Mechanisms for the control of gene activity during development

Analysis of oral cancer carcinogens in repeatedly heated cooking oils

Background

The consumption of fried food has assimilated itself as a part of food culture globally. Therefore, it is important to know the toxigenicity of cooking oils used when exposed to high temperatures. The incidence of oral cancer in recent years has been on the rise; ninety percent of the cancers present in the oral cavity are squamous cell carcinoma with multiple major contributing lifestyle factors such well as the presence of the human papilloma virus. Not all mechanisms of carcinogenesis are fully understood and are complex. Furthermore, most cooking oil manufacturers do not provide recommended cooking temperatures on their product labels. Instead, they typically advise storing oils away from direct sunlight and at room temperature, leaving consumers unaware of the safe usage lim-its during cooking.

Objective

This study was conducted to analyze repeated cooking oils available in Suva, Fiji for harmful levels of genotoxic carcinogens. Methodology: Six types of cooking oils (soya bean oil, olive oil, mustard oil, coconut oil, canola oil and sunflower oil) were analyzed for the presence of genotoxic carcinogens. The test group (T0-3) of oils were heated to 190 °C and tested for the presence of carcinogens using Gas chromatography Mass Spectroscopy after 1.5 h at recommended temperature (T0), reheated to 190 °C and tested after 1 h (T1), reheated to 190 °C and tested after 3 h (T2) and reheated to 190 °C and tested after 6 h (T3). The control group of oils were not heated and stored at recommended temperature before testing.

Results

The concentrations of Benzo[a]pyrene and Glycidol detected in the cooking oils tested were not significant, as they remained below 2 μg/kg. However, two measurable peaks in 3-monochloropropanediol (3-MCPD) were detected in olive oil (115.6 ng/ml) and Soya bean oil (117.2 ng/ml).

Conclusion

Elevated 3-MCPD levels were found in Soya bean and olive reheated cooking oils exceeding tolerable daily intake levels and indicating potential health risks. Future research should evaluate the carcinogenic potential of cooking oils in real-world settings, such as fast-food establishments. This could inform public health policies on safer oil usage practices and raise consumer awareness about the risks of consuming foods cooked with overheated or reused oils.

Gut microbiota and epigenetics in colorectal cancer: implications for carcinogenesis and therapeutic intervention

Colorectal cancer (CRC) is a leading cause of cancer-related deaths worldwide. The occurrence of CRC is associated with various genetic and epigenetic mutations in intestinal epithelial cells that transform them into adenocarcinomas. There is increasing evidence indicating the gut microbiota plays a crucial role in the regulation of host physiological processes. Alterations in gut microbiota composition are responsible for initiating carcinogenesis through diverse epigenetic modifications, including histone modifications, ncRNAs and DNA methylation. This work was designed to comprehensively review recent findings to provide insight into the associations between the gut microbiota and CRC at an epigenetic level. These scientific insights can be used in the future to develop effective strategies for early detection and treatment of CRC.

Association between Oral Cancer and Diet: An Update

Oral cancer, included within head and neck cancer, is the sixth most common malignant neoplasm in the world. The main etiological factors are tobacco and alcohol, although currently, diet is considered an important determinant for its development. Several dietary nutrients have specific mechanisms of action, contributing to both protection against cancer and increasing the risk for development, growth, and spread. Foods such as fruits, vegetables, curcumin, and green tea can reduce the risk of oral cancer, while the so-called pro-inflammatory diet, rich in red meat and fried foods, can enhance the risk of occurrence. Dietary factors with a protective effect show different mechanisms that complement and overlap with antioxidant, anti-inflammatory, anti-angiogenic, and anti-proliferative effects. The main limitation of in vivo studies is the complexity of isolating the effects related to each one of the nutrients and the relationship with other possible etiological mechanisms. On the contrary, in vitro studies allow determining the specific mechanisms of action of some of the dietary compounds. In conclusion, and despite research limitations, the beneficial effects of a diet rich in vegetables and fruits are attributed to different micronutrients that are also found in fish and animal products. These compounds show antioxidant, anti-inflammatory, anti-angiogenic, and anti-proliferative properties that have a preventive role in the development of oral and other types of cancer.

[Epigenetic effects of cannabis/tetrahydrocannabinol]

The almost pandemic spread of cannabis among adolescents and young adults, especially in France, justifies the attention given to the consequences, not only acute but also delayed, of this intoxication. In the latter case, epigenetic mechanisms occur. We will first recall various types of epigenetic modifications involving either chromatin histones, mainly methylations or acetylations, either DNA, by methylation of cytosines. Such modifications caused by the tetrahydrocannabinol/THC of cannabis can intervene: either at the level of gametes before procreation, or at different points of the life cycle. These epigenetic modifications are associated with an increase in vulnerability to drug addiction, involving dopamine D2 receptors in the nucleus accumbens, overexpression of enkephalin precursor synthesis, modifications of: CB1 receptors of endocannabinoids, glutamic acid receptors, GABA receptors, proteins involved in synaptic plasticity… These changes can also affect: immune system, cognitive activities, development of psychiatric diseases, related to disturbances of brain maturation. The knowledge that accumulates in this respect is the opposite of the ambient trivialization of this drug. They impose sending an alert to the public authorities and to the public, especially young people, warning on the risks associated with this drug use and abuse.

Polyphenols as Caloric-Restriction Mimetics and Autophagy Inducers in Aging Research

It has been thought that caloric restriction favors longevity and healthy aging where autophagy plays a vital role. However, autophagy decreases during aging and that can lead to the development of aging-associated diseases such as cancer, diabetes, neurodegeneration, etc. It was shown that autophagy can be induced by mechanical or chemical stress. In this regard, various pharmacological compounds were proposed, including natural polyphenols. Apart from the ability to induce autophagy, polyphenols, such as resveratrol, are capable of modulating the expression of pro- and anti-apoptotic factors, neutralizing free radical species, affecting mitochondrial functions, chelating redox-active transition metal ions, and preventing protein aggregation. Moreover, polyphenols have advantages compared to chemical inducers of autophagy due to their intrinsic natural bio-compatibility and safety. In this context, polyphenols can be considered as a potential therapeutic tool for healthy aging either as a part of a diet or as separate compounds (supplements). This review discusses the epigenetic aspect and the underlying molecular mechanism of polyphenols as an anti-aging remedy. In addition, the recent advances of studies on NAD-dependent deacetylase sirtuin-1 (SIRT1) regulation of autophagy, the role of senescence-associated secretory phenotype (SASP) in cells senescence and their regulation by polyphenols have been highlighted as well. Apart from that, the review also revised the latest information on how polyphenols can help to improve mitochondrial function and modulate apoptosis (programmed cell death).

Supplementing Genistein for Breeder Hens Alters the Fatty Acid Metabolism and Growth Performance of Offsprings by Epigenetic Modification

The experiment was designed to clarify the effect and molecular mechanism of maternal genistein (GEN) on the lipid metabolism and developmental growth of offspring chicks. Laying broiler breeder (LBB) hens were supplemented with 40 mg/kg genistein (GEN), while the control group was fed with the low-soybean meal diet. The offspring chicks were grouped according to the mother generation with 8 replicates each. Hepatic transcriptome data revealed 3915 differentially expressed genes (DEGs, P adjusted < 0.05, fold change > 1.5 or fold change < 0.67) between chicks in the two groups. Maternal GEN activated the GH-IGF1-PI3K/Akt signaling pathway, which promoted the developmental processes and cellular amino acid metabolic processes, as well as inhibited the apoptotic process. GEN treatment significantly increased the weight gain, breast muscle percentage, and liver index in chicks. PANTHER clustering analysis suggested that maternal GEN enhanced the antioxidant activity of chicks by the upregulation of gene (SOD3, MT1, and MT4) expression. Accordingly, the activities of T-AOC and T-SOD in the liver were increased after GEN treatment. The overrepresentation tests revealed that maternal GEN influenced the glycolysis, unsaturated fatty acid biosynthesis, acyl-coenzyme A metabolism, lipid transport, and cholesterol metabolism in the chick livers. Hepatic cholesterol and long-chain fatty acid were significantly decreased after GEN treatment. However, the level of arachidonic acid was higher in the livers of the GEN-treated group compared with the CON group. Moreover, GEN treatment enhanced fatty acid β-oxidation and upregulated PPARδ expression in the chick liver. ChIP-qPCR analysis indicated that maternal GEN might induce histone H3-K36 trimethylation in the promoter region of PPARδ gene (PPARD) through Iws1, methyltransferases. It also induced histone H4-K12 acetylation at the PPARD promoter through MYST2, which activated the PPAR signaling pathways in the chick livers. In summary, supplementing LBB hens with GEN can alter lipid metabolism in the offspring chicks through epigenetic modification and improve the antioxidative capability as well as growth performance.

The mechanisms of epigenetic inheritance: how diverse are they?

Although epigenetic inheritance (EI) is a rapidly growing field of modern biology, it still has no clear place in fundamental genetic concepts which are traditionally based on the hereditary role of DNA. Moreover, not all mechanisms of EI attract the same attention, with most studies focused on DNA methylation, histone modification, RNA interference and amyloid prionization, but relatively few considering other mechanisms such as stable inhibition of plastid translation. Herein, we discuss all known and some hypothetical mechanisms that can underlie the stable inheritance of phenotypically distinct hereditary factors that lack differences in DNA sequence. These mechanisms include (i) regulation of transcription by DNA methylation, histone modifications, and transcription factors, (ii) RNA splicing, (iii) RNA-mediated post-transcriptional silencing, (iv) organellar translation, (v) protein processing by truncation, (vi) post-translational chemical modifications, (vii) protein folding, and (viii) homologous and non-homologous protein interactions. The breadth of this list suggests that any or almost any regulatory mechanism that participates in gene expression or gene-product functioning, under certain circumstances, may produce EI. Although the modes of EI are highly variable, in many epigenetic systems, stable allelic variants can be distinguished. Irrespective of their nature, all such alleles have an underlying similarity: each is a bimodular hereditary unit, whose features depend on (i) a certain epigenetic mark (epigenetic determinant) in the DNA sequence or its product, and (ii) the DNA sequence itself (DNA determinant; if this is absent, the epigenetic allele fails to perpetuate). Thus, stable allelic epigenetic inheritance (SAEI) does not contradict the hereditary role of DNA, but involves additional molecular mechanisms with no or almost no limitations to their variety.

Epigenetic inheritance systems contribute to the evolution of a germline

Differentiation within multicellular organisms is controlled by epigenetic markers transmitted across cell division. The process of differentiation will modify these epigenetic markers so that information that one cell type possesses can be lost in the transition to another. Many of the systems that encode these markers also exist in unicellular organisms but do not control differentiation. Thus, during the evolution of multicellularity, epigenetic inheritance systems were probably exapted for their current use in differentiation. We show that the simultaneous use of an information carrier for differentiation and transmission across generations can lead to the evolution of cell types that do not directly contribute to the progeny of the organism and ergo a germ-soma distinction. This shows that an intrinsic instability during a transition from unicellularity to multicellularity may contribute to widespread evolution of a germline and its maintenance, a phenomenon also relevant to the evolution of eusociality. The difference in epigenetic information contents between different cell lines in a multicellular organism is also relevant for the full-success cloning of higher animals, as well as for the maintenance of single germlines over evolutionary timescales.This article is part of the themed issue 'The major synthetic evolutionary transitions'.

Molecular and Biochemical Methods Useful for the Epigenetic Characterization of Chromatin-Associated Proteins in Bivalve Molluscs

Bivalve molluscs constitute a ubiquitous taxonomic group playing key functions in virtually all ecosystems, and encompassing critical commercial relevance. Along with a sessile and filter-feeding lifestyle in most cases, these characteristics make bivalves model sentinel organisms routinely used for environmental monitoring studies in aquatic habitats. The study of epigenetic mechanisms linking environmental exposure and specific physiological responses (i.e., environmental epigenetics) stands out as a very innovative monitoring strategy, given the role of epigenetic modifications in acclimatization and adaptation. Furthermore, the heritable nature of many of those modifications constitutes a very promising avenue to explore the applicability of epigenetic conditioning and selection in management and restoration strategies. Chromatin provides a framework for the study of environmental epigenetic responses. Unfortunately, chromatin and epigenetic information are very limited in most non-traditional model organisms and even completely lacking in most environmentally and ecologically relevant organisms. The present work aims to provide a comprehensive and reproducible experimental workflow for the study of bivalve chromatin. First, a series of guidelines for the molecular isolation of genes encoding chromatin-associated proteins is provided, including information on primers suitable for conventional PCR, Rapid Amplification of cDNA Ends (RACE), genome walking and quantitative PCR (qPCR) experiments. This section is followed by the description of methods specifically developed for the analysis of histone and SNBP proteins in different bivalve tissues, including protein extraction, purification, separation and immunodetection. Lastly, information about available antibodies, their specificity and performance is also provided. The tools and protocols described here complement current epigenetic analyses (usually limited to DNA methylation) by incorporating the study of structural elements modulating chromatin dynamics.

Nuts and Dried Fruits: An Update of Their Beneficial Effects on Type 2 Diabetes

Nuts and dried fruit are essential foods in the Mediterranean diet. Their frequent consumption has been associated with the prevention and/or the management of such metabolic conditions as type 2 diabetes (T2D), metabolic syndrome and cardiovascular diseases. Several previous reviews of epidemiological studies and clinical trials have evaluated the associations of nuts and/or dried fruit with various metabolic disorders. However, no reviews have focused on the mechanisms underlying the role of nuts and/or dried fruit in insulin resistance and T2D. This review aims to report nut and dried-fruit nutritional interventions in animals and humans, and to focus on mechanisms that could play a significant role in the prevention and treatment of insulin resistance and T2D.

Recent developments in epigenetics of pediatric asthma

PURPOSE OF REVIEW

The goal of this review was to systematically analyze recent studies updating our knowledge on the role of epigenetic mechanisms in childhood asthma.

RECENT FINDINGS

A systematic literature search was conducted that identified 23 fresh articles published within the last 5 years reporting the results of human studies on the relationships between epigenetic modifications and childhood asthma or its/related phenotypes. In almost all these studies, meaningful associations between levels of epigenetic marks (DNA methylation and/or histone modifications) and pediatric asthma or its/related phenotypes have been observed. In addition, many studies identified by our screening analyzed those associations in the context of environmental factors, such as pollution, tobacco smoke, farming, or diet, showing in a huge majority a modifying effect of those exposures.

SUMMARY

The results of our systematic literature search provide a strong support for the role of epigenetic mechanisms in (mediating the effects of environmental exposure on) pediatric asthma. This knowledge may possibly be translated into diagnostic and/or therapeutic approaches.

Environmental epigenetics: A promising venue for developing next-generation pollution biomonitoring tools in marine invertebrates

Environmental epigenetics investigates the cause-effect relationships between specific environmental factors and the subsequent epigenetic modifications triggering adaptive responses in the cell. Given the dynamic and potentially reversible nature of the different types of epigenetic marks, environmental epigenetics constitutes a promising venue for developing fast and sensible biomonitoring programs. Indeed, several epigenetic biomarkers have been successfully developed and applied in traditional model organisms (e.g., human and mouse). Nevertheless, the lack of epigenetic knowledge in other ecologically and environmentally relevant organisms has hampered the application of these tools in a broader range of ecosystems, most notably in the marine environment. Fortunately, that scenario is now changing thanks to the growing availability of complete reference genome sequences along with the development of high-throughput DNA sequencing and bioinformatic methods. Altogether, these resources make the epigenetic study of marine organisms (and more specifically marine invertebrates) a reality. By building on this knowledge, the present work provides a timely perspective highlighting the extraordinary potential of environmental epigenetic analyses as a promising source of rapid and sensible tools for pollution biomonitoring, using marine invertebrates as sentinel organisms. This strategy represents an innovative, groundbreaking approach, improving the conservation and management of natural resources in the oceans.

Small molecule control of chromatin remodeling

Control of cellular transcriptional programs is based on reversible changes in chromatin conformation that affect access of the transcriptional machinery to specific gene promoters. Chromatin conformation is in turn controlled by the concerted effects of reversible, covalent modification of the DNA and histone components of chromatin, along with topographical changes in DNA-histone interactions; all of these chromatin-modifying reactions are catalyzed by specific enzymes and are communicated to the transcriptional machinery by proteins that recognize and bind to unique, covalent modifications at specific chromatin sites (so-called reader proteins). Over the past decade, considerable progress has been made in the discovery of potent and selective small molecule modulators of specific chromatin-modifying proteins. Here we review the progress that has been made toward small molecule control of these mechanisms and the potential clinical applications of such small molecule modulators of chromatin remodeling.

Interplay between transcriptional control and chromatin regulation in the oligodendrocyte lineage

The recent years have been characterized by a surge of studies on the role of transcription factors and histone modifications in regulating the progression of progenitors into oligodendrocytes. This review summarizes this body of evidence and presents an integrated view of transcriptional networks and epigenetic regulators defining proliferating progenitors and their differentiation along the oligodendrocyte lineage. We suggest that transcription factors in proliferating progenitors have direct access to DNA, due to predominantly euchromatic nuclei. As progenitors differentiate, however, transcriptional competence is modulated by the formation of heterochromatin, which modifies the association of DNA with nucleosomal histones and renders the access of transcription factors dependent on the activity of epigenetic modulators. These concepts are delineated within the context of development, and the potential functional implications are discussed.

Diet, the gut microbiome, and epigenetics

Increasingly, the gut microbiome is implicated in the etiology of cancer, not only as an infectious agent but also by altering exposure to dietary compounds that influence disease risk. Whereas the composition and metabolism of the gut microbiome is influenced by diet, the gut microbiome can also modify dietary exposures in ways that are beneficial or detrimental to the human host. The colonic bacteria metabolize macronutrients, either as specialists or in consortia of bacteria, in a variety of diverse metabolic pathways. Microbial metabolites of diet can also be epigenetic activators of gene expression that may influence cancer risk in humans. Epigenetics involves heritable changes in gene expression via post-translational and post-transcriptional modifications. Microbial metabolites can influence epigenetics by altering the pool of compounds used for modification or by directly inhibiting enzymes involved in epigenetic pathways. Colonic epithelium is immediately exposed to these metabolites, although some metabolites are also found in systemic circulation. In this review, we discuss the role of the gut microbiome in dietary metabolism and how microbial metabolites may influence gene expression linked to colon cancer risk.

Epigenetics: general characteristics and implications for oral health

Genetic information such as DNA sequences has been limited to fully explain mechanisms of gene regulation and disease process. Epigenetic mechanisms, which include DNA methylation, histone modification and non-coding RNAs, can regulate gene expression and affect progression of disease. Although studies focused on epigenetics are being actively investigated in the field of medicine and biology, epigenetics in dental research is at the early stages. However, studies on epigenetics in dentistry deserve attention because epigenetic mechanisms play important roles in gene expression during tooth development and may affect oral diseases. In addition, understanding of epigenetic alteration is important for developing new therapeutic methods. This review article aims to outline the general features of epigenetic mechanisms and describe its future implications in the field of dentistry.

Epigenome-wide DNA methylation in hearing ability: new mechanisms for an old problem

Epigenetic regulation of gene expression has been shown to change over time and may be associated with environmental exposures in common complex traits. Age-related hearing impairment is a complex disorder, known to be heritable, with heritability estimates of 57–70%. Epigenetic regulation might explain the observed difference in age of onset and magnitude of hearing impairment with age. Epigenetic epidemiology studies using unrelated samples can be limited in their ability to detect small effects, and recent epigenetic findings in twins underscore the power of this well matched study design. We investigated the association between venous blood DNA methylation epigenome-wide and hearing ability. Pure-tone audiometry (PTA) and Illumina HumanMethylation array data were obtained from female twin volunteers enrolled in the TwinsUK register. Two study groups were explored: first, an epigenome-wide association scan (EWAS) was performed in a discovery sample (n = 115 subjects, age range: 47–83 years, Illumina 27 k array), then replication of the top ten associated probes from the discovery EWAS was attempted in a second unrelated sample (n = 203, age range: 41–86 years, Illumina 450 k array). Finally, a set of monozygotic (MZ) twin pairs (n = 21 pairs) within the discovery sample (Illumina 27 k array) was investigated in more detail in an MZ discordance analysis. Hearing ability was strongly associated with DNA methylation levels in the promoter regions of several genes, including TCF25 (cg01161216, p = 6.6×10⁻⁶), FGFR1 (cg15791248, p = 5.7×10⁻⁵) and POLE (cg18877514, p = 6.3×10⁻⁵). Replication of these results in a second sample confirmed the presence of differential methylation at TCF25 (p(replication) = 6×10⁻⁵) and POLE (p(replication) = 0.016). In the MZ discordance analysis, twins' intrapair difference in hearing ability correlated with DNA methylation differences at ACP6 (cg01377755, r = −0.75, p = 1.2×10⁻⁴) and MEF2D (cg08156349, r = −0.75, p = 1.4×10⁻⁴). Examination of gene expression in skin, suggests an influence of differential methylation on expression, which may account for the variation in hearing ability with age.

Epigenetics and memigenetics

The field of epigenetics is expanding rapidly, yet there is persistent uncertainty in the definition of the term. The word was coined in the mid-twentieth century as a descriptor of how intrinsic, yet largely unknown, forces act with genes to channel progenitor cells along pathways of differentiation. Near the end of the twentieth century, epigenetics was defined more specifically as the study of changes in gene activity states. In some definitions, only those activity states that are inherited across cell division were considered. Other definitions were broader, also including activity states that are transient, or occurring in non-dividing cells. The greatest point of disagreement in these current definitions, is if the term should concern only inherited activity states. To alleviate this disparity, an alternative term, 'memigenetics', could be used in place of epigenetics to describe inherited chromatin activity states. The advantage of this term is that it is self-defining, and would serve to emphasize the important concept of cell memory. It would also free the term epigenetics to be used in a broader sense in accord with the meaning of the prefix 'epi', that is, as a descriptor of what is 'over' DNA at any point in time.

Mapping human epigenomes

As the second dimension to the genome, the epigenome contains key information specific to every type of cells. Thousands of human epigenome maps have been produced in recent years thanks to rapid development of high throughput epigenome mapping technologies. In this review, we discuss the current epigenome mapping toolkit and utilities of epigenome maps. We focus particularly on mapping of DNA methylation, chromatin modification state, and chromatin structures, and emphasize the use of epigenome maps to delineate human gene regulatory sequences and developmental programs. We also provide a perspective on the progress of the epigenomics field and challenges ahead.

Pharmacogenomics of opioids and perioperative pain management

Inadequate pain relief and adverse effects from analgesics remain common in children and adults during the perioperative period. Opioids are the most commonly used analgesics in children and adults to treat perioperative pain. Narrow therapeutic index and a large interpatient variability in response to opioids are clinically significant, with inadequate pain relief at one end of the spectrum and serious side effects, such as respiratory depression and excessive sedation due to relative overdosing, at the other end. Personalizing analgesia during the perioperative period attempts to maximize pain relief while minimizing adverse events from therapy. While various factors influence response to treatment among surgical patients, age, sex, race and pharmacogenetic differences appear to play major roles in predicting outcome. Genetic factors include a subset of genes that modulate the proteins involved in pain perception, pain pathway, analgesic metabolism (pharmacokinetics), transport and receptor signaling (pharmacodynamics). While results from adult genetic studies can provide direction for pediatric studies, they have limited direct applicability, as children's genetic predispositions to analgesic response may be influenced by developmental and behavioral components, altered sensitivity to analgesics and variation in gene-expression patterns. We have reviewed the available evidence on improving and personalizing pain management with opioids and the significance of individualizing analgesia, in order to maximize analgesic effect with minimal adverse effects with opioids. While the early evidence on individual genotype associations with pain, analgesia and opioid adverse outcome are promising, the large amount of conflicting data in the literature suggests that there is a need for larger and more robust studies with appropriate population stratification and consideration of nongenetic and other genetic risk factors. Although the clinical evidence and the prospect of being able to provide point-of-care genotyping to enable clinicians to deliver personalized analgesia for individual patients is still not available, positioning our research to identify all possible major genetic and nongenetic risk factors of an individual patient, advancing less expensive point-of-care genotyping technology and developing easy-to-use personalized clinical decision algorithms will help us to improve current clinical and economic outcomes associated with pain and opioid pain management.

Epigenetic cancer prevention mechanisms in skin cancer

Epigenetics is an important emerging area for study of mechanisms of cancer prevention. In recent years, it has been realized that cancer prevention agents, derived from natural dietary sources, impact cancer cell survival by modulating epigenetic processes. In the present manuscript, we review key epigenetic regulatory mechanisms and examine the impact of sulforaphane and green tea polyphenols on these processes. We also discuss available information on the epigenetics in the context of skin cancer. These studies indicate that diet-derived chemopreventive agents modulate DNA methylation status and histone modification via multiple processes and point to additional areas for study of epigenetic mechanisms in skin cancer.

Critical developmental periods in the pathogenesis of hypertension

Hypertension is one of the major risk factor of cardiovascular diseases, but after a century of clinical and basic research, the discrete etiology of this disease is still not fully understood. One reason is that blood pressure is a quantitative trait with multifactorial determination. Numerous genes, environmental factors as well as epigenetic factors should be considered. There is no doubt that although the full manifestation of hypertension and other cardiovascular diseases usually occurs predominantly in adulthood and/or senescence, the roots can be traced back to early ontogeny. The detailed knowledge of the ontogenetic changes occurring in the cardiovascular system of experimental animals during particular critical periods (developmental windows) could help to solve this problem in humans and might facilitate the age-specific prevention of human hypertension. We thus believe that this approach might contribute to the reduction of cardiovascular morbidity among susceptible individuals in the future.

Influence of age on wound healing and fibrosis

The incidence and severity of fibrotic lung diseases increase with age, but very little is known about how age-related changes affect the mechanisms that underlie disease emergence and progression. Normal ageing includes accumulation of DNA mutations, oxidative and cell stresses, mitochondria dysfunction, increased susceptibility to apoptosis, telomere length dysfunction and differential gene expression as a consequence of epigenetic changes and miR regulation. These inevitable ageing-related phenomena may cause dysfunction and impaired repair capacity of lung epithelial cells, fibroblasts and MSCs. As a consequence, the composition of the extracellular matrix changes and the dynamic interaction between cells and their environment is damaged, resulting ultimately in predisposition for several diseases. This review summarizes what is known about age-related molecular changes that are implicated in the pathobiology of lung fibrosis in lung tissue.

The evolution of information storage and heredity

Many important transitions in evolution are associated with novel ways of storing and transmitting information. The storage of information in DNA sequence, and its transmission through DNA replication, is a fundamental hereditary system in all extant organisms, but it is not the only way of storing and transmitting information, and has itself replaced, and evolved from, other systems. A system that transmits information can have limited heredity or indefinite heredity. With limited heredity, the number of different possible types is commensurate with, or below, that of the individuals. With indefinite heredity, the number of possible types greatly exceeds the number of individuals in any realistic system. Recent findings suggest that the emergence and subsequent evolution of very different hereditary systems, from autocatalytic chemical cycles to natural language, accompanied the major evolutionary transitions in the history of life.

Epigenetic histone acetylation and deacetylation mechanisms in experimental models of neurodegenerative disorders

INTRODUCTION

Epigenetic modifications, such as histone acetylation and deacetylation, are responsible for maintaining chromatin stability. As such, they have been implicated in a wide range of neurodegenerative disorders.

METHODS

Histone acetylation involves the presentation of an acetyl group to lysine residues at the N terminus of histone proteins. Conversely, histone deacetylation involves the detachment of acetyl groups. Transcriptionally active chromatin is linked to acetylated histones, and in mouse neurons, is implicated in proper learning and memory.

DISCUSSION

Proper functioning of histone deacetylases (HDACs) plays a pivotal role in histone acetylation homeostasis.

RESULTS

A wide range of brain disorders are associated with improper balances within histone acetylation mechanisms, resulting in transcriptional dysfunction and translational disparities. Treatment modalities with various HDAC inhibitors have emerged as potential new strategies for therapeutic intervention in neurodegenerative disease. HDAC inhibitors enhance synaptic plasticity, learning and memory in neurodegenerative disorders, such as Alzheimer's disease (AD), Huntington's disease (HD) and Parkinson's disease (PD). In this review, we discuss a variety of in vitro cellular models and in vivo mouse models of neurodegenerative diseases and the potential application of HDAC inhibitors to prevent and treat these disorders.

Epigenetic diet: impact on the epigenome and cancer

A number of bioactive dietary components are of particular interest in the field of epigenetics. Many of these compounds display anticancer properties and may play a role in cancer prevention. Numerous studies suggest that a number of nutritional compounds have epigenetic targets in cancer cells. Importantly, emerging evidence strongly suggests that consumption of dietary agents can alter normal epigenetic states as well as reverse abnormal gene activation or silencing. Epigenetic modifications induced by bioactive dietary compounds are thought to be beneficial. Substantial evidence is mounting proclaiming that commonly consumed bioactive dietary factors act to modify the epigenome and may be incorporated into an 'epigenetic diet'. Bioactive nutritional components of an epigenetic diet may be incorporated into one's regular dietary regimen and used therapeutically for medicinal or chemopreventive purposes. This article will primarily focus on dietary factors that have been demonstrated to influence the epigenome and that may be used in conjunction with other cancer prevention and chemotherapeutic therapies.

Local and global epigenetic regulation of V(D)J recombination

Despite using the same Rag recombinase machinery expressed in both lymphocyte lineages, V(D)J recombination of immunoglobulins only occurs in B cells and T cell receptor recombination is confined to T cells. This vital segregation of recombination targets is governed by the coordinated efforts of several epigenetic mechanisms that control both the general chromatin accessibility of these loci to the Rag recombinase, and the movement and synapsis of distal gene segments in these enormous multigene AgR loci, in a lineage and developmental stage-specific manner. These mechanisms operate both locally at individual gene segments and AgR domains, and globally over large distances in the nucleus. Here we will discuss the roles of several epigenetic components that regulate V(D)J recombination of the immunoglobulin heavy chain locus in B cells, both in the context of the locus itself, and of its 3D nuclear organization, focusing in particular on non-coding RNA transcription. We will also speculate about how several newly described epigenetic mechanisms might impact on AgR regulation.

Epigenetic choreographers of neurogenesis in the adult mammalian brain

Epigenetic mechanisms regulate cell differentiation during embryonic development and also serve as important interfaces between genes and the environment in adulthood. Neurogenesis in adults, which generates functional neural cell types from adult neural stem cells, is dynamically regulated by both intrinsic state-specific cell differentiation cues and extrinsic neural niche signals. Epigenetic regulation by DNA and histone modifiers, non-coding RNAs and other self-sustained mechanisms can lead to relatively long-lasting biological effects and maintain functional neurogenesis throughout life in discrete regions of the mammalian brain. Here, we review recent evidence that epigenetic mechanisms carry out diverse roles in regulating specific aspects of adult neurogenesis and highlight the implications of such epigenetic regulation for neural plasticity and disorders.

The epigenetic role of non-coding RNA transcription and nuclear organization in immunoglobulin repertoire generation

Within the lymphocyte lineages, restriction of immunoglobulin V(D)J recombination to B cells and T cell receptor (TCR) recombination to T cells is governed by a myriad of epigenetic mechanisms that control the chromatin accessibility of these loci to the Rag recombinase machinery in a lineage and developmental stage-specific manner. These mechanisms operate both locally at individual gene segments, and globally over large chromatin domains in these enormous multigene loci. In this review we will explore the established and emerging roles of three aspects of epigenetic regulation that contribute to large-scale control of the immunoglobulin heavy chain locus in B cells: non-coding RNA transcription, regulatory elements, and nuclear organization. Recent conceptual and technological advances have produced a paradigm shift in our thinking about how these components regulate gene expression in general and V(D)J recombination in particular.

Epigenetic targets of bioactive dietary components for cancer prevention and therapy

The emergent interest in cancer epigenetics stems from the fact that epigenetic modifications are implicated in virtually every step of tumorigenesis. More interestingly, epigenetic changes are reversible heritable changes that are not due to the alteration in DNA sequence but have potential to alter gene expression. Dietary agents consist of many bioactive ingredients which actively regulate various molecular targets involved in tumorigenesis. We present evidence that numerous bioactive dietary components can interfere with various epigenetic targets in cancer prevention and therapy. These agents include curcumin (turmeric), genistein (soybean), tea polyphenols (green tea), resveratrol (grapes), and sulforaphane (cruciferous vegetables). These bioactive components alter the DNA methylation and histone modifications required for gene activation or silencing in cancer prevention and therapy. Bioactive components mediate epigenetic modifications associated with the induction of tumor suppressor genes such as p21^WAF1/CIP1 and inhibition of tumor promoting genes such as the human telomerase reverse transcriptase during tumorigenesis processes. Here, we present considerable evidence that bioactive components and their epigenetic targets are associated with cancer prevention and therapy which should facilitate novel drug discovery and development. In addition, remarkable advances in our understanding of basic epigenetic mechanisms as well as the rapid progress that is being made in developing powerful new technologies, such as those for sensitive and quantitative detection of epigenetic and epigenomic changes in cancer biology, hold great promise for novel epigenetic approaches to cancer prevention and therapy.

Epigenetic transgenerational actions of environmental factors in disease etiology

The ability of environmental factors to promote a phenotype or disease state not only in the individual exposed but also in subsequent progeny for successive generations is termed transgenerational inheritance. The majority of environmental factors such as nutrition or toxicants such as endocrine disruptors do not promote genetic mutations or alterations in DNA sequence. However, these factors do have the capacity to alter the epigenome. Epimutations in the germline that become permanently programmed can allow transmission of epigenetic transgenerational phenotypes. This review provides an overview of the epigenetics and biology of how environmental factors can promote transgenerational phenotypes and disease.

Epigenetics and biomarkers in the staging of neuropsychiatric disorders

Epigenetics, or alterations in the phenotype or gene expression due to mechanisms other than changes in the underlying DNA sequence, reflects the sensitivity and responsiveness of human and animal brains in constantly varying circumstances regulating gene expression profiles that define the biomarkers and present the ultimate phenotypical outcomes, such as cognition and emotion. Epigenetics is associated with functionally relevant alterations to the genome in such a fashion that under the particular conditions of early, adolescent, and adult life, environmental signals may activate intracellular pathways that remodel the "epigenome," triggering changes in gene expression and neural function. Thus, genetic influences in neuropsychiatric disorders that are subject to clinical staging, epigenetics in schizophrenia, epigenetic considerations in the expression of sensorimotor gating resulting from disease conditions, biomarkers of drug use and addiction, current notions on the role of dopamine in schizophrenia spectrum disorders, and the discrete interactions of biomarkers in persistent memory were to greater or lesser extents reflected upon. The relative contributions of endophenotypes and epistasis for mediating epigenetic phenomena and the outcomes as observed in the analysis of biomarkers appear to offer a multitude of interactive combinations to further complicate the labyrinthine machinations of diagnosis, intervention, and prognosis.

Epigenetics: origins and implications for cancer epidemiology

This paper provides information on the evolution of the 'epigenetics' concept since Aristotle and draws attention to the importance of epigenetic implications for cancer epidemiology in the years to come. Clearly, to understand origins of the concept of epigenetics, it is worthwhile to consider historical arguments associated with evolution. Equally clearly, in the last half of the 20th century, great advances in the understanding of epigenetics and, more specifically, great advances in the understanding of epigenetics in cancer have been made. However, reaping the full benefits of epigenetics lies beyond the predominant experimental studies of today. In general, epigenetics opens many doors in the field of cancer, but it also adds another level of complex, inter-related, and multi-dimensional information to research, and to its interpretation. Overall, future cancer studies should consider, or at least be sensitive to, epigenetic effects and mechanisms. Moving the focus beyond 'pristine' inheritance via DNA alone, cancer epidemiology investigating epigenetic exposures such as environmental factors (exposure to heavy metals, air pollution, arsenic and other toxins), dietary patterns (starvation, famine, contamination), and lifestyle habits (smoking, level of physical activity, and BMI) in populations has the prospect to significantly benefit future cancer prevention and treatment schemes.

Malignant conditions in children born after assisted reproductive technology

This article reviews the risks of childhood malignancies and imprinting disorders in children born after assisted reproductive technology (ART). It is recognized that there is a theoretical potential of developing an excess of malignancies in children born after ART. With the advancement and introduction of newer techniques in ART there is an increase in the micromanipulation of gametes and embryos in vitro and extended exposure to the in vitro environment. These include the use of gonadotropins for superovulation, intracytoplasmic sperm injection, blastocyst culture, assisted hatching, and preimplantation genetic diagnosis. Although these approaches aim to enhance pregnancy rates and its outcome, the risk of associated long-term health hazards cannot be disregarded. More recently there is some evidence suggesting a link between ART and epigenetic alterations leading to DNA modifications and imprinting disorders. Two of these genetic imprinting disorders that are known to cause birth defects and childhood malignancies, Beckwith-Wiedmann syndrome and Angelman syndrome have been associated with ART. Systemic reviews of the literature identified published studies, but were unable to identify the precise risks of imprinting disorders and childhood cancers in children conceived with ART. Overall, most studies have not shown any increase in the incidence of childhood cancers after ART. With more women resorting to ART, careful counseling should be offered to all couples especially those requiring intracytoplasmic sperm injection for abnormal sperm parameters.

TARGET AUDIENCE

Obstetricians & Gynecologists, Family Physicians.

LEARNING OBJECTIVES

After completion of this article, the reader should be able to distinguish for patients the lack of irrefutable evidence for an increased risk of childhood malignancies in children conceived using assisted reproductive technology (ART), explain potential mechanisms of injury to the gametes and/or embryo during ART which might predispose to childhood illness, and appraise future articles on this topic for credibility both to likelihood of true relationship to possible childhood cancers as well as biologic basis for potential relationship.

Developmental programming and endocrine disruptor effects on reproductive neuroendocrine systems

The ability of a species to reproduce successfully requires the careful orchestration of developmental processes during critical time points, particularly the late embryonic and early postnatal periods. This article begins with a brief presentation of the evidence for how gonadal steroid hormones exert these imprinting effects upon the morphology of sexually differentiated hypothalamic brain regions, the mechanisms underlying these effects, and their implications in adulthood. Then, I review the evidence that aberrant exposure to hormonally-active substances such as exogenous endocrine-disrupting chemicals (EDCs), may result in improper hypothalamic programming, thereby decreasing reproductive success in adulthood. The field of endocrine disruption has shed new light on the discipline of basic reproductive neuroendocrinology through studies on how early life exposures to EDCs may alter gene expression via non-genomic, epigenetic mechanisms, including DNA methylation and histone acetylation. Importantly, these effects may be transmitted to future generations if the germline is affected via transgenerational, epigenetic actions. By understanding the mechanisms by which natural hormones and xenobiotics affect reproductive neuroendocrine systems, we will gain a better understanding of normal developmental processes, as well as develop the potential ability to intervene when development is disrupted.

A validated whole-genome association study of efficient food conversion in cattle

The genetic factors that contribute to efficient food conversion are largely unknown. Several physiological systems are likely to be important, including basal metabolic rate, the generation of ATP, the regulation of growth and development, and the homeostatic control of body mass. Using whole-genome association, we found that DNA variants in or near proteins contributing to the background use of energy of the cell were 10 times as common as those affecting appetite and body-mass homeostasis. In addition, there was a genic contribution from the extracellular matrix and tissue structure, suggesting a trade-off between efficiency and tissue construction. Nevertheless, the largest group consisted of those involved in gene regulation or control of the phenotype. We found that the distribution of micro-RNA motifs was significantly different for the genetic variants associated with residual feed intake than for the genetic variants in total, although the distribution of promoter sequence motifs was not different. This suggests that certain subsets of micro-RNA are more important for the regulation of this trait. Successful validation depended on the sign of the allelic association in different populations rather than on the strength of the initial association or its size of effect.

Chromatin, epigenetics and stem cells

Epigenetics is a term that has changed its meaning with the increasing biological knowledge on developmental processes. However, its current application to stem cell biology is often imprecise and is conceptually problematic. This article addresses two different subjects, the definition of epigenetics and chromatin states of stem and differentiated cells. We describe mechanisms that regulate chromatin changes and provide an overview of chromatin states of stem and differentiated cells. Moreover, a modification of the current epigenetics definition is proposed that is not restricted by the heritability of gene expression throughout cell divisions and excludes translational gene expression control.

The role of oxidative stress in carcinogenesis

Chemical carcinogenesis follows a multistep process involving both mutation and increased cell proliferation. Oxidative stress can occur through overproduction of reactive oxygen and nitrogen species through either endogenous or exogenous insults. Important to carcinogenesis, the unregulated or prolonged production of cellular oxidants has been linked to mutation (induced by oxidant-induced DNA damage), as well as modification of gene expression. In particular, signal transduction pathways, including AP-1 and NFkappaB, are known to be activated by reactive oxygen species, and they lead to the transcription of genes involved in cell growth regulatory pathways. This review examines the evidence of cellular oxidants' involvement in the carcinogenesis process, and focuses on the mechanisms for production, cellular damage produced, and the role of signaling cascades by reactive oxygen species.

What causes seasonality of birth in schizophrenia?

An excess of winter-spring births (and/or a decrease of summer births) has consistently been observed in schizophrenia (SCZ). This observation may provide a significant clue about the causes of the disease if specific factors which cause the phenomenon can be determined. This paper reviews several studies which investigated factors correlated with this observation in SCZ, in an attempt to determine which factors more likely cause the seasonality. Among the candidates of the factors are meteorological variables (such as ambient temperature), several infections, maternal hormones, sperm quality, nutrition and external toxins. A variation of procreation might also have an effect. Among the factors, the most extensively studied are temperature and viral infections. Some of them have appeared promising, but further studies are definitely required. Several challenges, including complicated correlations of the factors and determination of the susceptible period during pregnancy, need to be overcome. Comparisons of the data from areas and cohorts with different patterns of the candidate factors may be helpful. Animal studies may also help investigate the molecular and physiological mechanisms of the phenomenon.

Developmental dynamics: toward a biologically plausible evolutionary psychology

There has been a conceptual revolution in the biological sciences over the past several decades. Evidence from genetics, embryology, and developmental biology has converged to offer a more epigenetic, contingent, and dynamic view of how organisms develop. Despite these advances, arguments for the heuristic value of a gene-centered, predeterministic approach to the study of human behavior and development have become increasingly evident in the psychological sciences during this time. In this article, the authors review recent advances in genetics, embryology, and developmental biology that have transformed contemporary developmental and evolutionary theory and explore how these advances challenge gene-centered explanations of human behavior that ignore the complex, highly coordinated system of regulatory dynamics involved in development and evolution.

The changing concept of epigenetics

We discuss the changing use of epigenetics, a term coined by Conrad Waddington in the 1940s, and how the epigenetic approach to development differs from the genetic approach. Originally, epigenetics referred to the study of the way genes and their products bring the phenotype into being. Today, it is primarily concerned with the mechanisms through which cells become committed to a particular form or function and through which that functional or structural state is then transmitted in cell lineages. We argue that modern epigenetics is important not only because it has practical significance for medicine, agriculture, and species conservation, but also because it has implications for the way in which we should view heredity and evolution. In particular, recognizing that there are epigenetic inheritance systems through which non-DNA variations can be transmitted in cell and organismal lineages broadens the concept of heredity and challenges the widely accepted gene-centered neo-Darwinian version of Darwinism.

Epigenetics and DNA methylation come of age in toxicology

A wide variety of chemical and physical agents have the potential to produce adverse effects by causing heritable changes to the genome, resulting in heritable alterations in phenotype. These are often assumed to be a consequence of mutation. However, mutagenesis is not the only mechanism underlying heritable alterations to the genome. It is important to understand that there may also be an epigenetic basis for this. DNA methylation is the epigenetic mechanism that this review focuses upon. We indicate how altered methylation may play a key role in a variety of chemical-induced toxicities, including, but not limited to, carcinogenesis, and we point out how an assessment of methylation status can provide important information as a component of an overall safety assessment.