Oxygen free radicals and metallothionein

The Current State of Knowledge Regarding the Genetic Predisposition to Sports and Its Health Implications in the Context of the Redox Balance, Especially Antioxidant Capacity

The significance of physical activity in sports is self-evident. However, its importance is becoming increasingly apparent in the context of public health. The constant desire to improve health and performance suggests looking at genetic predispositions. The knowledge of genes related to physical performance can be utilized initially in the training of athletes to assign them to the appropriate sport. In the field of medicine, this knowledge may be more effectively utilized in the prevention and treatment of cardiometabolic diseases. Physical exertion engages the entire organism, and at a basic physiological level, the organism's responses are primarily related to oxidant and antioxidant reactions due to intensified cellular respiration. Therefore, the modifications involve the body adjusting to the stresses, especially oxidative stress. The consequence of regular exercise is primarily an increase in antioxidant capacity. Among the genes considered, those that promote oxidative processes dominate, as they are associated with energy production during exercise. What is missing, however, is a look at the other side of the coin, which, in this case, is antioxidant processes and the genes associated with them. It has been demonstrated that antioxidant genes associated with increased physical performance do not always result in increased antioxidant capacity. Nevertheless, it seems that maintaining the oxidant-antioxidant balance is the most important thing in this regard.

Preparation of a novel metallothionein-AuNP composite material by genetic modification and AuS covalent combination

Metallothionein (MTs) can be used in the prevention and treatment of tumors and diabetes due to its antioxidant properties. However, it is necessary to solve its non-transmembrane properties and further improve its antioxidant activity, increase its fluorescence visualization and enhance its stability to meet practical applications in the biomedical field. Here, we report the preparation of a novel metallothionein-AuNP composite material with high transmembrane ability, fluorescence visualization, antioxidant activity, and stability by genetic modification (introducing transduction peptide TAT, fluorescence tag GFP and increasing sulfydryl groups) and immobilization technology (covalently bonding with AuNPs). The transmembrane activity of modified proteins was verified by immunofluorescence. Increasing the sulfhydryl content within a certain range can enhance the antioxidant activity of the protein. In addition, GFP were used to further simplify the imaging of the metallothionein-AuNP composite in cells. XPS results indicated that AuNPs can immobilize metallothionein through AuS covalent bonds. TGA characterization and degradation experiments showed that thermal and degradation stability of the immobilized material was significantly improved. This work provides new ideas to construct metallothionein composites with high transmembrane ability, antioxidant activity, fluorescence visualization and stability to meet novel applications in the biomedical field.

Nisin lantibiotic prevents NAFLD liver steatosis and mitochondrial oxidative stress following periodontal disease by abrogating oral, gut and liver dysbiosis

Oral microbiome dysbiosis mediates chronic periodontal disease, gut microbial dysbiosis, and mucosal barrier disfunction that leads to steatohepatitis via the enterohepatic circulation. Improving this dysbiosis towards health may improve liver disease. Treatment with antibiotics and probiotics have been used to modulate the microbial, immunological, and clinical landscape of periodontal disease with some success. The aim of the present investigation was to evaluate the potential for nisin, an antimicrobial peptide produced by Lactococcus lactis, to counteract the periodontitis-associated gut dysbiosis and to modulate the glycolipid-metabolism and inflammation in the liver. Periodontal pathogens, namely Porphyromonas gingivalis, Treponema denticola, Tannerella forsythia and Fusobacterium nucleatum, were administrated topically onto the oral cavity to establish polymicrobial periodontal disease in mice. In the context of disease, nisin treatment significantly shifted the microbiome towards a new composition, commensurate with health while preventing the harmful inflammation in the small intestine concomitant with decreased villi structural integrity, and heightened hepatic exposure to bacteria and lipid and malondialdehyde accumulation in the liver. Validation with RNA Seq analyses, confirmed the significant infection-related alteration of several genes involved in mitochondrial dysregulation, oxidative phosphorylation, and metal/iron binding and their restitution following nisin treatment. In support of these in vivo findings indicating that periodontopathogens induce gastrointestinal and liver distant organ lesions, human autopsy specimens demonstrated a correlation between tooth loss and severity of liver disease. Nisin's ability to shift the gut and liver microbiome towards a new state commensurate with health while mitigating enteritis, represents a novel approach to treating NAFLD-steatohepatitis-associated periodontal disease.

Aldehyde accumulation in Mycobacterium tuberculosis with defective proteasomal degradation results in copper sensitivity

Mycobacterium tuberculosis is a major human pathogen and the causative agent of tuberculosis disease. M. tuberculosis is able to persist in the face of host-derived antimicrobial molecules nitric oxide (NO) and copper (Cu). However, M. tuberculosis with defective proteasome activity is highly sensitive to NO and Cu, making the proteasome an attractive target for drug development. Previous work linked NO susceptibility with the accumulation of para-hydroxybenzaldehyde (pHBA) in M. tuberculosis mutants with defective proteasomal degradation. In this study, we found that pHBA accumulation was also responsible for Cu sensitivity in these strains. We showed that exogenous addition of pHBA to wild-type M. tuberculosis cultures sensitized bacteria to Cu to a degree similar to that of a proteasomal degradation mutant. We determined that pHBA reduced the production and function of critical Cu resistance proteins of the regulated in copper repressor (RicR) regulon. Furthermore, we extended these Cu-sensitizing effects to an aldehyde that M. tuberculosis may face within the macrophage. Collectively, this study is the first to mechanistically propose how aldehydes can render M. tuberculosis susceptible to an existing host defense and could support a broader role for aldehydes in controlling M. tuberculosis infections. IMPORTANCE M. tuberculosis is a leading cause of death by a single infectious agent, causing 1.5 million deaths annually. An effective vaccine for M. tuberculosis infections is currently lacking, and prior infection does not typically provide robust immunity to subsequent infections. Nonetheless, immunocompetent humans can control M. tuberculosis infections for decades. For these reasons, a clear understanding of how mammalian immunity inhibits mycobacterial growth is warranted. In this study, we show aldehydes can increase M. tuberculosis susceptibility to copper, an established antibacterial metal used by immune cells to control M. tuberculosis and other microbes. Given that activated macrophages produce increased amounts of aldehydes during infection, we propose host-derived aldehydes may help control bacterial infections, making aldehydes a previously unappreciated antimicrobial defense.

A novel metallothionein gene HcMT from halophyte shrub Halostachys caspica respond to cadmium and sodium stress

Cadmium (Cd) and sodium (Na) are two of the most phytotoxic metallic elements causing environmental and agricultural problems. Metallothioneins (MTs) play an important role in the adaptation to abiotic stress. We previously isolated a novel type 2 MT gene from Halostachys caspica (H. caspica), named HcMT, which responded to metal and salt stress. To understand the regulatory mechanisms controlling HcMT expression, we cloned the HcMT promoter and characterized its tissue-specific and spatiotemporal expression patterns. β-Glucuronidase (GUS) activity analysis showed that the HcMT promoter was responsive to CdCl2, CuSO4, ZnSO4 and NaCl stress. Therefore, we further investigated the function of HcMT under abiotic stress in yeast and Arabidopsis thaliana (Arabidopsis). In CdCl2, CuSO4 or ZnSO4 stress, HcMT significantly enhanced the metal ions tolerance and accumulation in yeast through function as a metal chelator. Moreover, the HcMT protein also protected yeast cells from NaCl, PEG and hydrogen peroxide (H2O2) toxicity with less effectiveness. However, transgenic Arabidopsis carrying HcMT gene only displayed tolerance to CdCl2 and NaCl, accompanying by higher content of Cd2+ or Na+ and lower H2O2, compared to wild-type (WT) plants. Next, we demonstrated that the recombinant HcMT protein has the ability to bind Cd2+ and the potential of scavenging ROS (reactive oxygen species) in vitro. This result further confirmed that the role of HcMT to influence plants to CdCl2 and NaCl stress may bind metal ions and scavenge ROS. Overall, we described the biological functions of HcMT and developed a metal- and salt-inducible promoter system for using in genetic engineering.

Double- or Triple-Tiered Protection: Prospects for the Sustainable Application of Copper-Based Antimicrobial Compounds for Another Fourteen Decades

Copper (Cu)-based antimicrobial compounds (CBACs) have been widely used to control phytopathogens for nearly fourteen decades. Since the first commercialized Bordeaux mixture was introduced, CBACs have been gradually developed from highly to slightly soluble reagents and from inorganic to synthetic organic, with nanomaterials being a recent development. Traditionally, slightly soluble CBACs form a physical film on the surface of plant tissues, separating the micro-organisms from the host, then release divalent or monovalent copper ions (Cu²⁺ or Cu⁺) to construct a secondary layer of protection which inhibits the growth of pathogens. Recent progress has demonstrated that the release of a low concentration of Cu²⁺ may elicit immune responses in plants. This supports a triple-tiered protection role of CBACs: break contact, inhibit microorganisms, and stimulate host immunity. This spatial defense system, which is integrated both inside and outside the plant cell, provides long-lasting and broad-spectrum protection, even against emergent copper-resistant strains. Here, we review recent findings and highlight the perspectives underlying mitigation strategies for the sustainable utilization of CBACs.

A familial natural short sleep mutation promotes healthy aging and extends lifespan in Drosophila

Sleep loss typically imposes negative effects on animal health. However, humans with a rare genetic mutation in the dec2 gene ( dec2 P384R ) present an exception; these individuals sleep less without the usual effects associated with sleep deprivation. Thus, it has been suggested that the dec2 P384R mutation activates compensatory mechanisms that allows these individuals to thrive with less sleep. To test this directly, we used a Drosophila model to study the effects of the dec2 P384R mutation on animal health. Expression of human dec2 P384R in fly sleep neurons was sufficient to mimic the short sleep phenotype and, remarkably, dec2 P384R mutants lived significantly longer with improved health despite sleeping less. The improved physiological effects were enabled, in part, by enhanced mitochondrial fitness and upregulation of multiple stress response pathways. Moreover, we provide evidence that upregulation of pro-health pathways also contributes to the short sleep phenotype, and this phenomenon may extend to other pro-longevity models.

Quercetin as a Dietary Supplementary Flavonoid Alleviates the Oxidative Stress Induced by Lead Toxicity in Male Wistar Rats

Quercetin is a naturally existing plant pigment belonging to the flavonoid group; it is contained in a wide range of vegetables and fruits. The accumulated evidence points to the potential uses of quercetin in protection of some disease conditions. Lead is one of the highly toxicant heavy metals that are widely spread in the environment and implicated in a wide spectrum of industries. No previous study has been reported to evaluate the effect of quercetin on lead toxicity. Therefore, the present study was conducted to elucidate some aspects of quercetin bioactivities in regard to its ability to combat the oxidative stress induced by lead toxicity. For this purpose, a total of sixty male Wistar rats were randomly and equally divided into three groups of 20 animals each; untreated control animals (group 1), lead-exposed animals (group 2; exposed to lead daily by oral gavage at the dose of 80 mg/Kg b.w.), and group 3 of animals, which were exposed to lead and daily received quercetin (10 h gap time between lead exposure and the receiving of quercetin) by oral gavage at the dose of 350 mg/Kg b.w. The experiment period was 8 weeks. All the assayed hematological and biochemical parameters of animals exposed to lead were significantly altered compared with the untreated control levels. Animals exposed to lead (group 2) exhibited significant decrements of the erythrocytic and total leucocytic counts, hemoglobin concentration, packed cell volume percent, total proteins, albumin and globulin. These animals also disclosed significantly decreased levels of antioxidant markers including total thiols, catalase and glutathione. On the other hand, these animals demonstrated significant increments in the levels of bilirubin, urea, creatinine, BUN, serum enzymes, H₂O₂ and MDA. Animals exposed to lead and given quercetin (group 3) exhibited improvement of these parameters, which were brought back at varying degrees toward the untreated control levels. Basing on the improvements of the assayed hematological and biochemical parameters, it was concluded that quercetin as a dietary supplement can act efficiently as an antioxidant to counteract the oxidative stress induced by lead toxicity and to maintain the oxidant antioxidant balance.

Multifunctional Metallothioneins as a Target for Neuroprotection in Parkinson's Disease

Parkinson's disease (PD) is characterized by motor symptoms based on a loss of nigrostriatal dopaminergic neurons and by non-motor symptoms which precede motor symptoms. Neurodegeneration accompanied by an accumulation of α-synuclein is thought to propagate from the enteric nervous system to the central nervous system. The pathogenesis in sporadic PD remains unknown. However, many reports indicate various etiological factors, such as oxidative stress, inflammation, α-synuclein toxicity and mitochondrial impairment, drive neurodegeneration. Exposure to heavy metals contributes to these etiopathogenesis and increases the risk of developing PD. Metallothioneins (MTs) are cysteine-rich metal-binding proteins; MTs chelate metals and inhibit metal-induced oxidative stress, inflammation and mitochondrial dysfunction. In addition, MTs possess antioxidative properties by scavenging free radicals and exert anti-inflammatory effects by suppression of microglial activation. Furthermore, MTs recently received attention as a potential target for attenuating metal-induced α-synuclein aggregation. In this article, we summarize MTs expression in the central and enteric nervous system, and review protective functions of MTs against etiopathogenesis in PD. We also discuss neuroprotective strategies for the prevention of central dopaminergic and enteric neurodegeneration by targeting MTs. This review highlights multifunctional MTs as a target for the development of disease-modifying drugs for PD.

Structural Role of Cadmium and Zinc in Metallothionein Oxidation by Hydrogen Peroxide: The Resilience of Metal-Thiolate Clusters

Oxidative stress is a state involving an imbalance of reactive oxygen species in a cell and is linked to a variety of diseases. The metal-binding protein metallothionein (MT) may play a role in protection due to its high cysteine content. Many studies have shown that oxidative stress will cause MT to both form disulfide bonds and release bound metals. However, studies on the more biologically relevant partially metalated MTs have been largely neglected. Additionally, most studies to date have used spectroscopic methods that cannot detect specific intermediate species. In this paper, we describe the oxidation and the subsequent metal displacement pathway of fully and partially metalated MTs with hydrogen peroxide. The rates of the reactions were monitored using electrospray ionization mass spectrometry (ESI-MS) techniques, which resolved and characterized the individual intermediate M_x(SH)_yMT species. The rate constants were calculated for each species formation. Through ESI-MS and circular dichroism spectroscopy, it was found that the three metals in the β-domain were the first to be released from the fully metalated MTs. The Cd(II) in the partially metalated Cd(II)-bound MTs rearranged to form a protective Cd₄MT cluster structure upon exposure to oxidation. The partially metalated Zn(II)-bound MTs oxidized at a faster rate as the Zn(II) did not rearrange in response to oxidation. Additionally, density functional theory calculations showed that the terminally bound cysteines were more negative and thus more susceptible to oxidation than the bridging cysteines. The results of this study highlight the importance of metal-thiolate structures and metal identity in MT's response to oxidation.

An Assessment of MT1A (rs11076161), MT2A (rs28366003) and MT1L (rs10636) Gene Polymorphisms and MT2 Concentration in Women with Endometrial Pathologies

Several studies have indicated a relationship between metallothionein (MT) polymorphisms and the development of different pathologies, including neoplastic diseases. However, no studies thus far have been conducted on the influence of MT polymorphisms and the development of endometrial lesions, including endometrial cancer. This study included 140 patients with normal endometrial tissue, endometrial polyps, uterine myomas and endometrial cancer. The tissue MT2 concentration was determined using the ELISA method. MT1A, MT2A and MT1L polymorphisms were analyzed using TaqMan real-time PCR genotyping assays. We found no statistical difference between the tissue MT2 concentration in patients with EC vs. benign endometrium (p = 0.579). However, tissue MT2 concentration was significantly different between uterine fibromas and normal endometrial tissue samples (p = 0.019). Menopause status did not influence the tissue MT2 concentration (p = 0.282). There were no significant associations between the prevalence of MT1A, MT2A and MT1L polymorphisms and MT2 concentration. The age, menopausal status, and diabetes status of patients were identified as EC risk factors.

Quantitative plasma proteomics identifies metallothioneins as a marker of acute-on-chronic liver failure associated acute kidney injury

Background

Acute kidney injury (AKI) considerably increases the risk of short-term mortality in acute-on-chronic liver failure (ACLF) but predicting AKI is not possible with existing tools. Our study aimed at de novo discovery of AKI biomarkers in ACLF.

Methods

This observational study had two phases- (A) Discovery phase in which quantitative proteomics was carried-out with day-of-admission plasma from ACLF patients who initially had no-AKI but either progressed to AKI (n=10) or did not (n=9) within 7 days of admission and, (B) Validation phase in which selected biomarkers from the discovery phase were validated by ELISA in a larger set of ACLF plasma samples (n=93) followed by sub-group analyses.

Results

Plasma proteomics revealed 56 differentially expressed proteins in ACLF patients who progressed to AKI vs those who did not. The metallothionein protein-family was upregulated in patients who progressed to AKI and was validated by ELISA as significantly elevated in both- (i) ACLF-AKI vs no-AKI (p-value ≤ 0.0001) and (ii) progression to AKI vs no-progression to AKI (p-value ≤ 0.001). AUROC for AKI vs no-AKI was 0.786 (p-value ≤0.001) and for progression to AKI vs no-progression to AKI was 0.7888 (p-value ≤0.001). Kaplan-Meier analysis revealed that ACLF patients with plasma MT concentration >5.83 ng/mL had a high probability of developing AKI by day 7 (p-value ≤0.0001). High expression of metallothionein genes was found in post-mortem liver biopsies of ACLF patients.

Conclusion

Day-of-admission measurements of plasma metallothionein can act as predictive biomarkers of AKI in ACLF.

Heterologous Expression of Human Metallothionein Gene HsMT1L Can Enhance the Tolerance of Tobacco (Nicotiana nudicaulis Watson) to Zinc and Cadmium

Metallothionein (MT) is a multifunctional inducible protein in animals, plants, and microorganisms. MT is rich in cysteine residues (10-30%), can combine with metal ions, has a low molecular weight, and plays an essential biological role in various stages of the growth and development of organisms. Due to its strong ability to bind metal ions and scavenge free radicals, metallothionein has been used in medicine, health care, and other areas. Zinc is essential for plant growth, but excessive zinc (Zn) is bound to poison plants, and cadmium (Cd) is a significant environmental pollutant. A high concentration of cadmium can significantly affect the growth and development of plants and even lead to plant death. In this study, the human metallothionein gene HsMT1L under the control of the CaMV 35S constitutive promoter was transformed into tobacco, and the tolerance and accumulation capacity of transgenic tobacco plants to Zn and Cd were explored. The results showed that the high-level expression of HsMT1L in tobacco could significantly enhance the accumulation of Zn²⁺ and Cd²⁺ in both the aboveground parts and the roots compared to wild-type tobacco plants and conferred a greater tolerance to Zn and Cd in transgenic tobacco. Subcellular localization showed that HsMT1L was localized to the nucleus and cytoplasm in the tobacco. Our study suggests that HsMT1L can be used for the phytoremediation of soil for heavy metal removal.

Metallothionein Expression as a Physiological Response against Metal Toxicity in the Striped Rockcod Trematomus hansoni

Metal bioaccumulation and metallothionein (MT) expression were investigated in the gills and liver of the red-blooded Antarctic teleost Trematomus hansoni to evaluate the possibility for this species to face, with adequate physiological responses, an increase of copper and cadmium concentrations in its tissues. Specimens of this Antarctic fish were collected from Terra Nova Bay (Ross Sea) and used for a metal exposure experiment in controlled laboratory conditions. The two treatments led to a significant accumulation of both metals and increased gene transcription only for the MT-1. The biosynthesis of MTs was verified especially in specimens exposed to Cd, but most of these proteins were soon oxidized, probably because they were involved in cell protection against oxidative stress risk by scavenging reactive oxygen species. The obtained data highlighted the phenotypic plasticity of T. hansoni, a species that evolved in an environment characterized by naturally high concentrations of Cu and Cd, and maybe the possibility for the Antarctic fish to face the challenges of a world that is becoming more toxic every day.

Metallothionein gene expression in rat tissues: response to dietary restriction after orally dichlorodiphenyldichloroethylene (DDE) exposure and high-fat feeding

Dichlorodiphenyldichloroethylene (DDE) is an environmental pollutant that accumulates in adipose tissue through the food chain. Hypercaloric, high-fat diet is considered to promote the accumulation of toxic lipophilic substances in tissues, whereas the loss of body fat through caloric restriction results in a recirculation of these substances. In rats, oral administration of DDE causes the onset of tissues damage; the concomitant intake of a high-fat diet ameliorates tissues status, probably because of the entrapment of the lipophilic substance in fat depots. Recent evidence demonstrates that DDE alters the expression of metallothioneins, proteins involved in cellular defense from oxidative stress, in a diet- and tissue-specific manner. This study is aimed to verify if 2 weeks of caloric restriction after the oral DDE treatment can modify metallothionein gene expression in tissues of high-fat fed rats. Real-time PCR analysis demonstrates that metallothionein gene expression after calorie restriction is tissue-specific and strongly influenced by both previous dietary conditions and DDE exposure. To avoid misleading conclusions on the interference of toxic xenobiotics on metallothionein gene expression is particularly important to consider the tissue, the cellular conditions, and the nutritional status of the animals, especially when the protein is used as an index of cells health.

Metallothionein 2A with Antioxidant and Antitumor Activity Is Upregulated by Caffeic Acid Phenethyl Ester in Human Bladder Carcinoma Cells

Functions of metallothionein 2A (MT2A) in bladder cancer have not been extensively explored even though metallothioneins are regarded as modulators in several biological regulations including oxidation and cancerous development. We evaluated MT2A in bladder carcinoma cells in terms of the mechanisms of regulation and the underlying functions. MT2A overexpression not only downregulated endogenous ROS but also blocked ROS induced by H₂O₂. We used the annexin V-FITC apoptosis assay to determine the modulation of H₂O₂-induced cell apoptosis by MT2A expression. Results of immunoblot and reporter assays indicated that caffeic acid phenethyl ester (CAPE) treatment induced MT2A and heme oxygenase-1 (HO-1) expressions; moreover, the involvement of CAPE in either upregulation of the HO-1 expression or downregulation of endogenous ROS is MT2A dependent in bladder carcinoma cells. Knockdown of MT2A increased invasion and cell growth in vitro and in vivo, whereas ectopic overexpression of MT2A had the reverse effect in bladder carcinoma cells. Unlike bladder cancer tissues, the real-time reverse transcriptase-polymerase chain reaction (RT-qPCR) analysis showed a significant level of MT2A mRNA in the normal bladder tissues. Collectively, our results indicated that MT2A is acting as an antioxidant and also a tumor suppressor in human bladder carcinoma cells.

Chronic Intestinal Disorders in Humans and Pets: Current Management and the Potential of Nutraceutical Antioxidants as Alternatives

Simple Summary

Chronic disorders of the intestinal tract (CID) are characterized by signs of inflammation of the intestine for a period of at least three weeks. Both humans and pets can be affected by these disorders. Different therapeutic approaches can be selected to treat patients and the use of natural products has been increased in the last decade, since oxidative stress plays a key role in the progression of the chronic intestinal disorders. In this review, the antioxidant proprieties of several natural products with potential for treatment of CID in human and veterinary medicine are highlighted. Unfortunately, few clinical trials report the use of these products for treating CID in humans and none in animals.

Abstract

Chronic intestinal disorders (CID) are characterized by persistent, or recurrent gastrointestinal (GI) signs present for at least three weeks. In human medicine, inflammatory bowel disease (IBD) is a group of chronic GI diseases and includes Crohn’s disease (CD) and ulcerative colitis (UC). On the other hand, the general term chronic enteropathies (CE) is preferred in veterinary medicine. Different therapeutic approaches to these diseases are used in both humans and pets. This review is focused on the use of traditional therapies and nutraceuticals with specific antioxidant properties, for the treatment of CID in humans and animal patients. There is strong evidence of the antioxidant properties of the nutraceuticals included in this review, but few studies report their use for treating CID in humans and none in animals. Despite this fact, the majority of the nutraceuticals described in the present article could be considered as promising alternatives for the regular treatment of CID in human and veterinary medicine.

The Bioinorganic Chemistry of Mammalian Metallothioneins

The functions, purposes, and roles of metallothioneins have been the subject of speculations since the discovery of the protein over 60 years ago. This article guides through the history of investigations and resolves multiple contentions by providing new interpretations of the structure-stability-function relationship. It challenges the dogma that the biologically relevant structure of the mammalian proteins is only the one determined by X-ray diffraction and NMR spectroscopy. The terms metallothionein and thionein are ambiguous and insufficient to understand biological function. The proteins need to be seen in their biological context, which limits and defines the chemistry possible. They exist in multiple forms with different degrees of metalation and types of metal ions. The homoleptic thiolate coordination of mammalian metallothioneins is important for their molecular mechanism. It endows the proteins with redox activity and a specific pH dependence of their metal affinities. The proteins, therefore, also exist in different redox states of the sulfur donor ligands. Their coordination dynamics allows a vast conformational landscape for interactions with other proteins and ligands. Many fundamental signal transduction pathways regulate the expression of the dozen of human metallothionein genes. Recent advances in understanding the control of cellular zinc and copper homeostasis are the foundation for suggesting that mammalian metallothioneins provide a highly dynamic, regulated, and uniquely biological metal buffer to control the availability, fluctuations, and signaling transients of the most competitive Zn(II) and Cu(I) ions in cellular space and time.

Metabolomic profiling of plasma from middle-aged and advanced-age male mice reveals the metabolic abnormalities of carnitine biosynthesis in metallothionein gene knockout mice

Metallothionein (MT) is a family of low molecular weight, cysteine-rich proteins that regulate zinc homeostasis and have potential protective effects against oxidative stress and toxic metals. MT1 and MT2 gene knockout (MTKO) mice show shorter lifespans than wild-type (WT) mice. In this study, we aimed to investigate how MT gene deficiency accelerates aging. We performed comparative metabolomic analyses of plasma between MTKO and WT male mice at middle age (50-week-old) and advanced age (100-week-old) using liquid chromatography with time-of-flight mass spectrometry (LC-TOF-MS). The concentration of N6,N6,N6-trimethyl-L-lysine (TML), which is a metabolic intermediate in carnitine biosynthesis, was consistently higher in the plasma of MTKO mice compared to that of WT mice at middle and advanced age. Quantitative reverse transcription PCR (RT-PCR) analysis revealed remarkably lower mRNA levels of Tmlhe, which encodes TML dioxygenase, in the liver and kidney of male MTKO mice compared to that of WT mice. L-carnitine is essential for β-oxidation of long-chain fatty acids in mitochondria, the activity of which is closely related to aging. Our results suggest that reduced carnitine biosynthesis capacity in MTKO mice compared to WT mice led to metabolic disorders of fatty acids in mitochondria in MTKO mice, which may have caused shortened lifespans.

Metallothionein 2 activation by pravastatin reinforces epithelial integrity and ameliorates radiation-induced enteropathy

Background

Radiotherapy or accidental exposure to ionizing radiation causes severe damage of healthy intestinal tissues. Intestinal barrier function is highly sensitive to ionizing radiation, and loss of epithelial integrity results in mucosal inflammation, bacterial translocation, and endotoxemia. Few studies have of epithelial integrity as a therapeutic target to treat radiation toxicity. Here, we examined the effects of pravastatin (PS) and the molecular mechanisms underlying epithelial integrity on radiation-induced enteropathy.

Methods

The radio-mitigative effects of PS were evaluated in a minipig model by quantifying clinical symptoms, and performing histological and serological analyses and mRNA sequencing in intestinal tissues. To evaluate the role of intercellular junctions on radiation damage, we used tight junction regulator and metallothionein 2 (MT2) as treatments in a mouse model of radiation-induced enteropathy. Caco-2 monolayers were used to examine functional epithelial integrityand intercellular junction expression.

Finding

Using a minipig model of pharmaceutical oral bioavailability, we found that PS mitigated acute radiation-induced enteropathy. PS-treated irradiated minipigs had mild clinical symptoms, lower intestinal inflammation and endotoxin levels, and improved gastrointestinal integrity, compared with control group animals. The results of mRNA sequencing analysis indicated that PS treatment markedly influenced intercellular junctions by inhibiting p38 MAPK signaling in the irradiated intestinal epithelium. The PS-regulated gene MT2 improved the epithelial barrier via enhancement of intercellular junctions in radiation-induced enteropathy.

Interpretation

PS regulated epithelial integrity by modulating MT2 in radiation-damaged epithelial cells. These findings suggested that maintenance of epithelial integrity is a novel therapeutic target for treatment of radiation-induced gastrointestinal damage.

Funding

As stated in the Acknowledgments

Effects of Copper Nanoparticles on mRNA and Small RNA Expression in Human Hepatocellular Carcinoma (HepG2) Cells

With the advancement of nanotechnology, nanoparticles are widely used in many different industrial processes and consumer products. Copper nanoparticles (Cu NPs) are among the most toxic nanomaterials. We investigated Cu NPs toxicity in Human Hepatocellular carcinoma (HepG2) cells by examining signaling pathways, and microRNA/mRNA interactions. We compared the effects of exposures to Cu NPs at various concentrations and CuCl₂ was used as a control. The number of differentially expressed mRNA did not follow a linear dose-response relationship for either Cu NPs or CuCl₂ treatments. The most significantly altered genes and pathways by Cu NPs exposure were NRF2 (nuclear factor erythroid 2 related factor 2)-mediated oxidative stress response, protein ubiquitination, Tumor protein p53 (p53), phase I and II metabolizing enzymes, antioxidant proteins and phase III detoxifying gene pathways.Messenger RNA-microRNA interaction from MicroRNA Target Filter Analyses revealed more signaling pathways altered in Cu NPs treated samples than transcriptomics alone, including cell proliferation, DNA methylation, endoplasmic reticulum (ER) stress, apoptosis, autophagy, reactive oxygen species, inflammation, tumorigenesis, extracellular matrix/angiogenesis and protein synthesis. In contrast, in the control (CuCl₂) treated samples showed mostly changes in inflammation mainly through regulation of the Nuclear Factor Kappa-light-chain-enhancer of Activated B-cells (NFκB). Further, some RNA based parameters that showed promise as biomarkers of Cu NPs exposure including both well and lesser known genes: heme oxygenase 1 (HMOX1), heat shock protein, c-Fos proto-oncogene, DNA methyltransferases, and glutamate-cysteine ligase modifier subunit (GCLM, part of the glutathione synthesis pathway). The differences in signaling pathways altered by the Cu NPs and CuCl₂ treatments suggest that the effects of the Cu NPs were not the results of nanomaterial dissolution to soluble copper ions.

Proinflammatory response caused by lead nanoparticles triggered by engulfed nanoparticles

In this study, the cellular effects of lead (Pb) nanoparticles with a primary particle size of 80 nm were evaluated in two types of cell lines: human lung carcinoma A549 and macrophage-differentiated THP-1 cells (dTHP-1). The cellular responses induced by the Pb nanoparticles varied among the cell types. Exposure to Pb nanoparticles for 24 h at a concentration of 100 μg/ml induced interleukin-8 (IL-8) expression in dTHP-1 cells. Induction of IL-8 expression in A549 was lower than dTHP-1 cells. Pb nanoparticles also induced the gene expression of heme oxygenase-1 in dTHP-1 cells but not in A549 cells. Though cellular uptake of Pb nanoparticles was observed in both the cell types, the amount of internalized Pb particles was lower in A549 cells than that in dTHP-1 cells. Gene expression of metallothionein 2A was remarkably enhanced by Pb nanoparticle exposure in dTHP-1 cells. Compared with Pb nanoparticles, induction of cytokines caused by lead nitrate (Pb[NO₃ ]₂ ), a water-soluble Pb compound, was smaller. In conclusion, the present study revealed that Pb nanoparticles induced a stronger cellular response than Pb(NO₃ )₂ , primarily by eliciting cytokine production, in a cell type-dependent manner.

Zinc and Selenium in Inflammatory Bowel Disease: Trace Elements with Key Roles?

Inflammatory bowel disease (IBD) is a chronic inflammatory condition that may emerge at a young age and often lasts for life. It often goes through phases of recurrence and remission and has a devastating effect on quality of life. The exact etiology of the disease is still unclear, but it appears that an inappropriate immune response to intestinal flora bacteria in people with a genetic predisposition may cause the disease. Managing inflammatory bowel disease is still a serious challenge. Oxidative stress and free radicals appear to be involved in the pathogenesis of this disease, and a number of studies have suggested the use of antioxidants as a therapeutic approach. The antioxidant and anti-inflammatory properties of some trace elements have led some of the research to focus on studying these trace elements in inflammatory bowel disease. Zinc and selenium are among the most important trace elements that have significant anti-inflammatory and antioxidant properties. Some studies have shown the importance of these trace elements in inflammatory bowel disease. In this review, we have attempted to provide a comprehensive overview of the findings of these studies and to gather current knowledge about the association of these trace elements with the inflammatory process and inflammatory bowel disease.

Common carp exposed to binary mixtures of Cd(II) and Zn(II): A study on metal bioaccumulation and ion-homeostasis

The aquatic environment receives a wide variety of contaminants that interact with each other, influencing their mutual toxicity. Therefore, studies of mixtures are needed to fully understand their deleterious effects on aquatic organisms. In the present experiment, we aimed to assess the effects of Cd and Zn mixtures in common carp during a one-week exposure. The used nominal waterborne metal levels were 0.02, 0.05 and 0.10 µM for Cd and 3, 7.5 and 15 µM for Zn. Our results showed on the one hand a fast Cd increase and on the other hand a delayed Zn accumulation. In the mixture scenario an inhibition of Cd accumulation due to Zn was marked in the liver but temporary in the gills. For Zn, the delayed accumulation gives an indication of the efficient homeostasis of this essential metal. Between the different mixtures, a stimulation of Zn accumulation by Cd rather than an inhibition was seen in the highest metal mixtures. However, when compared to an earlier single Zn exposure, a reduced Zn accumulation was observed. Metallothionein gene expression was quickly activated in the analysed tissues suggesting that the organism promptly responded to the stressful situation. Finally, the metal mixture did not alter tissue electrolyte levels.

Elevated metallothionein expression in long-lived species mediates the influence of cadmium accumulation on aging

Cadmium (Cd) accumulates with aging and is elevated in long-lived species. Metallothioneins (MTs), small cysteine-rich proteins involved in metal homeostasis and Cd detoxification, are known to be related to longevity. However, the relationship between Cd accumulation, the role of MTs, and aging is currently unclear. Specifically, we do not know if long-lived species evolved an efficient metal stress response by upregulating their MT levels to reduce the toxic effects of environmental pollutants, such as Cd, that accumulate over their longer life span. It is also unknown if the number of MT genes, their expression, or both protect the organisms from potentially damaging effects during aging. To address these questions, we reanalyzed several cross-species studies and obtained data on MT expression and Cd accumulation in long-lived mouse models. We confirmed a relationship between species maximum life span in captive mammals and their Cd content in liver and kidney. We found that although the number of MT genes does not affect longevity, gene expression and protein amount of specific MT paralogs are strongly related to life span in mammals. MT expression rather than gene number may influence the high Cd levels and longevity of some species. In support of this, we found that overexpression of MT-1 accelerated Cd accumulation in mice and that tissue Cd was higher in long-lived mouse strains with high MT expression. We conclude that long-lived species have evolved a more efficient stress response by upregulating the expression of MT genes in presence of Cd, which contributes to elevated tissue Cd levels.

Importance of Genetic Polymorphisms in MT1 and MT2 Genes in Metals Homeostasis and Their Relationship with the Risk of Acute Pancreatitis Occurrence in Smokers-Preliminary Findings

This study was aimed at evaluating the changes in metallothionein (MT) concentration in the blood of patients with acute pancreatitis (AP) and healthy subjects, taking into account the extracellular (plasma) and intracellular (erythrocyte lysate) compartments. The impact of single-nucleotide polymorphisms (SNPs) in the MT1A (rs11640851), MT1B (rs964372) and MT2A (rs10636) genes on MT concentration and their association with the concentration of metals (Cu, Zn, Cd) and ceruloplasmin as Cu-related proteins were analyzed. The concentration of a high-sensitivity C-reactive protein (hs-CRP) and IL-6 as markers of inflammation, and malonyldialdehyde (MDA), superoxide dismutase (SODs) activity and the value of total antioxidant capacity (TAC) as parameters describing the pro/antioxidative balance were also assessed. In the AP patient groups, an increased MT concentration in erythrocyte lysate compared to healthy subjects was shown, especially in individuals with the GG genotype for rs964372 in the MT1B gene. A Zn concentration was especially decreased in the blood of smoking AP patients with the AA genotype for SNP rs11640851 in the MT1A gene and the GC genotype for SNP rs10636 in MT2A, compared to non-smokers with AP, which was accompanied by an increase in the value of the Cu/Zn ratio. The exposure to tobacco smoke xenobiotics increased the risk of AP occurrence in subjects with the CC genotype for SNP rs11640851 in the MT1A gene by more than fourfold. The investigated polymorphisms, rs11640851 in the MT1A gene, rs964372 in the MT1B gene and rs10636 in the MT2A gene, seem to be an important factor in maintaining homeostasis in an organism under oxidative stress conditions.

Structurally restricted Bi(III) metallation of apo-βMT1a: metal-induced tangling

Non-toxic bismuth salts are used in anti-ulcer medications and to protect against nephrotoxicity from anticancer drugs. Bismuth salts also induce metallothionein (MT), a metal-binding protein that lacks a formal secondary structure. We report the impact on the metallation properties of Bi(III) to the 9-cysteine β fragment of MT as a function of cysteine accessibility using electrospray ionization mass spectrometry. At pH 7.4, Bi2βMT formed cooperatively. Cysteine modification shows that each Bi(III) was terminally bound to three cysteinyl thiolates. Non-cooperative Bi(III) binding was observed at pH 2.3, where cysteine accessibility is increased. However, competition from H4EDTA inhibited Bi(III) binding. When GdmCl, a well-known denaturing agent, was used to increase cysteine accessibility of the apoβMT at pH 7.4, a greater fraction of Bi3βMT formed using all nine cysteines. The change in binding profile and equilibrium of Bi2βMT was determined as a function of acidification, which changed as a result of competition with H4EDTA. There was no Bi(III) transfer between Bi2βMT, Cd3βMT, and Zn3βMT. This lack of metal exchange and the resistance towards binding the third Bi(III) suggest a rigidity in the Bi2βMT binding sites that inhibits Bi(III) mobility. These experiments emphasize the conformational control of metallation that results in substantially different metallated products: at pH 7.4 (many cysteines buried) Bi2βMT, whereas at pH 7.4 (all cysteines accessible) enhanced formation of Bi3βMT. These data suggest that the addition of the first two Bi(III) crosslinks the protein, blocking access to the remaining three cysteines for the third Bi(III), as a result of tangle formation.

Stage-, sex- and tissue-related changes in H2O2, glutathione concentration, and glutathione-dependent enzymes activity in Aiolopus thalassinus (Orthoptera: Acrididae) from heavy metal polluted areas

This study is part of a large project carried out at the Cairo University, Egypt, and focused on assessing physiological and biochemical changes in Aiolopus thalassinus under the influence of environmental pollution with heavy metals (Pb, Cd, Cu, and Zn). The study aimed to investigate parameters related to maintaining redox balance, with particular emphasis on stage-, sex- and tissue-dependent differences in H₂O₂ and glutathione (GSH) levels and activity of selected enzymes involved in GSH metabolism. A noticeable increase in the concentration of H₂O₂ was found, especially in the gut of 5th instar nymphs and females from the highly polluted site. An increase in GSH concentration was significant, especially in the gut of adult A. thalassinus from the high polluted site. However, recycling of reduced form of glutathione in the gut by glutathione reductase (GR) was relevant only for females from the high polluted site. Nymphs and females generally showed higher glutathione S-transferase (GST) activity, especially in the gut. These stage- and sex-related differences can result from different growth dynamic and various reproductive functions of nymphs and both sexes. The digestive track is in direct contact with xenobiotics consumed with food. Nymphs are characterized by vigorous growth, they feed intensively, and their development processes are associated with substantial oxygen consumption. Also, maintaining the antioxidant system at a high level can be more important for females than males due to egg production over a long period. It appears that de novo GSH synthesis is a favorable and cost-effective adaptation mechanism for A. thalassinus living in the high polluted site.

Common and particular biochemical responses of Unio tumidus to herbicide, pharmaceuticals and their combined exposure with heating

The priority list of freshwater pollutants is increasingly amended by pharmaceuticals. Their impact on the aquatic biota can be modulated by the presence of typical pollutants, like pesticides, and/or abnormal heating. The aim of this study was to elucidate potentially hazardous impact of combined environmental factors on the freshwater mussels by analyzing various sets of biochemical markers. We treated the bivalve molluscs of Unio tumidus with non-steroidal anti-inflammatory drug diclofenac (Dc, 2 nM), calcium antagonist and antihypertensive drug nifedipine (Nf, 2 nM) or organophosphonate glyphosate-based herbicide Roundup MAX (Rn, 79 nM of glyphosate) at 18 °C as well as with the mixture of these substances at 18 °C (Mix) or 25 °C (MixT) during 14 days. The concentrations used were correspondent to the environmentally relevant levels. The biomarkers of stress and toxicity were evaluated in digestive gland, except the lysosomal membrane stability measured in hemocytes. Exposures caused an oxidative stress due to the decreased SOD and GST activities and GSH/GSSG ratio, increased levels of thiobarbituric acid-reactive substances and protein carbonyls (with some exceptions). Dc increased cathepsin D activity in lysosomes. Nf increased lysosomal membrane stability and caspase-3 activity. Rn caused a dramatic distortion of metallo-thiolome due to increased levels of GSH and metallothionein-related thiols (MTSH) as well as depletion of Zn, Cu and Cd in the composition of metallothioneins, and decreased Zn/Cu molar ratio in the tissue. The particular toxicity of Rn was also attested by decreased lysosomal membrane stability and cholinesterase activity. Canonical discriminant analysis separated Rn-, Mix- and MixT-groups from the joint set of C-, Dc- and Nf-groups. Generally, compound-specific effects were expressed in U. tumidus responses to the mixtures, but in MixT-group some effects were particular or extremely strong. Multi-marker approach and integrative analysis proved to be a useful tool for understanding possible future risks to freshwater mussels under a combination of xenobiotics and warming climate.

Antioxidant Defenses in the Human Eye: A Focus on Metallothioneins

The human eye, the highly specialized organ of vision, is greatly influenced by oxidants of endogenous and exogenous origin. Oxidative stress affects all structures of the human eye with special emphasis on the ocular surface, the lens, the retina and its retinal pigment epithelium, which are considered natural barriers of antioxidant protection, contributing to the onset and/or progression of eye diseases. These ocular structures contain a complex antioxidant defense system slightly different along the eye depending on cell tissue. In addition to widely studied enzymatic antioxidants, including superoxide dismutase, glutathione peroxidase, catalase, peroxiredoxins and selenoproteins, inter alia, metallothioneins (MTs) are considered antioxidant proteins of growing interest with further cell-mediated functions. This family of cysteine rich and low molecular mass proteins captures and neutralizes free radicals in a redox-dependent mechanism involving zinc binding and release. The state of the art of MTs, including the isoforms classification, the main functions described to date, the Zn-MT redox cycle as antioxidant defense system, and the antioxidant activity of Zn-MTs in the ocular surface, lens, retina and its retinal pigment epithelium, dependent on the number of occupied zinc-binding sites, will be comprehensively reviewed.

Induction of metallothionein isoforms in cultured bovine aortic endothelial cells exposed to cadmium

Metallothionein (MT) is an inducible protein with cytoprotective activity against heavy metals such as cadmium, zinc, and copper. MT-1 and MT-2 are the isoforms of MT induced by and bind the heavy metals. Bovine aortic endothelial cells contain three types of MT genes, namely, MT-1A, MT-1E, and MT-2A; however, the associated protein expression of these MT isoforms has not been identified. In the present study, the expression of MT subisoform proteins in cells treated with cadmium chloride was identified using a high-performance liquid chromatography-inductively coupled plasma-mass spectrometry system. It was revealed that: (1) transcriptional induction of MT-1A by cadmium was markedly more sensitive than that of MT-1E/2A; (2) MT-1A and MT-2A proteins were the predominant MT subisoforms induced by cadmium; and (3) there might be differentiation in the functions of MT-1 and MT-2 against cadmium cytotoxicity, although the actual roles of the MT isoforms in the cells were not distinct. This is the first study to show the differential induction of isoforms of MT proteins in vascular endothelial cells by cadmium.

Adipocyte hypertrophy parallels alterations of mitochondrial status in a cell model for adipose tissue dysfunction in obesity

AIMS

Adipocyte hypertrophy is the main cause of obesity. A deeper understanding of the molecular mechanisms regulating adipocyte dysfunction may help to plan strategies to treat/prevent obesity and its metabolic complications. Here, we investigated in vitro the molecular alterations associated with early adipocyte hypertrophy, focusing on mitochondrial dysfunction.

MAIN METHODS

As model of adipocyte hypertrophy, we employed 3T3-L1 preadipocytes firstly differentiated into mature adipocytes, then cultured with long-chain fatty acids. As a function of differentiation and hypertrophy, we assessed triglyceride content, lipid droplet size, radical homeostasis by spectrophotometry and microscopy, as well as the expression of PPARγ, adiponectin and metallothioneins. Mitochondrial status was investigated by electron microscopy, oxygraph 2 k (O2K) high-resolution respirometry, fluorimetry and western blot.

KEY FINDINGS

Compared to mature adipocytes, hypertrophic adipocytes showed increased triglyceride accumulation and lipid peroxidation, larger or unique lipid droplet, up-regulated expression of PPARγ, adiponectin and metallothioneins. At mitochondrial level, early-hypertrophic adipocytes exhibited: (i) impaired mitochondrial oxygen consumption with parallel reduction in the mitochondrial complexes; (ii) no changes in citrate synthase and HSP60 expression, and in the inner mitochondrial membrane polarization; (iii) no stimulation of mitochondrial fatty acid oxidation. Our findings indicate that the content, integrity, and catabolic activity of mitochondria were rather unchanged in early hypertrophic adipocytes, while oxygen consumption and oxidant production were altered.

SIGNIFICANCE

In the model of early adipocyte hypertrophy exacerbated oxidative stress and impaired mitochondrial respiration were observed, likely depending on reduction in the mitochondrial complexes, without changes in mitochondrial mass and integrity.

Zinc L-Carnosine Protects CCD-18co Cells from L-Buthionine Sulfoximine-Induced Oxidative Stress via the Induction of Metallothionein and Superoxide Dismutase 1 Expression

Zinc L-carnosine (ZnC) is the chelate form of zinc and L-carnosine and is one of the zinc supplements available in the market. This study aims to determine the protective effects of ZnC against L-buthionine sulfoximine (BSO)-induced oxidative stress in CCD-18co human normal colon fibroblast cell line. CCD-18co cells were pretreated with ZnC (0-100 μM) for 24 h before the induction of oxidative stress by BSO (1 mM) for another 24 h. Results from this present study demonstrated that ZnC up to the concentration of 100 μM was not cytotoxic to CCD-18co cells. Induction with BSO significantly increased the intracellular reactive oxygen species (ROS) levels and reduced the intracellular glutathione (GSH) levels in CCD-18co cells. Pretreatment with ZnC was able to attenuate the increment in intracellular ROS level in CCD-18co cells significantly in a concentration-dependent manner. However, ZnC did not have any effects on intracellular GSH levels and Nrf2 activation. Mechanistically, pretreatment with ZnC was able to upregulate the expression of metallothionein (MT) and superoxide dismutase 1 (SOD1) in CCD-18co cells. Results from dual-luciferase reporter gene assay reported that ZnC was able to increase the MRE-mediated relative luciferase activities in a concentration-dependent manner, suggesting that the induction of MT expression by ZnC was due to the activation of MTF-1 signaling pathway. Taken together, our current findings suggest that ZnC can protect CCD-18co cells from BSO-induced oxidative stress via the induction of MT and SOD1 expression.

Metallothionein levels in gingival crevicular fluid, saliva and serum of smokers and non-smokers with chronic periodontitis

BACKGROUND

Metallothionein (MT), a cysteine rich protein is involved as a radical scavenger in several pathological conditions associated with oxidative stress; however, its role in periodontal disease still remains elusive. The aim of this cross-sectional study is to determine the serum, saliva and gingival crevicular fluid (GCF) levels of MT in smokers (S) and non-smokers (NS) with chronic periodontitis (CP), and compare them with those of periodontally healthy (PH) individuals.

METHODS

A total of 85 participants were enrolled: 45 patients with CP (23 S [CP+S] and 22 NS [CP+NS]) and 40 PH individuals (20 S [PH+S] and 20 NS [PH+NS]). In all the study participants, clinical periodontal parameters (plaque index, gingival index, sulcus bleeding index, probing depth, and clinical attachment level) were recorded and samples of serum, saliva and GCF were collected. Enzyme-linked immunosorbent assay was used to determine the levels of MT in the samples.

RESULTS

All periodontal clinical parameters were significantly higher in the CP groups as compared to PH groups (P < 0.05). MT levels in CP+S group were significantly raised in comparison to other three groups. There was no statistically significant difference in MT levels among CP+NS and PH+S groups (P > 0.05); however, relatively higher levels were observed in GCF and saliva in CP+NS group. When all the study groups were observed together, MT levels were positively correlated with clinical parameters.

CONCLUSIONS

Results of present study suggest that smoking and CP can induce the synthesis of MT owing to increased oxidative stress and heavy metals intoxication. Further longitudinal studies with large sample size and an interventional arm are needed to substantiate the role of MT as a potential biomarker in periodontitis.

Cu Homeostasis in Bacteria: The Ins and Outs

Copper (Cu) is an essential trace element for all living organisms and used as cofactor in key enzymes of important biological processes, such as aerobic respiration or superoxide dismutation. However, due to its toxicity, cells have developed elaborate mechanisms for Cu homeostasis, which balance Cu supply for cuproprotein biogenesis with the need to remove excess Cu. This review summarizes our current knowledge on bacterial Cu homeostasis with a focus on Gram-negative bacteria and describes the multiple strategies that bacteria use for uptake, storage and export of Cu. We furthermore describe general mechanistic principles that aid the bacterial response to toxic Cu concentrations and illustrate dedicated Cu relay systems that facilitate Cu delivery for cuproenzyme biogenesis. Progress in understanding how bacteria avoid Cu poisoning while maintaining a certain Cu quota for cell proliferation is of particular importance for microbial pathogens because Cu is utilized by the host immune system for attenuating pathogen survival in host cells.

Role for Metallothionein-3 in the Resistance of Human U87 Glioblastoma Cells to Temozolomide

Metallothioneins (MTs) are metal-binding proteins that are overexpressed in various human cancers and are thought to be associated with resistance to cytotoxic drugs. The knowledge on MT expression, regulation, and function in human gliomas is limited. We found that MT3 mRNA was highly expressed in cell lines derived from grade IV gliomas (i.e., A172 and U87 cells), as compared to grade II astrocytoma cells (i.e., 1321N1). Different from 1321N1, U87 cells were partly resistant to the alkylating drug, temozolomide (TMZ) (100 μM for 96 h), which induced a massive accumulation of U87 into the S and G2 fractions of the cell cycle but not apoptotic death. Silencing of MT3 did not significantly affect U87 cell proliferation and survival, but it delayed G1/S transition and favored the occurrence of apoptosis in TMZ-treated cells. Accordingly, the combination of MT3 silencing and TMZ treatment increased the protein levels of checkpoint kinase-1, which was ultimately responsible for the lasting G1 arrest and death of double treated U87 cells.

Oxidative stress and mitochondrial dysfunction in organophosphate pesticide-induced neurotoxicity and its amelioration: a review

Organophosphorus pesticides (OPs) are widely used for controlling pests worldwide. The inhibitory effects of these pesticides on acetylcholinesterase lead to neurotoxic damages. The oxidative stress is responsible for several neurological diseases, including Parkinson's disease, seizure, depression, and Alzheimer's disease. Strong evidence suggests that dysfunction of mitochondria and oxidative stress are involved in neurological diseases. OPs can disturb the function of mitochondria by inducing oxidative stress. In the present study, we tried to highlight the role of dysfunction of mitochondria and the induction of oxidative stress in the neurotoxicity induced by OPs. Additionally, the amelioration of OP-induced oxidative damage and mitochondrial dysfunctional through the chemical and natural antioxidants have been discussed.

Metallothionein 2A gene polymorphisms in relation to diseases and trace element levels in humans

Human metallothioneins are a superfamily of low molecular weight intracellular proteins, whose synthesis can be induced by essential elements (primarily Zn and Cu), toxic elements and chemical agents, and stress-producing conditions. Of the four known isoforms in the human body MT2 is the most common. The expression of metallothioneins is encoded by a multigene family of linked genes and can be influenced by single nucleotide polymorphisms (SNPs) in these genes. To date, 24 SNPs in the MT2A gene have been identified with the incidence of about 1 % in various population groups, and three of them were shown to affect physiological and pathophysiological processes. This review summarises current knowledge about these three SNPs in the MT2A gene and their associations with element concentrations in the body of healthy and diseased persons. The most investigated SNP is rs28366003 (MT2A -5 A/G). Reports associate it with longevity, cancer (breast, prostate, laryngeal, and in paranasal sinuses), and chronic renal disease. The second most investigated SNP, rs10636 (MT2A +838G/C), is associated with breast cancer, cardiovascular disease, and type 2 diabetes. Both are also associated with several metal/metalloid concentrations in the organism. The third SNP, rs1610216 (MT2A -209A/G), has been studied for association with type 2 diabetes, cardiomyopathy, hyperglycaemia, and Zn concentrations. Metallothionein concentrations and MT2A polymorphisms have a potential to be used as biomarkers of metal exposure and clinical markers of a number of chronic diseases. This potential needs to be studied and verified in a large number of well-defined groups of participants (several hundreds and thousands) with a focus on particular physiological or pathological condition and taking into consideration other contributing factors, such as environmental exposure and individual genetic and epigenetic makeup.

Integrated, multicohort analysis reveals unified signature of systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is a complex autoimmune disease that follows an unpredictable disease course and affects multiple organs and tissues. We performed an integrated, multicohort analysis of 7,471 transcriptomic profiles from 40 independent studies to identify robust gene expression changes associated with SLE. We identified a 93-gene signature (SLE MetaSignature) that is differentially expressed in the blood of patients with SLE compared with healthy volunteers; distinguishes SLE from other autoimmune, inflammatory, and infectious diseases; and persists across diverse tissues and cell types. The SLE MetaSignature correlated significantly with disease activity and other clinical measures of inflammation. We prospectively validated the SLE MetaSignature in an independent cohort of pediatric patients with SLE using a microfluidic quantitative PCR (qPCR) array. We found that 14 of the 93 genes in the SLE MetaSignature were independent of IFN-induced and neutrophil-related transcriptional profiles that have previously been associated with SLE. Pathway analysis revealed dysregulation associated with nucleic acid biosynthesis and immunometabolism in SLE. We further refined a neutropoiesis signature and identified underappreciated transcripts related to immune cells and oxidative stress. In our multicohort, transcriptomic analysis has uncovered underappreciated genes and pathways associated with SLE pathogenesis, with the potential to advance clinical diagnosis, biomarker development, and targeted therapeutics for SLE.

Ccrn4l as a pre-dose marker for prediction of cisplatin-induced hepatotoxicity susceptibility

Clinical cisplatin use is often limited by its drug-induced liver injury (DILI). Particularly, individual differences in susceptibility to DILI can cause life-threatening medical conditions. This study aimed to uncover the inherent genetic factors determining individual variations in hepatotoxicity susceptibility. Rats were subjected to liver biopsy and a 3-week postoperative recovery period before cisplatin administration. At 2 days post-treatment with cisplatin, the rats exhibited histopathological and serum biochemical alterations in the liver, and changes in hydrogen peroxide and cytochrome P450-2E1 levels. Based on these results of liver-related biochemical markers, 32 rats were grouped into the susceptible (top five) and resistant (bottom five) groups. Using RNA-sequencing, we compared gene expressions in the liver pre-biopsied from these two groups before cisplatin treatment and found 161 differently expressed genes between the Susceptible and Resistant groups. Among them, the clock-controlled Ccrn4l responsible for 'rhythmic process' was identified as a common gene downregulated inherently prior to drug exposure in both cisplatin- and acetaminophen-sensitive animals. Additionally, low Ccrn4l levels before cisplatin treatment in the Susceptible group were maintained even after treatment, with decreased antioxidants, increased nitration, and apoptosis. The relationship of Ccrn4l with catalase and mitochondrial RNAs in the liver was confirmed by correlation of their hepatic levels among individuals and similar patterns of circadian variation in their mRNA expression. Remarkably, Ccrn4l knockdown promoted cisplatin-induced mitochondrial dysfunction in WB-F344 cells with antioxidant catalase and apoptosis-related Bax changes. Inherent individual hepatic Ccrn4l level might be a novel factor affecting cisplatin-induced hepatotoxicity susceptibility, possibly through regulation of mitochondrial and antioxidant functions.

Combination of Broccoli Sprout Extract and Zinc Provides Better Protection against Intermittent Hypoxia-Induced Cardiomyopathy Than Monotherapy in Mice

Nuclear factor-E2-related factor 2 (Nrf2) and metallothionein have each been reported to protect against chronic intermittent hypoxia- (IH-) induced cardiomyopathy. Sulforaphane-rich broccoli sprout extract (BSE) and zinc can effectively induce Nrf2 and metallothionein, respectively, to protect against IH-induced cardiomyopathy via antioxidative stress. However, whether the cardiac protective effects of the combination of BSE and zinc can be synergistic or the same has not been evaluated. In this study, we treated 8-week-old C57BL/6J mice with BSE and/or zinc during exposure to IH for 8 weeks. Cardiac dysfunction, as determined by echocardiography, and pathological remodeling and abnormalities, including cardiac fibrosis, inflammation, and oxidative damage, examined by histopathology and western blotting, were clearly observed in IH mice but were not significant in IH mice treated with either BSE, zinc, or zinc/BSE. Furthermore, the effects of the combined treatment with BSE and zinc were always greater than those of single treatments. Nrf2 function and metallothionein expression in the heart increased to a greater extent using the combination of BSE and zinc than using BSE or zinc alone. These findings for the first time indicate that the dual activation of Nrf2 and metallothionein by combined treatment with BSE and zinc may be more effective than monotherapy at preventing the development of IH-induced cardiomyopathy.

Metallome of cerebrovascular endothelial cells infected with Toxoplasma gondii using μ-XRF imaging and inductively coupled plasma mass spectrometry

In this study, we measured the levels of elements in human brain microvascular endothelial cells (ECs) infected with T. gondii. ECs were infected with tachyzoites of the RH strain, and at 6, 24, and 48 hours post infection (hpi), the intracellular concentrations of elements were determined using a synchrotron-microfocus X-ray fluorescence microscopy (μ-XRF) system. This method enabled the quantification of the concentrations of Zn and Ca in infected and uninfected (control) ECs at sub-micron spatial resolution. T. gondii-hosting ECs contained less Zn than uninfected cells only at 48 hpi (p < 0.01). The level of Ca was not significantly different between infected and control cells (p > 0.05). Inductively Coupled Plasma Mass Spectrometry (ICP-MS) analysis revealed infection-specific metallome profiles characterized by significant increases in the intracellular levels of Zn, Fe, Mn and Cu at 48 hpi (p < 0.01), and significant reductions in the extracellular concentrations of Co, Cu, Mo, V, and Ag at 24 hpi (p < 0.05) compared with control cells. Zn constituted the largest part (74%) of the total metal composition (metallome) of the parasite. Gene expression analysis showed infection-specific upregulation in the expression of five genes, MT1JP, MT1M, MT1E, MT1F, and MT1X, belonging to the metallothionein gene family. These results point to a possible correlation between T. gondii infection and increased expression of MT1 isoforms and altered intracellular levels of elements, especially Zn and Fe. Taken together, a combined μ-XRF and ICP-MS approach is promising for studies of the role of elements in mediating host-parasite interaction.

Metallothionein Protects the Heart Against Myocardial Infarction via the mTORC2/FoxO3a/Bim Pathway

Aims: Cardiac-specific overexpression of metallothionein (MT) has been shown to be beneficial in ischemic heart disease, but the detailed mechanisms through which MT protects against myocardial infarction (MI) remain unknown. This study assessed the involvement of the mTORC2/FoxO3a/Bim pathway in the cardioprotective effects of MT. Results: MI was induced in wild-type (FVB) mice and in cardiac-specific MT-overexpressing transgenic (MT-TG) mice by ligation of the left anterior descending (LAD) coronary artery. Cardiac function was better; infarct size and cardiomyocyte apoptosis were lower in MT-TG mice than in FVB mice after MI. Moreover, MT-TG mice exhibited better phenotypes after LAD ligation than FVB mice treated with Mn(III)tetrakis (1-methyl-4-pyridyl) porphyrin pentachloride (MnTMPyP; a reactive oxygen species [ROS] scavenger) and cardiac-specific catalase-overexpressing transgenic (CAT-TG) mice, which showed the same ROS levels as MT-TG mice after MI. Activation of mechanistic target of rapamycin complex 2 (mTORC2) was essential for the cardioprotective effects of MT against MI. In addition, MT attenuated the downregulation of phospho-FoxO3a after MI, inhibiting the expression of the apoptosis-associated gene Bim, located downstream of FoxO3a, and reducing the level of apoptosis after MI. To mimic ischemic-injured FVB and MT-TG mice in vitro, H9c2 and MT-overexpressing H9c2 (H9c2MT7) cardiomyocytes were subjected to oxygen and glucose deprivation, with the results being consistent with those obtained in vivo. Innovation and Conclusion: The cardioprotective effects of MT against MI are not entirely dependent upon its ability to eliminate ROS. Rather, MT overexpression mostly protects against MI through the mTORC2-FoxO3a-Bim pathway.

Protection against diabetic cardiomyopathy is achieved using a combination of sulforaphane and zinc in type 1 diabetic OVE26 mice

Sulforaphane (SFN) can effectively induce nuclear factor E2–related factor 2 (Nrf2), and zinc (Zn) can effectively induce metallothionein (MT), both of which have been shown to protect against diabetic cardiomyopathy (DCM). However, it is unclear whether combined treatment with SFN and Zn offers better cardiac protection than either one alone. Here, we treated 5‐week‐old OVE mice that spontaneously develop type 1 diabetes with SFN and/or Zn for 18 weeks. Cardiac dysfunction, by echocardiography, and pathological alterations and remodelling, shown by cardiac hypertrophy, fibrosis, inflammation and oxidative damage, examined by histopathology, Western blotting and real‐time PCR, were observed in OVE mice. All these dysfunction and pathological abnormalities seen in OVE mice were attenuated in OVE mice with treatment of either SFN, Zn or SFN/Zn, and the combined treatment with SFN/Zn was better than single treatments at ameliorating DCM. In addition, combined SFN and Zn treatment increased Nrf2 function and MT expression in the heart of OVE mice to a greater extent than SFN or Zn alone. This indicates that the dual activation of Nrf2 and MT by combined treatment with SFN and Zn may be more effective than monotherapy at preventing the development of DCM via complementary, additive mechanisms.

Regulatory role of metallothionein-1/2 on development of sex differences in a high-fat diet-induced obesity

AIMS

To evaluate the role of metallothionein (MT) in sex differences of obesity, we examined the effect of MT on regulation of lipid accumulation in female and male wild type (WT) and MT1/MT2-null (MT-KO) mice.

MAIN METHODS

Male and female WT and MT-KO mice fed standard diet (SD) or high-fat diet (HFD) for 35 weeks. Surgical castration in male mice was also performed to examine the effects of androgen on fat accumulation under HFD condition.

KEY FINDINGS

The fat mass and size of adipocytes in white adipose tissue (WAT) was greater in adult MT-KO mice than in WT mice after 35 weeks of SD feeding without gender differences, suggesting a role of MT in limiting WAT development during normal growth in both sexes. In female mice fed HFD, weights of WAT and body were greater in MT-KO mice than in WT mice, indicating that MT had a preventive role against excess fat accumulation. In male mice fed HFD, WAT weight hardly increased in MT-KO mice compared to the increase in WT mice. Surgically castrated WT males fed HFD had lower WAT weight compared with sham-treated mice, although castrated MT-KO males fed HFD had greater increases in WAT weight compared with sham-treated mice and castrated WT males.

SIGNIFICANCE

These data suggest that MT could enhance the preventive action of estrogen against excess fat accumulation, on the contrary, MT augmented the ability of androgen to increase fat accumulation. MT may act to modify the susceptibility to obesity under sex hormones.