Nickel ions inhibit histone demethylase JMJD1A and DNA repair enzyme ABH2 by replacing the ferrous iron in the catalytic centers

Profiling Metal-Induced Genotoxic Endpoints

Many toxic metals are involved in the initiation and progression of DNA damage that can result in the activation of DNA damage response machinery at double- and single-stranded DNA; this response can result in global and gene-specific DNA alteration. The toxicological profiles from the Agency for Toxic Substances and Disease Registry (ATSDR) and several other studies have demonstrated the influence of metal exposure-induced genotoxic endpoints and epigenetic modifications. Our review systematically summarizes accumulating evidence from ATSDR toxicological profiles and the available literature that demonstrate a possible induction of various genotoxic endpoints and metal exposures. We include in this article studies on chromium, arsenic, nickel, lead, mercury, and zinc.

Air pollution and pregnancy

Increased fossil fuel usage and extreme climate change events have led to global increases in greenhouse gases and particulate matter with 99% of the world's population now breathing polluted air that exceeds the World Health Organization's recommended limits. Pregnant women and neonates with exposure to high levels of air pollutants are at increased risk of adverse health outcomes such as maternal hypertensive disorders, postpartum depression, placental abruption, low birth weight, preterm birth, infant mortality, and adverse lung and respiratory effects. While the exact mechanism by which air pollution exerts adverse health effects is unknown, oxidative stress as well as epigenetic and immune mechanisms are thought to play roles. Comprehensive, global efforts are urgently required to tackle the health challenges posed by air pollution through policies and action for reducing air pollution as well as finding ways to protect the health of vulnerable populations in the face of increasing air pollution.

Advances in bioleaching of waste lithium batteries under metal ion stress

In modern societies, the accumulation of vast amounts of waste Li-ion batteries (WLIBs) is a grave concern. Bioleaching has great potential for the economic recovery of valuable metals from various electronic wastes. It has been successfully applied in mining on commercial scales. Bioleaching of WLIBs can not only recover valuable metals but also prevent environmental pollution. Many acidophilic microorganisms (APM) have been used in bioleaching of natural ores and urban mines. However, the activities of the growth and metabolism of APM are seriously inhibited by the high concentrations of heavy metal ions released by the bio-solubilization process, which slows down bioleaching over time. Only when the response mechanism of APM to harsh conditions is well understood, effective strategies to address this critical operational hurdle can be obtained. In this review, a multi-scale approach is used to summarize studies on the characteristics of bioleaching processes under metal ion stress. The response mechanisms of bacteria, including the mRNA expression levels of intracellular genes related to heavy metal ion resistance, are also reviewed. Alleviation of metal ion stress via addition of chemicals, such as spermine and glutathione is discussed. Monitoring using electrochemical characteristics of APM biofilms under metal ion stress is explored. In conclusion, effective engineering strategies can be proposed based on a deep understanding of the response mechanisms of APM to metal ion stress, which have been used to improve bioleaching efficiency effectively in lab tests. It is very important to engineer new bioleaching strains with high resistance to metal ions using gene editing and synthetic biotechnology in the near future.

Nickel-induced alterations to chromatin structure and function

Nickel (Ni), a heavy metal is prevalent in the atmosphere due to both natural and anthropogenic activities. Ni is a carcinogen implicated in the development of lung and nasal cancers in humans. Furthermore, Ni exposure is associated with a number of chronic lung diseases in humans including asthma, chronic bronchitis, emphysema, pulmonary fibrosis, pulmonary edema and chronic obstructive pulmonary disease (COPD). While Ni compounds are weak mutagens, a number of studies have demonstrated the potential of Ni to alter the epigenome, suggesting epigenomic dysregulation as an important underlying cause for its pathogenicity. In the eukaryotic nucleus, the DNA is organized in a three-dimensional (3D) space through assembly of higher order chromatin structures. Such an organization is critically important for transcription and other biological activities. Accumulating evidence suggests that by negatively affecting various cellular regulatory processes, Ni could potentially affect chromatin organization. In this review, we discuss the role of Ni in altering the chromatin architecture, which potentially plays a major role in Ni pathogenicity.

Epigenetic Regulation in Chromium-, Nickel- and Cadmium-Induced Carcinogenesis

Environmental and occupational exposure to heavy metals, such as hexavalent chromium, nickel, and cadmium, are major health concerns worldwide. Some heavy metals are well-documented human carcinogens. Multiple mechanisms, including DNA damage, dysregulated gene expression, and aberrant cancer-related signaling, have been shown to contribute to metal-induced carcinogenesis. However, the molecular mechanisms accounting for heavy metal-induced carcinogenesis and angiogenesis are still not fully understood. In recent years, an increasing number of studies have indicated that in addition to genotoxicity and genetic mutations, epigenetic mechanisms play critical roles in metal-induced cancers. Epigenetics refers to the reversible modification of genomes without changing DNA sequences; epigenetic modifications generally involve DNA methylation, histone modification, chromatin remodeling, and non-coding RNAs. Epigenetic regulation is essential for maintaining normal gene expression patterns; the disruption of epigenetic modifications may lead to altered cellular function and even malignant transformation. Therefore, aberrant epigenetic modifications are widely involved in metal-induced cancer formation, development, and angiogenesis. Notably, the role of epigenetic mechanisms in heavy metal-induced carcinogenesis and angiogenesis remains largely unknown, and further studies are urgently required. In this review, we highlight the current advances in understanding the roles of epigenetic mechanisms in heavy metal-induced carcinogenesis, cancer progression, and angiogenesis.

Conformational Dynamics of Human ALKBH2 Dioxygenase in the Course of DNA Repair as Revealed by Stopped-Flow Fluorescence Spectroscopy

Elucidation of physicochemical mechanisms of enzymatic processes is one of the main tasks of modern biology. High efficiency and selectivity of enzymatic catalysis are mostly ensured by conformational dynamics of enzymes and substrates. Here, we applied a stopped-flow kinetic analysis based on fluorescent spectroscopy to investigate mechanisms of conformational transformations during the removal of alkylated bases from DNA by ALKBH2, a human homolog of Escherichia coli AlkB dioxygenase. This enzyme protects genomic DNA against various alkyl lesions through a sophisticated catalytic mechanism supported by a cofactor (Fe(II)), a cosubstrate (2-oxoglutarate), and O₂. We present here a comparative study of conformational dynamics in complexes of the ALKBH2 protein with double-stranded DNA substrates containing N1-methyladenine, N3-methylcytosine, or 1,N6-ethenoadenine. By means of fluorescent labels of different types, simultaneous detection of conformational transitions in the protein globule and DNA substrate molecule was performed. Fitting of the kinetic curves by a nonlinear-regression method yielded a molecular mechanism and rate constants of its individual steps. The results shed light on overall conformational dynamics of ALKBH2 and damaged DNA during the catalytic cycle.

Ameliorative or corrective effects of Fig "Ficus carica" extract on nickel-induced hepatotoxicity in Wistar rats

Many heavy metals and metalloids (e.g., Pb, Cd, and Ni) can contaminate the environment and cause severe health problems. Through this study, investigated the possible corrective effects of Ficus carica extract (FCE) against nickel (Ni) induced stress response and damage on the liver of rats. Male Wistar rats were divided into four groups (8 rats per group) and co-treated with FCE (350 mg/kg) and exposed to Nickel chloride (10 mg/kg) for 4 weeks. The volatile compounds of FCE were characterized by solid phase micro-extraction (SPME) coupled with GC-MS, and the biochemical parameters of stress were determined. The SPME-GC/MS analysis of FCE indicated the presence of thirty (30) phyto-bioactive compounds including alcohols, aldehydes, organic acids, ketones, furans, terpenes, ester and others. The best capacity for scavenging DPPH free radicals and metal chelating were found with the IC50 values of 0.49 and 2.91 mg/mL, respectively. Ni induced damage to various macromolecules. Malondialdehyde, protein carbonyls, alanine aminotransferase and gamma glutamyl transferarse levels were significantly increased in Ni exposed group compared to control group and co-treatment with FCE reduced the levels of these parameters. In conclusion, current findings showed that Ni-induced oxidative damage and the administration of FCE can improve correct and restore the alteration in the rat liver.

Epigenetic mechanisms in metal carcinogenesis

Many metals exhibit genotoxic and/or carcinogenic effects. These toxic metals can be found ubiquitously - in drinking water, food, air, general use products, in everyday and occupational settings. Exposure to such carcinogenic metals can result in serious health disorders, including cancer. Arsenic, cadmium, chromium, nickel, and their compounds have already been recognized as carcinogens by the International Agency for Research on Cancer. This review summarizes a wide range of epigenetic mechanisms contributing to carcinogenesis induced by these metals, primarily including, but not limited to, DNA methylation, miRNA regulation, and histone posttranslational modifications. The mechanisms are described and discussed both from a metal-centric and a mechanism-centric standpoint. The review takes a broad perspective, putting the mechanisms in the context of real-life exposure, and aims to assist in guiding future research, particularly with respect to the assessment and control of exposure to carcinogenic metals and novel therapy development.

Profiling the Regulation of Histone Methylation and Demethylation by Metabolites and Metals

Here we describe how to profile the contribution of metabolism and implication of metals to histone methylation and demethylation. The techniques described with the adequate protocols are metabolomics, quantitative proteomics, inductively coupled mass spectrometry and nanoscale secondary ion mass spectrometry.

Epithelial-mesenchymal transition: Insights into nickel-induced lung diseases

Nickel compounds are environmental toxicants, prevalent in the atmosphere due to their widespread use in several industrial processes, extensive consumption of nickel containing products, as well as burning of fossil fuels. Exposure to nickel is associated with a multitude of chronic inflammatory lung diseases including asthma, chronic obstructive pulmonary disease (COPD) and pulmonary fibrosis. In addition, nickel exposure is implicated in the development of nasal and lung cancers. Interestingly, a common pathogenic mechanism underlying the development of diseases associated with nickel exposure is epithelial-mesenchymal transition (EMT). EMT is a process by which the epithelial cells lose their junctions and polarity and acquire mesenchymal traits, including increased ability to migrate and invade. EMT is a normal and essential physiological process involved in differentiation, development and wound healing. However, EMT also contributes to a number of pathological conditions, including fibrosis, cancer and metastasis. Growing evidence suggest that EMT induction could be an important outcome of nickel exposure. In this review, we discuss the role of EMT in nickel-induced lung diseases and the mechanisms associated with EMT induction by nickel exposure.

Immunological Mechanisms of Metal Allergies and the Nickel-Specific TCR-pMHC Interface

Besides having physiological functions and general toxic effects, many metal ions can cause allergic reactions in humans. We here review the immune events involved in the mediation of metal allergies. We focus on nickel (Ni), cobalt (Co) and palladium (Pd), because these allergens are among the most prevalent sensitizers (Ni, Co) and immediate neighbors in the periodic table of the chemical elements. Co-sensitization between Ni and the other two metals is frequent while the knowledge on a possible immunological cross-reactivity using in vivo and in vitro approaches remains limited. At the center of an allergic reaction lies the capability of a metal allergen to form T cell epitopes that are recognized by specific T cell receptors (TCR). Technological advances such as activation-induced marker assays and TCR high-throughput sequencing recently provided new insights into the interaction of Ni2+ with the αβ TCR-peptide-major histocompatibility complex (pMHC) interface. Ni2+ functionally binds to the TCR gene segment TRAV9-2 or a histidine in the complementarity determining region 3 (CDR3), the main antigen binding region. Thus, we overview known, newly identified and hypothesized mechanisms of metal-specific T cell activation and discuss current knowledge on cross-reactivity.

Integration of Epigenetic Mechanisms into Non-Genotoxic Carcinogenicity Hazard Assessment: Focus on DNA Methylation and Histone Modifications

Epigenetics involves a series of mechanisms that entail histone and DNA covalent modifications and non-coding RNAs, and that collectively contribute to programing cell functions and differentiation. Epigenetic anomalies and DNA mutations are co-drivers of cellular dysfunctions, including carcinogenesis. Alterations of the epigenetic system occur in cancers whether the initial carcinogenic events are from genotoxic (GTxC) or non-genotoxic (NGTxC) carcinogens. NGTxC are not inherently DNA reactive, they do not have a unifying mode of action and as yet there are no regulatory test guidelines addressing mechanisms of NGTxC. To fil this gap, the Test Guideline Programme of the Organisation for Economic Cooperation and Development is developing a framework for an integrated approach for the testing and assessment (IATA) of NGTxC and is considering assays that address key events of cancer hallmarks. Here, with the intent of better understanding the applicability of epigenetic assays in chemical carcinogenicity assessment, we focus on DNA methylation and histone modifications and review: (1) epigenetic mechanisms contributing to carcinogenesis, (2) epigenetic mechanisms altered following exposure to arsenic, nickel, or phenobarbital in order to identify common carcinogen-specific mechanisms, (3) characteristics of a series of epigenetic assay types, and (4) epigenetic assay validation needs in the context of chemical hazard assessment. As a key component of numerous NGTxC mechanisms of action, epigenetic assays included in IATA assay combinations can contribute to improved chemical carcinogen identification for the better protection of public health.

Nickel in terrestrial biota: Comprehensive review on contamination, toxicity, tolerance and its remediation approaches

Nickel (Ni) has been a subject of interest for environmental, physiological, biological scientists due to its dual effect (toxicity and essentiality) in terrestrial biota. In general, the safer limit of Ni is 1.5 μg g^-1 in plants and 75-150 μg g^-1 in soil. Litreature review indicates that Ni concentrations have been estimated up to 26 g kg^-1 in terrestrial, and 0.2 mg L^-1 in aquatic resources. In case of vegetables and fruits, mean Ni content has been reported in the range of 0.08-0.26 and 0.03-0.16 mg kg^-1. Considering, Ni toxicity and its potential health hazards, there is an urgent need to find out the suitable remedial approaches. Plant vascular (>80%) and cortical (<20%) tissues are the major sequestration site (cation exchange) of absorbed Ni. Deciphering molecular mechanisms in transgenic plants have immense potential for enhancing Ni phytoremediation and microbial remediation efficiency. Further, it has been suggested that integrated bioremediation approaches have a potential futuristic path for Ni decontamination in natural resources. This systematic review provides insight on Ni effects on terrestrial biota including human and further explores its transportation, bioaccumulation through food chain contamination, human health hazards, and possible Ni remediation approaches.

Insights into The Function and Regulation of Jumonji C Lysine Demethylases as Hypoxic Responsive Enzymes

Cellular responses to hypoxia (low oxygen) are governed by oxygen sensitive signaling pathways. Such pathways, in part, are controlled by enzymes with oxygen-dependent catalytic activity, of which the role of prolyl 4-hydroxylases has been widely reviewed. These enzymes inhibit hypoxic response by inducing the oxygen-dependent degradation of hypoxia-inducible factor 1α, the master regulator of the transcriptional hypoxic response. Jumonji C domain-containing lysine demethylases are similar enzymes which share the same oxygen-dependent catalytic mechanism as prolyl 4- hydroxylases. Traditionally, the role of lysine demethylases has been studied in relation to demethylation activity against histone substrates, however, within the past decade an increasing number of nonhistone protein targets have been revealed, some of which have a key role in survival in the hypoxic tumor microenvironment. Within this review, we highlight the involvement of methyllysine in the hypoxic response with a focus on the HIF signaling pathway, the regulation of demethylase activity by oxygen, and provide insights into notable areas of future hypoxic demethylase research.

Bridging the gap between toxicity and carcinogenicity of mineral fibres by connecting the fibre crystal-chemical and physical parameters to the key characteristics of cancer

Airborne fibres and particularly asbestos represent hazards of great concern for human health because exposure to these peculiar particulates may cause malignancies such as lung cancer and mesothelioma. Currently, many researchers worldwide are focussed on fully understanding the patho-biological mechanisms leading to carcinogenesis prompted by pathogenic fibres. Along this line, the present work introduces a novel approach to correlate how and to what extent the physical/crystal-chemical and morphological parameters (including length, chemistry, biodurability, and surface properties) of mineral fibres cause major adverse effects with an emphasis on asbestos. The model described below conceptually attempts to bridge the gap between toxicity and carcinogenicity of mineral fibres and has several implications: 1) it provides a tool to measure the toxicity and pathogenic potential of asbestos minerals, allowing a quantitative rank of the different types (e.g. chrysotile vs. crocidolite); 2) it can predict the toxicity and pathogenicity of "unregulated" or unclassified fibres; 3) it reveals the parameters of a mineral fibre that are active in stimulating key characteristics of cancer, thus offering a strategy for developing specific cancer prevention strategies and therapies. Chrysotile, crocidolite and fibrous glaucophane are described here as mineral fibres of interest.

Detoxification mechanisms of nickel sulfate in nematode Caenorhabditis elegans

Nickel is the most prevailing metal allergen with the highest sensitization rate among the "TOP 25" contact allergens and can affect about 15% of the human population. It is an essential trace metal in plants, animals, and humans. However, the environmental levels of nickel are considerably higher than what is needed for human life. Exposure to high levels of nickel can lead to skin allergies, lung fibrosis, and carcinogenesis. Few existing studies have closely examined the toxicity of nickel, let alone investigated the effective detoxification pathways. Here, we developed a high-throughput screening platform to comprehensively evaluate the nickel toxicity in wild-type C. elegans and explore the underlying detoxification mechanisms in transgenic nematodes. We demonstrated that nickel exerted multiple toxic effects on growth, brood size, feeding, and locomotion in C. elegans. Of which, brood size is the most sensitive endpoint. Nickel was found to first bind to phytochelatin (PC) after entering the worms' body and this PC-Ni complex was further transported by the ABC transporter, CeHMT-1, into the coelomocytes for further detoxification. Our study also demonstrated that the high-throughput screening platform is a promising system for evaluation and investigation of the ecological risks of heavy metals.

Environmental influence on neurodevelopmental disorders: Potential association of heavy metal exposure and autism

Environmental factors have been severally established to play major roles in the pathogenesis of neurodevelopmental disorders including autism spectrum disorder (ASD). ASD is a neurodevelopmental disorder that is associated with symptoms that reduce the quality of life of affected individuals such as social interaction deficit, cognitive impairment, intellectual disabilities, restricted and repetitive behavioural patterns. ASD pathogenesis has been associated with environmental and genetic factors that alter physiologic processes during development. Here, we review literatures highlighting the environmental impact on neurodevelopmental disorders, and mechanisms by which environmental toxins may influence neurodevelopment. Furthermore, this review discusses reports highlighting neurotoxic metals (specifically, lead, mercury, cadmium, nickel and manganese) as environmental risk factors in the aetiology of ASD. This work, thus suggests that improving the environment could be vital in the management of ASD.

Non-Heme Monooxygenase ThoJ Catalyzes Thioholgamide β-Hydroxylation

Thioviridamide-like compounds, including thioholgamides, are ribosomally synthesized and post-translationally modified peptide natural products with potent anticancer cell activity and an unprecedented structure. Very little is known about their biosynthesis, and we were intrigued by the β-hydroxy-N1, N3-dimethylhistidinium moiety found in these compounds. Here we report the construction of a heterologous host capable of producing thioholgamide with a 15-fold increased yield compared to the wild-type strain. A knockout of thoJ, encoding a predicted nonheme monooxygenase, shows that ThoJ is essential for thioholgamide β-hydroxylation. The crystal structure of ThoJ exhibits a typical mono/dioxygenase fold with conserved key active-site residues. Yet, ThoJ possesses a very large substrate binding pocket that appears suitable to receive a cyclic thioholgamide intermediate for hydroxylation. The improved production of the heterologous host will enable the dissection of the individual biosynthetic steps involved in biosynthesis of this exciting RiPP family.

Polyadenylation of Histone H3.1 mRNA Promotes Cell Transformation by Displacing H3.3 from Gene Regulatory Elements

Replication-dependent canonical histone messenger RNAs (mRNAs) do not terminate with a poly(A) tail at the 3' end. We previously demonstrated that exposure to arsenic, an environmental carcinogen, induces polyadenylation of canonical histone H3.1 mRNA, causing transformation of human cells in vitro. Here we report that polyadenylation of H3.1 mRNA increases H3.1 protein, resulting in displacement of histone variant H3.3 at active promoters, enhancers, and insulator regions, leading to transcriptional deregulation, G2/M cell-cycle arrest, chromosome aneuploidy, and aberrations. In support of these observations, knocking down the expression of H3.3 induced cell transformation, whereas ectopic expression of H3.3 attenuated arsenic-induced cell transformation. Notably, arsenic exposure also resulted in displacement of H3.3 from active promoters, enhancers, and insulator regions. These data suggest that H3.3 displacement might be central to carcinogenesis caused by polyadenylation of H3.1 mRNA upon arsenic exposure. Our findings illustrate the importance of proper histone stoichiometry in maintaining genome integrity.

Therapeutic potential of ALKB homologs for cardiovascular disease

Cardiovascular diseases (CVDs) are the leading causes of human death. Recently, ALKB homologs, including ALKBH1-8 and FTO, have been found to have a variety of biological functions, such as histone demethylation, RNA demethylation, and DNA demethylation. These functions may regulate the physiological and pathological processes of CVDs, including inflammation, oxidative stress, cell apoptosis, and mitochondrial, endothelial, and fat metabolism dysfunction. In the present review, we summarize the biological functions of ALKB homologs and the relationship between the ALKB homologs and CVDs. Importantly, we discuss the roles of ALKB homologs in the regulation of oxidative stress, inflammation, autophagy, and DNA damage in CVDs, as well as the practical applications of ALKB homologs inhibitors or agonists in treating CVDs. In conclusion, the ALKBH family might be a promising target for CVDs therapy.

Pathogenic Mechanisms and Therapeutic Implication in Nickel-Induced Cell Damage

Background:

Nickel (Ni) is mostly applied in a number of industrial areas such as printing inks, welding, alloys, electronics and electrical professions. Occupational or environmental exposure to nickel may lead to cancer, allergy reaction, nephrotoxicity, hepatotoxicity, neurotoxicity, as well as cell damage, apoptosis and oxidative stress.

Methods:

In here, we focused on published studies about cell death, carcinogenicity, allergy reactions and neurotoxicity, and promising agents for the prevention and treatment of the toxicity by Ni.

Results:

Our review showed that in the last few years, more researches have focused on reactive oxygen species formation, oxidative stress, DNA damages, apoptosis, interaction with involving receptors in allergy and mitochondrial damages in neuron induced by Ni.

Conclusion:

The collected data in this paper provide useful information about the main toxicities induced by Ni, also, their fundamental mechanisms, and how to discover new ameliorative agents for prevention and treatment by reviewing agents with protective and therapeutic consequences on Ni induced toxicity.

Metals and Mechanisms of Carcinogenesis

Metal exposure is pervasive and not limited to sporadic poisoning events or toxic waste sites. Hundreds of millions of people around the globe are affected by chronic metal exposure, which is associated with serious health concerns, including cancer, as demonstrated in a variety of studies at the molecular, systemic, and epidemiologic levels. Metal-induced toxicity and carcinogenicity are sophisticated and complex in nature. This review provides a broad context and holistic view of currently available studies on the mechanisms of metal-induced carcinogenesis. Specifically, we focus on the five most prevalent carcinogenic metals, arsenic, nickel, cadmium, chromium, and beryllium, and their potential to drive carcinogenesis in humans. A comprehensive understanding of the mechanisms behind the development of metal-induced cancer can provide valuable insights for therapeutic intervention involving molecular targets in metal-induced carcinogenesis.

Crucial Functions of the JMJD1/KDM3 Epigenetic Regulators in Cancer

Epigenetic changes are one underlying cause for cancer development and often due to dysregulation of enzymes modifying DNA or histones. Most Jumonji C domain-containing (JMJD) proteins are histone lysine demethylases (KDM) and therefore epigenetic regulators. One JMJD subfamily consists of JMJD1A/KDM3A, JMJD1B/KDM3B, and JMJD1C/KDM3C that are roughly 50% identical at the amino acid level. All three JMJD1 proteins are capable of removing dimethyl and monomethyl marks from lysine 9 on histone H3 and might also demethylate histone H4 on arginine 3 and nonhistone proteins. Analysis of knockout mice revealed critical roles for JMJD1 proteins in fertility, obesity, metabolic syndrome, and heart disease. Importantly, a plethora of studies demonstrated that especially JMJD1A and JMJD1C are overexpressed in various tumors, stimulate cancer cell proliferation and invasion, and facilitate efficient tumor growth. However, JMJD1A may also inhibit the formation of germ cell tumors. Likewise, JMJD1B appears to be a tumor suppressor in acute myeloid leukemia, but a tumor promoter in other cancers. Notably, by reducing methylation levels on histone H3 lysine 9, JMJD1 proteins can profoundly alter the transcriptome and thereby affect tumorigenesis, including through upregulating oncogenes such as CCND1, JUN, and MYC This epigenetic activity of JMJD1 proteins is sensitive to heavy metals, oncometabolites, oxygen, and reactive oxygen species, whose levels are frequently altered within cancer cells. In conclusion, inhibition of JMJD1 enzymatic activity through small molecules is predicted to be beneficial in many different cancers, but not in the few malignancies where JMJD1 proteins apparently exert tumor-suppressive functions.

Purification of Polyhistidine-Tagged Proteins by Immobilized Metal Affinity Chromatography

Immobilized metal affinity chromatography (IMAC) is based on the affinity of polyhistidine tracts for divalent metal cations (usually Ni²⁺) immobilized as transition metal chelate complexes on a chromatography resin. The main protocol here is optimized for use of Ni²⁺-NTA resin to purify soluble 6xHis-tagged proteins by a straightforward batch method during the binding step, followed by gravity flow for washes and elution. This protocol does not require any specialized equipment other than a simple glass or plastic column. IMAC resins can be used in multiple formats, including batch, gravity flow, centrifuge columns, and fast performance liquid chromatography (FPLC) systems. FPLC systems are designed specifically for the chromatographic separations of proteins and other biomolecules. These systems typically contain multiple pumps, an in-line UV absorption monitor, conductivity meter, pH meter, fraction collector, and other options that allow for the simultaneous purification, analysis, and fractionation of the sample. When linked with the appropriate instruments, an FPLC can become a high-precision, automated instrument that separates proteins at a high resolution. An alternative protocol is included here that describes 6xHis-tagged protein purification using FPLC. Procedures for the cleaning and regeneration of the IMAC resin for reuse are also described, and, finally, considerations for storing purified proteins are discussed.

Aspartate/asparagine-β-hydroxylase: a high-throughput mass spectrometric assay for discovery of small molecule inhibitors

The human 2-oxoglutarate dependent oxygenase aspartate/asparagine-β-hydroxylase (AspH) catalyses the hydroxylation of Asp/Asn-residues in epidermal growth factor-like domains (EGFDs). AspH is upregulated on the surface of malign cancer cells; increased AspH levels correlate with tumour invasiveness. Due to a lack of efficient assays to monitor the activity of isolated AspH, there are few reports of studies aimed at identifying small-molecule AspH inhibitors. Recently, it was reported that AspH substrates have a non-canonical EGFD disulfide pattern. Here we report that a stable synthetic thioether mimic of AspH substrates can be employed in solid phase extraction mass spectrometry based high-throughput AspH inhibition assays which are of excellent robustness, as indicated by high Z'-factors and good signal-to-noise/background ratios. The AspH inhibition assay was applied to screen approximately 1500 bioactive small-molecules, including natural products and active pharmaceutical ingredients of approved human therapeutics. Potent AspH inhibitors were identified from both compound classes. Our AspH inhibition assay should enable the development of potent and selective small-molecule AspH inhibitors and contribute towards the development of safer inhibitors for other 2OG oxygenases, e.g. screens of the hypoxia-inducible factor prolyl-hydroxylase inhibitors revealed that vadadustat inhibits AspH with moderate potency.

Nickel: Human Health and Environmental Toxicology

Nickel is a transition element extensively distributed in the environment, air, water, and soil. It may derive from natural sources and anthropogenic activity. Although nickel is ubiquitous in the environment, its functional role as a trace element for animals and human beings has not been yet recognized. Environmental pollution from nickel may be due to industry, the use of liquid and solid fuels, as well as municipal and industrial waste. Nickel contact can cause a variety of side effects on human health, such as allergy, cardiovascular and kidney diseases, lung fibrosis, lung and nasal cancer. Although the molecular mechanisms of nickel-induced toxicity are not yet clear, mitochondrial dysfunctions and oxidative stress are thought to have a primary and crucial role in the toxicity of this metal. Recently, researchers, trying to characterize the capability of nickel to induce cancer, have found out that epigenetic alterations induced by nickel exposure can perturb the genome. The purpose of this review is to describe the chemical features of nickel in human beings and the mechanisms of its toxicity. Furthermore, the attention is focused on strategies to remove nickel from the environment, such as phytoremediation and phytomining.

A Single-Turnover Kinetic Study of DNA Demethylation Catalyzed by Fe(II)/α-Ketoglutarate-Dependent Dioxygenase AlkB

AlkB is a Fe(II)/α-ketoglutarate-dependent dioxygenase that repairs some alkylated bases of DNA and RNA in Escherichia coli. In the course of catalysis, oxidation of a co-substrate (α-ketoglutarate, αKG) leads to the formation of a highly reactive ‘oxyferryl’ enzyme-bound intermediate, Fe(IV) = O, ensuring hydroxylation of the alkyl nucleobase adducts. Previous studies have revealed that AlkB is a flexible protein and can adopt different conformations during interactions with cofactors and DNA. To assess the conformational dynamics of the enzyme in complex with single- or double-stranded DNA in real-time mode, we employed the stopped-flow fluorescence method. N¹-Methyladenine (m¹A) introduced into a sequence of 15-mer oligonucleotides was chosen as the specific damage. Single-turnover kinetics were monitored by means of intrinsic fluorescence of the protein’s Trp residues, fluorescent base analogue 2-aminopurine (2aPu), and a dye–quencher pair (FAM/BHQ1). For all the fluorescent labels, the fluorescent traces showed several phases of consistent conformational changes, which were assigned to specific steps of the enzymatic process. These data offer an overall picture of the structural dynamics of AlkB and DNA during their interaction.

Nickel Carcinogenesis Mechanism: DNA Damage

Nickel (Ni) is known to be a major carcinogenic heavy metal. Occupational and environmental exposure to Ni has been implicated in human lung and nasal cancers. Currently, the molecular mechanisms of Ni carcinogenicity remain unclear, but studies have shown that Ni-caused DNA damage is an important carcinogenic mechanism. Therefore, we conducted a literature search of DNA damage associated with Ni exposure and summarized known Ni-caused DNA damage effects. In vitro and vivo studies demonstrated that Ni can induce DNA damage through direct DNA binding and reactive oxygen species (ROS) stimulation. Ni can also repress the DNA damage repair systems, including direct reversal, nucleotide repair (NER), base excision repair (BER), mismatch repair (MMR), homologous-recombination repair (HR), and nonhomologous end-joining (NHEJ) repair pathways. The repression of DNA repair is through direct enzyme inhibition and the downregulation of DNA repair molecule expression. Up to now, the exact mechanisms of DNA damage caused by Ni and Ni compounds remain unclear. Revealing the mechanisms of DNA damage from Ni exposure may contribute to the development of preventive strategies in Ni carcinogenicity.

Analysis of nickel distribution by synchrotron radiation X-ray fluorescence in nickel-induced early- and late-phase allergic contact dermatitis in Hartley guinea pigs

BACKGROUND

Nickel-induced allergic contact dermatitis (Ni-ACD) is a global health problem. More detailed knowledge on the skin uptake of haptens is required. This study aimed to investigate the penetration process and distribution of nickel in skin tissues with late phase and early phase of Ni-ACD to understand the mechanisms of metal allergy.

METHODS

Forty Hartley guinea pigs were divided into four groups according to the NiSO4 sensitizing concentration and the NiSO4 challenged concentration: the 5% NiSO4-group, 5% to 10% (sensitization-challenge; late phase group); 10% NiSO4-group, 10% to 10% (sensitization-challenge; early-phase group); and the positive and negative controls. Pathological biopsies were performed on each group. The depth profile of nickel element concentration in the skin of guinea pigs was detected by synchrotron radiation micro X-ray fluorescence spectroscopy (SR-μ-XRF) and micro X-ray absorption near-edge spectroscopy (μ-XANES).

RESULTS

In each section, the nickel element concentration in both the 5% NiSO4-group and 10% NiSO4-group was significantly higher than that in the negative control group. In the upper 300-μm section of skin for the early phase group, the nickel element concentration was significantly higher than that in the lower section of skin. In deeper sections (>200 μm) of skin, the concentration of nickel in the early phase group was approximately equal to that in the late phase group. The curve of the late phase group was flat, which means that the nickel element concentration was distributed uniformly by SR-μ-XRF. According to the XANES data for the 10% NiSO4 metal salt solution, structural changes occurred in the skin model sample, indicating that nickel was not present in the Ni aqueous ionic state but in the nickel-binding protein.

CONCLUSIONS

This study showed that the distribution of the nickel element concentration in ACD skin tissue was different between the early phase and late phase groups. The nickel element was not present in the Ni aqueous ionic state but bound with certain proteins to form a complex in the stratum corneum in ACD model tissue.

Concise Review of Nickel Human Health Toxicology and Ecotoxicology

Nickel (Ni) metal and Ni compounds are widely used in applications like stainless steel, alloys, and batteries. Nickel is a naturally occurring element in water, soil, air, and living organisms, and is essential to microorganisms and plants. Thus, human and environmental nickel exposures are ubiquitous. Production and use of nickel and its compounds can, however, result in additional exposures to humans and the environment. Notable human health toxicity effects identified from human and/or animal studies include respiratory cancer, non-cancer toxicity effects following inhalation, dermatitis, and reproductive effects. These effects have thresholds, with indirect genotoxic and epigenetic events underlying the threshold mode of action for nickel carcinogenicity. Differences in human toxicity potencies/potentials of different nickel chemical forms are correlated with the bioavailability of the Ni2+ ion at target sites. Likewise, Ni2+ has been demonstrated to be the toxic chemical species in the environment, and models have been developed that account for the influence of abiotic factors on the bioavailability and toxicity of Ni2+ in different habitats. Emerging issues regarding the toxicity of nickel nanoforms and metal mixtures are briefly discussed. This review is unique in its covering of both human and environmental nickel toxicity data.

The small members of the JMJD protein family: Enzymatic jewels or jinxes?

Jumonji C domain-containing (JMJD) proteins are mostly epigenetic regulators that demethylate histones. However, a hitherto neglected subfamily of JMJD proteins, evolutionarily distant and characterized by their relatively small molecular weight, exerts different functions by hydroxylating proteins and RNA. Recently, unsuspected proteolytic and tyrosine kinase activities were also ascribed to some of these small JMJD proteins, further increasing their enzymatic versatility. Here, we discuss the ten human small JMJD proteins (HIF1AN, HSPBAP1, JMJD4, JMJD5, JMJD6, JMJD7, JMJD8, RIOX1, RIOX2, TYW5) and their diverse physiological functions. In particular, we focus on the roles of these small JMJD proteins in cancer and other maladies and how they are modulated in diseased cells by an altered metabolic milieu, including hypoxia, reactive oxygen species and oncometabolites. Because small JMJD proteins are enzymes, they are amenable to inhibition by small molecules and may represent novel targets in the therapy of cancer and other diseases.

Anatomical and morphological changes of the juniper under the influence of heavy metals in condition of man-induced load

Reaction of the plant body in polluted conditions allows estimating the anthropogenic impact on the environment. The aim of this work is to study anatomical and morphological changes of juniper in terms of the polymetallic pollution of the environment and under the influence of heavy metals. The assessment of some heavy metals impact on juniper was conducted after the planting of seed samples in the soil and obtaining good germination. The juniper has been treated with heavy metal solutions in the lab for 4 months. To determine the anatomical structures of the leaves of the juniper, the samples were fixed by the Strasburger-Fleming method. Under the influence of urban air, negative anatomical and morphological changes of juniper were discovered, the significant increase in the thickness of the needles, the thickness of the conducting bundle and the thickness of the epidermis was noted, that, apparently, provides higher resistance to man-induced pollution. It is shown that the process of environmental restoration can be done due to self-purification by using adsorption properties of leaves of woody plants, for example juniper, that is able to absorb heavy metals (lead, cadmium, cobalt, chromium, nickel, zinc and copper) from urban air. It was first discovered that the effects of heavy metals (lead and nickel) as the nutrient medium leads to the significant changes of the leaves’ anatomical structure (the swelling of the phloem, some decondensation in the mesophyll). The research results allow recommending the juniper for phytoremediation, bioindication and landscape gardening of cities and settlements in different countries.

Anti-cancer activity of hierarchical ZSM-5 zeolites synthesized from rice-based waste materials

We report the organic template-free synthesis of hierarchical ZSM-5 zeolite using waste materials, by a simple hydrothermal method and their excellent anti-cancer activity against A549 human lung epithelial cell lines.

Nickel(ii) inhibits the oxidation of DNA 5-methylcytosine in mammalian somatic cells and embryonic stem cells

Nickel(ii) inhibits Tet-mediated oxidation of DNA 5-methylcytosine in mammalian cells.

Ni induces the CRR1-dependent regulon revealing overlap and distinction between hypoxia and Cu deficiency responses in Chlamydomonas reinhardtii

The selectivity of metal sensors for a single metal ion is critical for cellular metal homeostasis. A suite of metal-responsive regulators is required to maintain a prescribed balance of metal ions ensuring that each apo-protein binds the correct metal. However, there are cases when non-essential metals ions disrupt proper metal sensing. An analysis of the Ni-responsive transcriptome of the green alga Chlamydomonas reinhardtii reveals that Ni artificially turns on the CRR1-dependent Cu-response regulon. Since this regulon also responds to hypoxia, a combinatorial transcriptome analysis was leveraged to gain insight into the mechanisms by which Ni interferes with the homeostatic regulation of Cu and oxygen status. Based on parallels with the effect of Ni on the hypoxic response in animals, we propose that a possible link between Cu, oxygen and Ni sensing is an as yet uncharacterized prolyl hydroxylase that regulates a co-activator of CRR1. This analysis also identified transcriptional responses to the pharmacological activation of the Cu-deficiency regulon. Although the Ni-responsive CRR1 regulon is composed of 56 genes (defined as the primary response), 259 transcripts responded to Ni treatment only when a copy of the wild-type CRR1 gene was present. The genome-wide impact of CRR1 target genes on the transcriptome was also evident from the 210 transcripts that were at least 2-fold higher in the crr1 strain, where the abundance of many CRR1 targets was suppressed. Additionally, we identified 120 transcripts that responded to Ni independent of CRR1 function. The putative functions of the proteins encoded by these transcripts suggest that high Ni results in protein damage.

Molecular mechanisms of nickel induced neurotoxicity and chemoprevention

Nickel (Ni) is widely used in many industrial sectors such as alloy, welding, printing inks, electrical and electronics industries. Excessive environmental or occupational exposure to Ni may result in tumor, contact dermatitis, as well as damages to the nervous system. In recent years, more and more research has demonstrated that Ni induced nerve damages are related to mitochondrial dysfunction. In this paper, we try to characterize Ni induced neurotoxicity as well as the underlying mechanisms, and how to find new drugs for chemoprevention, by reviewing chemicals with neuroprotective effects on Ni induced neurotoxicity.

Copper Inhibits the AlkB Family DNA Repair Enzymes under Wilson's Disease Condition

Disturbed metabolism of copper ions can cause diseases such as Wilson's disease (WD). In this work, we investigated the inhibitory effect of Cu(II) ion in vitro on the AlkB family DNA repair enzymes, which are members of the Fe(II)/alpha-ketoglutarate-dependent dioxygenase and include human ALKBH2, ALKBH3, and E. coli AlkB proteins. None of the three proteins was significantly inhibited under normal cellular copper concentrations. However, under WD related condition, we observed that the activities of all three enzymes were strongly suppressed (from 95.2 to 100.0%). We also noted the repair efficiency under ds-DNA condition was less susceptible than ss-DNA to the inhibition.

Nickel induces transcriptional down-regulation of DNA repair pathways in tumorigenic and non-tumorigenic lung cells

The heavy metal nickel is a known carcinogen, and occupational exposure to nickel compounds has been implicated in human lung and nasal cancers. Unlike many other environmental carcinogens, however, nickel does not directly induce DNA mutagenesis, and the mechanism of nickel-related carcinogenesis remains incompletely understood. Cellular nickel exposure leads to signaling pathway activation, transcriptional changes and epigenetic remodeling, processes also impacted by hypoxia, which itself promotes tumor growth without causing direct DNA damage. One of the mechanisms by which hypoxia contributes to tumor growth is the generation of genomic instability via down-regulation of high-fidelity DNA repair pathways. Here, we find that nickel exposure similarly leads to down-regulation of DNA repair proteins involved in homology-dependent DNA double-strand break repair (HDR) and mismatch repair (MMR) in tumorigenic and non-tumorigenic human lung cells. Functionally, nickel induces a defect in HDR capacity, as determined by plasmid-based host cell reactivation assays, persistence of ionizing radiation-induced DNA double-strand breaks and cellular hypersensitivity to ionizing radiation. Mechanistically, we find that nickel, in contrast to the metalloid arsenic, acutely induces transcriptional repression of HDR and MMR genes as part of a global transcriptional pattern similar to that seen with hypoxia. Finally, we find that exposure to low-dose nickel reduces the activity of the MLH1 promoter, but only arsenic leads to long-term MLH1 promoter silencing. Together, our data elucidate novel mechanisms of heavy metal carcinogenesis and contribute to our understanding of the influence of the microenvironment on the regulation of DNA repair pathways.

Nickel(II) Inhibits Tet-Mediated 5-Methylcytosine Oxidation by High Affinity Displacement of the Cofactor Iron(II)

Ten-eleven translocation (Tet) family proteins are Fe(II)- and 2-oxoglutarate-dependent dioxygenases that regulate the dynamics of DNA methylation by catalyzing the oxidation of DNA 5-methylcytosine (5mC). To exert physiologically important functions, redox-active iron chelated in the catalytic center of Tet proteins directly involves the oxidation of the multiple substrates. To understand the function and interaction network of Tet dioxygenases, it is interesting to obtain high affinity and a specific inhibitor. Surprisingly, here we found that natural Ni(II) ion can bind to the Fe(II)-chelating motif (HXD) with an affinity of 7.5-fold as high as Fe(II). Consistently, we further found that Ni(II) ion can displace the cofactor Fe(II) of Tet dioxygenases and inhibit Tet-mediated 5mC oxidation activity with an estimated IC₅₀ of 1.2 μM. Essentially, Ni(II) can be used as a high affinity and selective inhibitor to explore the function and dynamics of Tet proteins.

Epigenetics: The third pillar of nitric oxide signaling

Nitric oxide (NO), the endogenously produced free radical signaling molecule, is generally thought to function via its interactions with heme-containing proteins, such as soluble guanylyl cyclase (sGC), or by the formation of protein adducts containing nitrogen oxide functional groups (such as S-nitrosothiols, 3-nitrotyrosine, and dinitrosyliron complexes). These two types of interactions result in a multitude of down-stream effects that regulate numerous functions in physiology and disease. Of the numerous purported NO signaling mechanisms, epigenetic regulation has gained considerable interest in recent years. There is now abundant experimental evidence to establish NO as an endogenous epigenetic regulator of gene expression and cell phenotype. Nitric oxide has been shown to influence key aspects of epigenetic regulation that include histone posttranslational modifications, DNA methylation, and microRNA levels. Studies across disease states have observed NO-mediated regulation of epigenetic protein expression and enzymatic activity resulting in remodeling of the epigenetic landscape to ultimately influence gene expression. In addition to the well-established pathways of NO signaling, epigenetic mechanisms may provide much-needed explanations for poorly understood context-specific effects of NO. These findings provide more insight into the molecular mechanisms of NO signaling and increase our ability to dissect its functional role(s) in specific micro-environments in health and disease. This review will summarize the current state of NO signaling via epigenetic mechanisms (the "third pillar" of NO signaling).

Ni exposure impacts the pool of free Fe and modifies DNA supercoiling via metal-induced oxidative stress in Escherichia coli K-12

The biology of nickel has been widely studied in mammals because of its carcinogenic properties, whereas few studies have been performed in microorganisms. In the present work, changes accompanying stress caused by nickel were evaluated at the cellular level using RNA-Seq in Escherichia coli K-12. Interestingly, a very large number of genes were found to be deregulated by Ni stress. Iron and oxidative stress homeostasis maintenance were among the most highly enriched functional categories, and genes involved in periplasmic copper efflux were among the most highly upregulated. These results suggest that the deregulation of Fe and Cu homeostatic genes is caused by a release of free Cu and Fe ions in the cell which in turn activate the Cu and Fe homeostatic systems. The content of Cu was not significantly affected upon the addition of Ni to the growth medium, nor were the Cus and CopA Cu-efflux systems important for the survival of bacteria under Ni stress In contrast the addition of Ni slightly decreased the amount of cellular Fe and activated the transcription of Fur regulated genes in a Fur-dependent manner. Cu or Fe imbalance together with oxidative stress might affect the structure of DNA. Further experiments revealed that Ni alters the state of DNA folding by causing a relaxed conformation, a phenomenon that is reversible by addition of the antioxidant Tiron or the Fe chelator Dip. The Tiron-reversible DNA relaxation was also observed for Fe and to a lesser extent with Cu but not with Co. DNA supercoiling is well recognized as an integral aspect of gene regulation. Moreover our results show that Ni modifies the expression of several nucleoid-associated proteins (NAPs), important agents of DNA topology and global gene regulation. This is the first report describing the impact of metal-induced oxidative on global regulatory networks.

Nickel Release, ROS Generation and Toxicity of Ni and NiO Micro- and Nanoparticles

Occupational exposure to airborne nickel is associated with an elevated risk for respiratory tract diseases including lung cancer. Therefore, the increased production of Ni-containing nanoparticles necessitates a thorough assessment of their physical, chemical, as well as toxicological properties. The aim of this study was to investigate and compare the characteristics of nickel metal (Ni) and nickel oxide (NiO) particles with a focus on Ni release, reactive oxygen species (ROS) generation, cellular uptake, cytotoxicity and genotoxicity. Four Ni-containing particles of both nano-size (Ni-n and NiO-n) and micron-size (Ni-m1 and Ni-m2) were tested. The released amount of Ni in solution was notably higher in artificial lysosomal fluid (e.g. 80–100 wt% for metallic Ni) than in cell medium after 24h (ca. 1–3 wt% for all particles). Each of the particles was taken up by the cells within 4 h and they remained in the cells to a high extent after 24 h post-incubation. Thus, the high dissolution in ALF appeared not to reflect the particle dissolution in the cells. Ni-m1 showed the most pronounced effect on cell viability after 48 h (alamar blue assay) whereas all particles showed increased cytotoxicity in the highest doses (20–40 μg cm²) when assessed by colony forming efficiency (CFE). Interestingly an increased CFE, suggesting higher proliferation, was observed for all particles in low doses (0.1 or 1 μg cm^-2). Ni-m1 and NiO-n were the most potent in causing acellular ROS and DNA damage. However, no intracellular ROS was detected for any of the particles. Taken together, micron-sized Ni (Ni-m1) was more reactive and toxic compared to the nano-sized Ni. Furthermore, this study underlines that the low dose effect in terms of increased proliferation observed for all particles should be further investigated in future studies.

Specific histone modifications were associated with the PAH-induced DNA damage response in coke oven workers

To investigate whether polycyclic aromatic hydrocarbon (PAH) exposure is associated with specific histone modifications and whether DNA damage triggers epigenetic alterations, we recruited 190 male workers with occupational exposure to PAHs and 100 male control workers from Benxi Steel Plant, Liaoning province, China. Urinary 1-hydroxypyrene (1-OHP), DNA damage, specific histone modification levels and the expression of selected DNA damage response (DDR) genes were measured in peripheral blood lymphocytes (PBLCs) of the subjects. The results showed that trimethylated Lys 27 of histone H3 (H3K27me3) and trimethylated Lys 36 of histone H3 (H3K36me3) were elevated in the PAH-exposed group (both P < 0.001), while trimethylated Lys H3 of histone H3 (H3K4me3) was decreased compared to the unexposed group (P < 0.001). Notably, H3K36me3 was positively associated with the level of internal exposure marker 1-OHP (β = 0.197; P < 0.001) and the degree of DNA damage (β = 0.175; P < 0.001) in all subjects, indicating that the PAH-induced DNA damage response might be mediated by H3K36me3 and/or H3K4me3 modifications. Particularly, the ChIP-qPCR assay revealed that the modifications of H3K36me3 were enriched in the gene body of DDR genes, MGMT and MLH1. The up-regulation of MGMT and MLH1 was correlated with the elevated H3K36me3 in the PAH-exposed workers (P < 0.001). Collectively, we revealed that H3K36me3 could be an indicator of PAH exposure and might be involved in the transcriptional regulation of DNA repair genes in response to DNA damage.

Minireview: Epigenomic Plasticity and Vulnerability to EDC Exposures

The epigenome undergoes significant remodeling during tissue and organ development, which coincides with a period of exquisite sensitivity to environmental exposures. In the case of endocrine-disrupting compounds (EDCs), exposures can reprogram the epigenome of developing tissues to increase susceptibility to diseases later in life, a process termed "developmental reprogramming." Both DNA methylation and histone modifications have been shown to be vulnerable to disruption by EDC exposures, and several mechanisms have been identified by which EDCs can reprogram the epigenome. These include altered methyl donor availability, loss of imprinting control, changes in dioxygenase activity, altered expression of noncoding RNAs, and activation of cell signaling pathways that can phosphorylate, and alter the activity of, histone methyltransferases. This altered epigenomic programming can persist across the life course, and in some instances generations, to alter gene expression in ways that correlate with increased disease susceptibility. Together, these studies on developmental reprogramming of the epigenome by EDCs are providing new insights into epigenomic plasticity that is vulnerable to disruption by environmental exposures.