Glutathione S-transferase Family Research Articles

A novel biomarker for marine environmental pollution of pi-class glutathione S-transferase from Mytilus coruscus

Glutathione S-transferases (GSTs) are the superfamily of phase II detoxification enzymes that play crucial roles in innate immunity. In this study, a pi-class GST homolog was identified from Mytilus coruscus (named as McGST1, KC525103). The full-length cDNA sequence of McGST1 was 621bp with a 5ʹ untranslated region (UTR) of 70bp and a 3ʹ-UTR of 201bp. The deduced amino acid sequence was 206 residues in length with theoretical pI/MW of 5.60/23.72kDa, containing the conserved G-site and diversiform H-site. BLASTn analysis and phylogenetic relationship strongly suggested that this cDNA sequence was a member of pi class GST family. The prediction of secondary structure displayed a preserved N-terminal and a C-terminal comprised with α-helixes. Quantitative real time RT-PCR showed that constitutive expression of McGST1 was occurred, with increasing order in mantle, muscle, gill, hemocyte, gonad and hepatopancreas. The stimulation of bacterial infection, heavy metals and 180CST could up-regulate McGST1 mRNA expression in hepatopancreas with time-dependent manners. The maximum expression appeared at 6h after pathogenic bacteria injected, with 10-fold in Vibrio alginolyticus and 16-fold in Vibrio harveyi higher than that of the control. The highest point of McGST1 mRNA appeared at different time for exposure to copper (10-fold at day 15), cadmium (9-fold at day10) and 180 CST (10-fold at day 15). These results suggested that McGST1 played a significant role in antioxidation and might potentially be used as indicators and biomarkers for detection of marine environmental pollution.

Isolation and characterization of differentially expressed genes in petals of chrysanthemum mutant cultivars developed by irradiation

Chrysanthemum is one of the most popular ornamental plants, whose petal colors are primarily determined by pigments including flavonoids/anthocyanins and carotenoids. To develop chrysanthemum cultivars with various petal colors, mutation breeding targeting alteration of pigmentation pattern has been performed. A radiation-induced mutant line, ‘ARTI-purple’, showed a flower color altered from the original bright pink to purple. In this study, we used suppression subtractive hybridization to analyze transcripts and characterize the differential gene expression of chrysanthemum petals between the mutant ‘ARTI-purple’ and its wild-type Chrysanthemum×morifolium cultivar ‘Argus’. One hundred and seventy-six genes were identified (e-value≤1e−5) and classified based on sequence homology to genes with known or putative functions. The genes were categorized functionally by gene ontology analysis and their tentative pathways were confirmed using the TAIR database. The analyses revealed that these genes were related to carbohydrate metabolism, biosynthesis of secondary metabolites, and lipid metabolism. Six genes in a Kyoto encyclopedia of genes and genomes (KEGG) pathway which included the largest number of differentially expressed genes were selected for validation by quantitative PCR, and most of them showed higher expression levels compared with the wild-type. In addition, we isolated two novel clones (PC06E06 and PC08C09) having glutathione S-transferase (GST) family conserved domains and one clone (PC02G08) having a Multidrug and toxic compound extrusion (MATE) family conserved domain based on analysis using conserved domain database (CDD). The expressions of PC08C09 and PC02G08 were upregulated in ‘ARTI-purple’, which implies that anthocyanin accumulation pattern might be altered in mutant. In this study, we identified several differentially expressed genes between ‘Argus’ and ‘ARTI-purple’. The analysis suggested that several metabolic genes as well as glutathione S-transferases and MATEs might be involved in the control of flower pigmentation in chrysanthemum.

Identification of glutathione S-transferase (GST) genes from a dark septate endophytic fungus (Exophiala pisciphila) and their expression patterns under varied metals stress.

Glutathione S-transferases (GSTs) compose a family of multifunctional enzymes that play important roles in the detoxification of xenobiotics and the oxidative stress response. In the present study, twenty four GST genes from the transcriptome of a metal-tolerant dark septate endophyte (DSE), Exophiala pisciphila, were identified based on sequence homology, and their responses to various heavy metal exposures were also analyzed. Phylogenetic analysis showed that the 24 GST genes from E. pisciphila (EpGSTs) were divided into eight distinct classes, including seven cytosolic classes and one mitochondrial metaxin 1-like class. Moreover, the variable expression patterns of these EpGSTs were observed under different heavy metal stresses at their effective concentrations for inhibiting growth by 50% (EC50). Lead (Pb) exposure caused the up-regulation of all EpGSTs, while cadmium (Cd), copper (Cu) and zinc (Zn) treatments led to the significant up-regulation of most of the EpGSTs (p < 0.05 to p < 0.001). Furthermore, although heavy metal-specific differences in performance were observed under various heavy metals in Escherichia coli BL21 (DE3) transformed with EpGSTN-31, the over-expression of this gene was able to enhance the heavy metal tolerance of the host cells. These results indicate that E. Pisciphila harbored a diverse of GST genes and the up-regulated EpGSTs are closely related to the heavy metal tolerance of E. pisciphila. The study represents the first investigation of the GST family in E. pisciphila and provides a primary interpretation of heavy metal detoxification for E. pisciphila.

The silkworm glutathione S-transferase gene noppera-bo is required for ecdysteroid biosynthesis and larval development

Insect molting and metamorphosis are tightly controlled by ecdysteroids, which are important steroid hormones that are synthesized from dietary sterols in the prothoracic gland. One of the ecdysteroidogenic genes in the fruit fly Drosophila melanogaster is noppera-bo (nobo), also known as GSTe14, which encodes a member of the epsilon class of glutathione S-transferases. In D. melanogaster, nobo plays a crucial role in utilizing cholesterol via regulating its transport and/or metabolism in the prothoracic gland. However, it is still not known whether the orthologs of nobo from other insects are also involved in ecdysteroid biosynthesis via cholesterol transport and/or metabolism in the prothoracic gland. Here we report genetic evidence showing that the silkworm Bombyx mori ortholog of nobo (nobo-Bm; GSTe7) is essential for silkworm development. nobo-Bm is predominantly expressed in the prothoracic gland. To assess the functional importance of nobo-Bm, we generated a B. mori genetic mutant of nobo-Bm using TALEN-mediated genome editing. We show that loss of nobo-Bm function causes larval arrest and a glossy cuticle phenotype, which are rescued by the application of 20-hydroxyecdysone. Moreover, the prothoracic gland cells isolated from the nobo-Bm mutant exhibit an abnormal accumulation of 7-dehydrocholesterol, a cholesterol metabolite. These results suggest that the nobo family of glutathione S-transferases is essential for development and for the regulation of sterol utilization in the prothoracic gland in not only the Diptera but also the Lepidoptera. On the other hand, loss of nobo function mutants of D. melanogaster and B. mori abnormally accumulates different sterols, implying that the sterol utilization in the PG is somewhat different between these two insect species.

Oxidative Stress and Antioxidant Defense in Endometriosis and Its Malignant Transformation.

The aim of this study was to investigate the role of redox status in endometriosis and its malignant transformation. A search was conducted between 1990 and 2014 through the English language literature (online MEDLINE PubMed database) using the keywords endometriosis combined with malignant transformation, oxidative stress, and antioxidant defense. In benign endometriosis, autoxidation and Fenton reaction of hemoglobin from the ferrous Fe2+ (oxyhemoglobin) state to the ferric Fe3+ (methemoglobin) state lead to production of excess reactive oxygen species (ROS) such as O2 − and ∙OH. Hemoglobin, heme, and iron derivatives in endometriotic cysts cause distortion in the homeostatic redox balance. Excess oxidative stress could trigger DNA damage and cell death. In contrast, endometriosis-associated ovarian cancer (EAOC) might be associated with an effective antioxidant defense, including heme oxygenases, cytochrome P450 family, and glutathione transferase family. The pattern of redox balance supports that enhanced antioxidants may be involved in the pathogenesis of malignant transformation. In conclusion, oxidant/antioxidant balance function is a double-edged sword, promoting cell death or carcinogenesis. Upregulation of antioxidant functions in endometriotic cyst may result in restoration of cell survival and subsequent malignant transformation.

Glutathione S-transferase polymorphisms in varicocele patients: a meta-analysis

The glutathione S-transferase (GST) family represents a major group of detoxification and antioxidant enzymes. Studies have shown that high oxidative stress levels are associated with varicocele. The objective of this study was to assess the relationship between GSTM1 and GSTT1 null polymorphisms and varicocele using a study group of 497 varicocele patients and 476 control subjects. A systematic literature search (for articles published up to September 2014) utilizing Google Scholar and PubMed was conducted. The chi-square-based Q test and I(2) index were used to evaluate data from retrieved studies. The possible publication bias was evaluated by Begg funnel plot and the Egger test. No statistically significant association was found between GSTM1 or GSTT1 null genotypes and varicocele in the overall data analysis. In a subgroup analysis, only the null GSTM1 genotype was observed at a significantly higher frequency in Caucasian varicocele patients. In the Chinese subgroup, no association was established between the GSTM1 and GSTT1 null genotypes and this condition. More attention should be drawn to oxidative stress-related pathological manifestations for Caucasian varicocele patients.

Glutathione S transferase (GSTP 1, GSTM 1, and GSTT 1) gene polymorphisms in Egyptian patients with acute myeloid leukemia.

The super family of glutathione S-transferases (GSTs) is composed of multiple isoenzymes with significant evidence of functional polymorphic variation. GSTs detoxify potentially mutagenic and toxic DNA-reactive electrophiles, including metabolites of several chemotherapeutic agents, some of which are suspected human carcinogens. Polymorphisms within the phase II metabolizer enzymes GST T1, GST M1, and GST P1 affect the body's ability to detoxify a range of potential leukemogens encountered in the environment. To address how differences in the human GST isoenzyme expression patterns influence cancer susceptibility, prognosis, and treatment. A total of 50 patients with acute myeloid leukemia (AML), as well as 50 age and sex matched apparently healthy volunteers were genotyped for GSTP 1, GSTM 1, and GSTT 1 gene polymorphisms using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) and conventional polymerase chain reaction (PCR), respectively. For GSTP1 313 A → G (GSTP1 Ile105Val) polymorphism, It was found that the wild genotype (AA) was significantly higher among control subjects (P value = 0.0277), while the frequency of heteromutant genotype (AG) and mutant G allele (AG + GG) was significantly higher among patients (P value = 0.0402, P value = 0.0277, respectively). For GSTM1 and GSTT1gene, we found statistically significantly higher frequency among patients regarding homozygous gene deletion (P value = 0.0005). We demonstrated that GSTM1 null or GSTT1 null genotypes may be considered independent risk factors for AML with no impact on prognosis and GSTP1 * 105 genotype is a prognostic factor, adding independent information to the routine laboratory parameters and cytogenetic and molecular alterations of the tumor cells.

Molecular cloning, characterization and positively selected sites of the glutathione S-transferase family from Locusta migratoria.

Glutathione S-transferases (GSTs) are multifunctional enzymes that are involved in the metabolism of endogenous and exogenous compounds and are related to insecticide resistance. The purpose of this study was to provide new information on the molecular characteristics and the positive selection of locust GSTs. Based on the transcriptome database, we sequenced 28 cytosolic GSTs and 4 microsomal GSTs from the migratory locust (Locusta migratoria). We assigned the 28 cytosolic GSTs into 6 classes—sigma, epsilon, delta, theta, omega and zeta, and the 4 microsomal GSTs into 2 subclasses—insect and MGST3. The tissue- and stage-expression patterns of the GSTs differed at the mRNA level. Further, the substrate specificities and kinetic constants of the cytosolic GSTs differed markedly at the protein level. The results of likelihood ratio tests provided strong evidence for positive selection in the delta class. The result of Bayes Empirical Bayes analysis identified 4 amino acid sites in the delta class as positive selection sites. These sites were located on the protein surface. Our findings will facilitate the elucidation of the molecular characteristics and evolutionary aspects of insect GST superfamily.

A Halloween gene noppera-bo encodes a glutathione S-transferase essential for ecdysteroid biosynthesis via regulating the behaviour of cholesterol in Drosophila

In insects, the precise timing of moulting and metamorphosis is strictly guided by ecdysteroids that are synthesised from dietary cholesterol in the prothoracic gland (PG). In the past decade, several ecdysteroidogenic enzymes, some of which are encoded by the Halloween genes, have been identified and characterised. Here, we report a novel Halloween gene, noppera-bo (nobo), that encodes a member of the glutathione S-transferase family. nobo was identified as a gene that is predominantly expressed in the PG of the fruit fly Drosophila melanogaster. We generated a nobo knock-out mutant, which displayed embryonic lethality and a naked cuticle structure. These phenotypes are typical for Halloween mutants showing embryonic ecdysteroid deficiency. In addition, the PG-specific nobo knock-down larvae displayed an arrested phenotype and reduced 20-hydroxyecdysone (20E) titres. Importantly, both embryonic and larval phenotypes were rescued by the administration of 20E or cholesterol. We also confirm that PG cells in nobo loss-of-function larvae abnormally accumulate cholesterol. Considering that cholesterol is the most upstream material for ecdysteroid biosynthesis in the PG, our results raise the possibility that nobo plays a crucial role in regulating the behaviour of cholesterol in steroid biosynthesis in insects.

Glutathione-S-transferase: a minor allergen in birch pollen due to limited release from hydrated pollen.

BackgroundRecently, a protein homologous to glutathione-S-transferases (GST) was detected in prominent amounts in birch pollen by proteomic profiling. As members of the GST family are relevant allergens in mites, cockroach and fungi we investigated the allergenic relevance of GST from birch (bGST).MethodologybGST was expressed in Escherichia coli, purified and characterized by mass spectrometry. Sera from 217 birch pollen-allergic patients were tested for IgE-reactivity to bGST by ELISA. The mediator-releasing activity of bGST was analysed with IgE-loaded rat basophil leukaemia cells (RBL) expressing human FcεRI. BALB/c mice were immunized with bGST or Bet v 1. Antibody and T cell responses to either protein were assessed. IgE-cross-reactivity between bGST with GST from house dust mite, Der p 8, was studied with murine and human sera in ELISA. The release kinetics of bGST and Bet v 1 from birch pollen were assessed in water, simulated lung fluid, 0.9% NaCl and PBS. Eluted proteins were quantified by ELISA and analysed by immunoblotting.Principle findingsOnly 13% of 217 birch pollen-allergic patients showed IgE-reactivity to bGST. In RBL assays bGST induced mediator release. Immunization of mice with bGST induced specific IgE and a Th2-dominated cellular immune response comparably to immunization with Bet v 1. bGST did not cross-react with Der p 8. In contrast to Bet v 1, only low amounts of bGST were released from pollen grains upon incubation in water and the different physiological solutions.Conclusion/SignificanceAlthough bGST is abundant in birch pollen, immunogenic in mice and able to induce mediator release from effector cells passively loaded with specific IgE, it is a minor allergen for birch pollen-allergic patients. We refer this discrepancy to its limited release from hydrated pollen. Hence, bGST is an example demonstrating that allergenicity depends mainly on rapid elution from airborne particles.

Cytoprotective and regulatory functions of glutathione S-transferases in cancer cell proliferation and cell death.

Glutathione S-transferases (GSTs) family of enzymes is best known for their cytoprotective role and their involvement in the development of anticancer drug resistance. Recently, emergence of non-detoxifying properties of GSTs has provided them with significant biological importance. Addressing the complex interactions of GSTs with regulatory kinases will help in understanding its precise role in tumor pathophysiology and in designing GST-centered anticancer strategies. We reviewed all published literature addressing the detoxification and regulatory roles of GSTs in the altered biology of cancer and evaluating novel agents targeting GSTs for cancer therapy. The role of GSTs, especially glutathione S-transferase P1 isoform in tumoral drug resistance, has been the cause of intense debate. GSTs have been demonstrated to interact with different protein partners and modulate signaling pathways that control cell proliferation, differentiation and apoptosis. These specific functions of GSTs could lead to the development of new therapeutic approaches and to the identification of some interesting candidates for preclinical and clinical development. This review focuses on the crucial role played by GSTs in the development of resistance to anticancer agents and the major findings regarding the different modes of action of GSTs to regulate cell signaling.

Molecular cloning and expression of glutathione S-transferases involved in propargite resistance of the carmine spider mite, Tetranychus cinnabarinus (Boisduval)

The carmine spider mite (CSM) Tetranychus cinnabarinus has become a serious pest in China and has developed resistance to acaricide propargite as it is used to control mites worldwide including T. cinnabarinus. In this study, a resistant colony of T. cinnabarinus, PRR34 (37.78-fold resistant ratio), was established after 34 generations of propargite selection, and cross-resistance patterns of 7 other acaricides were determined in comparison with a susceptible strain (SS). The contribution of detoxification enzymes to propargite tolerance were investigated using biological, biochemical and molecular approaches. Enzyme inhibitor synergist tests suggested glutathione S-transferases (GST) involvement in propargite-resistance of PRR34, and GST activity against 1-chloro-2,4-dinitrobenzene (CDNB) was correlated with the development of resistance. Eight novel GST genes (TcGSTd1, TcGSTd2, TcGSTm1, TcGSTm2, TcGSTm3, TcGSTm4 and TcGSTm5) were cloned, and phylogenetic analysis showed that the eight GST genes were most closely related to GST family delta and mu from Tetranychusurticae. Quantitative RT-PCR revealed that the expression level of GSTs in PPR34 strain increased in larvae, nymphs and adults, while decreased in eggs compared with that of SS. Collectively, these results support a role of GSTs in mediating resistance to propargite in the PRR34 strain. TcGSTd1,TcGSTd2 and TcGSTm2 genes might play significant roles in propargite resistance of CSM, especially at adult stage. This is the first attempt to define specific genes involved in GST mediated propargite resistance of T. cinnabarinus at the transcriptional level.

Phylogenetic analysis of the GST family in Anopheles (Nyssorhynchus) darlingi

Anopheles darlingi Root, 1926 and Anopheles gambiae (Diptera: Culicidae) are the most important human malaria vectors in South America and Africa, respectively. The two species are estimated to have diverged 100 million years ago. Studies on the phylogenetics and evolution of gene sequences, such as glutathione S-transferase (GST) in disease-transmitting mosquitoes are scarce. The sigma class GST (KC890767) from the transcriptome of An. darlingi captured in the Brazilian Amazon was studied by in silico hybridization, and mapped to chromosome 3 of An. gambiae. The sigma class GST of An. darlingi was used for phylogenetic analyses to understand the GST base composition of the most recent common ancestor between An. darlingi, Anopheles gambiae, Aedes aegypti and Culex quinquefasciatus. The GST (KC890767) of An. darlingi was studied to generate the main divergence branches using a Neighbor-Joining and bootstrapping approaches to confirm confidence levels on the tree nodes that separate the An. darlingi and other mosquito species. The results showed divergence between An. gambiae, Ae. Aegypti, Cx. quinquefasciatus, and Phlebotomus papatasi as outgroup, and the homology relationship between sigma class GST of An. darlingi and GSTS1_1 gene of An. gambiae was valuable for phylogenetic and evolutionary studies.

Highlight: Delaying the Call of Death--Genome-Wide Study of Long-Lived Fruit Flies

Highlight: Delaying the Call of Death--Genome-Wide Study of Long-Lived Fruit Flies

Influence of GSTT1, GSTM1 and GSTP1 Polymorphisms on the Development of Breast Cancer

Introduction: Every year, more than 10 million women are diagnosed worldwide with breast cancer. Breast cancer remains the leading cause of death from malignancy in women. In Mexico about 12 Mexican women die every day from this disease. Glutathione S-transferase (GST) family consists of a group of isoenzymes involved in Phase II detoxification of xenobiotics by glutathione conjugation. There have been reports showing GST polymorphisms as a risk factor for developing cancer. Objective: Determine if the frequencies of polymorphisms of GSTT1, GSTM1 and GSTP1 are associated with breast cancer development. Materials and Methods: We studied 22 women with breast cancer and a control group of 30 women. DNA was extracted from blood. Polymorphisms of T1 and M1 were identified by multiplex PCR. The identification of GSTP1b (exon 5) and GSTP1c (exon 6), was performed separately by RFLP-PCR, using BsmAI and AciI enzymes respectively. Results: Frequencies of polymorphisms were as follows: for breast cancer group 33% null GSTT1 vs 40% null in the control, 32% null GSTM1 vs 63% of control; 63% heterozygote GSTP1b P1a/P1b and 18% homozygote P1b/P1b, vs 53% heterozygote and 20% homozygote in the control, 41% heterozygote P1a/P1c GSTP1c and 0% homozygote vs 10% heterozygote P1c/P1c and 0% homozygote control. Significant differences were found between GSTM1 and GSTP1c polymorphisms with GSTM1 null percentage higher in the control group and a higher frequency of P1c heterozygotes in the cancer group. Conclusion: As this is a pilot study where the results showed no association with breast cancer, further investigation is required on the involvement of GST genes in neoplasm development.

GSTT1, GSTM1, and GSTP1 polymorphisms as a prognostic factor in women with breast cancer

The glutathione S-transferase (GST) family comprises phase-II cellular detoxification enzymes that catalyze the conjugation of chemotherapy drugs to glutathione and act on the apoptotic pathway. The aim of this study was to determine whether polymorphisms of the GSTT1, GSTM1, and GSTP1 genes are associated with different rates of overall survival (OS) and disease-free survival (DFS) after neoadjuvant chemotherapy in the management of locally advanced breast cancer, using either simple or combined analyses, and in relation to the post-therapy axillary lymph node status. Forty women with invasive ductal carcinoma of the breast submitted to neoadjuvant chemotherapy with 5-fluorouracil, epirubicin, and cyclophosphamide were genotyped for GSTT1, GSTM1, and GSTP1. Comparisons were performed for the three genes, either isolated or in pairs, in polymorphic or wild-type combinations. Finally, the OS and DFS of patients were analyzed with respect to axillary lymph node status and with respect to wild-type or polymorphic presentations of each gene. No statistically significant difference in OS and DFS was evident between women with wild-type or polymorphic forms of the genes, either isolated or in pairs, after neoadjuvant chemotherapy. By contrast, after treatment, lymph node-negative women had better OS and DFS only in the presence of polymorphisms of GSTP1, and improved DFS only in the presence of the polymorphic types of GSTT1 and GSTM1 compared to women with positive lymph nodes. The presence of polymorphic forms of GSTP1, GSTM1, and GSTT1 was crucial to conferring better OS and DFS among women with negative axillary lymph nodes.

GST gene polymorphisms and the risk of colorectal cancer development.

Increasingly often, molecular studies of colorectal cancer focus on low penetrance genes. Among the factors potentially modifying the risk of contracting colorectal cancer is the glutathione S-transferase (GST) gene family, encoding enzymes of the glutathione transferase type. Proteins of the GST family (glutathione S-transferases) are enzymes detoxifying a wide range of hazardous substances, such as reactive oxygen species (ROS) or xenobionts. Thus, their role, among other things, is the protection of DNA against oxidative damage, which may lead to mutations, and in consequence, favour carcinogenesis. GST gene polymorphisms may affect the functioning of the encoded enzymes, exerting an effect on the level of DNA damage, and therefore may have an indirect influence on the risk of the development of cancer. At present, there are many studies available concerning GST gene polymorphisms as factors modulating the risk of developing cancer, including colorectal cancer.

Growth Hormone Alters the Glutathione S-Transferase and Mitochondrial Thioredoxin Systems in Long-Living Ames Dwarf Mice

Ames dwarf mice are deficient in growth hormone (GH), prolactin, and thyroid-stimulating hormone and live significantly longer than their wild-type (WT) siblings. The lack of GH is associated with stress resistance and increased longevity. However, the mechanism underlying GH's actions on cellular stress defense have yet to be elucidated. In this study, WT or Ames dwarf mice were treated with saline or GH (WT saline, Dwarf saline, and Dwarf GH) two times daily for 7 days. The body and liver weights of Ames dwarf mice were significantly increased after 7 days of GH administration. Mitochondrial protein levels of the glutathione S-transferase (GST) isozymes, K1 and M4 (GSTK1 and GSTM4), were significantly higher in dwarf mice (Dwarf saline) when compared with WT mice (WT saline). GH administration downregulated the expression of GSTK1 proteins in dwarf mice. We further investigated GST activity from liver lysates using different substrates. Substrate-specific GST activity (bromosulfophthalein, dichloronitrobenzene, and 4-hydrox-ynonenal) was significantly reduced in GH-treated dwarf mice. In addition, GH treatment attenuated the activity of thioredoxin and glutaredoxin in liver mitochondria of Ames mice. Importantly, GH treatment suppressed Trx2 and TrxR2 mRNA expression. These data indicate that GH has a role in stress resistance by altering the functional capacity of the GST system through the regulation of specific GST family members in long-living Ames dwarf mice. It also affects the regulation of thioredoxin and glutaredoxin, factors that regulate posttranslational modification of proteins and redox balance, thereby further influencing stress resistance.

Bisphenol A‐associated alterations in the expression and epigenetic regulation of genes encoding xenobiotic metabolizing enzymes in human fetal liver

Alterations in xenobiotic metabolizing enzyme (XME) expression across the life course, along with genetic, nutritional, and environmental regulation, can influence how organisms respond to toxic insults. In this study, we investigated the hypothesis that in utero exposure to the endocrine active compound, bisphenol A (BPA), influences expression and epigenetic regulation of phase I and II XME genes during development. Using healthy 1st to 2nd trimester human fetal liver specimens quantified for internal BPA levels, we examined XME gene expression using PCR Array (n = 8) and RNA-sequencing (n = 12) platforms. Of the greater than 160 XME genes assayed, 2 phase I and 12 phase II genes exhibited significantly reduced expression with higher BPA levels, including isoforms from the carboxylesterase, catechol O-methyltransferase, glutathione S-transferase, sulfotransferase, and UDP-glucuronosyltransferase families. When the promoters of these candidate genes were evaluated in silico, putative binding sites for the E-twenty-six (ETS) and activator protein1 (AP1) related transcription factor families were identified and unique to 97% of all candidate transcripts. Interestingly, many ETS binding sites contain cytosine-guanine dinucleotides (CpGs) within their consensus sequences. Thus, quantitative analysis of CpG methylation of three candidate genes was conducted across n = 50 samples. Higher BPA levels were associated with increased site-specific methylation at COMT (P < 0.005) and increased average methylation at SULT2A1 (P < 0.020) promoters. While toxicological studies have traditionally focused on high-dose effects and hormonal receptor mediated regulation, our findings suggest the importance of low-dose effects and nonclassical mechanisms of endocrine disruption during development.

Impact of the genes UGT1A1, GSTT1, GSTM1, GSTA1, GSTP1 and NAT2 on acute alcohol-toxic hepatitis

Abstract Alcohol metabolism causes cellular damage by changing the redox status of cells. In this study, we investigated the relationship between genetic markers in genes coding for enzymes involved in cellular redox stabilization and their potential role in the clinical outcome of acute alcohol-induced hepatitis. Study subjects comprised 60 patients with acute alcohol-induced hepatitis. The control group consisted of 122 healthy non-related individuals. Eight genetic markers of the genes UGT1A1, GSTA1, GSTP1, NAT2, GSTT1 and GSTM1 were genotyped. GSTT1 null genotype was identified as a risk allele for alcohol-toxic hepatitis progression (OR 2.146, P=0.013). It was also found to correlate negatively with the level of prothrombin (β= −11.05, P=0.037) and positively with hyaluronic acid (β=170.4, P=0.014). NAT2 gene alleles rs1799929 and rs1799930 showed opposing associations with the activity of the biochemical markers γ-glutamyltransferase and alkaline phosphatase; rs1799929 was negatively correlated with γ-glutamyltransferase (β=−261.3, P=0.018) and alkaline phosphatase (β= −270.5, P=0.032), whereas rs1799930 was positively correlated with Γ-glutamyltransferase (β=325.8, P=0.011) and alkaline phosphatase (β=374.8, P=0.011). Enzymes of the glutathione S-transferase family and NAT2 enzyme play an important role in the detoxification process in the liver and demonstrate an impact on the clinical outcome of acute alcohol-induced hepatitis.