The familial amyotrophic lateral sclerosis-associated A4V SOD1 mutant is not able to regulate aerobic glycolysis

Under certain stress conditions, astrocytes operate in aerobic glycolysis, a process controlled by pyruvate dehydrogenase (PDH) inhibition through its E1 α subunit (Pda1) phosphorylation. This supplies lactate to neurons, which save glucose to obtain NADPH to, among other roles, counteract reactive oxygen species. A failure in this metabolic cooperation causes severe damage to neurons. In this work, using humanized Saccharomyces cerevisiae cells in which its endogenous Cu/Zn Superoxide Dismutase (SOD1) was replaced by human ortholog, we investigated the role of human SOD1 (hSOD1) in aerobic glycolysis regulation and its implications to amyotrophic lateral sclerosis (ALS), a neurodegenerative disease. Yeast cells ferment glucose even in the presence of oxygen and switch to respiratory metabolism after glucose exhaustion. However, like cells of SOD1-knockout strain, cells expressing A4V mutant of hSOD1 growing on glucose showed a respiratory phenotype, i.e., low glucose and high oxygen consumptions and low intracellular oxidation levels in response to peroxide stress, contrary to cells expressing wild-type (WT) SOD1 (yeast or human). The A4V mutation in hSOD1 is linked to ALS. In contrast to WT SOD1 strains, PDH activity of both sod1Δ and A4V hSOD1 cells did not change in response to a metabolic shift toward oxidative metabolism, which was associated to lower Pda1 phosphorylation levels under growth on glucose. Taken together, our results suggest that A4V mutant cannot regulate aerobic glycolysis via Pda1 phosphorylation the same way WT hSOD1, which might be linked to problems observed in the motor neurons of ALS patients with the SOD1 A4V mutation.

A redox-based characterization of human immune cell subsets by polychromatic flow cytometry

Cellular redox state determinants are traditionally studied using fluorescent microscopy and immunoblot analysis; however, no procedure has been developed for simultaneous measurement in various immune cell subsets. Here, we present a flow cytometry assay for measuring antioxidant defense systems and reactive oxygen species simultaneously in T, B, and natural killer lymphocytes. We describe steps for preparing and treating peripheral blood mononuclear cells, surface and dye staining, cell fixation/permeabilization, and intracellular staining. We then detail machine standardization, acquisition, and analysis.

A water-soluble manganese(II) octanediaoate/phenanthroline complex acts as an antioxidant and attenuates alpha-synuclein toxicity

The overproduction of reactive oxygen species (ROS) induces oxidative stress, a well-known process associated with aging and several human pathologies, such as cancer and neurodegenerative diseases. A large number of synthetic compounds have been described as antioxidant enzyme mimics, capable of eliminating ROS and/or reducing oxidative damage. In this study, we investigated the antioxidant activity of a water-soluble 1,10-phenantroline-octanediaoate Mn²⁺-complex on cells under oxidative stress, and assessed its capacity to attenuate alpha-synuclein (aSyn) toxicity and aggregation, a process associated with increased oxidative stress. This Mn²⁺-complex exhibited a significant antioxidant potential, reducing intracelular oxidation and increasing oxidative stress resistance in S. cerevisiae cells and in vivo, in G. mellonella, increasing the activity of the intracellular antioxidant enzymes superoxide dismutase and catalase. Strikingly, the Mn²⁺-complex reduced both aSyn oligomerization and aggregation in human cell cultures and, using NMR and DFT/molecular docking we confirmed its interaction with the C-terminal region of aSyn. In conclusion, the Mn²⁺-complex appears as an excellent lead for the design of new phenanthroline derivatives as alternative compounds for preventing oxidative damages and oxidative stress - related diseases.

1,2-Dehydropyrrolizidine Alkaloids: Their Potential as a Dietary Cause of Sporadic Motor Neuron Diseases

Sporadic motor neuron diseases (MNDs), such as amyotrophic lateral sclerosis (ALS), can be caused by spontaneous genetic mutations. However, many sporadic cases of ALS and other debilitating neurodegenerative diseases (NDDs) are believed to be caused by environmental factors, subject to considerable debate and requiring intensive research. A common pathology associated with MND development involves progressive mitochondrial dysfunction and oxidative stress in motor neurons and glial cells of the central nervous system (CNS), leading to apoptosis. Consequent degeneration of skeletal and respiratory muscle cells can lead to death from respiratory failure. A significant number of MND cases present with cancers and liver and lung pathology. This Perspective explores the possibility that MNDs could be caused by intermittent, low-level dietary exposure to 1,2-dehydropyrrolizidine alkaloids (1,2-dehydroPAs) that are increasingly recognized as contaminants of many foods consumed throughout the world. Nontoxic, per se, 1,2-dehydroPAs are metabolized, by particular cytochrome P450 (CYP450) isoforms, to 6,7-dihydropyrrolizines that react with nucleophilic groups (-NH, -SH, -OH) on DNA, proteins, and other vital biochemicals, such as glutathione. Many factors, including aging, gender, smoking, and alcohol consumption, influence CYP450 isoform activity in a range of tissues, including glial cells and neurons of the CNS. Activation of 1,2-dehydroPAs in CNS cells can be expected to cause gene mutations and oxidative stress, potentially leading to the development of MNDs and other NDDs. While relatively high dietary exposure to 1,2-dehydroPAs causes hepatic sinusoidal obstruction syndrome, pulmonary venoocclusive disease, neurotoxicity, and diverse cancers, this Perspective suggests that, at current intermittent, low levels of dietary exposure, neurotoxicity could become the primary pathology that develops over time in susceptible individuals, along with a tendency for some of them to also display liver and lung pathology and diverse cancers co-occurring with some MND/NDD cases. Targeted research is recommended to investigate this proposal.

SOD1, more than just an antioxidant

During cellular respiration, radicals, such as superoxide, are produced, and in a large concentration, they may cause cell damage. To combat this threat, the cell employs the enzyme Cu/Zn Superoxide Dismutase (SOD1), which converts the radical superoxide into molecular oxygen and hydrogen peroxide, through redox reactions. Although this is its main function, recent studies have shown that the SOD1 has other functions that deviates from its original one including activation of nuclear gene transcription or as an RNA binding protein. This comprehensive review looks at the most important aspects of human SOD1 (hSOD1), including the structure, properties, and characteristics as well as transcriptional and post-translational modifications (PTM) that the enzyme can receive and their effects, and its many functions. We also discuss the strategies currently used to analyze it to better understand its participation in diseases linked to hSOD1 including Amyotrophic Lateral Sclerosis (ALS), cancer, and Parkinson.

Characterization of the activity, aggregation, and toxicity of heterodimers of WT and ALS-associated mutant Sod1

Aggregation of the antioxidant enzyme Sod1 represents common factors of both familial (fALS) and sporadic cases of ALS, a fatal neurodegenerative disease. Although many ALS studies have focused on Sod1 homodimers/homomers, the investigation of Sod1 heterodimers/heteromers remains controversial and has mostly been performed with recombinant proteins in vitro, in the absence of a cellular environment. By using living cells, this study sheds light into a critical issue in the context of fALS, the high toxicity of the WT–mutant heteromeric inclusions, especially WT–A4V heteromers which accumulate both in human cells as well as in chronologically aged yeast cells. Besides the aggregation, we proposed that an inefficient heteromer response against oxidative conditions might contribute to fALS-linked mutant hSod1 toxicity.

Mutations in Cu/Zn superoxide dismutase (Sod1) have been reported in both familial and sporadic amyotrophic lateral sclerosis (ALS). In this study, we investigated the behavior of heteromeric combinations of wild-type (WT) and mutant Sod1 proteins A4V, L38V, G93A, and G93C in human cells. We showed that both WT and mutant Sod1 formed dimers and oligomers, but only mutant Sod1 accumulated in intracellular inclusions. Coexpression of WT and hSod1 mutants resulted in the formation of a larger number of intracellular inclusions per cell than that observed in cells coexpressing WT or mutant hSod1. The number of inclusions was greater in cells expressing A4V hSod1. To eliminate the contribution of endogenous Sod1, and better evaluate the effect of ALS-associated mutant Sod1 expression, we expressed human Sod1 WT and mutants in human cells knocked down for endogenous Sod1 (Sod1-KD), and in sod1Δ yeast cells. Using Sod1-KD cells we found that the WT–A4V heteromers formed higher molecular weight species compared with A4V and WT homomers. Using the yeast model, in conditions of chronological aging, we concluded that cells expressing Sod1 heterodimers showed decreased antioxidant activity, increased oxidative damage, reduced longevity, and oxidative stress-induced mutant Sod1 aggregation. In addition, we also found that ALS-associated Sod1 mutations reduced nuclear localization and, consequently, impaired the antioxidant response, suggesting this change in localization may contribute to disease in familial ALS. Overall, our study provides insight into the molecular underpinnings of ALS and may open avenues for the design of future therapeutic strategies.

Exploiting Post-mitotic Yeast Cultures to Model Neurodegeneration

Over the last few decades, the budding yeast Saccharomyces cerevisiae has been extensively used as a valuable organism to explore mechanisms of aging and human age-associated neurodegenerative disorders. Yeast models can be used to study loss of function of disease-related conserved genes and to investigate gain of function activities, frequently proteotoxicity, exerted by non-conserved human mutant proteins responsible for neurodegeneration. Most published models of proteotoxicity have used rapidly dividing cells and suffer from a high level of protein expression resulting in acute growth arrest or cell death. This contrasts with the slow development of neurodegenerative proteotoxicity during aging and the characteristic post-mitotic state of the affected cell type, the neuron. Here, we will review the efforts to create and characterize yeast models of neurodegeneration using the chronological life span model of aging, and the specific information they can provide regarding the chronology of physiological events leading to neurotoxic proteotoxicity-induced cell death and the identification of new pathways involved.

Current Therapeutic Molecules and Targets in Neurodegenerative Diseases Based on in silico Drug Design

BACKGROUND

As the number of elderly persons increases, neurodegenerative diseases are becoming ubiquitous. There is currently a great need for knowledge concerning management of oldage neurodegenerative diseases; the most important of which are: Alzheimer's disease, Parkinson's disease, Amyotrophic Lateral Sclerosis, and Huntington's disease.

OBJECTIVE

To summarize the potential of computationally predicted molecules and targets against neurodegenerative diseases.

METHOD

Review of literature published since 1997 against neurodegenerative diseases, utilizing as keywords: in silico, Alzheimer's disease, Parkinson's disease, Amyotrophic Lateral Sclerosis ALS, and Huntington's disease was conducted.

RESULTS AND CONCLUSION

Due to the costs associated with experimentation and current ethical law, performing experiments directly on living organisms has become much more difficult. In this scenario, in silico techniques have been successful and have become powerful tools in the search to cure disease. Researchers use the Computer Aided Drug Design pipeline which: 1) generates 3- dimensional structures of target proteins through homology modeling 2) achieves stabilization through molecular dynamics simulation, and 3) exploits molecular docking through large compound libraries. Next generation sequencing is continually producing enormous amounts of raw sequence data while neuroimaging is producing a multitude of raw image data. To solve such pressing problems, these new tools and algorithms are required. This review elaborates precise in silico tools and techniques for drug targets, active molecules, and molecular docking studies, together with future prospects and challenges concerning possible breakthroughs in Alzheimer's, Parkinson's, Amyotrophic Lateral Sclerosis, and Huntington's disease.

The second International Symposium on Fungal Stress: ISFUS

The topic of 'fungal stress' is central to many important disciplines, including medical mycology, chronobiology, plant and insect pathology, industrial microbiology, material sciences, and astrobiology. The International Symposium on Fungal Stress (ISFUS) brought together researchers, who study fungal stress in a variety of fields. The second ISFUS was held in May 8-11 2017 in Goiania, Goiás, Brazil and hosted by the Instituto de Patologia Tropical e Saúde Pública at the Universidade Federal de Goiás. It was supported by grants from CAPES and FAPEG. Twenty-seven speakers from 15 countries presented their research related to fungal stress biology. The Symposium was divided into seven topics: 1. Fungal biology in extreme environments; 2. Stress mechanisms and responses in fungi: molecular biology, biochemistry, biophysics, and cellular biology; 3. Fungal photobiology in the context of stress; 4. Role of stress in fungal pathogenesis; 5. Fungal stress and bioremediation; 6. Fungal stress in agriculture and forestry; and 7. Fungal stress in industrial applications. This article provides an overview of the science presented and discussed at ISFUS-2017.

Implications of fALS Mutations on Sod1 Function and Oligomerization in Cell Models

Among the familial forms of amyotrophic lateral sclerosis (fALS), 20% are associated with the Cu,Zn-superoxide dismutase (Sod1). fALS is characterized by the accumulation of aggregated proteins and the increase in oxidative stress markers. Here, we used the non-invasive bimolecular fluorescence complementation (BiFC) assay in human H4 cells to investigate the kinetics of aggregation and subcellular localization of Sod1 mutants. We also studied the effect of the different Sod1 mutants to respond against oxidative stress by following the levels of reactive oxygen species (ROS) after treatment with hydrogen peroxide. Our results showed that only 30% of cells transfected with A4VSod1 showed no inclusions while for the other Sod1 mutants tested (L38V, G93A and G93C), this percentage was at least 70%. In addition, we found that 10% of cells transfected with A4VSod1 displayed more than five inclusions per cell and that A4V and G93A Sod1 formed inclusions more rapidly than L38V and G93C Sod1. Expression of WTSod1 significantly decreased the intracellular oxidation levels in comparison with expression of fALS Sod1 mutants, suggesting the mutations induce a functional impairment. All fALS mutations impaired nuclear localization of Sod1, which is important for maintaining genomic stability. Consistently, expression of WTSod1, but not of fALS Sod1 mutants, reduced DNA damage, as measured by the comet assay. Altogether, our study sheds light into the effects of fALS Sod1 mutations on inclusion formation, dynamics, and localization as well as on antioxidant response, opening novel avenues for investigating the role of fALS Sod1 mutations in pathogenesis.

Protein trafficking in the mitochondrial intermembrane space: mechanisms and links to human disease

Mitochondria fulfill a diverse range of functions in cells including oxygen metabolism, homeostasis of inorganic ions and execution of apoptosis. Biogenesis of mitochondria relies on protein import pathways that are ensured by dedicated multiprotein translocase complexes localized in all sub-compartments of these organelles. The key components and pathways involved in protein targeting and assembly have been characterized in great detail over the last three decades. This includes the oxidative folding machinery in the intermembrane space, which contributes to the redox-dependent control of proteostasis. Here, we focus on several components of this system and discuss recent evidence suggesting links to human proteopathy.

Oxidative Stress and Amyloid Toxicity: Insights From Yeast

Alzheimer's disease is the most common neurodegenerative disorder. One of the factors that promotes neurodegeneration is the accumulation of senile plaques formed by Aβ peptide. In this paper, it was analyzed that if oxidative stress is cause or consequence of amyloid cascade and the role of antioxidant defense system in this process, using S. cerevisiae (with a multicopy plasmid containing the Aβ1-42 sequence) as experimental model. Cells grown on glycerol were more tolerant than when grown on glucose, strengthening the role of the antioxidant defense system against Aβ accumulation. Antioxidant defense deficiency did not change the pattern of amyloid aggregation. On the other hand, the presence of Aβ increased the level of intracellular oxidation and induced the activity of catalase, superoxide dismutase, and aconitase. Peroxissomal catalase deficient cells (Δcta1), were more sensitive to Aβ toxicity than the wild type strain, while mitochondrial superoxide dismutase (Sod2) deficient cells displayed the highest frequency of petites. Besides, Aβ alters the oxygen consumption and the activity of complex III and IV. Taken together, our results point out that the Aβ toxicity mechanism involves an oxidative stress induction by increasing ROS production into the mitochondria, where Cta1 and Sod2 play a crucial role in the regulation of the redox balance. J. Cell. Biochem. 118: 1442-1452, 2017. © 2016 Wiley Periodicals, Inc.

Metal-based superoxide dismutase and catalase mimics reduce oxidative stress biomarkers and extend life span of Saccharomyces cerevisiae

Aging is a natural process characterized by several biological changes. In this context, oxidative stress appears as a key factor that leads cells and organisms to severe dysfunctions and diseases. To cope with reactive oxygen species and oxidative-related damage, there has been increased use of superoxide dismutase (SOD)/catalase (CAT) biomimetic compounds. Recently, we have shown that three metal-based compounds {[Fe(HPClNOL)Cl2]NO3, [Cu(HPClNOL)(CH3CN)](ClO4)2 and Mn(HPClNOL)(Cl)2}, harboring in vitro SOD and/or CAT activities, were critical for protection of yeast cells against oxidative stress. In this work, treating Saccharomyces cerevisiae with these SOD/CAT mimics (25.0 µM/1 h), we highlight the pivotal role of these compounds to extend the life span of yeast during chronological aging. Evaluating lipid and protein oxidation of aged cells, it becomes evident that these mimics extend the life expectancy of yeast mainly due to the reduction in oxidative stress biomarkers. In addition, the treatment of yeast cells with these mimics regulated the amounts of lipid droplet occurrence, consistent with the requirement and protection of lipids for cell integrity during aging. Concerning SOD/CAT mimics uptake, using inductively coupled plasma mass spectrometry, we add new evidence that these complexes, besides being bioabsorbed by S. cerevisiae cells, can also affect metal homeostasis. Finally, our work presents a new application for these SOD/CAT mimics, which demonstrate a great potential to be employed as antiaging agents. Taken together, these promising results prompt future studies concerning the relevance of administration of these molecules against the emerging aging-related diseases such as Parkinson's, Alzheimer's and Huntington's.

Oxidative folding in the mitochondrial intermembrane space: A regulated process important for cell physiology and disease

Mitochondria are fundamental organelles with a complex internal architecture that fulfill important diverse functions including iron–sulfur cluster assembly and cell respiration. Intense work for more than 30 years has identified the key protein import components and the pathways involved in protein targeting and assembly. More recently, oxidative folding has been discovered as one important mechanism for mitochondrial proteostasis whilst several human disorders have been linked to this pathway. We describe the molecular components of this pathway in view of their putative redox regulation and we summarize available evidence on the connections of these pathways to human disorders.

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Mitochondria are the cell center of iron–sulfur cluster assembly and cell respiration.

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The MIA pathway has recently been linked to Fe/S pathways, Ca^2 + uptake and apoptosis.

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Mitochondria along with the ER and peroxisomes are major sources of ROS.

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Many diseases have been linked to mitochondrial dysfunction.

Thiol redox homeostasis in neurodegenerative disease

This review provides an overview of the biochemistry of thiol redox couples and the significance of thiol redox homeostasis in neurodegenerative disease. The discussion is centred on cysteine/cystine redox balance, the significance of the x_c⁻ cystine–glutamate exchanger and the association between protein thiol redox balance and neurodegeneration, with particular reference to Alzheimer's disease, Parkinson's disease, amyotrophic lateral sclerosis and glaucoma. The role of thiol disulphide oxidoreductases in providing neuroprotection is also discussed.

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An overview of the biochemistry of thiol redox couples.

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The significance of thiol redox homoeostasis in neurodegenerative disease.

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The association between the x_c⁻ cystine–glutamate exchanger and glutamate-mediated toxicity.

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The role of thiol disulphide oxidoreductases in neuroprotection.

Finding inhibitors of mutant superoxide dismutase-1 for amyotrophic lateral sclerosis therapy from traditional chinese medicine

Superoxide dismutase type 1 (SOD1) mutations cause protein aggregation and decrease protein stability, which are linked to amyotrophic lateral sclerosis (ALS) disease. This research utilizes the world's largest traditional Chinese medicine (TCM) database to search novel inhibitors of mutant SOD1, and molecular dynamics (MD) simulations were used to analyze the stability of protein that interacted with docked ligands. Docking results show that hesperidin and 2,3,5,4'-tetrahydroxystilbene-2-O- β -D-glucoside (THSG) have high affinity to mutant SOD1 and then dopamine. For MD simulation analysis, hesperidin and THSG displayed similar value of RMSD with dopamine, and the migration analysis reveals stable fluctuation at the end of MD simulation time. Interestingly, distance between the protein and ligand has distinct difference, and hesperidin changes the position from initial binding site to the other place. In flexibility of residues analysis, the secondary structure among all complexes does not change, indicating that the structure are not affect ligand binding. The binding poses of hesperidin and THSG are similar to dopamine after molecular simulation. Our result indicated that hesperidin and THSG might be potential lead compound to design inhibitors of mutant SOD1 for ALS therapy.

The role of s-nitrosylation and s-glutathionylation of protein disulphide isomerase in protein misfolding and neurodegeneration

Neurodegenerative diseases involve the progressive loss of neurons, and a pathological hallmark is the presence of abnormal inclusions containing misfolded proteins. Although the precise molecular mechanisms triggering neurodegeneration remain unclear, endoplasmic reticulum (ER) stress, elevated oxidative and nitrosative stress, and protein misfolding are important features in pathogenesis. Protein disulphide isomerase (PDI) is the prototype of a family of molecular chaperones and foldases upregulated during ER stress that are increasingly implicated in neurodegenerative diseases. PDI catalyzes the rearrangement and formation of disulphide bonds, thus facilitating protein folding, and in neurodegeneration may act to ameliorate the burden of protein misfolding. However, an aberrant posttranslational modification of PDI, S-nitrosylation, inhibits its protective function in these conditions. S-nitrosylation is a redox-mediated modification that regulates protein function by covalent addition of nitric oxide- (NO-) containing groups to cysteine residues. Here, we discuss the evidence for abnormal S-nitrosylation of PDI (SNO-PDI) in neurodegeneration and how this may be linked to another aberrant modification of PDI, S-glutathionylation. Understanding the role of aberrant S-nitrosylation/S-glutathionylation of PDI in the pathogenesis of neurodegenerative diseases may provide insights into novel therapeutic interventions in the future.