenatal testing compared to prenatal diagnosis in high-risk pregnant women

BACKGROUND

To investigate the detectability of non-invasive prenatal testing (NIPT) after prenatal screening to detect foetal chromosomal abnormalities in pregnant women at high risk, and the number of foetal abnormalities could be missed by NIPT.

METHODS

From January 2009 to March 2018, 3,099 pregnant women at high risk for trisomy 21 and 18 according to the results of prenatal serological screening were enrolled in this study. The women underwent amniocentesis at 18-23 weeks, as well as karyotype testing and/or chromosomal microarray analyses (CMA). We assessed the ability of NIPT to detect chromosomal abnormalities.

RESULTS

In all, 177 (5.7%, 177/3,099) chromosomal abnormalities were identified. These included 129 (72.9%) abnormal numbers of chromosomes, 6 (3.4%) chromosome structural abnormalities, and 42 (23.7%) other abnormalities, including copy number variation, inversions, and chromosome additions/deletions. Of the 177 (70.0%) chromosomal abnormalities, 124 were detected and 53 were missed by NIPT.

CONCLUSIONS

NIPT could miss 30.0% of the chromosomal abnormalities detected by amniocentesis and cytogenetic testing. This proportion will likely decrease in the future due to further development of NIPT.

Multiple Glycation Sites in Blood Plasma Proteins as an Integrated Biomarker of Type 2 Diabetes Mellitus

Type 2 diabetes mellitus (T2DM) is one of the most widely spread metabolic diseases. Because of its asymptomatic onset and slow development, early diagnosis and adequate glycaemic control are the prerequisites for successful T2DM therapy. In this context, individual amino acid residues might be sensitive indicators of alterations in blood glycation levels. Moreover, due to a large variation in the half-life times of plasma proteins, a generalized biomarker, based on multiple glycation sites, might provide comprehensive control of the glycemic status across any desired time span. Therefore, here, we address the patterns of glycation sites in highly-abundant blood plasma proteins of T2DM patients and corresponding age- and gender-matched controls by comprehensive liquid chromatography-mass spectrometry (LC-MS). The analysis revealed 42 lysyl residues, significantly upregulated under hyperglycemic conditions. Thereby, for 32 glycation sites, biomarker behavior was demonstrated here for the first time. The differentially glycated lysines represented nine plasma proteins with half-lives from 2 to 21 days, giving access to an integrated biomarker based on multiple protein-specific Amadori peptides. The validation of this biomarker relied on linear discriminant analysis (LDA) with random sub-sampling of the training set and leave-one-out cross-validation (LOOCV), which resulted in an accuracy, specificity, and sensitivity of 92%, 100%, and 85%, respectively.

Striking while the iron is hot: Iron metabolism and ferroptosis in neurodegeneration

Perturbations in iron homeostasis and iron accumulation feature in several neurodegenerative disorders including Alzheimer's disease (AD), Parkinson's disease (PD) and Amyotrophic lateral sclerosis (ALS). Proteins such as α-synuclein, tau and amyloid precursor protein that are pathologically associated with neurodegeneration are involved in molecular crosstalk with iron homeostatic proteins. Quantitative susceptibility mapping, an MRI based non-invasive technique, offers proximal evaluations of iron load in regions of the brain and powerfully predicts cognitive decline. Further, small molecules that target elevated iron have shown promise against PD and AD in preclinical studies and clinical trials. Despite these strong links between altered iron homeostasis and neurodegeneration the molecular biology to describe the association between enhanced iron levels and neuron death, synaptic impairment and cognitive decline is ill defined. In this review we discuss the current understanding of brain iron homeostasis and how it may be perturbed under pathological conditions. Further, we explore the ramifications of a novel cell death pathway called ferroptosis that has provided a fresh impetus to the "metal hypothesis" of neurodegeneration. While lipid peroxidation plays a central role in the execution of this cell death modality the removal of iron through chelation or genetic modifications appears to extinguish the ferroptotic pathway. Conversely, tissues that harbour elevated iron may be predisposed to ferroptotic damage. These emerging findings are of relevance to neurodegeneration where ferroptotic signalling may offer new targets to mitigate cell death and dysfunction.

Switching on Endogenous Metal Binding Proteins in Parkinson's Disease

The formation of cytotoxic intracellular protein aggregates is a pathological signature of multiple neurodegenerative diseases. The principle aggregating protein in Parkinson’s disease (PD) and atypical Parkinson’s diseases is α-synuclein (α-syn), which occurs in neural cytoplasmic inclusions. Several factors have been found to trigger α-syn aggregation, including raised calcium, iron, and copper. Transcriptional inducers have been explored to upregulate expression of endogenous metal-binding proteins as a potential neuroprotective strategy. The vitamin-D analogue, calcipotriol, induced increased expression of the neuronal vitamin D-dependent calcium-binding protein, calbindin-D28k, and this significantly decreased the occurrence of α-syn aggregates in cells with transiently raised intracellular free Ca, thereby increasing viability. More recently, the induction of endogenous expression of the Zn and Cu binding protein, metallothionein, by the glucocorticoid analogue, dexamethasone, gave a specific reduction in Cu-dependent α-syn aggregates. Fe accumulation has long been associated with PD. Intracellularly, Fe is regulated by interactions between the Fe storage protein ferritin and Fe transporters, such as poly(C)-binding protein 1. Analysis of the transcriptional regulation of Fe binding proteins may reveal potential inducers that could modulate Fe homoeostasis in disease. The current review highlights recent studies that suggest that transcriptional inducers may have potential as novel mechanism-based drugs against metal overload in PD.

Alpha-synuclein inhibits Snx3-retromer-mediated retrograde recycling of iron transporters in S. cerevisiae and C. elegans models of Parkinson's disease

We probed the role of alpha-synuclein (α-syn) in modulating sorting nexin 3 (Snx3)-retromer-mediated recycling of iron transporters in Saccharomyces cerevisiae and Caenorhabditis elegans. In yeast, the membrane-bound heterodimer Fet3/Ftr1 is the high affinity iron importer. Fet3 is a membrane-bound multicopper ferroxidase, whose ferroxidase domain is orthologous to human ceruloplasmin (Cp), that oxidizes external Fe+2 to Fe+3; the Fe+3 ions then channel through the Ftr1 permease into the cell. When the concentration of external iron is low (<1 µM), Fet3/Ftr1 is maintained on the plasma membrane by retrograde endocytic-recycling; whereas, when the concentration of external iron is high (>10 µM), Fet3/Ftr1 is endocytosed and shunted to the vacuole for degradation. We discovered that α-syn expression phenocopies the high iron condition: under the low iron condition (<1 µM), α-syn inhibits Snx3-retromer-mediated recycling of Fet3/Ftr1 and instead shunts Fet3/Ftr1 into the multivesicular body pathway to the vacuole. α-Syn inhibits recycling by blocking the association of Snx3-mCherry molecules with endocytic vesicles, possibly by interfering with the binding of Snx3 to phosphatidylinositol-3-monophosphate. In C. elegans, transgenic worms expressing α-syn exhibit an age-dependent degeneration of dopaminergic neurons that is partially rescued by the iron chelator desferoxamine. This implies that α-syn-expressing dopaminergic neurons are susceptible to changes in iron neurotoxicity with age, whereby excess iron enhances α-syn-induced neurodegeneration. In vivo genetic analysis indicates that α-syn dysregulates iron homeostasis in worm dopaminergic neurons, possibly by inhibiting SNX-3-mediated recycling of a membrane-bound ortholog of Cp (F21D5.3), the iron exporter ferroportin (FPN1.1), or both.

Ceruloplasmin replacement therapy ameliorates neurological symptoms in a preclinical model of aceruloplasminemia

Aceruloplasminemia is a monogenic disease caused by mutations in the ceruloplasmin gene that result in loss of protein ferroxidase activity. Ceruloplasmin plays a role in iron homeostasis, and its activity impairment leads to iron accumulation in liver, pancreas, and brain. Iron deposition promotes diabetes, retinal degeneration, and progressive neurodegeneration. Current therapies mainly based on iron chelation, partially control systemic iron deposition but are ineffective on neurodegeneration. We investigated the potential of ceruloplasmin replacement therapy in reducing the neurological pathology in the ceruloplasmin-knockout (CpKO) mouse model of aceruloplasminemia. CpKO mice were intraperitoneal administered for 2 months with human ceruloplasmin that was able to enter the brain inducing replacement of the protein levels and rescue of ferroxidase activity. Ceruloplasmin-treated mice showed amelioration of motor incoordination that was associated with diminished loss of Purkinje neurons and reduced brain iron deposition, in particular in the choroid plexus. Computational analysis showed that ceruloplasmin-treated CpKO mice share a similar pattern with wild-type animals, highlighting the efficacy of the therapy. These data suggest that enzyme replacement therapy may be a promising strategy for the treatment of aceruloplasminemia.

The Altered Expression of microRNA408 Influences the Arabidopsis Response to Iron Deficiency

MicroRNAs contribute to the adaptation of plants to varying environmental conditions by affecting systemic mineral nutrient homeostasis. Copper and iron deficiencies antagonistically control the expression of Arabidopsis thaliana microRNA408 (miR408), which post-transcriptionally regulates laccase-like multicopper oxidase family members LAC3, LAC12, and LAC13. In this work, we used miR408 T-DNA insertion mutants (408-KO1 and 408-KO2) and a previously characterized transgenic line overexpressing miR408 (35S:408-14) to explore how miR408 influences copper- and iron-dependent metabolism. We observed that the altered expression of miR408 diminished plant performance and the activation of the iron-regulated genes under iron-deficient conditions. Consistently with the low expression of the miR408-target laccases, we showed that the vascular bundle lignification of the 35S:408-14 plants diminished. The decrease in the phenoloxidase and ferroxidase activities exhibited by wild-type plants under iron deficiency did not occur in the 408-KO1 plants, probably due to the higher expression of laccases. Finally, we observed that the hydrogen peroxide levels under iron starvation were altered in both the 408-KO1 and 35S:408-14 lines. Taken together, these results suggest that Arabidopsis plants with modified miR408 levels undergo multiple deregulations under iron-deficient conditions.

Aceruloplasminemia: Waiting for an Efficient Therapy

Aceruloplasminemia is an ultra-rare hereditary disorder caused by defective production of ceruloplasmin. Its phenotype is characterized by iron-restricted erythropoiesis and tissue iron overload, diabetes, and progressive retinal and neurological degeneration. Ceruloplasmin is a ferroxidase that plays a critical role in iron homeostasis through the oxidation and mobilization of iron from stores and subsequent incorporation of ferric iron into transferrin (Tf), which becomes available for cellular uptake via the Tf receptor. In addition, ceruloplasmin has antioxidant properties preventing the production of deleterious reactive oxygen species via the Fenton reaction. Some recent findings suggest that aceruloplasminemia phenotypes can be more heterogeneous than previously believed, varying within a wide range. Within this large heterogeneity, microcytosis with or without anemia, low serum iron and high serum ferritin, and diabetes are the early hallmarks of the disease, while neurological manifestations appear 10-20 years later. The usual therapeutic approach is based on iron chelators that are efficacious in reducing systemic iron overload. However, they have demonstrated poor efficacy in counteracting the progression of neurologic manifestations, and also often aggravate anemia, thereby requiring drug discontinuation. Open questions remain regarding the mechanisms leading to neurological manifestation and development of diabetes, and iron chelation therapy (ICT) efficacy. Recent studies in animal models of aceruloplasminemia support the possibility of new therapeutic approaches by parenteral ceruloplasmin administration. In this review we describe the state of the art of aceruloplasminemia with particular attention on the pathogenic mechanisms of the disease and therapeutic approaches, both current and perspective.

Elevated microRNA-520d-5p in the serum of patients with Parkinson's disease, possibly through regulation of cereloplasmin expression

Iron metabolism dysfunction and redox-active iron-induced oxidative stress in the brain may contribute to the pathogenesis of Parkinson's disease. We have previously demonstrated that reduced serum ceruloplasmin level exacerbates nigral iron deposition in Parkinson's disease, although the underlying cause of the low serum ceruloplasmin level in Parkinson's disease remains unknown. Fluorescent quantitative real-time polymerase chain reaction analysis revealed that patients with Parkinson's disease had higher serum levels of microRNA (miR)-520d-5p than controls (p = 0.0011). Patients with Alzheimer's disease or multiple system atrophy did not have significantly elevated miR-520d-5p levels. Expression of miR-520d-5p did not correlate with disease severity or the motor phenotype of Parkinson's disease. Luciferase assays confirmed that miR-520d-5p was associated with ceruloplasmin gene expression, as predicted by the TargetScan tool and miRBase. In vitro experiments showed that miR-520d-5p reduced ceruloplasmin gene expression in the U251 astrocyte cell line. Our data suggest that miR-520d-5p may be a potential regulator of ceruloplasmin gene expression in vitro.

OxInflammation: From Subclinical Condition to Pathological Biomarker

Inflammation is a complex systemic response evolved to cope with cellular injury, either due to infectious agents or, in general, with sporadic events challenging tissue integrity and function. Researchers involved in different fields have the tendency to look at the inflammatory response with different angles, according to their specific interest. Established its complexity, one of the most evident features of the inflammatory response is the generation of a pro-oxidative environment due to the production of high fluxes of pro-oxidant species. This production begins locally, close to the sites of tissue damage or infection, but eventually becomes a chronic challenge for the organism, if the inflammatory response is not properly controlled. In this review, we focus on this specific aspect of chronic, low-level sub-clinical inflammatory response. We propose the term "OxInflammation" as a novel operative term describing a permanent pro-oxidative feature that interact, in a positive feed-back manner, to a not yet clinically detectable inflammatory process, leading in a long run (chronically) to a systemic/local damage, as a consequence of the cross talk between inflammatory, and oxidative stress mediators. Therefore, it could be useful to analyze inflammatory markers in pathologies where there is an alteration of the redox homeostasis, although an inflammatory status is not clinically evident.

Neurotoxicity Linked to Dysfunctional Metal Ion Homeostasis and Xenobiotic Metal Exposure: Redox Signaling and Oxidative Stress

SIGNIFICANCE

Essential metals such as copper, iron, manganese, and zinc play a role as cofactors in the activity of a wide range of processes involved in cellular homeostasis and survival, as well as during organ and tissue development. Throughout our life span, humans are also exposed to xenobiotic metals from natural and anthropogenic sources, including aluminum, arsenic, cadmium, lead, and mercury. It is well recognized that alterations in the homeostasis of essential metals and an increased environmental/occupational exposure to xenobiotic metals are linked to several neurological disorders, including neurodegeneration and neurodevelopmental alterations. Recent Advances: The redox activity of essential metals is key for neuronal homeostasis and brain function. Alterations in redox homeostasis and signaling are central to the pathological consequences of dysfunctional metal ion homeostasis and increased exposure to xenobiotic metals. Both redox-active and redox-inactive metals trigger oxidative stress and damage in the central nervous system, and the exact mechanisms involved are starting to become delineated.

CRITICAL ISSUES

In this review, we aim to appraise the role of essential metals in determining the redox balance in the brain and the mechanisms by which alterations in the homeostasis of essential metals and exposure to xenobiotic metals disturb the cellular redox balance and signaling. We focus on recent literature regarding their transport, metabolism, and mechanisms of toxicity in neural systems.

FUTURE DIRECTIONS

Delineating the specific mechanisms by which metals alter redox homeostasis is key to understand the pathological processes that convey chronic neuronal dysfunction in neurodegenerative and neurodevelopmental disorders. Antioxid. Redox Signal. 28, 1669-1703.

Reward-enhanced encoding improves relearning of forgotten associations

Research on human memory has shown that monetary incentives can enhance hippocampal memory consolidation and thereby protect memory traces from forgetting. However, it is not known whether initial reward may facilitate the recovery of already forgotten memories weeks after learning. Here, we investigated the influence of monetary reward on later relearning. Nineteen healthy human participants learned object-location associations, for half of which we offered money. Six weeks later, most of these associations had been forgotten as measured by a test of declarative memory. Yet, relearning in the absence of any reward was faster for the originally rewarded associations. Thus, associative memories encoded in a state of monetary reward motivation may persist in a latent form despite the failure to retrieve them explicitly. Alternatively, such facilitation could be analogous to the renewal effect observed in animal conditioning, whereby a reward-associated cue can reinstate anticipatory arousal, which would in turn modulate relearning. This finding has important implications for learning and education, suggesting that even when learned information is no longer accessible via explicit retrieval, the enduring effects of a past prospect of reward could facilitate its recovery.

A Proposed Mechanism for Neurodegeneration in Movement Disorders Characterized by Metal Dyshomeostasis and Oxidative Stress

Shared molecular pathologies between distinct neurodegenerative disorders offer unique opportunities to identify common mechanisms of neuron death, and apply lessons learned from one disease to another. Neurotoxic superoxide dismutase 1 (SOD1) proteinopathy in SOD1-associated familial amyotrophic lateral sclerosis (fALS) is recapitulated in idiopathic Parkinson disease (PD), suggesting that these two phenotypically distinct disorders share an etiological pathway, and tractable therapeutic target(s). Despite 25 years of research, the molecular determinants underlying SOD1 misfolding and toxicity in fALS remain poorly understood. The absence of SOD1 mutations in PD highlights mounting evidence that SOD1 mutations are not the sole cause of SOD1 protein misfolding occasioning oligomerization and toxicity, reinforcing the importance of non-genetic factors, including protein metallation and post-translational modification in determining SOD1 stability and function. We propose that these non-genetic factors underlie the misfolding and dysfunction of SOD1 and other proteins in both PD and fALS, constituting a shared and tractable pathway to neurodegeneration.

Copper and ceruloplasmin dyshomeostasis in serum and cerebrospinal fluid of multiple sclerosis subjects

Although many studies have been carried out in order to understand the implication of copper (Cu) in the pathogenesis of multiple sclerosis (MS), the exact role that this metal plays in the disease is not still clear. Because of the lack of information in this subject, the present study compared the serum and cerebrospinal (CSF) levels of copper in MS patients in respect to a control group, matched for age and sex, finding a significant increase of metal concentrations, in both biological fluids of MS subjects. To confirm the possible impairment of Cu metabolism, we analyzed ceruloplasmin (Cp) level and activity, seeing as this protein is an established peripheral marker in diseases associated with Cu imbalance. By comparing these two parameters between control and MS subjects, we found an increase of Cp levels, associated with a decrease in Cp activity, in the second group. By analysing these data, free copper levels were calculated, significantly increased in serum of MS subjects; the increase in free copper could be one of the predisposing factors responsible for the Cu altered levels in CSF of MS patients. At the same time, this alteration could be attributable to the inability to incorporate Cu by Cp, probably due to the high oxidative environment found in serum of MS patients. Overall, all these copper alterations may play a role in MS pathogenesis.

Maillard Proteomics: Opening New Pages

Protein glycation is a ubiquitous non-enzymatic post-translational modification, formed by reaction of protein amino and guanidino groups with carbonyl compounds, presumably reducing sugars and α-dicarbonyls. Resulting advanced glycation end products (AGEs) represent a highly heterogeneous group of compounds, deleterious in mammals due to their pro-inflammatory effect, and impact in pathogenesis of diabetes mellitus, Alzheimer's disease and ageing. The body of information on the mechanisms and pathways of AGE formation, acquired during the last decades, clearly indicates a certain site-specificity of glycation. It makes characterization of individual glycation sites a critical pre-requisite for understanding in vivo mechanisms of AGE formation and developing adequate nutritional and therapeutic approaches to reduce it in humans. In this context, proteomics is the methodology of choice to address site-specific molecular changes related to protein glycation. Therefore, here we summarize the methods of Maillard proteomics, specifically focusing on the techniques providing comprehensive structural and quantitative characterization of glycated proteome. Further, we address the novel break-through areas, recently established in the field of Maillard research, i.e., in vitro models based on synthetic peptides, site-based diagnostics of metabolism-related diseases (e.g., diabetes mellitus), proteomics of anti-glycative defense, and dynamics of plant glycated proteome during ageing and response to environmental stress.