Roles of zinc and copper in modulating the oxidative refolding of bovine copper, zinc superoxide dismutase

Leukocytospermia and/or Bacteriospermia: Impact on Male Infertility

Infertility is a globally underestimated public health concern affecting almost 190 million people, i.e., about 17.5% of people during their lifetime, while the prevalence of male factor infertility is about 7%. Among numerous other causes, the prevalence of male genital tract infections reportedly ranges between 10% and 35%. Leukocytospermia is found in 30% of infertile men and up to 20% in fertile men. Bacterial infections cause an inflammatory response attracting leukocytes, which produce reactive oxygen species (ROS) and release cytokines, both of which can cause damage to sperm, rendering them dysfunctional. Although leukocytospermia and bacteriospermia are both clinical conditions that can negatively affect male fertility, there is still debate about their impact on assisted reproduction outcomes and management. According to World Health Organization (WHO) guidelines, leukocytes should be determined by means of the Endtz test or with monoclonal antibodies against CD15, CD68 or CD22. The cut-off value proposed by the WHO is 1 × 106 peroxidase-positive cells/mL. For bacteria, Gram staining and semen culture are regarded as the "gold standard", while modern techniques such as PCR and next-generation sequencing (NGS) are allowing clinicians to detect a wider range of pathogens. Whereas the WHO manual does not specify a specific value as a cut-off for bacterial contamination, several studies consider semen samples with more than 103 colony-forming units (cfu)/mL as bacteriospermic. The pathogenic mechanisms leading to sperm dysfunction include direct interaction of bacteria with the male germ cells, bacterial release of spermatotoxic substances, induction of pro-inflammatory cytokines and ROS, all of which lead to oxidative stress. Clinically, bacterial infections, including "silent" infections, are treatable, with antibiotics being the treatment of choice. Yet, non-steroidal antiphlogistics or antioxidants should also be considered to alleviate inflammatory lesions and improve semen quality. In an assisted reproduction set up, sperm separation techniques significantly reduce the bacterial load in the semen. Nonetheless, contamination of the semen sample with skin commensals should be prevented by applying relevant hygiene techniques. In patients where leukocytospermia is detected, the causes (e.g. infection, inflammation, varicocele, smoking, etc.) of the leukocyte infiltration have to be identified and addressed with antibiotics, anti-inflammatories or antioxidants in cases where high oxidative stress levels are detected. However, no specific strategy is available for the management of leukocytospermia. Therefore, the relationship between bacteriospermia and leukocytospermia as well as their specific impact on functional sperm parameters and reproductive outcome variables such as fertilization or clinical pregnancy must be further investigated. The aim of this narrative review is to provide an update on the current knowledge on leukocytospermia and bacteriospermia and their impact on male fertility.

Protein Carbonyl, Lipid Peroxidation, Glutathione and Enzymatic Antioxidant Status in Male Wistar Brain Sub-regions After Dietary Copper Deficiency

Copper a quintessential transitional metal is required for development and function of normal brain and its deficiency has been associated with impairments in brain function. The present study investigates the effects of dietary copper deficiency on brain sub-regions of male Wistar rats for 2-, 4- and 6-week. Pre-pubertal rats were divided into four groups: negative control (NC), copper control (CC), pairfed (PF) and copper deficient (CD). In brain sub regions total protein concentration, glutathione concentration and Cu-Zn SOD activity were down regulated after 2-, 4- and 6 weeks compared to controls and PF groups. Significant increase in brain sub regions was observed in protein carbonyl and lipid peroxidation concentration as well as total SOD, Mn SOD and catalase activities after 2-, 4- and 6 weeks of dietary copper deficiency. Experimental evidences indicate that impaired copper homeostasis has the potential to generate reactive oxygen species enhancing the susceptibility to oxidative stress by inducing up- and down-regulation of non-enzymatic and enzymatic profile studied in brain sub regions causing loss of their normal function which can consequently lead to deterioration of cell structure and death if copper deficiency is prolonged.

A New Concept in Antidiabetic Therapeutics: A Concerted Removal of Labile Iron and Intracellular Deposition of Zinc

BACKGRUOUND

The inflammatory process is known to be an integral part of the pathophysiology of type 2 diabetes mellitus (T2DM). The "labile," redox-active iron, serving as a catalyst in Fenton reaction, producing the deleterious reactive oxygen species, triggering and maintaining inflammation, is hypothesized to play a causative role in this process. Concenter Biopharma continued the development of a new platform of iron chelators (Zygosids), first initiated at the Hebrew University of Jerusalem, Israel (HUJI), acting via the novel mechanism, based on a sequestration of the labile redox-active iron and its substitution by zinc or gallium. The mode of action of Zygosids is based on the higher affinity of the metal-binding moiety of the complex to Fe3+ in comparison to already bound ion, leading to rapid release of the ion of another metal and chelation of Fe3+. Concomitantly, zinc ion, released by the complex, is known for its antidiabetic and anti-inflammatory role.

METHODS

The therapeutic effect of zinc-desferrioxamine (Zygosid-50) and gallium-desferrioxamine, was tested on fat sand rat (Psammomys obesus) model of diet-induced T2DM and on Leprdb transgenic diabetic mice.

RESULTS

Zygosids demonstrated an ability to noticeably reduce blood glucose and insulin levels and improve the lipid profile. Moreover, an ability to mitigate insulin resistance by >90% was shown on the sand rat model. In addition, a potent anti-inflammatory effect, expressed as a diminishment of the proinflammatory cytokines in tissue levels, was demonstrated.

CONCLUSION

Zygosids demonstrated robust therapeutic efficacy in treatment of T2DM. Importantly, no adverse effects were detected, in all the experiments, indicating high safety profile.

Oxidative Stress in Pregnancy

Recent years have seen an increased interest in the role of oxidative stress (OS) in pregnancy. Pregnancy inherently heightens susceptibility to OS, a condition fueled by a systemic inflammatory response that culminates in an elevated presence of reactive oxygen species (ROS) and reactive nitrogen species (RNS) in the circulatory system. The amplified OS in pregnancy can trigger a series of detrimental outcomes such as underdevelopment, abnormal placental function, and a host of pregnancy complications, including pre-eclampsia, embryonic resorption, recurrent pregnancy loss, fetal developmental anomalies, intrauterine growth restriction, and, in extreme instances, fetal death. The body's response to mitigate the uncontrolled increase in RNS/ROS levels requires trace elements that take part in non-enzymatic and enzymatic defense processes, namely, copper (Cu), zinc (Zn), manganese (Mn), and selenium (Se). Determination of ROS concentrations poses a challenge due to their short half-lives, prompting the use of marker proteins, including malondialdehyde (MDA), superoxide dismutase (SOD), glutathione peroxidase (GPx), glutathione reductase (GR), catalase (CAT), and glutathione (GSH). These markers, indicative of oxidative stress intensity, can offer indirect assessments of pregnancy complications. Given the limitations of conducting experimental studies on pregnant women, animal models serve as valuable substitutes for in-depth research. This review of such models delves into the mechanism of OS in pregnancy and underscores the pivotal role of OS markers in their evaluation.

Computational identification and experimental validation of anti-filarial lead molecules targeting metal binding/substrate channel residues of Cu/Zn SOD1 from Wuchereria bancrofti

Lymphatic filariasis (LF) is a neglected mosquito-borne parasitic disease, widely caused by Wuchereria bancrofti (Wb) in tropical and sub-tropical countries. During a blood meal, the filarial nematodes are transmitted to humans by the infected mosquito. To counter attack the invaded nematodes, the human immune system produces reactive oxygen species. However, the anti-oxidant enzymes of nematodes counteract the host oxidative cytotoxicity. Cu/Zn Superoxide dismutase (SOD1), a member of antioxidant enzymes and are widely used by the nematodes to sustain the host oxidative stress across its lifecycle, hence targeting SOD1 to develop suitable drug molecules would help to overcome the problems related to efficacy and activity of drugs upon different stages of nematodes. In order to find the potent inhibitors, a three-dimensional structure of Cu/Zn WbSOD1 was modelled and the structural stability was analysed through simulation studies. The structure-guided virtual screening approach has been used to identify lead molecules from the ChemBridge based on the docking score, ADMET properties and protein-ligand complex stability analysis. The identified compounds were observed to interact with the copper, metal binding residues (His48, His63, His80 and His120) and catalytically important residue Arg146, which play a crucial role in the disproportionation of incoming superoxide radicals of Cu/Zn WbSOD1. Further, in vitro validation of the selected leads in the filarial worm Setaria digitata exhibited higher inhibition and better IC50 compared to the standard drug ivermectin. Thus, the identified leads could potentially inhibit enzyme activity, which could subsequently act as drug candidates to control LF.Communicated by Ramaswamy H. Sarma.

The Trace Element Concentrations and Oxidative Stress Parameters in Afterbirths from Women with Multiple Pregnancies

The aim of this study was to evaluate the intensity of oxidative stress by measuring the concentrations of lipid peroxidation products (LPO) in fetal membrane, umbilical cord, and placenta samples obtained from women with multiple pregnancies. Additionally, the effectiveness of protection against oxidative stress was assessed by measuring the activity of antioxidant enzymes, including superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPX), and glutathione reductase (GR). Due to the role of iron (Fe), copper (Cu), and zinc (Zn) as cofactors for antioxidant enzymes, the concentrations of these elements were also analyzed in the studied afterbirths. The obtained data were compared with newborn parameters, selected environmental factors, and the health status of women during pregnancy to determine the relationship between oxidative stress and the health of women and their offspring during pregnancy. The study involved women (n = 22) with multiple pregnancies and their newborns (n = 45). The Fe, Zn, and Cu levels in the placenta, umbilical cord, and fetal membrane were determined using inductively coupled plasma atomic emission spectroscopy (ICP-OES) using an ICAP 7400 Duo system. Commercial assays were used to determine SOD, GPx, GR, CAT, and LPO activity levels. The determinations were made spectrophotometrically. The present study also investigated the relationships between trace element concentrations in fetal membrane, placenta, and umbilical cord samples and various maternal and infant parameters in women. Notably, a strong positive correlation was observed between Cu and Zn concentrations in the fetal membrane (p = 0.66) and between Zn and Fe concentrations in the placenta (p = 0.61). The fetal membrane Zn concentration exhibited a negative correlation with shoulder width (p = -0.35), while the placenta Cu concentration was positively correlated with placenta weight (p = 0.46) and shoulder width (p = 0.36). The umbilical cord Cu level was positively correlated with head circumference (p = 0.36) and birth weight (p = 0.35), while the placenta Fe concentration was positively correlated with placenta weight (p = 0.33). Furthermore, correlations were determined between the parameters of antioxidative stress (GPx, GR, CAT, SOD) and oxidative stress (LPO) and the parameters of infants and maternal characteristics. A negative correlation was observed between Fe and LPO product concentrations in the fetal membrane (p = -0.50) and placenta (p = -0.58), while the Cu concentration positively correlated with SOD activity in the umbilical cord (p = 0.55). Given that multiple pregnancies are associated with various complications, such as preterm birth, gestational hypertension, gestational diabetes, and placental and umbilical cord abnormalities, research in this area is crucial for preventing obstetric failures. Our results could serve as comparative data for future studies. However, we advise caution when interpreting our results, despite achieving statistical significance.

L-shaped association between dietary zinc intake and the risk of developing cardiovascular disease in Chinese adults: A cohort study

Background

Although the association of zinc (Zn) with cardiovascular disease (CVD) has been studied, no consensus has been reached on this relationship, particularly dietary Zn intake. The purpose of this study was to assess the effect of dietary Zn intake on the risk of CVD and to analyze whether this effect varied according to zinc consumption using representative data from China.

Methods

11,470 adults from the China Health and Nutrition Survey (CHNS) were eventually enrolled. The dietary information was collected by the 3 day 24-h dietary recalls combined with dietary weighting method. CVD was defined as participants with self-reported physician-diagnosed apoplexy and/or myocardial infarction during the follow-up. Cox regression was used to calculate the hazard ratios (HRs) of CVD with 95% confidence intervals. Restricted cubic spline function plus Cox regression was used to visualize the influence trend of dietary Zn intake on new-onset CVD and to test whether this trend is linear. 2-segment Cox regression was established to address the nonlinear trend.

Results

431 participants developed CVD, including 262 strokes and 197 myocardial infarctions. Compared with the lowest quintile (Q1), the adjusted hazard ratios and 95% confidence interval (CI) of CVD in Q2 to Q5 of dietary Zn intake were 0.72 (0.54, 0.97), 0.59 (0.42, 0.81), 0.50 (0.34, 0.72) and 0.44 (0.27, 0.71), respectively. The influence trend of dietary Zn intake on new-onset CVD was nonlinear and L-shaped. When dietary Zn intake <13.66 mg/day, increased dietary Zn intake was significantly associated with decreased risk of developing CVD (HR = 0.87, 95% CI: 0.82-0.92, p-value <0.0001).

Conclusion

An L-shaped trend was observed between dietary Zn intake and the risk of developing CVD, indicating that dietary Zn intake should be improved moderately, but not excessively, for the benefit of cardiovascular disease.

Computational insight into in silico analysis and molecular dynamics simulation of the dimer interface residues of ALS-linked hSOD1 forms in apo/holo states: a combined experimental and bioinformatic perspective

The aggregation of misfolded SOD1 proteins in neurodegenerative illnesses is a key pathological hallmark in amyotrophic lateral sclerosis (ALS). SOD1 is stabilized and enzymatically activated after binding to Cu/Zn and forming intramolecular disulfide. SOD1 aggregation/oligomerization is triggered by the dissociation of Cu and/or Zn ions. Therefore, we compared the possible effects of ALS-associated point mutations of the holo/apo forms of WT/I149T/V148G SOD1 variants located at the dimer interface to determine structural characterization using spectroscopic methods, computational approaches as well as molecular dynamics (MD) simulations. Predictive results of computational analysis of single-nucleotide polymorphisms (SNPs) suggested that mutant SOD1 has a deleterious effect on activity and structure destabilization. MD data analysis indicated that changes in flexibility, stability, hydrophobicity of the protein as well as increased intramolecular interactions of apo-SOD1 were more than holo-SOD1. Furthermore, a decrease in enzymatic activity in apo-SOD1 was observed compared to holo-SOD1. Comparative intrinsic and ANS fluorescence results of holo/apo-WT-hSOD1 and mutants indicated structural alterations in the local environment of tryptophan residue and hydrophobic patches, respectively. Experimental and MD data supported that substitution effect and metal deficiency of mutants (apo forms) in the dimer interface may promote the tendency to protein mis-folding and aggregation, consequently disrupting the dimer-monomer equilibrium and increased propensity to dissociation dimer into SOD-monomer ultimately leading to loss of stability and function. Overall, data analysis of apo/holo SOD1 forms on protein structure and function using computational and experimental studies will contribute to a better understanding of ALS pathogenicity.

A computational strategy for therapeutic development against superoxide dismutase (SOD1) amyloid formation: effect of polyphenols on the various events in the aggregation pathway

Pathology of superoxide dismutase 1 (SOD1) aggregation is linked to a neurodegenerative disease known as amyotrophic lateral sclerosis (ALS). Without suitable post-translational modifications (PTMs), the protein structure tends to become aggregation-prone. Understanding the role of PTMs and targeting the aggregation-prone SOD1 with small molecules can be used to design a strategy to inhibit its aggregation. Microsecond long molecular dynamics (MD) simulations followed by free energy surface (FES) analyses show that the loss of structure in the apo monomer happens locally and stepwise. Removing the disulfide bond from apoprotein leads to further instability in the zinc-binding loop, giving rise to non-native protein conformations. Further, it was found that these non-native conformations have a higher propensity to form a non-native dimer. We chose three structurally similar polyphenols based on their binding energies and investigated their impact on SOD1 aggregation kinetics. MD simulations of apo-SOD1^SH/corkscrew fibril-polyphenol complexes were also carried out. The effect of polyphenols was seen on fibril elongation as well. Based on the experiments and MD simulation results, it can be inferred that the choice of inhibitors is influenced not only by the binding energy but also by dimer interface stabilization, the proclivity to form non-native dimers, the propensity to break fibrils, and the propensity to decrease the rate of elongation. The polyphenols with 3' and 4' hydroxyl groups are better inhibitors of SOD1 aggregation.

Cloning and expression of recombinant human superoxide dismutase 1 (hSOD1) in Bacillus subtilis 1012

OBJECTIVE

We aimed to clone and express the human Cu, Zn superoxide dismutase (hSOD1) in Bacillus subtilis 1012. Also, we investigated the expression level of hSOD1 under different induction conditions.

RESULT

As an essential member of the antioxidant defense system in vivo, hSOD1 has become a therapeutic agent against host diseases, such as oxygen toxicity, acute inflammation, and radiation injury. The recombinant hSOD1 was successfully secreted extracellularly into B. subtilis 1012. The expression conditions were optimized, including inoculum size, different media, temperatures, and inducer concentrations. Finally, the highest level of hSOD1 was produced as a soluble form in Super rich medium by 2% inoculum with 0.2 mM of IPTG at 37 °C after the induction for 24 h. Besides, 20 g/L of lactose also displayed the same inductive effect on hSOD1 expression as that of IPTG (0.2 mM). Finally, the specific activity of purified hSOD1 was determined to be 1625 U/mg in the presence of 800 μM of Cu²⁺ and 20 μM of Zn²⁺.

CONCLUSIONS

We propose that the B. subtilis 1012-hSOD1 strain system has great potential in future industrial applications.

Oxidative stress in Hashimoto's thyroiditis: possible adjuvant therapies to attenuate deleterious effects

A number of studies have shown that oxidative stress is related to the pathogenesis of several immunological diseases, such as Hashimoto's thyroiditis (HT), although there is no plausible mechanism to explain it. Thus, we aimed at hypothesizing and providing some possible mechanisms linking oxidative stress to autoimmunity aspects and its implications for HT, as well as adjuvant therapeutic proposals to mitigate the deleterious effects. Our hypothesis is that deficient eating habits, autoimmune regulator gene predisposing gene, dysbiosis and molecular mimicry, unfolded proteins and stress in the endoplasmic reticulum, and thymus involution appear to be the main potential factors leading to HT oxidative stress. Likewise, we show that the use of minerals selenium and zinc, vitamins D and C, as well as probiotics, can be interesting adjuvant therapies for the control of oxidative damage and poor prognosis of HT. Further clinical trials are needed to understand the real beneficial and side effects of these supplements.

No Association of Hair Zinc Concentration with Coronary Artery Disease Severity and No Relation with Acute Coronary Syndromes

Cardiovascular diseases (CVDs) are the leading cause of death worldwide. Although zinc (Zn) was reported to have antioxidant, anti-inflammatory and protective properties in CVDs, its association with coronary artery disease (CAD) is still unclear. As methods commonly used to assess Zn levels in blood and urine do not show the full picture of the microelement supply, in this study, the nutritional status of Zn in patients with angiographically confirmed CAD was assessed using inductively coupled plasma optical emission spectrometry. We found no association between Zn and the severity of CAD evaluated with the Coronary Artery Surgery Study Score (p = 0.67). There were no statistically significant differences in Zn levels between patients with acute coronary syndrome and those with stable CAD (p = 0.937). A statically significant negative correlation was observed between Zn content and serum triglyceride concentration (p < 0.05). Patients with type 2 diabetes mellitus were found to have a significantly lower hair Zn content compared to non-diabetic individuals (p < 0.01). The role of Zn in the pathogenesis of CAD and its complications need further well-designed research as the moderation and supplementation of Zn dietary intake could be a simple intervention to reduce the CVDs risk.

Probing the polyphenolic flavonoid, morin as a highly efficacious inhibitor against amyloid(A4V) mutant SOD1 in fatal amyotrophic lateral sclerosis

Deposition of misfolded protein aggregates in key areas of human brain is the quintessential trait of various pertinent neurodegenerative disorders including amyotrophic lateral sclerosis (ALS). Genetic point mutations in Cu/Zn superoxide dismutase (SOD1) are found to be the most important contributing factor behind familial ALS. Especially, single nucleotide polymorphism (SNP) A4V is the most nocuous since it substantially decreases life expectancy of patients. Besides, the use of naturally occurring polyphenolic flavonoids is profoundly being advocated for palliating amyloidogenic behavior of proteopathic proteins. In the present analysis, through proficient computational tools, we have attempted to ascertain a pharmacodynamically promising flavonoid compound that effectively curbs the pathogenic behavior of A4V SOD1 mutant. Initial screening of flavonoids that exhibit potency against amyloids identified morin, myricetin and epigallocatechin gallate as promising leads. Further, with the help of feasible and yet adept protein-ligand interaction studies and stalwart molecular simulation analyses, we were able to observe that aforementioned flavonoids were able to considerably divert mutant A4V SOD1 from its distinct pathogenic behavior. Among which, morin showed the most curative potential against A4V SOD1. Therefore, morin holds a great therapeutic potential in contriving highly efficacious inhibitors in mitigating fatal and insuperable ALS.

Molecular and Biochemical Analysis of Duplicated Cytosolic CuZn Superoxide Dismutases of Rice and in silico Analysis in Plants

Superoxide dismutases (SODs, EC 1.15.1.1) are ubiquitous antioxidant metalloenzymes important for oxidative stress tolerance and cellular redox environment. Multiple factors have contributed toward the origin and diversity of SOD isoforms among different organisms. In plants, the genome duplication events, responsible for the generation of multiple gene copies/gene families, have also contributed toward the SOD diversity. However, the importance of such molecular events on the characteristics of SODs has not been studied well. This study investigated the effects of divergence on important characteristics of two block-duplicated rice cytosolic CuZn SODs (OsCSD1, OsCSD4), along with in silico assessment of similar events in other plants. The analysis revealed heterogeneity in gene length, regulatory regions, untranslated regions (UTRs), and coding regions of two OsCSDs. An inconsistency in the database-predicted OsCSD1 gene structure was also identified and validated experimentally. Transcript analysis showed differences in the basal levels and stress responsiveness of OsCSD1 and OsCSD4, and indicated the presence of two transcription start sites in the OsCSD1. At the amino acid level, the two OsCSDs showed differences at 18 sites; however, both exist as a homodimer, displaying typical CuZn SOD characteristics, and enhancing the oxidative stress tolerance of Escherichia coli cells. However, OsCSD4 showed higher specific activity as well as stability. The comparison of the two OsCSDs with reported thermostable CSDs from other plants identified regions likely to be associated with stability, while the homology modeling and superposition highlighted structural differences. The two OsCSDs displayed heteromeric interaction capability and forms an enzymatically active heterodimer (OsCSD1:OsCSD4) on co-expression, which may have significance as both are cytosolic. In silico analysis of 74 plant genomes revealed the prevalence of block duplications for multiple CSD copies (mostly cytosolic). The divergence and clustering analysis of CSDs suggested the possibility of an ancestral duplication event in monocots. Conserved SOD features indicating retention of SOD function among CSD duplicates were evident in few monocots and dicots. In most other species, the CSD copies lacked critical features and may not harbor SOD function; however, other feature-associated functions or novel functions might be present. These aspects of divergent CSD copies encoding co-localized CSDs may have implications in plant SOD functions in the cytosol and other organelles.

Hydrogen Peroxide and Amyotrophic Lateral Sclerosis: From Biochemistry to Pathophysiology

Free radicals are unstable chemical reactive species produced during Redox dyshomeostasis (RDH) inside living cells and are implicated in the pathogenesis of various neurodegenerative diseases. One of the most complicated and life-threatening motor neurodegenerative diseases (MND) is amyotrophic lateral sclerosis (ALS) because of the poor understanding of its pathophysiology and absence of an effective treatment for its cure. During the last 25 years, researchers around the globe have focused their interest on copper/zinc superoxide dismutase (Cu/Zn SOD, SOD1) protein after the landmark discovery of mutant SOD1 (mSOD1) gene as a risk factor for ALS. Substantial evidence suggests that toxic gain of function due to redox disturbance caused by reactive oxygen species (ROS) changes the biophysical properties of native SOD1 protein thus, instigating its fibrillization and misfolding. These abnormal misfolding aggregates or inclusions of SOD1 play a role in the pathogenesis of both forms of ALS, i.e., Sporadic ALS (sALS) and familial ALS (fALS). However, what leads to a decrease in the stability and misfolding of SOD1 is still in question and our scientific knowledge is scarce. A large number of studies have been conducted in this area to explore the biochemical mechanistic pathway of SOD1 aggregation. Several studies, over the past two decades, have shown that the SOD1-catalyzed biochemical reaction product hydrogen peroxide (H₂O₂) at a pathological concentration act as a substrate to trigger the misfolding trajectories and toxicity of SOD1 in the pathogenesis of ALS. These toxic aggregates of SOD1 also cause aberrant localization of TAR-DNA binding protein 43 (TDP-43), which is characteristic of neuronal cytoplasmic inclusions (NCI) found in ALS. Here in this review, we present the evidence implicating the pivotal role of H₂O₂ in modulating the toxicity of SOD1 in the pathophysiology of the incurable and highly complex disease ALS. Also, highlighting the role of H₂O₂ in ALS, we believe will encourage scientists to target pathological concentrations of H₂O₂ thereby halting the misfolding of SOD1.

Association between serum zinc concentrations and metabolic risk factors among Chinese children and adolescents

The aim of the present study was to examine whether serum Zn concentrations were associated with metabolic risk factors in Chinese children and adolescents. This was a cross-sectional study including 3241 participants, aged 6 to 17 years, from Jiangsu, China. Metabolic risk factors included fasting glucose (FG), total cholesterol (TC), TAG, HDL-cholesterol, LDL-cholesterol, systolic blood pressure and diastolic blood pressure. Data were analysed using multi-variable linear regression and generalised additive models, which were adjusted for age, sex, high-sensitive C-reactive protein, estimated glomerular filtration rate, BMI and region of residence, to assess the associations of serum Zn concentrations with metabolic risk factors. We observed a negative association between serum Zn concentrations and FG (coefficient = -0·532; 95 % CI -0·569, -0·495; P < 0·001). Moreover, TC (coefficient = 0·175; 95 % CI 0·127, 0·222; P < 0·001), HDL-cholesterol (coefficient = 0·137; 95 % CI 0·082, 0·193; P < 0·001) and LDL-cholesterol (coefficient = 0·195; 95 % CI 0·128, 0·263; P < 0·001) were found to be positively associated with Zn levels. A generalised additive model showed that the negative association between serum Zn and FG was weak at lower serum Zn concentrations and was stronger with the increase in serum Zn concentrations. Additionally, a U-shaped association between serum Zn and TAG was observed. Serum Zn concentrations were associated with FG, TC, TAG, HDL-cholesterol and LDL-cholesterol levels in Chinese children and adolescents. Lower levels of serum Zn were more likely related to a poor metabolic status.

Zinc, selenium and chromium co-supplementation improves insulin resistance by preventing hepatic endoplasmic reticulum stress in diet-induced gestational diabetes rats

Gestational diabetes mellitus (GDM) is one of the most common pregnancy complications and results in adverse outcomes for pregnant women and their offspring. Endoplasmic reticulum (ER) stress is associated with insulin resistance and implicates in the development of GDM. Zinc, selenium and chromium have been shown to maintain glucose homeostasis via multiple mechanisms, but how these trace elements affect the insulin resistance and ER stress in GDM are largely unknown. To address this, a GDM rat model was induced by feeding female Sprague-Dawley rats a high-fat (45%) and sucrose diet, while zinc (10 mg/kg.bw), selenium (20 ug/kg.bw), chromium (20 ug/kg.bw) were daily supplemented alone or in combination from 6 weeks before mating to the end of lactation period. Maternal metabolic parameters, hepatic ER stress and insulin signaling were analyzed. The results showed that zinc, selenium and chromium co-supplementation dramatically alleviated high-fat and sucrose-induced glucose intolerance and oxidative stress during entire experiment period. Hepatic ER stress as well as the unfolded protein response was activated in GDM dams, characterized by the up-regulation of glucose-regulated protein 78, phosphorylated the protein kinase RNA-like endoplasmic reticulum kinase, and the inositol-requiring enzyme 1α. Zinc, selenium and chromium supplementation significantly prevented this activation, by which contributes to the promotion of the phosphorylated protein kinase B related insulin signaling and maintenance of glucose homeostasis. In conclusion, zinc, selenium and chromium supplementation may be a promising way to prevent the development of GDM by alleviating hepatic ER stress.

Effect of zinc deficiency on chronic kidney disease progression and effect modification by hypoalbuminemia

Serum zinc (Zn) levels tend to be low in chronic kidney disease (CKD) patients. This cohort study was conducted to investigate the relationship between zinc deficiency and CKD progression. Patients were classified into two groups based on Zn levels < 60 μg/dl (low-Zn group, n = 160) and ≥ 60 μg/dl (high-Zn group, n = 152). The primary outcome was defined as end-stage kidney disease (ESKD) or death and was examined over a 1-year observation period. Overall, the mean Zn level was 59.6 μg/dl and the median eGFR was 20.3 ml/min/1.73 m². The incidence of the primary outcome was higher in the low-Zn group (p<0.001). Various Cox proportional hazards models adjusted for baseline characteristics showed higher risks of the primary outcome in the low-Zn group than in the high-Zn group. Competing risks analysis showed that low Zn levels were associated with ESKD but not with death. Moreover, in propensity score-matched analysis, the low-Zn group showed a higher risk of the primary outcome [adjusted hazard ratio 1.81 (95% confidence interval 1.02, 3.24)]. Furthermore, an interaction was observed between Zn and serum albumin levels (interaction p = 0.026). The results of this study indicate that zinc deficiency is a risk factor for CKD progression.

A Metal-Free, Disulfide Oxidized Form of Superoxide Dismutase 1 as a Primary Misfolded Species with Prion-Like Properties in the Extracellular Environments Surrounding Motor Neuron-Like Cells

Superoxide dismutase 1 (SOD1) is a metalloenzyme with high structural stability, but a lack of Cu and Zn ions decreases its stability and enhances the likelihood of misfolding, which is a pathological hallmark of amyotrophic lateral sclerosis (ALS). A growing body of evidence has demonstrated that misfolded SOD1 has prion-like properties such as transmissibility between cells and intracellular propagation of misfolding of natively folded SOD1. Recently, we found that SOD1 is misfolded in the cerebrospinal fluid of sporadic ALS patients, providing a route by which misfolded SOD1 spreads via the extracellular environment of the central nervous system. Unlike intracellular misfolded SOD1, it is unknown which extracellular misfolded species is most relevant to prion-like properties. Here, we determined a conformational feature of extracellular misfolded SOD1 that is linked to prion-like properties. Using culture media from motor neuron-like cells, NSC-34, extracellular misfolded wild-type, and four ALS-causing SOD1 mutants were characterized as a metal-free, disulfide oxidized form of SOD1 (apo-SOD1^S-S). Extracellular misfolded apo-SOD1^S-S exhibited cell-to-cell transmission from the culture medium to recipient cells as well as intracellular propagation of SOD1 misfolding in recipient cells. Furthermore, culture medium containing misfolded apo-SOD1^S-S exerted cytotoxicity to motor neuron-like cells, which was blocked by removal of misfolded apo-SOD1^S-S from the medium. We conclude that misfolded apo-SOD1^S-S is a primary extracellular species that is linked to prion-like properties.

Effects of Dose and Duration of Zinc Interventions on Risk Factors for Type 2 Diabetes and Cardiovascular Disease: A Systematic Review and Meta-Analysis

No meta-analysis has examined the effect of dose and duration of zinc interventions on their impact on risk factors for type 2 diabetes (T2D) or cardiovascular disease (CVD). This study aimed first to compare the effects of zinc interventions dichotomized as low versus high dose (<25 mg/d and ≥25 mg/d, respectively) and short versus long duration (<12 wk and ≥12 wk, respectively) on risk factors for T2D and CVD. Second, it discusses the results from the low-dose and long-duration meta-analyses as a foundation for understanding what impact a zinc-biofortification intervention could have on these risk factors. The PubMed and Cochrane Review databases were searched through January 2020 for full-text, human studies providing zinc supplements (alone) at doses ≤75 mg/d and a placebo. Data on study and sample characteristics and several T2D and CVD risk factors were extracted. There were 1042 and 974 participants receiving zinc and placebo, respectively, from 27 studies. Low-dose zinc supplementation (<25 mg/d) significantly benefited fasting blood glucose, insulin resistance, triglycerides, total cholesterol, and LDL cholesterol. High-dose zinc supplementation (≥25 mg/d) benefited glycated hemoglobin and insulin resistance. Short-duration interventions (<12 wk) benefited fasting blood glucose, insulin resistance, and triglycerides, while long-duration studies (≥12 wk) benefited fasting blood glucose, triglycerides, and total and LDL cholesterol. Effect sizes for low-dose and long-duration interventions were of equal or greater magnitude to those from high-dose or short-duration interventions. Low-dose and long-duration zinc supplementation each improved more risk factors for T2D and CVD than high-dose and short-duration interventions, respectively. It is currently unknown whether low doses of zinc delivered over long durations via a biofortified crop would similarly impact these risk factors. However, this review suggests that low-dose, long-duration zinc intake from supplements, and potentially biofortification, can benefit risk factors for T2D and CVD.

Reactivity of CuIN4 Flattened Complexes: Interplay between Coordination Geometry and Ligand Flexibility

The relation between redox activity and coordination geometry in Cu^IN₄ complexes indicates that more flattened structures tend to be more reactive. Such a preorganization of the ligand confers to the complex geometries closer to a transition state, which has been termed the "entatic" state in metalloproteins, more recently extending this concept for copper complexes. However, many aspects of the redox chemistry of Cu^I complexes cannot be explained only by flattening. For instance, the role of ligand flexibility in this context is an open debate nowadays. To analyze this point, we studied oxidation properties of a series of five monometallic Cu^I Schiff-base complexes, [Cu^I(L_n)]⁺, which span a range of geometries from a distorted square planar (n = 3) to a distorted tetrahedron (n = 6, 7). This stepped control of the structure around the Cu^I atom allows us to explore the effect of the flattening distortion on both the electronic and redox properties through the series. Experimental studies were complemented by a theoretical analysis based on density functional theory calculations. As expected, oxidation was favored in the flattened structures, spanning a broad potential window of 370 mV for the complete series. This orderly behavior was tested in the reductive dehalogenation reaction of tetrachloroethane (TCE). Kinetic studies show that Cu^I oxidation by TCE is faster as the flattening distortion is higher and the oxidation potentials of the metal are lower. However, the most reactive complex was not the more planar, contradicting the trend expected from oxidation potentials. The origin of this irregularity is related to ligand flexibility and its connection with the atom/electron transfer reaction path, highlighting the need to consider effects beyond flattening distortion to better understand the reactivity of this important class of complexes.

Molecular dynamics of far positioned surface mutations of Cu/Zn SOD1 promotes altered structural stability and metal-binding site: Structural clues to the pathogenesis of amyotrophic lateral sclerosis

Cu/Zn superoxide dismutase (SOD1) mutations are associated to the motor neuron disorder, amyotrophic lateral sclerosis (ALS), which is characterized by aggregates of the misfolded proteins. The distribution of mutations all over the three-dimensional structure of SOD1 makes it complex to determine the exact molecular mechanism underlying SOD1 destabilization and the associated ALS pathology. In this study, we have examined structure and dynamics of SOD1 protein upon two ALS associated point mutations at the surface residue Glu100 (E100G and E100K), which is located far from the Cu and Zn sites and dimer interface. The molecular dynamics simulations were performed for these mutants for 50ns using GROMACS package. Our results indicate that the mutations result in structural destabilization by affecting the gate keeping role of Glu100 and loss of electrostatic interactions on the protein surface which stabilizes the β-barrel structure of the native form. Further, these mutations could increase the fluctuations in the zinc-binding loop (loop IV), primarily due to loss of hydrogen bond between Asp101 and Arg79. The relaxed conformation of Arg79 further affects the native conformation of His80 and Asp83, that results in altered zinc site geometry and the structure of the substrate channel. Our results clearly suggest that, similar to the mutations located at metal sites/dimer interface/disulfide regions, the mutations at the far positioned site (Glu100) also induce significant conformational changes that could affect the metallation and structure of SOD1 molecule, resulting in formation of toxic intermediate species that cause ALS.

Respiratory Syncytial Virus-Induced Oxidative Stress Leads to an Increase in Labile Zinc Pools in Lung Epithelial Cells

Zinc supplementation in cell culture has been shown to inhibit various viruses, like herpes simplex virus, rotavirus, severe acute respiratory syndrome (SARS) coronavirus, rhinovirus, and respiratory syncytial virus (RSV). However, whether zinc plays a direct antiviral role in viral infections and whether viruses have adopted strategies to modulate zinc homeostasis have not been investigated. Results from clinical trials of zinc supplementation in infections indicate that zinc supplementation may be beneficial in a pathogen- or disease-specific manner, further underscoring the importance of understanding the interaction between zinc homeostasis and virus infections at the molecular level. We investigated the effect of RSV infection on zinc homeostasis and show that RSV infection in lung epithelial cells leads to modulation of zinc homeostasis. The intracellular labile zinc pool increases upon RSV infection in a multiplicity of infection (MOI)-dependent fashion. Small interfering RNA (siRNA)-mediated knockdown of the ubiquitous zinc uptake transporter ZIP1 suggests that labile zinc levels are increased due to the increased uptake by RSV-infected cells as an antiviral response. Adding zinc to culture medium after RSV infection led to significant inhibition of RSV titers, whereas depletion of zinc by a zinc chelator, N,N,N',N'-tetrakis(2-pyridinylmethyl)-1,2-ethanediamine (TPEN) led to an increase in RSV titers. The inhibitory effect of zinc was specific, as other divalent cations had no effect on RSV titers. Both RSV infection and zinc chelation by TPEN led to reactive oxygen species (ROS) induction, whereas addition of zinc blocked ROS induction. These results suggest a molecular link between RSV infection, zinc homeostasis, and oxidative-stress pathways and provide new insights for developing strategies to counter RSV infection.IMPORTANCE Zinc deficiency rates in developing countries range from 20 to 30%, and zinc supplementation trials have been shown to correct clinical manifestations attributed to zinc deficiency, but the outcomes in the case of respiratory infections have been inconsistent. We aimed at understanding the role of zinc homeostasis in respiratory syncytial virus (RSV) infection. Infection of lung epithelial cell lines or primary small-airway epithelial cells led to an increase in labile zinc pools, which was due to increased uptake of zinc. Zinc supplementation inhibited RSV replication, whereas zinc chelation had an opposing effect, leading to increases in RSV titers. Increases in labile zinc in RSV-infected cells coincided with induction of reactive oxygen species (ROS). Both zinc depletion and addition of exogenous ROS led to enhanced RSV infection, whereas addition of the antioxidant inhibited RSV, suggesting that zinc is part of an interplay between RSV-induced oxidative stress and the host response to maintain redox balance.

Effects of dietary zinc level on growth performance, lipolysis and expression of genes involved in the calcium/calmodulin-dependent protein kinase kinase-β/AMP-activated protein kinase pathway in juvenile Pacific white shrimp

The present study evaluated the effects of dietary Zn level on growth performance, serum and hepatopancreas metabolites, expression of genes involved in lipid and energy metabolism, and the signalling pathway of dietary Zn-induced lipolysis. Five isonitrogenous and isolipidic diets were formulated to contain different Zn levels: 46·4 (basal diet), 77·2, 87·0, 117·1 and 136·8 mg/kg, respectively. The results indicated that shrimp fed the diet containing Zn at 117·1 mg/kg had higher weight gain and specific growth rate, and the lowest feed intake and feed conversion rate, than shrimp fed the other diets. The deposition rate of Zn in whole body significantly decreased with increasing dietary Zn level. Dietary Zn prevented the accumulation of free radicals and improved antioxidant activities by increasing Cu/Zn superoxide dismutase and reducing malondialdehyde in hepatopancreas. Dietary Zn supplementation enhanced lipase activity and adiponectin, which could promote TAG breakdown and fatty acid oxidation and lead to reduced lipid in hepatopancreas. The mRNA expressions ofob-rb,adipor,camkkβ,ampk,cd36,mcdandcpt1involved in Zn-induced lipid catabolism were up-regulated, and the expressions ofsrebp,acc,fasandscd1were down-regulated. The mRNA levels of SLC39 family genes (zip3,zip9,zip11andzip14) in hepatopancreas were up-regulated with increasing dietary Zn level. The results demonstrated that dietary Zn level could significantly affect growth performance, tissue deposition of Zn, lipid metabolites and expression of genes involved in lipogenesis and lipolysis inLitopenaeus vannamei.

Fluctuation of biochemical, immunological, and antioxidant biomarkers in the blood of beluga (Huso huso) under effect of dietary ZnO and chitosan-ZnO NPs

The objective of the present study was to investigate the effects of dietary supplementation with zinc oxide (ZnO) and chitosan-zinc nanoparticles (chitosan-ZnO NPs) on biochemical, immunological, and antioxidant biomarkers in blood of juvenile belugas (Huso huso). The beluga juveniles with initial weight of 287 ± 46 g were fed with eight experimental diets containing 0 g kg^-1 ZnO (the control diet); 10, 20, and 40 mg kg^-1 ZnO; and 10, 20, and 40 mg kg^-1 chitosan-ZnO NPs and 36 mg kg^-1 chitosan. After 28 days of culture, the fish were fed with ZnO and chitosan-ZnO NP-supplemented diets showed a more significant increase in total antioxidant capacity (TAC), superoxide dismutase (SOD), catalase (CAT), glutathione (GSH), glutathione peroxidase (GPX), and glutathione S-transferase (GST) activity (p < 0.05) compared to the control group. There were no significant differences (p > 0.05) in malondialdehyde (MDA) and glucose level in all treatment groups. The results showed that with increasing levels of ZnO and chitosan-ZnO NPs, alternative complement activity (ACH50), and total immunoglobulin, total protein, albumin, and lysozyme had a significant increase in fish fed with ZnO and chitosan-ZnO NP-supplemented diets compared to the control group (p < 0.05). ALP, ALT, and AST enzyme activities showed significant difference between control and treatment groups (p > 0.05), while the levels of LDH enzyme activity, urea, and creatinine decreased by increasing both ZnO and chitosan-ZnO NP levels. These results demonstrated that dietary chitosan-ZnO NPs could improve the health status, immune function, and antioxidant capacity of the cultured beluga juvenile.

Molecular binding response of naringin and naringenin to H46R mutant SOD1 protein in combating protein aggregation using density functional theory and discrete molecular dynamics

Amyotrophic lateral sclerosis (ALS) is a calamitous neurodegenerative disorder characterized by denervation of upper and lower motor neurons. Numerous hypotheses suggest that toxic protein misfolding and aggregation cause ALS, similar to that of other neurodegenerative diseases, such as Alzheimers and Parkinsons. Protruding causes of familial ALS are mutations in the gene encoding Cu/Zn superoxide dismutase-1 (SOD1), which decrease protein stability and endorse protein aggregation. Thus, the interference concerning aggregate formation and destabilization in SOD1 is considered to be an impending therapeutic strategy. In this work, we utilized computational chemistry methods to initially study the effect of substitution mutation, His46Arg on SOD1 protein. Further, we described the interaction of two naturally occurring polyphenol compounds, naringin and naringenin with mutant SOD1 that is regarded to hinder the protein aggregation. Subsequently, the use of quantum chemical and molecular mechanics calculations speculated that naringin had a strong binding affinity with mutant SOD1 and impeded the formation of toxic aggregates than that of naringenin. Ultimately, we could conjecture that ingesting of polyphenol-rich foods in ALS patients may be regarded to improvise their living. Moreover, the findings from our study could pave a way in the field of structure-based drug design in developing potential anti-aggregation inhibitors against incurable ALS, affecting the human population.

Biochemical and functional characterization of OsCSD3, a novel CuZn superoxide dismutase from rice

Superoxide dismutases (SODs, EC 1.15.1.1) belong to an important group of antioxidant metalloenzymes. Multiple SODs exist for scavenging of reactive oxygen species (ROS) in different cellular compartments to maintain an intricate ROS balance. The present study deals with molecular and biochemical characterization of CuZn SOD encoded by LOC_Os03g11960 (referred to as OsCSD3), which is the least studied among the four rice isozymes. The OsCSD3 showed higher similarity to peroxisomal SODs in plants. The OsCSD3 transcript was up-regulated in response to salinity, drought, and oxidative stress. Full-length cDNA encoding OsCSD3 was cloned and expressed in Escherichia coli and analyzed for spectral characteristics. UV (ultraviolet)–visible spectroscopic analysis showed evidences of d–d transitions, while circular dichroism analysis indicated high β-sheet content in the protein. The OsCSD3 existed as homodimer (∼36 kDa) with both Cu2+ and Zn2+ metal cofactors and was substantially active over a wide pH range (7.0–10.8), with optimum pH of 9.0. The enzyme was sensitive to diethyldithiocarbamate but insensitive to sodium azide, which are the characteristics features of CuZn SODs. The enzyme also exhibited bicarbonate-dependent peroxidase activity. Unlike several other known CuZn SODs, OsCSD3 showed higher tolerance to hydrogen peroxide and thermal inactivation. Heterologous overexpression of OsCSD3 enhanced tolerance of E. coli sod double-knockout (ΔsodA ΔsodB) mutant and wild-type strain against methyl viologen-induced oxidative stress, indicating the in vivo function of this enzyme. The results show that the locus LOC_Os03g11960 of rice encodes a functional CuZn SOD with biochemical characteristics similar to the peroxisomal isozymes.

Zinc deficiency and cellular oxidative stress: prognostic implications in cardiovascular diseases

Zinc is an essential nutrient for human health and has anti-oxidative stress and anti-inflammatory functions. The association between zinc deficiency and the development of cardiovascular diseases (CVDs) has been supported by numerous studies. Supplementing zinc can reduce the risk of atherosclerosis and protect against myocardial infarction and ischemia/reperfusion injury. In this review we summarize the evidence in the literature, to consolidate the current knowledge on the dysregulation of zinc homeostasis in CVDs, and to explore the significant roles of the zinc homeostasis-regulatory proteins in cardiac physiology and pathophysiology. Moreover, this review also deliberates on the potential diagnostic and prognostic implications of zinc/zinc homeostasis-associated molecules (ZIP, ZnT, and MTs) in CVDs.

Dietary Zinc Intake and Its Association with Metabolic Syndrome Indicators among Chinese Adults: An Analysis of the China Nutritional Transition Cohort Survey 2015

The dietary zinc consumed in Chinese households has decreased over the past decade. However, the national dietary zinc intake in the last five years has seldom been investigated. Using data from 12,028 participants 18 to 64 years old (52.9% male) in the China Nutritional Transition Cohort Survey (CNTCS) 2015, we describe the intake of dietary zinc and the contributions of major foods and we examine the relationship between the level of dietary zinc intake and metabolic syndrome indicators, including blood pressure, fasting glucose, and triglycerides (TG), in Chinese adults. We assessed dietary zinc intake using 24 h recalls on three consecutive days. The mean daily dietary zinc intake for all participants was 10.2 milligrams per day (males 11.2 mg/day, females 9.4 mg/day, p < 0.001). The mean daily dietary zinc density for all participants was 5.2 mg/day per 1000 kilocalories. Among all participants, 31.0% were at risk of zinc deficiency, with dietary zinc intakes of less than the Estimated Average Requirement (EAR) (males 49.2%, females 14.8%, p < 0.050), and 49.9% had adequate dietary zinc intakes, equal to or greater than the recommended nutrient intake (RNI) (males 30.7%, females 67.0%, p < 0.050). We found substantial gender differences in dietary zinc intake and zinc deficiency, with nearly half of the men at risk of zinc deficiency. Males of younger age, with higher education and incomes, and who consumed higher levels of meat, had higher zinc intakes, higher zinc intake densities, and higher rates of meeting the EAR. Among all participants, grains, livestock meat, fresh vegetables, legumes, and seafood were the top five food sources of zinc, and their contributions to total dietary zinc intake were 39.5%, 17.3%, 8.9%, 6.4%, and 4.8%, respectively. The groups with relatively better dietary zinc intakes consumed lower proportions of grains and higher proportions of livestock meat. For males with adequate dietary zinc intake (≥RNI), TG levels increased by 0.219 millimoles per liter (mmol/L) compared with males with deficient dietary zinc intake ( Collapse

Key Words

• Chinese adults
• dietary zinc
• food source
• metabolic syndrome

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MESH Headings

• Adolescent
• Adult
• Asian People
• Blood Glucose/metabolism
• Blood Pressure/drug effects
• Body Mass Index
• China/epidemiology
• Cohort Studies
• Diet
• Dietary Carbohydrates/administration & dosage
• Dietary Fats/administration & dosage
• Dietary Proteins/administration & dosage
• Female
• Humans
• Male
• Metabolic Syndrome/blood
• Metabolic Syndrome/epidemiology
• Middle Aged
• Nutrition Assessment
• Nutritional Status
• Recommended Dietary Allowances
• Socioeconomic Factors
• Triglycerides/blood
• Vegetables
• Young Adult
• Zinc/administration & dosage
• Zinc/blood
• Zinc/deficiency

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Grants Collapse

Affiliation(s)

Yun Wang National Institute for Nutrition and Health, Chinese Center for Disease Control and Prevention, Beijing 100050, China.
Xiao-Fang Jia National Institute for Nutrition and Health, Chinese Center for Disease Control and Prevention, Beijing 100050, China.
Bing Zhang National Institute for Nutrition and Health, Chinese Center for Disease Control and Prevention, Beijing 100050, China.
Zhi-Hong Wang National Institute for Nutrition and Health, Chinese Center for Disease Control and Prevention, Beijing 100050, China.
Ji-Guo Zhang National Institute for Nutrition and Health, Chinese Center for Disease Control and Prevention, Beijing 100050, China.
Fei-Fei Huang National Institute for Nutrition and Health, Chinese Center for Disease Control and Prevention, Beijing 100050, China.
Chang Su National Institute for Nutrition and Health, Chinese Center for Disease Control and Prevention, Beijing 100050, China.
Yi-Fei Ouyang National Institute for Nutrition and Health, Chinese Center for Disease Control and Prevention, Beijing 100050, China.
Jian Zhao National Institute for Nutrition and Health, Chinese Center for Disease Control and Prevention, Beijing 100050, China.
Wen-Wen Du National Institute for Nutrition and Health, Chinese Center for Disease Control and Prevention, Beijing 100050, China.
Li Li National Institute for Nutrition and Health, Chinese Center for Disease Control and Prevention, Beijing 100050, China.
Hong-Ru Jiang National Institute for Nutrition and Health, Chinese Center for Disease Control and Prevention, Beijing 100050, China.
Ji Zhang National Institute for Nutrition and Health, Chinese Center for Disease Control and Prevention, Beijing 100050, China.
Hui-Jun Wang National Institute for Nutrition and Health, Chinese Center for Disease Control and Prevention, Beijing 100050, China.

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Evaluation of the health benefits of consumption of extruded tannin sorghum with unfermented probiotic milk in individuals with chronic kidney disease

This study investigated the chemical and nutritional composition of breakfast cereal based on whole sorghum, and the effect of its association with unfermented probiotic milk on the inflammation and oxidative stress of individuals with chronic kidney disease. Extruded sorghum breakfast meal presented higher carbohydrate concentration (approximately 71%), followed by protein (approximately 11%) and lipid (approximately 0.4%). When compared to extruded maize breakfast meal, it presented higher percentage of dietary fiber (p < 0.05), and higher content of phenolic compounds and tannin, consequently higher antioxidant activity (p < 0.05). Extruded sorghum breakfast cereal combined with unfermented probiotic milk decreased the C-reactive protein (p < 0.05) and malondialdehyde (p < 0.05) serum levels and increased the total antioxidant capacity and superoxide dismutase (p < 0.05) in patients with chronic kidney disease. Therefore, the extruded sorghum, source of tannin, anthocyanin, and dietary fiber, when consumed with unfermented probiotic milk alleviates the inflammation and oxidative stress in patients with chronic kidney disease.

Biological Spectrum of Amyotrophic Lateral Sclerosis Prions

Amyotrophic lateral sclerosis (ALS) and frontotemporal lobar dementia (FTLD) are two neurodegenerative diseases with distinct clinical features but common genetic causes and neuropathological signatures. Ten years after the RNA-binding protein TDP-43 was discovered as the main protein in the cytoplasmic inclusions that characterize ALS and FTLD, their pathogenic mechanisms have never seemed more complex. Indeed, discoveries of the past decade have revolutionized our understanding of these diseases, highlighting their genetic heterogeneity and the involvement of protein-RNA assemblies in their pathogenesis. Importantly, these assemblies serve as the foci of protein misfolding and mature into insoluble structures, which further recruit native proteins, turning them into misfolded forms. This self-perpetuating mechanism is a twisted version of classical prion replication that leads to amplification of pathological protein complexes that spread throughout the neuraxis, offering a pathogenic principle that underlies the rapid disease progression that characterizes ALS and FTLD.

Zinc status is associated with inflammation, oxidative stress, lipid, and glucose metabolism

A number of studies have reported that zinc plays a substantial role in the development of metabolic syndrome, taking part in the regulation of cytokine expression, suppressing inflammation, and is also required to activate antioxidant enzymes that scavenge reactive oxygen species, reducing oxidative stress. Zinc also plays a role in the correct functioning of lipid and glucose metabolism, regulating and forming the expression of insulin. In numerous studies, zinc supplementation has been found to improve blood pressure, glucose, and LDL cholesterol serum level. Deeper knowledge of zinc’s properties may help in treating metabolic syndrome, thus protecting against stroke and angina pectoris, and ultimately against death.

Cysteine to Serine Conversion at 111th Position Renders the Disaggregation and Retains the Stabilization of Detrimental SOD1 A4V Mutant Against Amyotrophic Lateral Sclerosis in Human-A Discrete Molecular Dynamics Study

Protein aggregation is a hallmark of various neurodegenerative disorders, such as amyotrophic lateral sclerosis (ALS) in humans. Mutations in Cu/Zn superoxide dismutase (SOD1) protein were found to be a prominent cause behind the majority of the familial ALS cases with abnormal protein aggregates. Herein, we report the biophysical characterization of the beneficial mutation C111S that stabilizes the SOD1 harboring A4V mutation, one of the most lethal diseases causing mutant that leads to protein destabilization and aggregation. In this study, we utilized discrete molecular dynamics (DMD) simulations, which stipulated an outlook over the systematic action of C111S mutation in the A4V mutant that stabilizes the protein and impedes the formation of protein aggregation. Herewith, the findings from our study manifested that the mutation of C111S in SOD1 could aid in regaining the protein structural conformations that protect against the formation of toxic aggregates, thereby hindering the disease pathogenicity subtly. Hence, our study provides a feasible pharmaceutical strategy in developing the treatment for incurable ALS affecting the mankind.

Deciphering the loss of metal binding due to mutation D83G of human SOD1 protein causing FALS disease

Mutations in Cu/Zn superoxide dismutase 1 (SOD1) protein are found to be the causative factor, behind the majority of familial amyotrophic later sclerosis (FALS) cases. The mutations particularly on the metal (Zn) binding residues are found to increase the disease onset in the individuals suffering from FALS, while the presence of the metal ion (Zn) is essential for the catalytic activity and retaining the protein stability. Thus in our study, we focused on one such metal binding mutant (D83G) and assessed the impact of the mutation on protein structure and function. The influence of mutation was examined dynamically, using discrete molecular dynamics on both the native and mutant SOD1 protein respectively. Accordingly, the variation in conformational stability, residual flexibility and protein compactness along with the change in conformational free energy were monitored over the entire dynamic period. Moreover, the motion of native and mutant SOD1 was also observed via the essential dynamics. Besides, the disparity in Zn ion binding was inspected through distance analysis and steered molecular dynamics, correspondingly. Therefore, the study provides a better understanding over the profound effect of mutation on SOD1, both structurally and functionally, using computational approaches.

Insights into the mechanisms of copper dyshomeostasis in amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis (ALS) is a severe neuromuscular disease characterised by a progressive loss of motor neurons that usually results in paralysis and death within 2 to 5 years after disease onset. The pathophysiological mechanisms involved in ALS remain largely unknown and to date there is no effective treatment for this disease. Here, we review clinical and experimental evidence suggesting that dysregulation of copper homeostasis in the central nervous system is a crucial underlying event in motor neuron degeneration and ALS pathophysiology. We also review and discuss novel approaches seeking to target copper delivery to treat ALS. These novel approaches may be clinically relevant not only for ALS but also for other neurological disorders with abnormal copper homeostasis, such as Parkinson's, Huntington's and Prion diseases.

Probing the inhibitory activity of epigallocatechin-gallate on toxic aggregates of mutant (L84F) SOD1 protein through geometry based sampling and steered molecular dynamics

Amyloid formation and protein aggregation are considered to be at the core of the disease pathology for the various neurodegenerative disorders such as Amyotrophic lateral sclerosis (ALS). Considerable experimental reports have suggested that epigallocatechin-gallate (EGCG), a natural polyphenol from the green tea inhibits the amyloid formation in multiple neurodegenerative disease. Mutations in SOD1 protein are considered to a key factor that contributes towards the rapid disease progression and the pathogenesis in both, the sporadic and familial form. In our study, we computationally examined the inhibitory action of EGCG against the native and the mutant SOD1 through molecular docking, steered molecular dynamics and conformational sampling methods From the outcome, we could conjecture that the protein destabilization and increased β-sheet propensity that occurred due to mutation were regained upon the binding of EGCG. Moreover, the concepts of the free energy landscape analysis are introduced to establish the visual appearance of protein aggregation upon mutation. Altogether, we come to know that the binding of EGCG on mutant SOD1 has reduced the formation of the toxic aggregates upon mutation. Hence, our study could be an initiative in deciphering the inhibitory action of EGCG against the aggregated mutant SOD1, which could be a therapeutic potential against the treatment for the incurable neurodegenerative disorder (ALS) affecting the mankind.

Computational investigation of the human SOD1 mutant, Cys146Arg, that directs familial amyotrophic lateral sclerosis

Molecular dynamics simulations along with the computational predictions used to assess the protein structural characterization as well as the conformational preferences of the monomeric native and mutant SOD1.

Computational investigation of curcumin, a natural polyphenol that inhibits the destabilization and the aggregation of human SOD1 mutant (Ala4Val)

Curcumin inhibits the aberrant aggregation in mutant SOD1 protein, thereby decreasing the propensity of β-sheets and the toxicity level.

Heterologous expression and biochemical characterization of a highly active and stable chloroplastic CuZn-superoxide dismutase from Pisum sativum

BACKGROUND

CuZn-Superoxide dismutase (SOD) is a unique enzyme, which can catalyzes the dismutation of inevitable metabolic product i.e.; superoxide anion into molecular oxygen and hydrogen peroxide. The enzyme has gained wide interest in pharmaceutical industries due to its highly acclaimed antioxidative properties. The recombinant expression of this protein in its enzymatically active and stable form is highly desired and hence optimization of culture conditions and characterization of the related biochemical properties are essential to explore the significance of the enzyme in physiological, therapeutic, structural and transgenic research.

RESULTS

High-level expression of the chloroplastic isoform of Pisum sativum CuZn-SOD was achieved at 18°C, upon isopropyl β-D-1-thiogalactopyranoside induction and the process was optimized for maximum recovery of the protein in its soluble (enzymatically active) form. Both crude and purified protein fractions display significant increase in activity following supplementation of defined concentration Cu (CuSO4) and Zn (ZnSO4). Yield of the purified recombinant protein was ~ 4 mg L(-1) of culture volume and the bacterial biomass was ~ 4.5 g L(-1). The recombinant pea chloroplastic SOD was found to possess nearly 6 fold higher superoxide dismutase activity and the peroxidase activity was also 5 fold higher as compared to commercially available CuZn-superoxide dismutase. The computational, spectroscopic and biochemical characterization reveals that the protein harbors all the characteristics features of this class of enzyme. The enzyme was found to be exceptionally stable as evident from pH and temperature incubation studies and maintenance of SOD activity upon prolonged storage.

CONCLUSIONS

Overexpression and purification strategy presented here describes an efficient protocol for the production of a highly active and stable CuZn-superoxide dismutase in its recombinant form in E. coli system. The strategy can be utilized for the large-scale preparation of active CuZn-superoxide dismutase and thus it has wide application in pharmaceutical industries and also for elucidating the potential of this protein endowed with exceptional stability and activity.

Wild-type Cu/Zn superoxide dismutase stabilizes mutant variants by heterodimerization

Mutations in the gene encoding Cu/Zn superoxide dismutase (SOD1) are responsible for a subset of amyotrophic lateral sclerosis cases presumably by the acquisition of as yet unknown toxic properties. Additional overexpression of wild-type SOD1 in mutant SOD1 transgenic mice did not improve but rather accelerated the disease course. Recently, it was documented that the presence of wild-type SOD1 (SOD(WT)) reduced the aggregation propensity of mutant SOD1 by the formation of heterodimers between mutant and SOD1(WT) and that these heterodimers displayed at least a similar toxicity in cellular and animal models. In this study we investigated the biochemical and biophysical properties of obligate SOD1 dimers that were connected by a peptide linker. Circular dichroism spectra indicate an increased number of unstructured residues in SOD1 mutants. However, SOD1(WT) stabilized the folding of heterodimers compared to mutant homodimers as evidenced by an increase in resistance against proteolytic degradation. Heterodimerization also reduced the affinity of mutant SOD1 to antibodies detecting misfolded SOD1. In addition, the formation of obligate dimers resulted in a detection of substantial dismutase activity even of the relatively labile SOD1(G85R) mutant. These data indicate that soluble, dismutase-active SOD1 dimers might contribute at least partially to mutant SOD1 toxicity.

A zinc complex of heparan sulfate destabilises lysozyme and alters its conformation

The naturally occurring anionic cell surface polysaccharide heparan sulfate is involved in key biological activities and is implicated in amyloid formation. Following addition of Zn-heparan sulfate, hen lysozyme, a model amyloid forming protein, resembled β-rich amyloid by far UV circular dichroism (increased β-sheet: +25%), with a significantly reduced melting temperature (from 68 to 58 °C) by fluorescence shift assay. Secondary structure stability of the Zn-heparan sulfate complex with lysozyme was also distinct from that with heparan sulfate, under stronger denaturation conditions using synchrotron radiation circular dichroism. Changing the cation associated with heparan sulfate is sufficient to alter the conformation and stability of complexes formed between heparan sulfate and lysozyme, substantially reducing the stability of the protein. Complexes of heparan sulfate and cations, such as Zn, which are abundant in the brain, may provide alternative folding routes for proteins.

Using yeast models to probe the molecular basis of amyotrophic lateral sclerosis

ALS (amyotrophic lateral sclerosis) is a fatal neurodegenerative disease attributable to the death of motor neurons. Associated with ALS are mutations in the genes encoding SOD1 (superoxide dismutase 1), FUS (fused in Sarcoma) protein and TDP-43 (TAR DNA-binding protein-43) each of which leads to aggregation of the respective protein. For example, the ALS-associated mutations in the hSOD1 (human SOD1) gene typically destabilize the native SOD homodimer, leading to misfolding, aggregation and degradation of SOD1. The ALS-associated pathology is not a consequence of the functional inactivation of SOD1 itself, but is rather due to a toxic gain-of-function triggered by mutant SOD1. Recently, the molecular basis of a number of human neurodegenerative diseases resulting from protein misfolding and aggregation, including fALS (familial ALS), was probed by using the baker's yeast, Saccharomyces cerevisiae, as a highly tractable model. Such studies have, for example, identified novel mutant SOD1-specific interactions and demonstrated that mutant SOD1 disrupts mitochondrial homoeostasis. Features of ALS associated with TDP-43 aggregation have also been recapitulated in S. cerevisiae including the identification of modulators of the toxicity of TDP-43. In this paper, we review recent studies of ALS pathogenesis using S. cerevisiae as a model organism and summarize the potential mechanisms involved in ALS progression.