Genetic variations in human glutathione transferase enzymes: significance for pharmacology and toxicology

The potential influence of GSTT1 null genetic polymorphism on coronary artery disease: A pilot study in a South Indian cohort

BACKGROUND

Indians are known to have the highest rates of coronary artery disease (CAD), with the conventional risk factors failing to explain the increased risk. Possible candidate genes to study both the environmental and genetic risk associated with CAD is the glutathione S-transferase (GST) family, as it is involved in detoxification.

METHODS

This case-control assessed the association between GSTM1 and GSTT1 polymorphisms in Indian patients with CAD. Fifty patients with CAD and 50 healthy volunteers were genotyped for the two polymorphisms by polymerase chain reaction. The genotype frequencies between the groups were compared, where a p-value of less than 0.05 was considered as statistically significant.

RESULTS

There was a significant inverse association between GSTT1 null polymorphism and CAD susceptibility.

Evaluation of oxidative stress-mediated cytotoxicity and genotoxicity of copper and flubendiamide: amelioration by antioxidants in vivo and in vitro

Present study was designed to evaluate toxic effects of copper (Cu) (@ 33 mg/kg b.wt.) and flubendimide (Flb) (@ 200 mg/kg b.wt.) alone and/or in combination on blood-biochemical indices, oxidative stress, and drug metabolizing enzymes (DMEs) in vivo in male Wistar rats following oral exposure continuously for 90 days and their immunotoxic (cyto-genotoxic and apoptotic) potential in vitro on thymocytes. In in vivo study, ameliorative potential of α-tocopherol was assessed, whereas α-tocopherol, curcumin, resveratrol, and catechin were evaluated for protective effect in vitro. Significantly (P < 0.05) increased AST activity and increment in total bilirubin, uric acid, creatinine, and BUN levels; however, reduction in total protein, GSH content, reduced activities of SOD and GST, and increased lipid peroxidation and GPx activity with severe degenerative changes in histopathological examination of liver and kidney in group of Cu and Flb were observed. Treatment with α-tocopherol improved biochemical variables, redox status, and histoarchitecture of liver and kidney tissues. Reduced hepatic CYP450, CYPb5, APH, UGT, and GST activities observed in both Cu and α-tocopherol alone and their combination groups, whereas significant increment in Flb alone, while α-tocopherol in combination with xenobiotics improved the activities of hepatic DMEs. Primary cell culture of thymocytes (106 cells/ml) exposed to Cu and Flb each @ 40 μM increased TUNEL+ve cells, micronuclei induction, DNA shearing, and comet formation establishes their apoptotic and genotoxic potential, whereas treatment with antioxidants showed concentration-dependent significant reduction and their order of potency on equimolar concentration (10 μM) basis is: curcumin > resveratrol > catechin = α-tocopherol.

Glutathione S-Transferases Mediate In Vitro and In Vivo Inactivation of Genipin: Implications for an Underlying Detoxification Mechanism

Genipin (GP), the reactive metabolite of geniposide (GE), is responsible for GE-induced hepatotoxicity. As a potential detoxification pathway, the inactivation of GP by glutathione S-transferases (GSTs) has not yet been characterized. In this study, the thiol-GSH conjugates of GP, M532-1 and M532-2 were first identified and the catalytic activities of GSTs were investigated both in vitro and in vivo. GSTA1-1 and GSTA4-4 showed high activity in the formation of both thiol-GSH conjugates, whereas GSTA4-4 specifically catalyzed M532-2 formation in vitro. The active GST isoforms protect against alkylation of N-acetylcysteine (NAC), a classic model nucleophile. GST inhibition attenuated M532-1 formation in rat bile, confirming the in vivo catalytic role of GSTs. In conclusion, this study demonstrated the inactivation of GP by GSTs and implied that interindividual variability of GSTs may be a risk factor for susceptibility to GE-induced hepatotoxicity.

Glutathione S-transferases Control astrocyte activation and neuronal health during neuroinflammation

Glutathione S-transferases (GST) are phase II detoxification enzymes of xenobiotic metabolism and readily expressed in the brain. Nevertheless, the current knowledge about their roles in the brain is limited. We have recently discovered that GSTM1 promotes the production of pro-inflammatory mediators by astrocytes and enhances microglial activation during acute brain inflammation. Here we report that GSTM1 significantly affects TNF-α-dependent transcriptional program in astrocytes and modulates neuronal activities and stress during brain inflammation. We have found that a reduced expression of GSTM1 in astrocytes downregulates the expression of pro-inflammatory genes while upregulating the expression of genes involved in interferon responses and fatty acid metabolism. Our data also revealed that GSTM1 reduction in astrocytes increased neuronal stress levels, attenuating neuronal activities during LPS-induced brain inflammation. Furthermore, we found that GSTM1 expression increased in the frontal cortex and hippocampus of aging mice. Thus, this study has further advanced our understanding of the role of Glutathione S-transferases in astrocytes during brain inflammation and paved the way for future studies to determine the critical role of GSTM1 in reactive astrocyte responses in inflammation and aging.

Interactions between Environmental Factors and Glutathione S-Transferase (GST) Genes with Respect to Detectable Blood Aluminum Concentrations in Jamaican Children

Aluminum (Al) is a metallic toxicant at high concentrations following natural or unnatural exposures. Dietary intake is considered as the main source of aluminum exposure in children. We used data from 366 typically developing (TD) children (ages 2−8 years) who participated as controls in an age- and sex-matched case−control study in Jamaica. We investigated additive and interactive associations among environmental factors and children’s genotypes for glutathione S-transferase (GST) genes (GSTT1, GSTM1, GSTP1), in relation to having a detectable blood aluminum concentration (BAlC) of >5.0 μg/L, using multivariable logistic regression models. Findings from interactive models revealed that the odds of having a detectable BAlC was significantly higher among children who ate string beans (p ≤ 0.01), whereas about 40% lower odds of having a detectable BAlC was observed in children with higher parental education level, (p = 0.02). A significant interaction between consumption of saltwater fish and GSTP1 in relation to having a detectable BAlC using either co-dominant or dominant genetic models (overall interaction p = 0.02 for both models) indicated that consumption of saltwater fish was associated with higher odds of having a detectable BAlC only among children with the GSTP1 Ile105Val Ile/Ile genotype using either co-dominant or dominant models [OR (95% CI) = 2.73 (1.07, 6.96), p = 0.04; and OR (95% CI) = 2.74 (1.08, 6.99), p = 0.03]. Since this is the first study from Jamaica that reports such findings, replication in other populations is warranted.

Proteomic, Transcriptomic, Mutational, and Functional Assays Reveal the Involvement of Both THF and PLP Sites at the GmSHMT08 in Resistance to Soybean Cyst Nematode

The serine hydroxymethyltransferase (SHMT; E.C. 2.1.2.1) is involved in the interconversion of serine/glycine and tetrahydrofolate (THF)/5,10-methylene THF, playing a key role in one-carbon metabolism, the de novo purine pathway, cellular methylation reactions, redox homeostasis maintenance, and methionine and thymidylate synthesis. GmSHMT08 is the soybean gene underlying soybean cyst nematode (SCN) resistance at the Rhg4 locus. GmSHMT08 protein contains four tetrahydrofolate (THF) cofactor binding sites (L129, L135, F284, N374) and six pyridoxal phosphate (PLP) cofactor binding/catalysis sites (Y59, G106, G107, H134, S190A, H218). In the current study, proteomic analysis of a data set of protein complex immunoprecipitated using GmSHMT08 antibodies under SCN infected soybean roots reveals the presence of enriched pathways that mainly use glycine/serine as a substrate (glyoxylate cycle, redox homeostasis, glycolysis, and heme biosynthesis). Root and leaf transcriptomic analysis of differentially expressed genes under SCN infection supported the proteomic data, pointing directly to the involvement of the interconversion reaction carried out by the serine hydroxymethyltransferase enzyme. Direct site mutagenesis revealed that all mutated THF and PLP sites at the GmSHMT08 resulted in increased SCN resistance. We have shown the involvement of PLP sites in SCN resistance. Specially, the effect of the two Y59 and S190 PLP sites was more drastic than the tested THF sites. This unprecedented finding will help us to identify the biological outcomes of THF and PLP residues at the GmSHMT08 and to understand SCN resistance mechanisms.

Transcriptional Dynamics Induced by Diapause Hormone in the Silkworm, Bombyx mori

Diapause is a form of dormancy that organisms use to adapt to extreme environments by exhibiting developmental arrest. In the silkworm, Bombyx mori, diapause is thought to be elicited by diapause hormone (DH) signaling, which consists of interactions between DH and the DH receptor (DHR). However, the steps downstream of the DH signaling pathway are largely unknown. In the present study, we directly injected synthesized DH into the female pupae of a multivoltine, non-diapausing strain at 36 h after pupation. We found that the mRNA level of DHR declined at 4 h and recovered at 12 h after the injection of DH. Thus, we sequenced the transcriptome of the ovaries at 4 h and 12 h after the injection of DH. We identified 60 and 221 differentially expressed genes at 4 h and 12 h after the injection, respectively. All DEGs were identified, relating to 20E-related genes, JH-related genes, cellular detoxification, ribosomal proteins, lipid metabolism, and epigenetic modifications. Eleven genes were selected from the above categories to verify the transcriptome data. The qRT-PCR and RNA-Seq expression patterns of the genes were consistent, which indicated the authenticity and reliability of the transcriptome data. This study dramatically expands upon our knowledge of gene expression variation at the early phase of DH release.

Early loss of glutathione -s- transferase (GST) activity during diverse forms of acute renal tubular injury

Glutathione‐S‐transferases (GSTs) are a diverse group of phase II detoxification enzymes which primarily evoke tissue protection via glutathione conjugation to xenobiotics and reactive oxygen species. Given their cytoprotective properties, potential changes in GST expression during AKI has pathophysiologic relevance. Hence, we evaluated total GST activity, and the mRNA responses of nine cytosolic GST isotypes (GST alpha1, kappa1, mu1/5, omega1, pi1 sigma1, theta1, zeta1 mRNAs), in five diverse mouse models of AKI (glycerol, ischemia/reperfusion; maleate, cisplatin, endotoxemia). Excepting endotoxemia, each AKI model significantly reduced GST activity (~35%) during both the AKI “initiation” (0‐4 h) and “maintenance” phases (18 or 72 h). During the AKI maintenance phase, increases in multiple GST mRNAs were observed. However, no improvement in GST activity resulted. Increased urinary GST excretion followed AKI induction. However, this could not explain the reduced renal GST activity given that it also fell in response to ex vivo renal ischemia (i.e., absent urinary excretion). GST alpha, a dominant proximal tubule GST isotype, manifested 5–10‐fold protein increases following AKI, arguing against GST proteolysis as the reason for the GST activity declines. Free fatty acids (FFAs) and lysophospholipids, which markedly accumulate during AKI, are known to bind to, and suppress, GST activity. Supporting this concept, arachidonic acid addition to renal cortical protein extracts caused rapid GST activity reductions. Based on these results, we conclude that diverse forms of AKI significantly reduce GST activity. This occurs despite increased GST transcription/translation and independent of urinary GST excretion. Injury‐induced generation of endogenous GST inhibitors, such as FFAs, appears to be a dominant cause.

Detoxification Role of Metabolic Glutathione S-Transferase (GST) Genes in Blood Lead Concentrations of Jamaican Children with and without Autism Spectrum Disorder

Glutathione S-transferases (GST) are involved in the detoxification of exogenous chemicals including lead (Pb). Using data from 344 pairs of autism spectrum disorder (ASD) cases and age- and sex-matched typically developing (TD) controls (2−8 years old) from Jamaica, we investigated the interaction between three GST genes and ASD status as determinants of blood Pb concentrations (BPbCs). We found that ASD cases had lower geometric mean BPbCs than TD children (1.74 vs. 2.27 µg/dL, p < 0.01). Using a co-dominant genetic model, ASD cases with the Ile/Val genotype for the GSTP1 Ile105Val polymorphism had lower GM BPbCs than TD controls, after adjusting for a known interaction between GSTP1 and GSTT1, child’s parish, socioeconomic status, consumption of lettuce, fried plantains, and canned fish (Ile/Val: 1.78 vs. 2.13 µg/dL, p = 0.03). Similarly, among carriers of the I/I or I/D (I*) genotype for GSTT1 and GSTM1, ASD cases had lower adjusted GM BPbCs than TD controls (GSTT1 I*: 1.61 vs. 1.91 µg/dL, p = 0.01; GSTM1 I*: 1.71 vs. 2.04 µg/dL, p = 0.01). Our findings suggest that genetic polymorphisms in GST genes may influence detoxification of Pb by the enzymes they encode in Jamaican children with and without ASD.

Gstm1/Gstt1 is essential for reducing cisplatin ototoxicity in CBA/CaJ mice

Cisplatin is a widely used chemotherapeutic agent. However, its clinical utility is limited because of cisplatin-induced ototoxicity. Glutathione S-transferase (GST) was found to play a vital role in reducing cisplatin ototoxicity in mice. Deletion polymorphisms of GSTM1 and GSTT1, members of the GST family, are common in humans and are presumed to be associated with cisplatin-induced hearing impairment. However, the specific roles of GSTM1 and GSTT1 in cisplatin ototoxicity are not completely clear. Here, under cisplatin treatment, simultaneous deletion of Gstm1 and Gstt1 lead to a more profound hearing loss in CBA/CaJ mice (Gstm1/Gstt1-DKO) than in wild-type mice. The Gstm1/Gstt1-DKO mice, in which phase II detoxification genes were upregulated, exhibited more severe oxidative stress and higher outer hair cell apoptosis in the cochleae than the control mice. Thus, our study revealed that Gstm1 and Gstt1 protect auditory hair cells from cisplatin-induced ototoxicity in the CBA/CaJ mice, and genetic screening for GSTM1 and GSTT1 polymorphisms could help determine a standard cisplatin dose for cancer patients undergoing chemotherapy.

Additive and Interactive Associations of Environmental and Sociodemographic Factors with the Genotypes of Three Glutathione S-Transferase Genes in Relation to the Blood Arsenic Concentrations of Children in Jamaica

Arsenic (As) is a metalloid that has been classified as a xenobiotic with toxic effects on human beings, especially on children. Since the soil in Jamaica contains As, dietary intake is considered the main source of As exposure in Jamaicans. In addition, glutathione S-transferase (GST) genes, including GSTT1, GSTP1, and GSTM1, play an important role in the metabolism of xenobiotics including As in humans. Using data from 375 typically developing children (2–8 years) in Jamaica, we investigated the environmental and sociodemographic factors, as well as their possible interactions with the children’s genotype for GST genes in relation to having a detectable level of blood As concentration (i.e., >1.3 μg/L). Using multivariable logistic regression, we have identified environmental factors significantly associated with blood As concentrations that include a child’s age, parental education levels, and the consumption of saltwater fish, cabbage, broad beans, and avocado (all p < 0.01). Based on the multivariable analysis including gene x environment interactions, we found that among children with the Ile/Ile genotype for GSTP1 Ile105Val, children who consumed avocado had higher odds of having a detectable blood As concentration compared to children who did not eat avocado.

Absence of Glutathione S-Transferase Theta 1 Gene Is Significantly Associated With Breast Cancer Susceptibility in Pakistani Population and Poor Overall Survival in Breast Cancer Patients: A Case-Control and Case Series Analysis

Purpose

Deletion of Glutathione S-Transferase Theta 1 (GSTT1) encoding gene is implicated in breast cancer susceptibility, clinical outcomes, and survival. Contradictory results have been reported in different studies. The present investigation based on a representative Pakistani population evaluated the GSTT1-absent genotype in breast cancer risk and prognosis.

Methods

A prospective study comprising case-control analysis and case series analysis components was designed. Peripheral blood samples were collected from enrolled participants. After DNA extraction, GSTT1 genotyping was carried out by a multiplex PCR with β-globin as an amplification control. Association evaluation of GSTT1 genotypes with breast cancer risk, specific tumor characteristics, and survival were the primary endpoints.

Results

A total of 264 participants were enrolled in the molecular investigation (3 institutions). The study included 121 primary breast cancer patients as cases and 143 age-matched female subjects, with no history of any cancer, as controls. A significant genetic association between GSTT1-absent genotype and breast cancer susceptibility (p-value: 0.03; OR: 2.13; 95% CI: 1.08-4.29) was reported. The case-series analysis showed lack of association of GSTT1 genotypes with menopause (p-value: 0.86), tumor stage (p-value: 0.12), grade (p-value: 0.32), and size (p-value: 0.07). The survival analysis revealed that GSTT1-absent genotype cases had a statistically significant shorter overall survival (OS) than those with the GSTT1-present genotype cases (mean OS: 23 months vs 33 months). The HR (95% CI) for OS in patients carrying GSTT1-absent genotype was 8.13 (2.91-22.96) when compared with the GSTT1-present genotype.

Conclusions

The present study is the first report of an independent significant genetic association between GSTT1-absent genotype and breast cancer susceptibility in a Pakistani population. It is also the foremost report of the association of this genotype with OS in breast cancer cases. Upon further validation, GSTT1 variation may serve as a marker for devising better population-specific strategies. The information may have translational implications in the screening and treatment of breast cancers.

GSTpi reduces DNA damage and cell death by regulating the ubiquitination and nuclear translocation of NBS1

Glutathione S-transferase pi (GSTpi) is an important phase II detoxifying enzyme that participates in various physiological processes, such as antioxidant, detoxification, and signal transduction. The high expression level of GSTpi has been reported to be related to drug-resistant and anti-inflammatory and it functioned via its non-catalytic ligandin. However, the previous protection mechanism of GSTpi in DNA damage has not been addressed so far. Nijmegen breakage syndrome 1 (NBS1) is one of the most important sensor proteins to detect damaged DNA. Here, we investigated the interaction between GSTpi and NBS1 in HEK-293 T cells and human breast adenocarcinoma cells during DNA damage. Our results showed that overexpression of GSTpi in cells by transfecting DNA vector decreased the DNA damage level after methyl methanesulfonate (MMS) or adriamycin (ADR) treatment. We found that cytosolic GSTpi could increase NBS1 ubiquitin-mediated degradation in unstimulated cells, which suggested that GSTpi could maintain the basal level of NBS1 during normal conditions. In response to DNA damage, GSTpi can be phosphorylated in Ser184 and inhibit the ubiquitination degradation of NBS1 mediated by Skp2 to recover NBS1 protein level. Phosphorylated GSTpi can further enhance NBS1 nuclear translocation to activate the ATM-Chk2-p53 signaling pathway. Finally, GSTpi blocked the cell cycle in the G2/M phase to allow more time for DNA damage repair. Thus, our finding revealed the novel mechanism of GSTpi via its Ser184 phosphorylation to protect cells from cell death during DNA damage and it enriches the function of GSTpi in drug resistance.

Role of Glutathione S-transferase Mu 1 and Glutathione S-transferases Theta 1 Polymorphism in the Risk of Developing Type 2 Diabetes Mellitus at Universitas Sumatera Utara Hospital, Medan

BACKGROUND: Diabetes mellitus is associated with an increased production of reactive oxygen species (ROS) and a reduction in antioxidant defense. Glutathione S-transferases (GSTs) is group of multifunction antioxidant enzyme can be used as important biomarkers for DM..  GSTM1, T1 genes variant polymorphism result in decreased or loss of enzyme activity. AIM: The study aimed to evaluate the role of GSTM1 and GSTT1 gene polymorphism in the risk of developing T2DM. METHODS: GSTM1 and GSTT1 polymorphisms were genotyped in 87 T2DM patients and 87 healthy control group to analyze their association with T2DM susceptibility by using multiplex Polymerase Chain Reaction (PCR). PCR products were electrophoresed using agarose 2%. Odds ratio (OR) with 95% confidence interval (CI) and P value were calculated using SPSS software (version 21.0). RESULTS: The genotype distribution of GSTM1 and GSTT1 were not different between T2DM patients and healthy control group (p = 0.542, OR= 0.780, CI 95%=0.350-1.737 and p=0.879, OR=1.047, CI 95%=0.577-1.903). The genotype distribution of combination of GSTM1 and GSTT1 were also not not different between T2DM patients and healthy control group (p = 0.640, OR= 0.640, CI 95%=0.224-1.83 and p=0.551, OR=0.721, CI 95%=0.245-2.120. CONCLUSION: In summary, this study showed that GSTT1 null, GSTM1 null, the combination of GSTM1 null and GSTT1 null genotype or combination of GSTM1 null and GSTT1 positive (or contrary) did not have any risk of developing T2DM at Universitas Sumatera Utara Hospital, Medan.  

Effect of titanium dioxide nanoparticles on DNA methylation of human peripheral blood mononuclear cells

The aim of the current study was to investigate the effect of well-characterized TiO₂ nanoparticles on DNA methylation of peripheral blood mononuclear cells (PBMCs) in vitro. Maximum non-toxic concentration of nanoparticles for PBMCs was determined by MTT assay. The effect of TiO₂ nanoparticles at concentrations of 25-100 μg/ml on DNA methylation of PBMCs was investigated by measuring the %5-mC alterations through an ELISA assay. The physicochemical analysis showed that the TiO₂ nanoparticles were crystalline, pure and in the anatase phase. Peaks related to Ti-O tensile vibrations were observed in the range of 1510 cm^-1. The size of nanoparticles was in the range of 39-74 nm with an average hydrodynamic diameter of 43.82 nm. According to the results of the MTT test, 100 μg/ml was found to be maximum non-toxic concentration. The %5-mC in treated PBMCs revealed that TiO₂ nanoparticles could lead to DNA hypomethylation in PBMCs. The %5-mC difference compared with the negative control was found to be 2.07 ± 1.02% (P = 0.03). The difference of %5-mC between the 25 and 100 μg/ml concentration of nanoparticles was statistically significant (P = 0.02). The results of the current study show that the TiO₂ nanoparticles cause DNA hypomethylation in PBMCs in a dose-response manner. Therefore, it is recommended to evaluate the effects of cytotoxicity and epigenotoxicity of commonly used nanoparticles before their use.

Effects of Lard and Vegetable Oils Supplementation Quality and Concentration on Laying Performance, Egg Quality and Liver Antioxidant Genes Expression in Hy-Line Brown

This study examined the effects of various types, quality, and levels of dietary oils on laying performance and the expression patterns of antioxidant-related genes in Hy-line brown laying hens. A total of 720 40-week-old Hy-line brown laying hens were fed the same corn-soybean basal meals but containing 0.5 or 1.5% normal or oxidized soybean oil or lard, a total of 8 treatments. The results showed that laying rate (LR) and fatty acids of raw yolk were significantly correlated dietary type of oil (p < 0.05). With the increasing concentration of normal oil, it significantly increased LR and decreased feed conversion ratio (FCR, feed/egg) and albumen height of laying hens. The oxidized oil significant decreased the production performance of laying hens; and adding 1.5% of oxidized lard into feeds could destroy the integrity of yolk spheres of cooked yolk. mRNA expression of liver antioxidant-related genes increased when dietary oxidized oils were added into feeds. By comparing different qualities oil effect on antioxidant-related genes, the expression of Glutathione S-Transferase Theta 1 (GSTT1), Glutathione S-Transferase Alpha 3 (GSTA3), Glutathione S-Transferase Omega 2 (GSTO2), and Superoxide Dismutase 2 (SOD2) were increased when dietary oils were oxidized, in which change of the GSTO2 expression was the most with 1.5% of oxidized soybean oil. In conclusion, the ideal type of oil for Hy-line brown layer hens is soybean comparing with lard in a corn-soybean diet, avoiding using of oxidized oil.

Associations of Metabolic Genes (GSTT1, GSTP1, GSTM1) and Blood Mercury Concentrations Differ in Jamaican Children with and without Autism Spectrum Disorder

We investigated interactive roles of three metabolic glutathione S-transferase (GST) genes (GSTP1, GSTT1, and GSTM1) and autism spectrum disorder (ASD) status in relation to blood Hg concentrations (BHC) of Jamaican children. We used data from 266 children (2-8 years) with ASD and their 1:1 age- and sex-matched typically developing (TD) controls. After adjusting General Linear Models for child’s age, socioeconomic status, consumption of leafy vegetables, fried plantain, canned fish, and the interaction between GSTP1 and GSTT1, we found significant interactions between GSTP1 and ASD status in relation to BHC either in a co-dominant or dominant genetic model for GSTP1(P < 0.001, P = 0.007, respectively). In the co-dominant model for the Ile105Val GSTP1 polymorphism, geometric mean (GM) BHC in ASD cases with genotype Ile/Ile were significantly higher than in cases with the Ile/Val genotype (0.73 vs. 0.48 µg/L, P = 0.01). In contrast, in TD controls with the Ile/Val genotype GM BHC were significantly higher than in those with the Ile/Ile genotype (0.72 vs. 0.49 µg/L, P = 0.03) or the Val/Val genotype (0.72 vs. 0.51 µg/L, P = 0.04). Although our findings are consistent with the role of GSTP1 in detoxification of Hg, replication in other populations is warranted.

Environmental Toxins Are a Major Cause of Bone Loss

The environmental metals cadmium, lead, and mercury, and chemicals such as pesticides, phthalates, and bisphenols, disrupt bone metabolism in many ways. Body levels of these toxins directly correlate, in a dose-dependent manner, with risk of fracture and osteoporosis. This editorial provides a brief summary of key research showing mechanisms of damage, sources, and key strategies to decrease body load.

The effects on antioxidant enzymes of PMMA/hydroxyapatite nanocomposites/composites

In this study, polymer-ceramic nanocomposites and/or composites were prepared by solution removal method using poly(methylmethacrylat) (PMMA) and nano-hydroxyapatite (nHA). They were characterized using X-ray diffraction (XRD), Fourier transform infrared-attenuated total reflection spectroscopy (FTIR-ATR), and differential thermal analysis/thermogravimetry (DTA/TG). Their effects and biocompatibilities on antioxidant enzymes were also investigated in detail. It has been shown that nHA was dramatically dispersed at nanoscale in the polymer matrix. The interaction occurred between OH groups of nHA and carbonyl groups of polymer and introduction of ceramic into the polymer matrix generally resulted in an increase in thermal stability. Nanocomposites and composites had different effects on enzyme activities. Samples synthesized in acetone increased enzyme activities for glutathione reductase (GR) and glucose-6 phosphate dehydrogenase (G6PD) enzymes, while inhibiting glutathione peroxidase (GPx) and catalase (CAT) enzyme activities. On the other hand, samples synthesized in tetrahydrofuran (THF) exhibited inhibitory behavior for G6PD and CAT enzymes. The samples synthesized in different media did not show any regularity on enzyme activities. The nanocomposites and/or composites prepared in acetone media were better hemocompatible than those in THF.

Metabolomics analysis reveals the protective effect of quercetin-3-O-galactoside (Hyperoside) on liver injury in mice induced by acetaminophen

We investigated the protective effect of Hyperoside (HPS) on liver injury induced by acetaminophen (APAP) in C57 mice. HPS was administered orally for 7 days and APAP was administered orally on the 7th day. Serum and liver samples were then collected for biochemical analyses, histopathology assessments, and metabolomics studies. Metabolites were assessed using a UHPLC-MS system. Principal component analysis (PCA) and orthogonal partial least squares discriminant analysis (OPLS-DA) were used to process the data. Pathway analyses were performed using Metaboanalyst 4.0. Western blot and qRT-PCR were used to determine the protein and mRNA levels, respectively. HPS interacted with active sites in CYP2E1 and caused protein degradation. In conclusion, our results suggested that HPS prevented the oxidative stress-induced liver injury caused by APAP. PRACTICAL APPLICATIONS: Hyperoside was shown to have potential protective and therapeutic effects against liver diseases. Male C57 mice were used to perform pharmacodynamic, pharmacology, and metabolomics evaluations. At a dose of 60 mg/kg, HPS prevented oxidative stress-induced liver injury caused by APAP by regulating the glutathione-related metabolites and enzymes through the inhibition of CYP2E1.

Mutations at the Serine Hydroxymethyltransferase Impact its Interaction with a Soluble NSF Attachment Protein and a Pathogenesis-Related Protein in Soybean

Resistance to soybean cyst nematodes (SCN) in “Peking-type” resistance is bigenic, requiring Rhg4-a and rhg1-a. Rhg4-a encodes a serine hydroxymethyltransferase (GmSHMT08) and rhg1-a encodes a soluble NSF attachment protein (GmSNAP18). Recently, it has been shown that a pathogenesis-related protein, GmPR08-Bet VI, potentiates the interaction between GmSHMT08 and GmSNAP18. Mutational analysis using spontaneously occurring and ethyl methanesulfonate (EMS)-induced mutations was carried out to increase our knowledge of the interacting GmSHMT08/GmSNAP18/GmPR08-Bet VI multi-protein complex. Mutations affecting the GmSHMT08 protein structure (dimerization and tetramerization) and interaction sites with GmSNAP18 and GmPR08-Bet VI proteins were found to impact the multi-protein complex. Interestingly, mutations affecting the PLP/THF substrate binding and catalysis did not affect the multi-protein complex, although they resulted in increased susceptibility to SCN. Most importantly, GmSHMT08 and GmSNAP18 from PI88788 were shown to interact within the cell, being potentiated in the presence of GmPR08-Bet VI. In addition, we have shown the presence of incompatibility between the GmSNAP18 (rhg1-b) of PI88788 and GmSHMT08 (Rhg4-a) from Peking. Components of the reactive oxygen species (ROS) pathway were shown to be induced in the SCN incompatible reaction and were mapped to QTLs for resistance to SCN using different mapping populations.

DEVELOPMENT OF PRIMARY OPEN-ANGLE GLAUCOMA AND DELETION POLYMORPHISM OF THE GLUTATHIONE-S-TRANSFERASE GENES

The aim of the research. To investigate the association of the development of primary open-angle glaucoma with deletion polymorphism of glutathione-S-transferase genes. Materials and methods. Under our observation there were 172 patients, residents of Ukraine with primary open-angle glaucoma I–IV stages. Analysis of the deletion polymorphism of GSTM1 and GSTT1 genes was performed by real-time polymerase chain reaction using unified TaqMan Mutation Detection Assays Life-Technology (USA) test systems. Statistical analysis of the obtained data was performed using the MedStat package and the statistical package MedCalc v.15.1 (MedCalc Software bvba). Results and discussion. The detection of null alleles of the GSTM1 gene was observed in 39 % of patients in the control group, in patients with POAG a significant increase in the frequency of deletion polymorphism to 50–56 % was observed with the progression of the disease in stages II-IV. In patients with stage IV disease, the effect of the zero GSTM1- null allele on POAG course was determined (χ2=3.97; p=0.047), and the null allele of GSTM1 doubled the probability of developing the disease (OR=2.01; 95 % CI=1.01–4.01) in patients of group 4 compared with control. The null allele of the GSTT1 gene in the control group was found in 31 %, an increase in the frequency of the GSTT1-null allele was also observed in the second and fourth stages of POAG from 41 % to 54 %. Statistically significant differences of GSTT1 gene allele frequencies were determined between the control group and all patients with POAG (χ2=4.43; p=0.03), between the control and the 4th group (χ2=7.64; p=0.01), and between the 1st and 4th groups (χ2=5.52; p=0.02). An association with the development of POAG (χ2=4.43; p=0.03) was determined for the deletion polymorphism of the GSTT1 gene when comparing the control group with the data of all patients with POAG (1–4 groups). At stratification by stages of POAG (that is, by groups of patients), an association with the development of POAG was determined only in patients of group 4 (χ2=7.64; p=0.01) compared with the control group. Conclusions. The association of the null allele of the GSTT1 gene with POAG was established (p=0.03). The presence of the GSTT1-null allele significantly increased the risk of developing POAG (OR=1.75; BI=1.04–2.96) compared with the control group. The presence of null alleles (GSTM1-null and GSTT1-null) of the GST deletion polymorphism significantly increased the risk of stage IV POAG (OR=2.01; BI=1.01–4.01 and OR=2.66; VI=1.32–5.37, respectively) compared with the control group, which indicated the effect of zero alleles on the rapid progression of the disease.

Association of GSTP1, GSTT1 and GSTM1 Gene Variants with Coronary Artery Disease in Iranian Population: A Case-Control Study

Background

Coronary artery disease (CAD) is a multifactorial disease that may be caused by the interaction between environmental and genetic risk factors. Glutathione S-transferases (GSTs) are known to participate in detoxification and metabolism of a wide range of xenobiotic compounds and oxidative stress products. Considering the interaction between environmental and genetic factors in CAD, we investigated the genetic polymorphisms of GSTM1, GSTT1, and GSTP1 in the Iranian population.

Patients and Methods

Two hundred and forty-four CAD cases and 281 healthy controls were studied. The genotype of GSTM1, GSTT1, and GSTP1 genes was determined by multiplex polymerase chain reaction (PCR) and PCR-restriction fragment length polymorphism (PCR-RFLP) techniques. Multivariable logistic regression analysis was used to calculate the odds ratios (ORs) and 95% confidence intervals (CI). Multifactor dimensionality reduction (MDR) analysis was also carried out to analyze the gene–gene and gene–environment interaction.

Results

The genotype and allele distribution of the three variations were not significantly different between CAD patients and controls (p > 0.05). The subgroup analysis revealed no significant gene–gene interactions or gene–gene combination effects linked to CAD susceptibility. However, MDR analysis selected the GSTM, GSTT pairwise and three genes combination models associated with the susceptibility to CAD. In addition, its result revealed that smoking in combination with GSTM1 (two-way) and GSTT, GSTP (three-way) genes might increase the risk of CAD. Furthermore, a significant interaction between GSTT1-null polymorphism and dyslipidemia was found in multivariable logistic regression analyses in the gene–environmental interactions on CAD risk.

Conclusion

Our results suggest that the GSTM1, GSTT1 and GSTP1 genetic variations are not directly associated with the susceptibility to CAD in Iranian patients. Due to MDR results, there might be a non-linear association between interactions of two or three genes and smoking with CAD. There is also an association between CAD risk factors and GST variations, which requires supplementary confirmation with larger sample sizes.

Endosulfan exposure alters transcription of genes involved in the detoxification and stress responses in Physella acuta

Endosulfan is a persistent pesticide that has been in use for more than five decades. During this time, it has contaminated soil, air, and water reservoirs worldwide. It is extremely toxic and harmful to beneficial non-target invertebrates, aquatic life, and even humans upon consumption, which is one of the many dangers of this pesticide since it biomagnifies in the food chain. The effects of three endosulfan concentrations (1, 10, and 100 µg/L) on the freshwater snail Physella acuta, an invasive cosmopolitan species, were examined over a week-long exposure period. Alterations in the expression of ten genes related to stress and xenobiotic detoxification were measured against the endogenous controls rpL10 and GAPDH by Real-Time polymerase chain reaction. Four genes are described here for the first time in this species, namely Hsp60, Grp78, GSTk1, and GSTm1. The rest of genes were Hsp90, sHsp16.6, cyp2u1, cyp3a7, cyp4f22, and MRP1. cyp2u1, sHsp16.6, and Grp78 expression were all altered by endosulfan. These results suggest a low pesticide concentration activates the acute response in P. acuta by affecting detoxification and stress responses and alter endoplasmic reticulum function and lipid metabolism. Furthermore, the newly identified genes extend the number of processes and cellular locations that can be analyzed in this organism.

In vitro and in vivo effects of flubendiamide and copper on cyto-genotoxicity, oxidative stress and spleen histology of rats and its modulation by resveratrol, catechin, curcumin and α-tocopherol

BACKGROUND

Living organisms are frequently exposed to more than one xenobiotic at a time either by ingestion of contaminated food/fodder or due to house-hold practices, occupational hazards or through environment. These xenobiotics interact individually or in combination with biological systems and act as carcinogen or produce other toxic effects including reproductive and degenerative diseases. Present study was aimed to investigate the cyto-genotoxic effects of flubendiamide and copper and ameliorative potential of certain natural phyotconstituent antioxidants.

METHOD

In vitro cytogenotoxic effects were evaluated by employing battery of assays including Propidium iodide staining, Tunel assay, Micronuclei, DNA fragmentation and Comet assay on isolated splenocytes and their prevention by resveratrol (5 and 10 μM), catechin (10 and 20 μM), curcumin (5 and 10 μM) and α-tocopherol (5, 10 and 20 μM). In vivo study was also undertaken daily oral administration of flubendiamide (200 mg/kg) or copper (33 mg/kg) and both these in combination, and also all these concurrently with of α-tocopherol to Wistar rats for 90 days.

RESULTS

Flubendiamide and copper produced concentration-dependent cytotoxic effects on splenocytes and at median lethal concentrations, flubendiamide (40 μM) and copper (40 μM) respectively produced 71 and 81% nonviable cells, higher number of Tunel+ve apoptotic cells, 7.86 and 9.16% micronucleus and 22.90 and 29.59 comets/100 cells and DNA fragmentation. In vivo study revealed significant (P < 0.05) increase in level of lipid peroxidation (LPO) and decrease in glutathione peroxidase (GPx), glutathione-S-transferase (GST) and superoxide dismutase (SOD) activities in groups exposed to flubendiamide or copper alone or both these in combination. Histopathological examination of rat spleens revealed depletion of lymphoid tissue, separation of splenocytes and rarification in splenic parenchyma of xenobiotic(s) treated groups.

CONCLUSION

Flubendiamide and copper induce oxidative stress and produce cytogenotoxic effects along with histoarchitectural changes in spleen. All four tested natural antioxidants (resveratrol, catechin, curcumin and α-tocopherol) reduced flubendiamide and copper-induced cytotoxic effects in rat splenocytes. Rat splenocytes are very sensitive to flubendiamide and copper-induced cytogenotoxicity, therefore, these can be effectively employed for screening of compounds for their cytogenotoxic potential. α-tocopherol was effective in restoring alterations in oxidative stress biomarkers and preventing histoarchitectural lesions in spleen.

Protein Expression Profile and Transcriptome Characterization of Penicillium expansum Induced by Meyerozyma guilliermondii

Antagonistic yeasts can inhibit fungal growth. In our previous research, Meyerozyma guilliermondii, one of the antagonistic yeasts, exhibited antagonistic activity against Penicillium expansum. However, the mechanisms, especially the molecular mechanisms of inhibiting activity of M. guilliermondii, are not clear. In this study, the protein expression profile and transcriptome characterization of P. expansum induced by M. guilliermondii were investigated. In P. expansum induced by M. guilliermondii, 66 proteins were identified as differentially expressed, among them six proteins were upregulated and 60 proteins were downregulated, which were associated with oxidative phosphorylation, ATP synthesis, basal metabolism, and response regulation. Simultaneously, a transcriptomic approach based on RNA-Seq was applied to annotate the genome of P. expansum and then studied the changes of gene expression in P. expansum treated with M. guilliermondii. The results showed that differentially expressed genes such as HEAT, Phosphoesterase, Polyketide synthase, ATPase, and Ras-association were significantly downregulated, in contrast to Cytochromes P450, Phosphatidate cytidylyltransferase, and Glutathione S-transferase, which were significantly upregulated. Interestingly, the downregulated differentially expressed proteins and genes have a corresponding relationship; these results revealed that these proteins and genes were important in the growth of P. expansum treated with M. guilliermondii.

The mercapturic acid pathway

The mercapturic acid pathway is a major route for the biotransformation of xenobiotic and endobiotic electrophilic compounds and their metabolites. Mercapturic acids (N-acetyl-l-cysteine S-conjugates) are formed by the sequential action of the glutathione transferases, γ-glutamyltransferases, dipeptidases, and cysteine S-conjugate N-acetyltransferase to yield glutathione S-conjugates, l-cysteinylglycine S-conjugates, l-cysteine S-conjugates, and mercapturic acids; these metabolites constitute a "mercapturomic" profile. Aminoacylases catalyze the hydrolysis of mercapturic acids to form cysteine S-conjugates. Several renal transport systems facilitate the urinary elimination of mercapturic acids; urinary mercapturic acids may serve as biomarkers for exposure to chemicals. Although mercapturic acid formation and elimination is a detoxication reaction, l-cysteine S-conjugates may undergo bioactivation by cysteine S-conjugate β-lyase. Moreover, some l-cysteine S-conjugates, particularly l-cysteinyl-leukotrienes, exert significant pathophysiological effects. Finally, some enzymes of the mercapturic acid pathway are described as the so-called "moonlighting proteins," catalytic proteins that exert multiple biochemical or biophysical functions apart from catalysis.

Beyond detoxification: Pleiotropic functions of multiple glutathione S-transferase isoforms protect mice against a toxic electrophile

Environmental and endogenous electrophiles cause tissue damage through their high reactivity with endogenous nucleophiles such as DNA, proteins, and lipids. Protection against damage is mediated by glutathione (GSH) conjugation, which can occur spontaneously or be facilitated by the glutathione S-transferase (GST) enzymes. To determine the role of GST enzymes in protection against electrophiles as well as the role of specific GST families in mediating this protection, we exposed mutant mouse lines lacking the GSTP, GSTM, and/or GSTT enzyme families to the model electrophile acrylamide, a ubiquitous dietary contaminant known to cause adverse effects in humans. An analysis of urinary metabolites after acute acrylamide exposure identified the GSTM family as the primary mediator of GSH conjugation to acrylamide. However, surprisingly, mice lacking only this enzyme family did not show increased toxicity after an acute acrylamide exposure. Therefore, GSH conjugation is not the sole mechanism by which GSTs protect against the toxicity of this substrate. Given the prevalence of null GST polymorphisms in the human population (approximately 50% for GSTM1 and 20–50% for GSTT1), a substantial portion of the population may also have impaired acrylamide metabolism. However, our study also defines a role for GSTP and/or GSTT in protection against acrylamide mediated toxicity. Thus, while the canonical detoxification function of GSTs may be impaired in GSTM null individuals, disease risk secondary to acrylamide exposure may be mitigated through non-canonical pathways involving members of the GSTP and/or GSTT families.

The Relation between Polymorphisms in Exon 5 and Exon 6 of GSTP1 Gene and the Risk of Lung Cancer in Iranian People

Objective:

The GSTP1 gene, which is located on chromosome 11q13, consists of 7 exons and 6 introns. There are two polymorphisms in GSTP1 that have been exposed to a transposition for codon 105 (Ile/Val) and 114 (Ala/Val) in exons 5 and 6, which have been studied previously in relation to lung cancer. Since the level of GSTP1 expression in lung tissues and other human epithelial tissues is high, GSTP1Val-105 polymorphism is recognized as a sensitive factor for tobacco-related cancers, especially lung cancer.

Methods:

One hundred and twenty tissue block samples of patients with lung cancers and 120 peripheral blood samples of the control group were obtained from two referral cancer centers in Tehran, Iran, from 2011 to 2016. Genomic DNA was extracted from tissue blocks and buffy coat of study cases to detect SNP of GSTP1 gene using Tetra-primer ARMS-PCR.

Results:

There was a notable correlation between the incidence of lung cancer and variant Val105 (P-value=0.001; OR=2/6; 95% CI=1.49-4.53) and Ile105 (P-value=0.003; OR=0.41; 95% CI=0.23-0.73). The odds ratio for lung cancer in the homozygous Ile105/Ile105 genotype was 3.56 times higher than that of individual with heterozygous Ile105/Val105 (P-value<0.001; OR=3/56; 95% CI=1.826-6.934) genotype, that was statistically significant. Furthermore, the results showed that there was no significant correlation between Ala114/Val114 genotypes and lung cancer. The BC (P-value=0.007; OR=0.16; 95% CI=0.04-0.61) and AA (P=0.001) genotypes were statistically significant (P-value <0.05); and for those who had AA genotype, the odds ratio was almost six times higher than those with BC genotype.

Conclusions:

The study of GSTP1 polymorphisms indicated that unlike the polymorphism in exon 5, the GSTP1 exon 6 polymorphism correlated with the lung cancer risk in the select group of Iranian people. Likewise, the potential use of this genetic polymorphism as a lung cancer predictor is confirmed.

Differential Effects of Human SP-A1 and SP-A2 on the BAL Proteome and Signaling Pathways in Response to Klebsiella pneumoniae and Ozone Exposure

Surfactant protein A (SP-A) plays critical roles in host defense, regulation of inflammation and surfactant metabolism in the lung. The human SP-A locus consists of two functional genes, SFTPA1 and SFTPA2 encoding surfactant proteins SP-A1 and SP-A2, respectively. Structural and functional differences exist between SP-A1 and SP-A2 in vitro and in vivo. Ozone is a major air pollutant with a negative impact on many biological processes. In this study we used humanized transgenic (hTG) SP-A1 and SP-A2 mice, and SP-A KO mice to study in vivo effects of SP-A1 and SP-A2 on the bronchoalveolar lavage (BAL) proteomic profile and associated signaling pathways in response to ozone or filtered air (FA) exposure and Klebsiella pneumoniae infection. The BAL samples were harvested 24 h after ozone (2 ppm for 3 h) or FA exposure and infection and analyzed by two-dimensional difference gel electrophoresis (2D-DIGE) and MALDI-ToF/ToF. We found: that (1) Ozone exposure, but not infection, is a major factor for increases in total BAL protein content. (2) A total of 36 proteins were identified, accounting for 89.62% of the BAL proteins resolved by the 2D-DIGE system. (3) The number of proteins in which levels were altered more than 25% following infection and FA exposure was: SP-A2 > SP-A1 > KO for male mice, and SP-A2 ≈ SP-A1 > KO for female mice. (4) The number of proteins with more than 25% increase/decrease after ozone exposure and infection was: SP-A2 > SP-A1 ≈ KO, with the majority being increases in male mice and decreases in female mice. (5) Eleven out of the 36 proteins, including annexin A5, glutathione S-transferase A4, SP-A1/SP-A2, and 14-3-3 zeta protein, exhibited significant differences among SP-A genotypes. The acute phase response (APR) that includes the NF-kB signaling pathway plays a critical role, followed by Nrf2-mediated oxidative response, and others. These associated with SP-A genotype, sex, and ozone-induced oxidative stress in response to infection. We concluded that human SP-A2 and SP-A1 exhibit differential genotype-and sex-dependent innate immune responses to microbial pathogens and/or ozone-induced oxidative stress by modulating proteomic patterns and signaling pathways in the lung.

Glutathione antioxidant system and methylmercury-induced neurotoxicity: An intriguing interplay

Methylmercury (MeHg) is a toxic chemical compound naturally produced mainly in the aquatic environment through the methylation of inorganic mercury catalyzed by aquatic microorganisms. MeHg is biomagnified in the aquatic food chain and, consequently, piscivorous fish at the top of the food chain possess huge amounts of MeHg (at the ppm level). Some populations that have fish as main protein's source can be exposed to exceedingly high levels of MeHg and develop signs of toxicity. MeHg is toxic to several organs, but the central nervous system (CNS) represents a preferential target, especially during development (prenatal and early postnatal periods). Though the biochemical events involved in MeHg-(neuro)toxicity are not yet entirely comprehended, a vast literature indicates that its pro-oxidative properties explain, at least partially, several of its neurotoxic effects. As result of its electrophilicity, MeHg interacts with (and oxidize) nucleophilic groups, such as thiols and selenols, present in proteins or low-molecular weight molecules. It is noteworthy that such interactions modify the redox state of these groups and, therefore, lead to oxidative stress and impaired function of several molecules, culminating in neurotoxicity. Among these molecules, glutathione (GSH; a major thiol antioxidant) and thiol- or selenol-containing enzymes belonging to the GSH antioxidant system represent key molecular targets involved in MeHg-neurotoxicity. In this review, we firstly present a general overview concerning the neurotoxicity of MeHg. Then, we present fundamental aspects of the GSH-antioxidant system, as well as the effects of MeHg on this system.

Homozygous deletion of both GSTM1 and GSTT1 genes is associated with higher CD4+ T cell counts in Ghanaian HIV patients

Glutathione S-transferase (GST) family of enzymes are involved in a two-stage detoxification process of a wide range of environmental toxins, carcinogens and xenobiotics. The GST enzymes play important roles in oxidative stress pathways, and polymorphisms in the GSTM1 and GSTT1 genes mediate susceptibility and outcome in different diseases. Human immunodeficiency virus (HIV) infection is associated with oxidative stress, but there is limited data on the frequency of deleted GSTM1 and GSTT1 genes in HIV/AIDS patients and their effect on progression among Ghanaians. This study sought to investigate the association between homozygous deletion of GSTM1 and GSTT1 genes (both null deletion) with HIV/AIDS disease progression in Ghanaian patients. HIV-infected individuals on antiretroviral therapy (ART), ART-naïve HIV patients, and HIV seronegative individuals were recruited for the study. HIV/AIDS disease progression was assessed by measuring CD4+ cell count and viral load of the patients, and GST polymorphism was determined by amplifying the GSTT1 and GSTM1 genes using multiplex PCR, with CYP1A1 gene as an internal control. The mean CD4+ count of patients that were naïve to ART (298 ± 243 cells/mm3) was significantly lower than that of patients on ART (604 ± 294 cells/mm3), and viral load was significantly lower in the ART-experienced group (30379 ± 15073 copies/mm3) compared to the ART-naïve group (209882 ± 75045 copies/mm3). Frequencies of GSTM1 and GSTT1 deletions were shown to be 21.9% and 19.8%, respectively, in the HIV patients, and patients with homozygous deletion of both GSTM1 and GSTT1 were more likely to have their CD4+ count rising above 350 cells/mm3 (OR = 6.44, 95% CI = 0.81-51.49, p = 0.039) suggesting that patients with homozygous deletion of GSTM1 and GSTT1 genes have slower disease progression. The findings of this study show that double deletion of glutathione S-transferases M1 and T1 is statistically associated with normal CD4+ count in patients diagnosed with HIV/AIDS. Further study is required to investigate the clinical importance of the both null deletion in HIV patients.

Diapause in a tropical oil-collecting bee: molecular basis unveiled by RNA-Seq

BACKGROUND

Diapause is a natural phenomenon characterized by an arrest in development that ensures the survival of organisms under extreme environmental conditions. The process has been well documented in arthropods. However, its molecular basis has been mainly studied in species from temperate zones, leaving a knowledge gap of this phenomenon in tropical species. In the present study, the Neotropical and solitary bee Tetrapedia diversipes was employed as a model for investigating diapause in species from tropical zones. Being a bivoltine insect, Tetrapedia diversipes produce two generations of offspring per year. The first generation, normally born during the wet season, develops faster than individuals from the second generation, born after the dry season. Furthermore, it has been shown that the development of the progeny, of the second generation, is halted at the 5th larval instar, and remains in larval diapause during the dry season. Towards the goal of gaining a better understanding of the diapause phenomenon we compared the global gene expression pattern, in larvae, from both reproductive generations and during diapause. The results demonstrate that there are similarities in the observed gene expression patterns to those already described for temperate climate models, and also identify diapause-related genes that have not been previously reported in the literature.

RESULTS

The RNA-Seq analysis identified 2275 differentially expressed transcripts, of which 1167 were annotated. Of these genes, during diapause, 352 were upregulated and 815 were downregulated. According to their biological functions, these genes were categorized into the following groups: cellular detoxification, cytoskeleton, cuticle, sterol and lipid metabolism, cell cycle, heat shock proteins, immune response, circadian clock, and epigenetic control.

CONCLUSION

Many of the identified genes have already been described as being related to diapause; however, new genes were discovered, for the first time, in this study. Among those, we highlight: Niemann-Pick type C1, NPC2 and Acyl-CoA binding protein homolog (all involved in ecdysteroid synthesis); RhoBTB2 and SASH1 (associated with cell cycle regulation) and Histone acetyltransferase KAT7 (related to epigenetic transcriptional regulation). The results presented here add important findings to the understanding of diapause in tropical species, thus increasing the comprehension of diapause-related molecular mechanisms.

Glutathionylation: a regulatory role of glutathione in physiological processes

Glutathione (γ-glutamyl-cysteinyl-glycine) is an intracellular thiol molecule and a potent antioxidant that participates in the toxic metabolism phase II biotransformation of xenobiotics. It can bind to a variety of proteins in a process known as glutathionylation. Protein glutathionylation is now recognised as one of important posttranslational regulatory mechanisms in cell and tissue physiology. Direct and indirect regulatory roles in physiological processes include glutathionylation of major transcriptional factors, eicosanoids, cytokines, and nitric oxide (NO). This review looks into these regulatory mechanisms through examples of glutathione regulation in apoptosis, vascularisation, metabolic processes, mitochondrial integrity, immune system, and neural physiology. The focus is on the physiological roles of glutathione beyond biotransformational metabolism.

Do GSTM1 and GSTT1 polymorphisms influence the risk of developing mitochondrial diseases in a Tunisian population?

Mitochondria play an essential role to supply the cell with metabolic energy in the form of adenosine triphosphate (ATP) through oxidative phosphorylation (OXPHOS). As a consequence, they are also the primary source of cellular reactive oxygen species (ROS) which can cause oxidative damage of individual respiratory chain complexes. Indeed, affected OXPHOS subunits result in decreases in ATP production and increases in ROS formation which generate oxidative phosphorylation deficiency leading to mitochondrial dysfunctions. It has been suggested that ROS play a vital role in the pathogenesis of mitochondrial diseases. To the best of our knowledge, this is the first study which aimed to investigate the genetic variant effect of the antioxidant enzymes GSTM1 and GSTT1 on mitochondrial disease among a Tunisian population. In this report, 109 patients with mitochondrial disease and 154 healthy controls were genotyped by multiplex PCR amplification, and data were analyzed by SPSS v20 software. The results showed that GSTM1 null genotype was found to be associated with mitochondrial disease with a protective effect; however, no significant association of GSTT1 polymorphism with mitochondrial disease risk was revealed. But, interestingly, our findings highlight that GSTM1 active and GSTT1 null genotype combination increased by three fold the risk of developing mitochondrial disease with p _c  = 0.020, notably mitochondrial myopathy with p _c  = 0.046 and Leigh syndrome with p _c  = 0.042. In conclusion, this study suggests that GSTM1 active and GSTT1 null genotype combination might be a risk factor in developing mitochondrial disease.

Association between arsenic metabolism gene polymorphisms and arsenic-induced skin lesions in individuals exposed to high-dose inorganic arsenic in northwest China

Individuals in a given environment contaminated with arsenic have different susceptibilities to disease, which may be related to arsenic metabolism, age, gender, genetics and other factors. This study recruited 850 subjects, including 331 cases and 519 controls, from populations exposed to high levels of arsenic in drinking water in northwest China. Genotypes were determined using a custom-by-design 48-Plex SNPscan^TM kit. The results indicated that subjects who carried at least one C allele for GSTO1 rs11191979 polymorphism, at least one A allele for GSTO1 rs2164624, at least one A allele for GSTO1 rs4925, the AG genotype for GSTO2 rs156697, the AG genotype or at least one G allele for GSTO2 rs2297235 or the GG genotype or at least one G allele for PNP rs3790064 had an increased risk of arsenic-related skin lesions. In addition, the haplotype CT between rs4925 and rs11191979 appeared to confer a high risk of arsenic-included skin lesions (OR = 1.377, 95% CI = 1.03–1.84), as did the haplotype GCG among rs156697, rs157077 and rs2297235 (OR = 2.197, 95% CI = 1.08–4.44). The results showed that the variants of GSTO1, GSTO2 and PNP render the susceptible toward developing arsenic-induced skin lesions in individuals exposed to high-dose inorganic arsenic in northwest China.

Designing Peptide and Protein Modified Hydrogels: Selecting the Optimal Conjugation Strategy

Hydrogels are used in a wide variety of biomedical applications including tissue engineering, biomolecule delivery, cell delivery, and cell culture. These hydrogels are often designed with a specific biological function in mind, requiring the chemical incorporation of bioactive factors to either mimic extracellular matrix or to deliver a payload to diseased tissue. Appropriate synthetic techniques to ligate bioactive factors, such as peptides and proteins, onto hydrogels are critical in designing materials with biological function. Here, we outline strategies for peptide and protein immobilization. We specifically focus on click chemistry, enzymatic ligation, and affinity binding for transient immobilization. Protein modification strategies have shifted toward site-specific modification using unnatural amino acids and engineered site-selective amino acid sequences to preserve both activity and structure. The selection of appropriate protein immobilization strategies is vital to engineering functional hydrogels. We provide insight into chemistry that balances the need for facile reactions while maintaining protein bioactivity or desired release.

Role of Metabolic Genes in Blood Aluminum Concentrations of Jamaican Children with and without Autism Spectrum Disorder

Aluminum is a neurotoxic metal with known health effects in animals and humans. Glutathione-S-transferase (GST) genes and enzymes play a major role in detoxification of several heavy metals. Besides a direct relationship with oxidative stress; aluminum decreases GST enzyme activities. Using data from 116 Jamaican children; age 2–8 years; with Autism Spectrum Disorder (ASD) and 116 sex- and age-matched typically developing (TD) children; we investigated the association of polymorphisms in three GST genes (GSTP1; GSTM1; and GSTT1) with mean blood aluminum concentrations in children with and without ASD. Using log-transformed blood aluminum concentration as the dependent variable in a linear regression model; we assessed the additive and interactive effects of ASD status and polymorphisms in the three aforementioned GST genes in relation to blood aluminum concentrations. Although none of the additive effects were statistically significant (all p > 0.16); we observed a marginally significant interaction between GSTP1 Ile105Val (rs1695) and ASD status (p = 0.07); even after controlling for parental education level and consumption of avocado; root vegetables; and tuna (canned fish). Our findings indicate a significantly lower (p < 0.03) adjusted geometric mean blood aluminum concentration for TD children who had the Val/Val genotype (14.57 µg/L); compared with those with Ile/Ile or Ile/Val genotypes who had an adjusted geometric mean of 23.75 µg/L. However; this difference was not statistically significant among the ASD cases (p = 0.76). Our findings indicate that ASD status may be a potential effect modifier when assessing the association between GSTP1 rs1695 and blood aluminum concentrations among Jamaican children. These findings require replication in other populations.

Distribution of genetic variants of oxidative stress metabolism genes: Paraoxonase 1 (PON1) and Glutathione S-transferase (GSTM1/GSTT1) in a population from Southeastern Mexico

BACKGROUND

Paraoxonase 1 (PON1) and glutathione S-transferases (GSTs) are involved in the biotransformation of xenobiotics. Variation in the enzyme concentration and activity suggests individual differences for the degree of protection against oxidative stress.

AIM

This study analysed the distribution of SNPs Q192R, L55M (PON1) and variants in GSTM1 and GSTT1 genes in a population from Southeastern Mexico.

SUBJECTS AND METHODS

One hundred and fifty-one Mexican Mestizo healthy volunteers were included. PON1 polymorphisms were determined by Taqman allele discrimination real time-PCR, whereas GSTM1 and GSTT1 genes were determined with a multiplex PCR-based method.

RESULTS

All genotypes were in Hardy-Weinberg equilibrium, except for GSTM1. The genotypic distributions of Q192R and L55M were 22% QQ, 48% QR, 30% RR, 62% LL, 34% LM and 4% MM, respectively, whereas the allele frequencies were 0.46 (Q), 0.54 (R), 0.79 (L) and 0.21 (M). The most frequent haplotype was R/L (46.7%). It was found that 31% and 9% of the individuals had the GSTM1 and GSTT1 null genotype, respectively. The frequency of the combined null genotype GSTM1*0/GSTT1*0 was 4.64%.

CONCLUSION

The results showed that the frequencies of polymorphisms of PON1, GSTM1 and GSTT1 in the Yucatán population differ to those observed in other ethnic groups and provide useful data for epidemiological studies.

Glutathione S-Transferase T1 (GSTT1) Null Polymorphism, Smoking, and Their Interaction in Coronary Heart Disease: A Comprehensive Meta-Analysis

BACKGROUND

The association between glutathione S-transferase T1 (GSTT1) null polymorphism and coronary heart disease (CHD) is inconsistent among studies, and data on the GSTT1 null genotype-smoking interplay in CHD is lacking. We conducted this meta-analysis to investigate the relationship between GSTT1 null polymorphism and CHD and to assess the potential interaction between GSTT1 null genotype and smoking.

METHODS

PubMed and EMBASE databases were searched up to 27 January 2016 using the appropriate terms. Odds ratios were pooled using either fixed-effects or random-effects models.

RESULTS

Twenty-nine articles including 31 studies with 15,004 cases and 35,597 controls were eligible. The random-effects model showed that the GSTT1 null genotype was associated with increased CHD risk (OR=1.213, 95%CI: 1.004-1.467; I²=90.4%). After excluding 10 studies detected by Galbraith plot, the fixed effects summary estimate also showed an increased risk of CHD (OR=1.14, 95% CI: 1.06-1.22; I²=27.7%). A case-only analysis including eight studies showed a statistically significant positive interaction between GSTT1 null polymorphism and smoking status on CHD (OR=1.34, 95% CI: 1.09-1.64; I²=0%). Sensitivity analyses further supported the associations. No publication bias was observed.

CONCLUSIONS

This meta-analysis suggests that GSTT1 null polymorphism is associated with the risk of CHD. To our knowledge, this is the first meta-analysis to prove a positive effect of the interaction between GSTT1 null genotype and smoking status on the risk of CHD. Future studies with detailed individual information are needed to confirm our findings.

Analyses of Genetic Variations of Glutathione S-Transferase Mu1 and Theta1 Genes in Bangladeshi Tannery Workers and Healthy Controls

Glutathione S-transferases (GSTs) belong to a group of multigene detoxification enzymes, which defend cells against oxidative stress. Tannery workers are at risk of oxidative damage that is usually detoxified by GSTs. This study investigated the genotypic frequencies of GST Mu1 (GSTM1) and GST Theta1 (GSTT1) in Bangladeshi tannery workers and healthy controls followed by their status of oxidative stress and total GST activity. Of the 188 individuals, 50.0% had both GSTM1 and GSTT1 (+/+), 12.2% had GSTM1 (+/-), 31.4% had GSTT1 (-/+) alleles, and 6.4% had null genotypes (-/-) with respect to both GSTM1 and GSTT1 alleles. Among 109 healthy controls, 54.1% were double positive, 9.2% had GSTM1 allele, 32.1% had GSTT1 allele, and 4.6% had null genotypes. Out of 79 tannery workers, 44.3% were +/+, 16.8% were +/-, 30.5% were -/+, and 8.4% were -/-. Though the polymorphic genotypes or allelic variants of GSTM1 and GSTT1 were distributed among the study subjects with different frequencies, the differences between the study groups were not statistically significant. GST activity did not vary significantly between the two groups and also among different genotypes while level of lipid peroxidation was significantly higher in tannery workers compared to controls irrespective of their GST genotypes.

Association study of Glutathione S-Transferase polymorphisms and risk of endometriosis in an Iranian population

BACKGROUND

Endometriosis influenced by both genetic and environmental factors. Associations of glutathione S-transferases (GSTs) genes polymorphisms in endometriosis have been investigated by various researchers; however, the results are not consistent.

OBJECTIVE

We examined the associations of GSTM1 and GSTT1 null genotypes and GSTP1 313 A/G polymorphisms with endometriosis in an Iranian population.

MATERIALS AND METHODS

In this case-control study, 151 women with diagnosis of endometriosis and 156 normal healthy women as control group were included. The genotyping was determined using multiplex PCR and PCR- RFLP methods.

RESULTS

The GSTM1 null genotype was significantly higher (p=0.027) in the cases (7.3%) than the control group (1.3%). There was no significant difference between the frequency of GSTT1 genotypes between the cases and controls. The GSTP1 313 AG genotype was significantly lower (p=0.048) in the case (33.1%) than the control group (44.4%).

CONCLUSION

Our results showed that GSTM1 and GSTP1 polymorphisms may be associated with susceptibility of endometriosis in Iranian women.

Oxidative Stress Genes, Antioxidants and Coronary Artery Disease in Type 2 Diabetes Mellitus

The worldwide increasing prevalence of obesity and sedentary lifestyle is the main cause of the rising incidence of T2DM. Due to chronic macrovascular and microvascular complications, T2DM represent a huge socioeconomic burden in the world. Oxidative stress is a key pathogenic mechanism implicated in diabetic coronary artery disease (CAD). Polymorphisms of oxidative stress genes are known to influence oxidative stress levels and are therefore thought to impact CAD pathogenesis. Identifying higher risk groups would be rational, since it would allow better sample selection and thus better results in antioxidant trials. In this review, we summarize the evidence of oxidative stress gene polymorphisms related to the pathogenesis of CAD. Moreover, we provide a review of antioxidants tested in subjects with CAD.

Hexavalent chromium induces apoptosis in male somatic and spermatogonial stem cells via redox imbalance

Hexavalent chromium [Cr(VI)], an environmental toxicant, causes severe male reproductive abnormalities. However, the actual mechanisms of toxicity are not clearly understood and have not been studied in detail. The present in vitro study aimed to investigate the mechanism of reproductive toxicity of Cr(VI) in male somatic cells (mouse TM3 Leydig cells and TM4 Sertoli cells) and spermatogonial stem cells (SSCs) because damage to or dysfunction of these cells can directly affect spermatogenesis, resulting in male infertility. Cr(VI) by inducing oxidative stress was cytotoxic to both male somatic cells and SSCs in a dose-dependent manner, and induced mitochondria-dependent apoptosis. Although the mechanism of Cr(VI)-induced cytotoxicity was similar in both somatic cells, the differences in sensitivity of TM3 and TM4 cells to Cr(VI) could be attributed, at least in part, to cell-specific regulation of P-AKT1, P-ERK1/2, and P-P53 proteins. Cr(VI) affected the differentiation and self-renewal mechanisms of SSCs, disrupted steroidogenesis in TM3 cells, while in TM4 cells, the expression of tight junction signaling and cell receptor molecules was affected as well as the secretory functions were impaired. In conclusion, our results show that Cr(VI) is cytotoxic and impairs the physiological functions of male somatic cells and SSCs.

Is there association between Glutathione S Transferases polymorphisms and cataract risk: a meta-analysis?

Background

Glutathione S transferase (GST) polymorphisms have been considered as risk factors for age-related cataracts, but the results remain controversial. In this study, we have performed a meta-analysis to evaluate the association between polymorphisms of GSTM1 and GSTT1 and cataract risk.

Methods

Published literature from PubMed and other databases were retrieved. The case–control studies regarding the association between GSTM1 or GSTT1 polymorphism and cataract risk were included. Pooled odds ratio (OR) and 95 % confidence interval (CI) were calculated using random- or fixed-effects model.

Results

Fifteen studies on GSTM1 (3,065 patients and 2,105 controls), and nine studies on GSTT1 (2,374 patients and 1,544 controls) were included. By pooling all the studies, GSTM1 null polymorphism was not associated with cataract risk, and this negative association maintained in subgroup analyses. However, GSTT1 null polymorphism was significantly associated with increased risk of posterior subcapsular (OR, 1.42; 95 % CI, 1.04–1.94) but not other subtypes of cataract. Stratified analyses demonstrated an association of GSTT1 null genotype with increased risk of cataract in Asian (OR, 1.44; 95 % CI, 1.14–1.83) but not Caucasian populations. In addition, seven pooled studies showed no association of cataract risk with the combined GSTM1 and GSTT1 null genotypes.

Conclusions

This meta-analysis suggests that GSTT1 null polymorphism is associated with increased risk of posterior subcapsular cataract. Given the limited sample size, the association between GSTT1 null polymorphism and cataract risk in Asian awaits further investigation.

Gene transcription patterns and energy reserves in Daphnia magna show no nanoparticle specific toxicity when exposed to ZnO and CuO nanoparticles

There is still a lot of contradiction on whether metal ions are solely responsible for the observed toxicity of ZnO and CuO nanoparticles to aquatic species. While most experiments have studied nanoparticle effects at organismal levels (e.g. mortality, reproduction), effects at lower levels of biological organization may clarify the role of metal ions, nanoparticles and nanoparticle aggregates. In this study, the effect of ZnO and CuO nanoparticles was tested at two lower levels: energy reserves and gene transcription and compared with zinc and copper salts. Daphnia magna was exposed during 96h to 10% immobilization concentrations of all chemicals, after which daphnids were sampled for determination of glycogen, lipid and protein concentration and for a differential gene transcription analysis using microarray. The dissolved, nanoparticle and aggregated fraction in the medium was characterized. The results showed that ZnO nanoparticles had largely dissolved directly after addition to the test medium. The CuO nanoparticles mostly formed aggregates, while only a small fraction dissolved. The exposure to zinc (both nano and metal salt) had no effect on the available energy reserves. However, in the copper exposure, the glycogen, lipid and protein concentration in the exposed daphnids was lower than in the unexposed ones. When comparing the nanoparticle (ZnO or CuO) exposed daphnids to the metal salt (zinc or copper salt) exposed daphnids, the microarray results showed no significantly differentially transcribed gene fragments. The results indicate that under the current exposure conditions the toxicity of ZnO and CuO nanoparticles to D. magna is solely caused by toxic metal ions.