MORC1 exhibits cross-species differential methylation in association with early life stress as well as genome-wide association with MDD

Effects of Early Stress Exposure on Anxiety-like Behavior and MORC1 Expression in Rats

Exposure to stress during early and late childhood can lead to long-lasting neurobiological and behavioral impairments. Although sensitive periods for stress exposure are well established, less is known about the trajectory of induced alterations throughout development. In this study, we investigated the impact of maternal separation (MS), social isolation, and their combination on anxiety-like behavior and gene expression across developmental stages. Sprague Dawley rats were exposed to one or both stressors and later assessed for anxiety-like behavior in juvenility, adolescence, and adulthood. mRNA levels of Morc1, a gene linked to early-life stress and depression, were measured in the medial prefrontal cortex to assess developmental changes. The results showed that MS had age- and sex-dependent effects on anxiety-like behavior. Juveniles exhibited less anxiety after MS, while adolescents showed more pronounced behavioral changes following social isolation. No behavioral changes were observed in adults. Males exhibited greater anxiety-like behavior than females in adolescence and adulthood, but not in juvenility. Female adults exposed to both MS and social isolation had significantly lower Morc1 expression compared to controls. These findings highlight the dynamic effects of early stress across the lifespan, underscoring the critical role of adolescence and differential stress susceptibility by age and sex.

DNA Methylation of PXDN Is Associated with Early-Life Adversity in Adult Mental Disorders

Early-life adversity (ELA) is characterized by exposure to traumatic events during early periods of life, particularly involving emotional, sexual and/or physical adversities during childhood. Mental disorders are strongly influenced by environmental and lifestyle-related risk factors including ELA. However, the molecular link between ELA and the risk of an adult mental disorder is still not fully understood. Evidence is emerging that long-lasting changes in the epigenetic processes regulating gene expression, such as DNA methylation, play an important role in the biological mechanisms linking ELA and mental disorders. Based on a recent study, we analyzed the DNA methylation of a specific CpG site within the gene PXDN-cg10888111-in blood in the context of ELA across a set of psychiatric disorders, namely Borderline Personality Disorder (BPD), Major Depressive Disorder (MDD) and Social Anxiety Disorder (SAD), and its potential contribution to their pathogenesis. We found significant hypermethylation in mentally ill patients with high levels of ELA compared to patients with low levels of ELA, whereas cg10888111 methylation in healthy control individuals was not affected by ELA. Further investigations revealed that this effect was driven by the MDD cohort. Providing a direct comparison of cg10888111 DNA methylation in blood in the context of ELA across three mental disorders, our results indicate the role of PXDN regulation in the response to ELA in the pathogenesis of mental disorders, especially MDD. Further studies will be needed to validate these results and decipher the corresponding biological network that is involved in the transmission of ELA to an adult mental disorder in general.

The Epigenetics of Animal Personality

Animal personality, consistent individual differences in behaviour, is an important concept for understanding how individuals vary in how they cope with environmental challenges. In order to understand the evolutionary significance of animal personality, it is crucial to understand the underlying regulatory mechanisms. Epigenetic marks such as DNA methylation are hypothesised to play a major role in explaining variation in phenotypic changes in response to environmental alterations. Several characteristics of DNA methylation also align well with the concept of animal personality. In this review paper, we summarise the current literature on the role that molecular epigenetic mechanisms may have in explaining personality variation. We elaborate on the potential for epigenetic mechanisms to explain behavioural variation, behavioural development and temporal consistency in behaviour. We then suggest future routes for this emerging field and point to potential pitfalls that may be encountered. We conclude that a more inclusive approach is needed for studying the epigenetics of animal personality and that epigenetic mechanisms cannot be studied without considering the genetic background.

Dissecting early life stress-induced adolescent depression through epigenomic approach

Early life stress (ELS), such as abuse and neglect during childhood, can lead to psychiatric disorders in later life. Previous studies have suggested that ELS can cause profound changes in gene expression through epigenetic mechanisms, which can lead to psychiatric disorders in adulthood; however, studies on epigenetic modifications associated with ELS and psychiatric disorders in adolescents are limited. Moreover, how these epigenetic modifications can lead to psychiatric disorders in adolescents is not fully understood. Commonly, DNA methylation, histone modification, and the regulation of noncoding RNAs have been attributed to the reprogramming of epigenetic profiling associated with ELS. Although only a few studies have attempted to examine epigenetic modifications in adolescents with ELS, existing evidence suggests that there are commonalities and differences in epigenetic profiling between adolescents and adults. In addition, epigenetic modifications are sex-dependent and are influenced by the type of ELS. In this review, we have critically evaluated the current evidence on epigenetic modifications in adolescents with ELS, particularly DNA methylation and the expression of microRNAs in both preclinical models and humans. We have also clarified the impact of ELS on psychiatric disorders in adolescents to predict the development of neuropsychiatric disorders and to prevent and recover these disorders through personalized medicine.

DNA Methylation in Depression and Depressive-Like Phenotype: Biomarker or Target of Pharmacological Intervention?

Major depressive disorder (MDD) is a debilitating psychiatric disorder, the third leading global cause of disability. Regarding aetiopathogenetic mechanisms involved in the onset of depressive disorders, the interaction between genetic vulnerability traits and environmental factors is believed to play a major role. Although much is still to be elucidated about the mechanisms through which the environment can interact with genetic background shaping the disease risk, there is a general agreement about a key role of epigenetic marking. In this narrative review, we focused on the association between changes in DNA methylation patterns and MDD or depressive-like phenotype in animal models, as well as mechanisms of response to antidepressant drugs. We discussed studies presenting DNA methylation changes at specific genes of interest and profiling analyses in both patients and animal models of depression. Overall, we collected evidence showing that DNA methylation could not only be considered as a promising epigenetic biomarker of pathology but could also help in predicting antidepressant treatment efficacy. Finally, we discussed the hypothesis that specific changes in DNA methylation signature could play a role in aetiopathogenetic processes as well as in the induction of antidepressant effect.

Structural and Functional Attributes of Microrchidia Family of Chromatin Remodelers

Chromatin remodelers affect the spatio-temporal dynamics of global gene-expression by structurally modulating and/or reorganizing the chromatin. Microrchidia (MORC) family is a relatively new addition to the four well studied families of chromatin remodeling proteins. In this review, we discuss the current understanding of the structural aspects of human MORCs as well as their epigenetic functions. From a molecular and systems-level perspective, we explore their participation in phase-separated structures, possible influence on various biological processes through protein-protein interactions, and potential extra-nuclear roles. We describe how dysregulation/dysfunction of MORCs can lead to various pathological conditions. We conclude by emphasizing the importance of undertaking integrated efforts to obtain a holistic understanding of the various biological roles of MORCs.

Prenatal psychological or metabolic stress increases the risk for psychiatric disorders: the "funnel effect" model

Adverse stressful experiences in utero can redirect fetal brain development, ultimately leading to increased risk for psychiatric disorders. Obesity during pregnancy can have similar effects as maternal stress, affecting mental health in the offspring. In order to explain how similar outcomes may originate from different prenatal conditions, we propose a "funnel effect" model whereby maternal psychological or metabolic stress triggers the same evolutionarily conserved response pathways, increasing vulnerability for psychopathology. In this context, the placenta, which is the main mother-fetus interface, appears to facilitate such convergence, re-directing "stress" signals to the fetus. Characterizing converging pathways activated by different adverse environmental conditions is fundamental to assess the emergence of risk signatures of major psychiatric disorders, which might enable preventive measures in risk populations, and open up new diagnostics, and potentially therapeutic approaches for disease prevention and health promotion already during pregnancy.

Meta-analysis of epigenome-wide associations between DNA methylation at birth and childhood cognitive skills

Cognitive skills are a strong predictor of a wide range of later life outcomes. Genetic and epigenetic associations across the genome explain some of the variation in general cognitive abilities in the general population and it is plausible that epigenetic associations might arise from prenatal environmental exposures and/or genetic variation early in life. We investigated the association between cord blood DNA methylation at birth and cognitive skills assessed in children from eight pregnancy cohorts within the Pregnancy And Childhood Epigenetics (PACE) Consortium across overall (total N = 2196), verbal (total N = 2206) and non-verbal cognitive scores (total N = 3300). The associations at single CpG sites were weak for all of the cognitive domains investigated. One region near DUSP22 on chromosome 6 was associated with non-verbal cognition in a model adjusted for maternal IQ. We conclude that there is little evidence to support the idea that variation in cord blood DNA methylation at single CpG sites is associated with cognitive skills and further studies are needed to confirm the association at DUSP22.

Periconception and Prenatal Exposure to Maternal Perceived Stress and Cord Blood DNA Methylation

BACKGROUND

Maternal prenatal stress is associated with physiologic and adverse mental health outcomes in the offspring, but the underlying biologic mechanisms are unknown. We examined the associations of maternal perceived stress, including preconception exposure, with DNA methylation (DNAm) alterations in the cord blood buffy coats of 358 singleton infants.

METHODS

Maternal perceived stress was measured prior to and throughout pregnancy in a cohort of women enrolled in Effects of Aspirin in Gestation and Reproduction Trial (EAGeR) trial. Perceived stress assessments based on a standardized Likert-scale were obtained in periconception (~2 months preconception and 2-8 weeks of gestation) and pregnancy (8-36 weeks of gestation). Cumulative perceived stress was estimated by calculating the predicted area under the curve of stress reported prior to and during pregnancy. DNAm was measured by the Infinium MethylationEPIC BeadChip. Multivariable robust linear regression was used to assess associations of perceived stress with individual CpG probes.

RESULTS

Based on a 0 to 3 scale, average reported preconception and early pregnancy stress were 0.76 (0.60) and 0.67 (0.50), respectively. Average mid- to late-pregnancy stress, based on a 0 to 10 scale, was 4.9 (1.6). Neither periconception nor pregnancy perceived stress were associated with individual CpG sites in neonatal cord blood (all false discovery rate [FDR] >5%).

CONCLUSION

No effects of maternal perceived stress exposure on array-wide cord blood neonatal methylation differences were found.

MORC protein family-related signature within human disease and cancer

The microrchidia (MORC) family of proteins is a highly conserved nuclear protein superfamily, whose members contain common domain structures (GHKL-ATPase, CW-type zinc finger and coiled-coil domain) yet exhibit diverse biological functions. Despite the advancing research in previous decades, much of which focuses on their role as epigenetic regulators and in chromatin remodeling, relatively little is known about the role of MORCs in tumorigenesis and pathogenesis. MORCs were first identified as epigenetic regulators and chromatin remodelers in germ cell development. Currently, MORCs are regarded as disease genes that are involved in various human disorders and oncogenes in cancer progression and are expected to be the important biomarkers for diagnosis and treatment. A new paradigm of expanded MORC family function has raised questions regarding the regulation of MORCs and their biological role at the subcellular level. Here, we systematically review the progress of researching MORC members with respect to their domain architectures, diverse biological functions, and distribution characteristics and discuss the emerging roles of the aberrant expression or mutation of MORC family members in human disorders and cancer development. Furthermore, the illustration of related mechanisms of the MORC family has made MORCs promising targets for developing diagnostic tools and therapeutic treatments for human diseases, including cancers.

Microbiome profiles are associated with cognitive functioning in 45-month-old children

Prenatal, perinatal, and postnatal factors have been shown to shape neurobiological functioning and alter the risk for mental disorders later in life. The gut microbiome is established early in life, and interacts with the brain via the brain-immune-gut axis. However, little is known about how the microbiome relates to early-life cognitive functioning in children. The present study, where the fecal microbiome of 380 children was characterized using 16S rDNA and metagenomic sequencing aimed to investigate the association between the microbiota and cognitive functioning of children at the age of 45 months measured with the Wechsler Preschool and Primary Scale of Intelligence (WPPSI-III). Overall the microbiome profile showed a significant association with cognitive functioning. A strong correlation was found between cognitive functioning and the relative abundance of an unidentified genus of the family Enterobacteriaceae. Follow-up mediation analyses revealed significant mediation effects of the level of this genus on the association of maternal smoking during pregnancy and current cigarette smoking with cognitive function. Metagenomic sequencing of a subset of these samples indicated that the identified genus was most closely related to Enterobacter asburiae. Analysis of metabolic potential showed a nominally significant association of cognitive functioning with the microbial norspermidine biosynthesis pathway. Our results indicate that alteration of the gut microflora is associated with cognitive functioning in childhood. Furthermore, they suggest that the altered microflora might interact with other environmental factors such as maternal cigarette smoking. Interventions directed at altering the microbiome should be explored in terms of improving cognitive functioning in young children.

The brain oxytocin and corticotropin-releasing factor systems in grieving mothers: What we know and what we need to learn

The bond between a mother and her child is the strongest bond in nature. Consequently, the loss of a child is one of the most stressful and traumatic life events that causes Prolonged Grief Disorder in up to 94 % of bereaved parents. While both parents are affected, mothers are of higher risk to develop mental health complications; yet, very little research has been done to understand the impact of the loss of a child, stillbirth and pregnancy loss on key neurobiological systems. The emotional impact of losing a child, e.g., Prolonged Grief Disorder, is likely accompanied by dysregulations in neural systems important for mental health. Among those are the neuropeptides contributing to attachment and stress processing. In this review, we present evidence for the involvement of the brain oxytocin (OXT) and corticotropin-releasing factor (CRF) systems, which both play a role in maternal behavior and the stress response, in the neurobiology of grief in mothers from a behavioral and molecular point of view. We will draw conclusions from reviewing relevant animal and human studies. However, the paucity of research on the tragic end to an integral bond in a female's life calls for the need and responsibility to conduct further studies on mothers experiencing the loss of a child both in the clinic and in appropriate animal models.

Morc1 as a potential new target gene in mood regulation: when and where to find in the brain

Recent animal and human studies connected the Morc family CW-type zinc finger 1 (Morc1) gene with early life stress and depression. Moreover, the Morc superfamily is related to epigenetic regulation in diverse nuclear processes. So far, the Morc1 gene was mainly studied in spermatogenesis, whereas its distribution and function in the brain are still unknown. In a first attempt to characterize Morc1 in the brain, we performed a Western Blot analysis as well as a real-time PCR analysis during different stages of development. Additionally, we detected Morc1 mRNA using real-time PCR in different mood-regulating brain areas in adult rats. We found that MORC1 protein as well as Morc1 mRNA is already expressed in the brain at embryonic day 14 and is stably expressed until adulthood. Furthermore, Morc1 mRNA is present in many important brain areas of mood regulation like the medial prefrontal cortex, the nucleus accumbens, the hippocampus, the hypothalamus, and the amygdala. The ample distribution in the brain and its molecular structure as a zinc finger protein indicate that Morc1 might act as a transcription factor. This function and its expression in mood-regulating areas already in the early brain development turn Morc1 into a possible candidate gene for mediating early life stress and depression.

MORC1 methylation and BDI are associated with microstructural features of the hippocampus and medial prefrontal cortex

BACKGROUND

Alterations in the hippocampus and prefrontal cortex (PFC) have frequently been reported in depressed patients. These parameters might prove to be a consistent finding in depression. In addition, peripheral DNA methylation of the MORC1 gene promoter showed stable associations with depression across independent samples. However, the question arises whether MORC1, supposedly acting as transcription factor, might also be involved in neurobiological alterations accompanying depression. This study further analyses the role of MORC1 in depression by investigating a potential correlation between peripheral MORC1 DNA methylation and neuronal structural properties previously associated with depression in humans.

METHODS

Beck Depression Inventory (BDI) was assessed in 52 healthy participants. DNA was extracted from buccal cells and MORC1 methylation correlated with micro- and macrostructural properties derived from magnetic resonance imaging (MRI) and neurite orientation dispersion and density imaging (NODDI) in the hippocampus and medial prefrontal cortex (mPFC).

RESULTS

MORC1 methylation was associated with volume reduction and neurite orientation dispersion and density markers in the hippocampus and mPFC. BDI was positively associated with neurite orientation dispersion and density markers in the hippocampus.

LIMITATIONS

The study was conducted in a small sample of healthy participants with subclinical depressive symptoms. Peripheral tissue was analyzed.

CONCLUSION

We found significant negative associations between peripheral MORC1 methylation and macro- and microstructural markers in the hippocampus and mPFC. Thus, MORC1 might be involved in neurobiological properties. Studies investigating neuronal methylation patterns of MORC1 are needed to support this hypothesis.

Prenatal maternal distress and immune cell epigenetic profiles at 3-months of age

BACKGROUND

Prenatal maternal distress predicts altered offspring immune outcomes, potentially via altered epigenetics. The role of different kinds of prenatal maternal distress on DNA methylation profiles is not understood.

METHODS

A sample of 117 women (APrON cohort) were followed from pregnancy to the postpartum period. Maternal distress (depressive symptoms, pregnancy-specific anxiety, stressful life events) were assessed mid-pregnancy, late-pregnancy, and 3-months postpartum. DNA methylation profiles were obtained from 3-month-old blood samples. Principal component analysis identified two epigenetic components, characterized as Immune Signaling and DNA Transcription through gene network analysis. Covariates were maternal demographics, pre-pregnancy body mass index, child sex, birth gestational age, and postpartum maternal distress. Penalized regression (LASSO) models were used.

RESULTS

Late-pregnancy stressful life events, b = 0.006, early-pregnancy depressive symptoms, b = 0.027, late-pregnancy depressive symptoms, b = 0.014, and pregnancy-specific anxiety during late pregnancy, b = -0.631, were predictive of the Immune Signaling component, suggesting that these aspects of maternal distress could affect methylation in offspring immune signaling pathways. Only early-pregnancy depressive symptoms was predictive of the DNA Transcription component, b = -0.0004, suggesting that this aspect of maternal distress is implicated in methylation of offspring DNA transcription pathways.

CONCLUSIONS

Exposure timing and kind of prenatal maternal distress could matter in the prediction of infant immune epigenetic profiles.

Early Biomarkers and Intervention Programs for the Infant Exposed to Prenatal Stress

Functional development of affective and reward circuits, cognition and response inhibition later in life exhibits vulnerability periods during gestation and early childhood. Extensive evidence supports the model that exposure to stressors in the gestational period and early postnatal life increases an individual's susceptibility to future impairments of functional development. Recent versions of this model integrate epigenetic mechanisms of the developmental response. Their understanding will guide the future treatment of the associated neuropsychiatric disorders. A combination of non-invasively obtainable physiological signals and epigenetic biomarkers related to the principal systems of the stress response, the Hypothalamic-Pituitary axis (HPA) and the Autonomic Nervous System (ANS), are emerging as the key predictors of neurodevelopmental outcomes. Such electrophysiological and epigenetic biomarkers can prove to timely identify children benefiting most from early intervention programs. Such programs should ameliorate future disorders in otherwise healthy children. The recently developed Early Family-Centered Intervention Programs aim to influence the care and stimuli provided daily by the family and improving parent/child attachment, a key element for healthy socio-emotional adult life. Although frequently underestimated, such biomarker-guided early intervention strategy represents a crucial first step in the prevention of future neuropsychiatric problems and in reducing their personal and societal impact.

Gaining a deeper understanding of social determinants of preterm birth by integrating multi-omics data

In the US, high rates of preterm birth (PTB) and profound Black-White disparities in PTB have persisted for decades. This review focuses on the role of social determinants of health (SDH), with an emphasis on maternal stress, in PTB disparity and biological embedding. It covers: (1) PTB disparity in US Black women and possible contributors; (2) the role of SDH, highlighting maternal stress, in the persistent racial disparity of PTB; (3) epigenetics at the interface between genes and environment; (4) the role of the genome in modifying maternal stress-PTB associations; (5) recent advances in multi-omics studies of PTB; and (6) future perspectives on integrating multi-omics with SDH to elucidate the Black-White disparity in PTB. Available studies have indicated that neither environmental exposures nor genetics alone can adequately explain the Black-White PTB disparity. Preliminary yet promising findings of epigenetic and gene-environment interaction studies underscore the value of integrating SDH with multi-omics in prospective birth cohort studies, especially among high-risk Black women. In an era of rapid advancements in biomedical sciences and technologies and a growing number of prospective birth cohort studies, we have unprecedented opportunities to advance this field and finally address the long history of health disparities in PTB. IMPACT: This review provides an overview of social determinants of health (SDH) with a focus on maternal stress and its role on Black-White disparity in preterm birth (PTB). It summarizes the available literature on the interplay of maternal stress with key biological layers (e.g., individual genome and epigenome in response to environmental stressors) and significant knowledge gaps. It offers perspectives that such knowledge may provide deeper insight into how SDH affects PTB and why some women are more vulnerable than others and underscores the critical need for integrating SDH with multi-omics in prospective birth cohort studies, especially among high-risk Black women.

Maternal separation in rats induces neurobiological and behavioral changes on the maternal side

The time after parturition is a sensitive period for mothers where they are prone to develop psychopathological symptoms. Studies investigating dams after separation from their pups (maternal separation, MS) showed that MS induces alterations similar to postpartum depression. This study aims to give further details on affected behavior and neurobiology of dams after MS. MS in rats from postnatal day 2-20 over four hours daily was performed. Upon reunion, maternal behavior, and ultrasonic vocalization (USV) of dams were measured. On the day of weaning, dams were tested for anxiety-like behavior in the elevated-plus-maze and marble burying test. Then Morc1 mRNA in the medial prefrontal cortex and Nr3c1 encoding the glucocorticoid receptor mRNA in the hippocampus were measured using real-time PCR to examine possible neurobiological correlates in psychopathology and social behavior. GABA and glutamate serum levels were analyzed by high-performance liquid chromatography as peripheral markers for stress-induced psychopathology. MS in dams increased maternal care towards pups even though both groups show high levels of maternal behavior even in late lactation. Furthermore, the emission of 50-kHz and 22-kHz USVs increased significantly. No differences in anxiety-like behavior were detected. MS further reduced Morc1 but not Nr3c1 expression. Serum GABA but not glutamate levels were significantly increased in separated dams. This study reinforces the benefit of investigating dams after MS for studying postpartum stress. Subclinical markers mainly connected to depression, namely Morc1 and GABA, proved to be useful allowing for earlier detection of symptoms of critical postpartum stress.

Long-term effects of stress early in life on microRNA-30a and its network: Preventive effects of lurasidone and potential implications for depression vulnerability

Exposure to early life stress can interfere with neurodevelopmental trajectories to increase the vulnerability for psychiatric disorders later in life. With this respect, epigenetic mechanisms play a key role for the long-lasting changes in brain functions that may elicit and sustain psychopathologic outcomes.

Here, we investigated DNA methylation changes as possible epigenetic mechanism mediating the effect of prenatal stress (PNS), an experimental paradigm associated with behavioral and molecular alterations relevant for psychiatric disorders. We identified 138 genes as being differentially methylated in the prefrontal cortex (PFC) and in the hippocampus (HIP) of male and female adult rats exposed to PNS. Among these genes, miR-30a and Neurod1 emerged as potential players for the negative outcomes associated with PNS exposure. Indeed, in addition to showing consistent methylation differences in both brain regions and in both sexes, and interacting with each other, they are both involved in Axon guidance and Neurotrophin signaling, which are important to neurodevelopmental disorders. We also found a significant reduction in the expression of a panel of genes (CAMK2A, c-JUN, LIMK1, MAP2K1, MAP2K2, PIK3CA and PLCG1) that belong to these two biological pathways and are also validated targets of miR-30a, pointing to a down-regulation of these pathways as a consequence of PNS exposure. Interestingly, we also found that miR-30a levels were significantly upregulated in depressed patients exposed to childhood trauma, as compared to control individuals. Importantly, we also found that a sub-chronic treatment with the atypical antipsychotic drug, lurasidone, during adolescence was able to prevent the up-regulation of miR-30a and normalized the expression of its target genes in response to PNS exposure.

Our results demonstrate that miR-30a undergoes epigenetic changes following early life stress exposure and suggest that this miRNA could play a key role in producing broad and long-lasting alterations in neuroplasticity-related pathways, contributing to the etiology of psychiatric disorders.

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MiR-30a and Neurod1 undergo epigenetic changes following PNS exposure.

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MiR-30 and Neurod1 are involved in Axon guidance and Neurotrophin signaling, two important pathways for neurodevelopment.

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We found lower expression levels of a panel of genes targeted by miR-30a.

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MiR-30a was significantly up-regulated in depressed patients exposed to childhood trauma.

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A chronic treatment with lurasidone during adolescence prevented the up-regulation of miR-30a following PNS exposure.

Early Life Stress Induced DNA Methylation of Monoamine Oxidases Leads to Depressive-Like Behavior

Major depressive disorder (MDD) is coming to be the regarded as one of the leading causes for human disabilities. Due to its complicated pathological process, the etiology is still unclear and the treatment is still targeting at the monoamine neurotransmitters. Early life stress has been known as a major cause for MDD, but how early life stress affects adult monoaminergic activity is not clear either. Recently, DNA methylation is considered to be the key mechanism of epigenetics and might play a role in early life stress induced mental illness. DNA methylation is an enzymatic covalent modification of DNA, has been one of the main epigenetic mechanisms investigated. The metabolic enzyme for the monoamine neurotransmitters, monoamine oxidases A/B (MAO A/MAO B) are the prime candidates for the investigation into the role of DNA methylation in mental disorders. In this review, we will review recent advances about the structure and physiological function of monoamine oxidases (MAO), brief narrative other factors include stress induced changes, early life stress, perinatal depression (PD) relationship with other epigenetic changes, such as DNA methylation, microRNA (miRNA). This review will shed light on the epigenetic changes involved in MDD, which may provide potential targets for future therapeutics in depression pathogenesis.

The epigenetics of perinatal stress

Early life adversity is associated with long-term effects on physical and mental health later in life, but the mechanisms are yet unclear. Epigenetic mechanisms program cell-type-specific gene expression during development, enabling one genome to be programmed in many ways, resulting in diverse stable profiles of gene expression in different cells and organs in the body. DNA methylation, an enzymatic covalent modification of DNA, has been one of the principal epigenetic mechanisms investigated. Emerging evidence is consistent with the idea that epigenetic processes are involved in embedding the impact of early-life experience in the genome and mediating between social environments and later behavioral phenotypes. Whereas there is evidence supporting this hypothesis in animal studies, human studies have been less conclusive. A major problem is the fact that the brain is inaccessible to epigenetic studies in humans and the relevance of DNA methylation in peripheral tissues to behavioral phenotypes has been questioned. In addition, human studies are usually confounded with genetic and environmental heterogeneity and it is very difficult to derive causality. The idea that epigenetic mechanisms mediate the life-long effects of perinatal adversity has attractive potential implications for early detection, prevention, and intervention in mental health disorders will be discussed.


Investigation of MORC1 DNA methylation as biomarker of early life stress and depressive symptoms

Early life stress (ELS) is associated with an increased risk of depression and this association may be mediated by epigenetic mechanisms. A previous epigenome-wide DNA methylation (DNAm) study investigating human newborns and two animal models of ELS suggested that the epigenetic regulator MORC1 is differentially methylated following ELS. The ELS-induced DNAm alterations were long-lasting in the animal models. However, whether this finding is also transferable to humans experiencing ELS in childhood was not investigated. Further, MORC1 may provide a link between ELS and adult depression, as MORC1 DNAm and genetic variants were found to be associated with depressive symptoms in humans. In the present study, we investigated the validity of MORC1 DNAm as a biomarker of ELS in humans and its role in linking ELS to depression later in life by studying childhood maltreatment. We analyzed whole blood MORC1 DNAm in an adult cohort (N = 151) that was characterized for both the presence of depressive symptoms and childhood maltreatment. Further, we investigated the association between MORC1 DNAm, depressive symptoms and childhood maltreatment in two additional cohorts (N = 299, N = 310). Overall, our data do not indicate an association of MORC1 DNAm with childhood maltreatment. An association of MORC1 DNAm with depressive symptoms was present in all cohorts, but was inconsistent in the specific CpG sites associated and the direction of effect (Tuebingen cohort: standardized β = 0.16, unstandardized β = 0.01, 95% CI [-0.0004, -0.0179], p = 0.061, PReDICT cohort: standardized β = -0.12, unstandardized β = -0.01, 95% CI [-0.0258, -0.0003], p = 0.045), Grady cohort: standardized β = 0.16, unstandardized β = 0.008, 95% CI [0.0019, 0.0143], p = 0.01). Our study thus suggests that peripheral MORC1 DNAm cannot serve as biomarker of childhood maltreatment in adults, but does provide further indication for the association of MORC1 DNAm with depressive symptoms.

Stress During Pregnancy and Epigenetic Modifications to Offspring DNA: A Systematic Review of Associations and Implications for Preterm Birth

Offspring born preterm (ie, before 37 weeks of gestation) are more likely to die or experience long-standing illness than full-term offspring. Maternal genetic variants (ie, heritable, stable variations in the genetic code) and epigenetic modifications (ie, chemical modifications to the genetic code that can affect which genes are turned on or off) in response to stress have been implicated in preterm birth. Fetal genetic variants have been linked to preterm birth though the role of offspring epigenetics in preterm birth remains understudied. This systematic review synthesizes the literature examining associations among stress during pregnancy and epigenetic modifications to offspring DNA, with 25 reports identified. Ten reports examined DNA methylation (ie, addition/removal of methyl groups to/from DNA) across the epigenome. The remainder examined DNA methylation near genes of interest, primarily genes linked to hypothalamic-pituitary-adrenal axis function (NR3C1, FKBP51), growth/immune function (IGF2), and socioemotional regulation (SLC6A4, OXTR). The majority of reports noted associations among stress and offspring DNA methylation, primarily when perceived stress, anxiety, or depression served as the predictor. Findings suggest that differences in offspring epigenetic patterns may play a role in stress-associated preterm birth and serve as targets for novel interventions.

Aberrant Epigenomic Modulation of Glucocorticoid Receptor Gene (NR3C1) in Early Life Stress and Major Depressive Disorder Correlation: Systematic Review and Quantitative Evidence Synthesis

Early life stress (ELS) induced by psychological trauma, child maltreatment, maternal separation, and domestic violence predisposes to psycho-behavioral pathologies during adulthood, namely major depressive disorder (MDD), anxiety, and bipolar affective disorder. While environmental data are available in illustrating this association, data remain to be established on the epigenomic underpinning of the nexus between ELS and MDD predisposition. Specifically, despite the observed aberrant epigenomic modulation of the NR3C1, a glucocorticoid receptor gene, in early social adversity and social threats in animal and human models, reliable scientific data for intervention mapping in reducing social adversity and improving human health is required. We sought to synthesize the findings of studies evaluating (a) epigenomic modulations, mainly DNA methylation resulting in MDD following ELS, (b) epigenomic modifications associated with ELS, and (c) epigenomic alterations associated with MDD. A systematic review and quantitative evidence synthesis (QES) were utilized with the random effect meta-analytic procedure. The search strategy involved both the PubMed and hand search of relevant references. Of the 1534 studies identified through electronic search, 592 studies were screened, 11 met the eligibility criteria for inclusion in the QES, and 5 examined ELS and MDD; 4 studies assessed epigenomic modulation and ELS, while 2 studies examined epigenomic modulations and MDD. The dense DNA methylation of the 1F exon of the NR3C1, implying the hypermethylated region of the glucocorticoid receptor gene, was observed in the nexus between ELS and MDD, common effect size (CES) = 14.96, 95%CI, 10.06-19.85. With respect to epigenomic modulation associated with child ELS, hypermethylation was observed, CES = 23.2%, 95%CI, 8.00-38.48. In addition, marginal epigenomic alteration was indicated in MDD, where hypermethylation was associated with increased risk of MDD, CES = 2.12%, 95%CI, -0.63-4.86. Substantial evidence supports the implication of NR3C1 and environmental interaction, mainly DNA methylation, in the predisposition to MDD following ELS. This QES further supports aberrant epigenomic modulation identified in ELS as well as major depressive episodes involving dysfunctional glucocorticoid-mediated negative feedback as a result of allostatic overload. These findings recommend prospective investigation of social adversity and its predisposition to the MDD epidemic via aberrant epigenomic modulation. Such data will facilitate early intervention mapping in reducing MDD in the United States population.

Implication of Spiritual Network Support System in Epigenomic Modulation and Health Trajectory

With challenges in understanding the multifactorial etiologies of disease and individual treatment effect heterogeneities over the past four decades, much has been acquired on how physical, chemical and social environments affect human health, predisposing certain subpopulations to adverse health outcomes, especially the socio-environmentally disadvantaged (SED). Current translational data on gene and adverse environment interaction have revealed how adverse gene-environment interaction, termed aberrant epigenomic modulation, translates into impaired gene expression via messenger ribonucleic acid (mRNA) dysregulation, reflecting abnormal protein synthesis and hence dysfunctional cellular differentiation and maturation. The environmental influence on gene expression observed in most literature includes physical, chemical, physicochemical and recently social environment. However, data are limited on spiritual or religious environment network support systems, which reflect human psychosocial conditions and gene interaction. With this limited information, we aimed to examine the available data on spiritual activities characterized by prayers and meditation for a possible explanation of the nexus between the spiritual network support system (SNSS) as a component of psychosocial conditions, implicated in social signal transduction, and the gene expression correlate. With the intent to incorporate SNSS in human psychosocial conditions, we assessed the available data on bereavement, loss of spouse, loneliness, social isolation, low socio-economic status (SES), chronic stress, low social status, social adversity (SA) and early life stress (ELS), as surrogates for spiritual support network connectome. Adverse human psychosocial conditions have the tendency for impaired gene expression through an up-regulated conserved transcriptional response to adversity (CTRA) gene expression via social signal transduction, involving the sympathetic nervous system (SNS), beta-adrenergic receptors, the hypothalamus-pituitary-adrenal (HPA) axis and the glucocorticoid response. This review specifically explored CTRA gene expression and the nuclear receptor subfamily 3 group C member 1 (NR3C1) gene, a glucocorticoid receptor gene, in response to stress and the impaired negative feedback, given allostatic overload as a result of prolonged and sustained stress and social isolation as well as the implied social interaction associated with religiosity. While more remains to be investigated on psychosocial and immune cell response and gene expression, current data on human models do implicate appropriate gene expression via the CTRA and NR3C1 gene in the SNSS as observed in meditation, yoga and thai-chi, implicated in malignant neoplasm remission. However, prospective epigenomic studies in this context are required in the disease causal pathway, prognosis and survival, as well as cautious optimism in the application of these findings in clinical and public health settings, due to unmeasured and potential confoundings implicated in these correlations.

Racial differences in skeletal fragility but not osteoarthritis among women and men with cerebral palsy

Background

Adults with cerebral palsy (CP) have increased risk for skeletal fragility and osteoarthritis. However, racial differences in these outcomes have not been examined. Such knowledge could improve patient-specific clinical care for the prevention and management of these conditions. The purpose of this study was to determine if there were racial differences in the prevalence of osteoporosis, all-cause fracture, and osteoarthritis among young and middle-aged adults with CP.

Methods

Data from 2016 were extracted from a random 20% sample of the Medicare fee-for-service database. International Classification of Diseases, Tenth Revision, Clinical Modification codes were used to identify 18-64 year olds with CP, as well as osteoporosis, all-cause fracture, osteoarthritis, and neurodevelopmental and noncommunicable disease comorbidities.

Results

Of the 16,488 adults with CP, 13,334 were White, 2477 were Black, and 677 were Hispanic. The age-standardized prevalence of osteoporosis (women: 12.9%, 9.0%, 8.3%, respectively; men: 9.2%, 4.8%, 7.9%, respectively) and fracture (women: 7.4%, 4.2%, 9.9%; men: 6.0%, 2.3%, 6.0%) was lower for Black adults with CP compared to White adults with CP (all p < 0.005). No racial differences were observed for age-standardized prevalence of osteoarthritis (women: 13.6%, 14.4%, 9.6%; men: 10.7%, 10.4%, 12.7%). The racial differences between Black and White adults with CP remained even after adjusting for age, U.S. region, neurodevelopmental comorbidities, and several noncommunicable diseases for osteoporosis (women: OR = 0.66, 99.5% CI = 0.48-0.91; men: OR = 0.51, 99.5% CI = 0.35-0.75) and fracture (women: OR = 0.57, 99.5% CI = 0.37-0.89; men: OR = 0.39, 99.5% CI = 0.23-0.68).

Conclusions

Study findings suggest racial differences in skeletal fragility among young and middle-aged adults with CP, with White women and men with CP having greater risk compared to Black women and men with CP. This study found no evidence of racial differences in the prevalence of osteoarthritis.

Stress reactivity in preschool-aged children: Evaluation of a social stress paradigm and investigation of the impact of prenatal maternal stress

Prenatal maternal stress is an established risk factor for somatic and psychological health of the offspring. A dysregulation of the hypothalamic-pituitary-adrenal (HPA) axis in offspring has been suggested as an important mechanism. However, the impact of prenatal stress on stress reactivity in preschool-aged children is not yet well understood. This is partly due to the fact that for this age group there is no stress test as well established as for older children and adults. In the present work a previously published stress test (Kryski et al., 2011) was evaluated in a large sample of 45-month-old children (n = 339). Furthermore, the relation between measures of prenatal maternal stress and cortisol reactivity was investigated. Prenatal stress was defined as psychopathology (self-report available for n = 339; expert-rating available for a subsample of n = 246) and perceived stress (n = 244) during pregnancy. The stress paradigm elicited significant increases in salivary cortisol 30 and 40 min after the test, and 60.8% of the children were classified as responders. Lower cortisol levels after the stress test were observed in the group of children with prenatal stress defined as maternal psychopathology (both self-reported and expert-rated). Maternal perceived stress as a continuous measure was not significantly associated with cortisol levels. However, when comparing children in the highest quartile of maternal perceived stress to all other children, significantly lower cortisol values were observed in the prenatally stressed group. The present study confirms the paradigm by Kryski et al. as an effective stress test for preschool-aged children. Moreover, it provides further evidence that prenatal stress impacts HPA axis reactivity. Future studies should target the timing, nature, and intensity of prenatal stressors and their effect on the stress response in offspring at different developmental stages.

Fetal glucocorticoid receptor (Nr3c1) deficiency alters the landscape of DNA methylation of murine placenta in a sex-dependent manner and is associated to anxiety-like behavior in adulthood

Prenatal stress defines long-term phenotypes through epigenetic programming of the offspring. These effects are potentially mediated by glucocorticoid release and by sex. We hypothesized that the glucocorticoid receptor (Gr, Nr3c1) fashions the DNA methylation profile of offspring. Consistent with this hypothesis, fetal Nr3c1 heterozygosity leads to altered DNA methylation landscape in fetal placenta in a sex-specific manner. There was a significant overlap of differentially methylated genes in fetal placenta and adult frontal cortex in Nr3c1 heterozygotes. Phenotypically, Nr3c1 heterozygotes show significantly more anxiety-like behavior than wildtype. DNA methylation status of fetal placental tissue is significantly correlated with anxiety-like behavior of the same animals in adulthood. Thus, placental DNA methylation might predict behavioral phenotypes in adulthood. Our data supports the hypothesis that Nr3c1 influences DNA methylation at birth and that DNA methylation in placenta correlates with adult frontal cortex DNA methylation and anxiety-like phenotypes.

Prenatal influences on temperament development: The role of environmental epigenetics

This review summarizes current knowledge and outlines future directions relevant to questions concerning environmental epigenetics and the processes that contribute to temperament development. Links between prenatal adversity, epigenetic programming, and early manifestations of temperament are important in their own right, also informing our understanding of biological foundations for social-emotional development. In addition, infant temperament attributes represent key etiological factors in the onset of developmental psychopathology, and studies elucidating their prenatal foundations expand our understanding of developmental origins of health and disease. Prenatal adversity can take many forms, and this overview is focused on the environmental effects of stress, toxicants, substance use/psychotropic medication, and nutrition. Dysregulation associated with attention-deficit/hyperactivity-disruptive disorders was noted in the context of maternal substance use and toxicant exposures during gestation, as well as stress. Although these links can be made based on the existing literature, currently few studies directly connect environmental influences, epigenetic programming, and changes in brain development/behavior. The chain of events starting with environmental inputs and resulting in alterations to gene expression, physiology, and behavior of the organism is driven by epigenetics. Epigenetics provides the molecular mechanism of how environmental factors impact development and subsequent health and disease, including early brain and temperament development.

A DNA Methylation Signature of Addiction in T Cells and Its Reversal With DHEA Intervention

Previous studies in animal models of cocaine craving have delineated broad changes in DNA methylation profiles in the nucleus accumbens. A crucial factor for progress in behavioral and mental health epigenetics is the discovery of epigenetic markers in peripheral tissues. Several studies in primates and humans have associated differences in behavioral phenotypes with changes in DNA methylation in T cells and brain. Herein, we present a pilot study (n = 27) showing that the T cell DNA methylation profile differentiates persons with a substance use disorder from controls. Intervention with dehydroepiandrosterone (DHEA), previously shown to have a long-term therapeutic effect on human addicts herein resulted in reversal of DNA methylation changes in genes related to pathways associated with the addictive state.

Methylation of MORC1: A possible biomarker for depression?

New findings identified the MORC1 gene as a link between early life stress and major depression. In this study, MORC1 methylation was investigated in 60 healthy human adults (30 women, 30 men) between 19 and 33 years of age. For analysis, DNA was isolated from buccal cells. The results show that DNA methylation in the MORC1 promoter region significantly correlates with the Beck Depression Inventory score in the examined non-clinical population. Sum score of birth complications, however, seems to correlate negatively with methylation. These findings further confirm that MORC1 is a stress sensitive gene and a possible biomarker for depression.

Impact on birth weight of maternal smoking throughout pregnancy mediated by DNA methylation

Background

Cigarette smoking has severe adverse health consequences in adults and in the offspring of mothers who smoke during pregnancy. One of the most widely reported effects of smoking during pregnancy is reduced birth weight which is in turn associated with chronic disease in adulthood. Epigenome-wide association studies have revealed that smokers show a characteristic “smoking methylation pattern”, and recent authors have proposed that DNA methylation mediates the impact of maternal smoking on birth weight. The aims of the present study were to replicate previous reports that methylation mediates the effect of maternal smoking on birth weight, and for the first time to investigate whether the observed mediation effects are sex-specific in order to account for known sex-specific differences in methylation levels.

Methods

Methylation levels in the cord blood of 313 newborns were determined using the Illumina HumanMethylation450K Beadchip. A total of 5,527 CpG sites selected on the basis of evidence from the literature were tested. To determine whether the observed association between maternal smoking and birth weight was attributable to methylation, mediation analyses were performed for significant CpG sites. Separate analyses were then performed in males and females.

Results

Following quality control, 282 newborns eventually remained in the analysis. A total of 25 mothers had smoked consistently throughout the pregnancy. The birthweigt of newborns whose mothers had smoked throughout pregnancy was reduced by >200g. After correction for multiple testing, 30 CpGs showed differential methylation in the maternal smoking subgroup including top “smoking methylation pattern” genes AHRR, MYO1G, GFI1, CYP1A1, and CNTNAP2. The effect of maternal smoking on birth weight was partly mediated by the methylation of cg25325512 (PIM1); cg25949550 (CNTNAP2); and cg08699196 (ITGB7). Sex-specific analyses revealed a mediating effect for cg25949550 (CNTNAP2) in male newborns.

Conclusion

The present data replicate previous findings that methylation can mediate the effect of maternal smoking on birth weight. The analysis of sex-dependent mediation effects suggests that the sex of the newborn may have an influence. Larger studies are warranted to investigate the role of both the identified differentially methylated loci and the sex of the newborn in mediating the association between maternal smoking during pregnancy and birth weight.

Electronic supplementary material

The online version of this article (10.1186/s12864-018-4652-7) contains supplementary material, which is available to authorized users.

The Role of DNA Methylation in Drug Addiction: Implications for Diagnostic and Therapeutics

Drug addiction is a devastating health problem that is a very heavy burden on the individual affected and the society in general. Recent research defines addiction as a neurobehavioral disorder. Underpinning biological mechanisms of drug addiction are abnormal neuronal and brain activity following acute and repeated drug exposure. Abnormal gene expression is found in reward and decision-making brain regions of addicts and in animal models and is possibly responsible for changes in brain function. DNA methylation is an epigenetic modification that regulates gene expression. Global and site-specific changes in DNA methylation are observed in addiction. Here, we discuss recent findings on the involvement of DNA methylation in drug addiction from animal and human studies. We also propose future directions for utilizing DNA methylation-based approaches for diagnosis, therapeutics, and evaluation of response to therapy in drug addiction.

Epigenetic Landscapes of the Adversity-Exposed Brain

It is understood that adversity during development has the power to alter behavioral trajectories, and the role of the epigenome in that relationship is currently under intense investigation. Several studies in both nonhuman animals and humans have established a link between early adversity and epigenetic regulation of genes heavily implicated in the stress response, plasticity and cognition, and psychiatric disorders such as depression and anxiety. Thus the relatively recent surge of studies centering on the epigenetic outcomes of stress has great potential to inform treatments and interventions for psychiatric disorder precipitated by early adversity. Here we review what we know and what we do not know, and suggest approaches to help further elucidate the relationship between early adversity, epigenetics, and behavior.

DNA methylation of APBA3 and MCF2 in borderline personality disorder: Potential biomarkers for response to psychotherapy

Borderline personality disorder (BPD) is a severe and complex mental disease associated with high suicidal tendencies and hospitalization rates. Accumulating evidence suggests that epigenetic mechanisms are implicated in the etiology of BPD. A recent epigenome-wide study identified several novel genes which are epigenetically dysregulated in BPD. Those genes include APBA3 and MCF2. Psychotherapy such as Dialectical Behavior Therapy (DBT), an established treatment for BPD, provides an excellent setting to investigate environmental influences on epigenetic mechanisms in order to identify biomarkers for disease status and therapy success. However, the effects of DBT on epigenetic regulation has only been researched in one previous study analyzing BDNF. In the present study, we aimed to investigate the role of DNA methylation of APBA3 and MCF2 as possible biomarkers for treatment outcome in BPD, whilst validating the previous findings of differential DNA methylation in a cohort of 44 BPD patients and 44 well-matched healthy control individuals. Unexpectedly, we did not detect significant DNA methylation differences between patients and control individuals. However, we found a high correlation between the methylation status of APBA3 and MCF2 and therapy outcome: before DBT treatment, both genes were significantly higher methylated in patients responding to therapy compared to patients that did not respond. Our study is the first to report results pointing to possible predictive epigenetic biomarkers of DBT outcome in BPD patients. Following replication in independent cohorts, our finding could facilitate the development of more personalized therapy concepts for BPD patients by including epigenetic information.

Maternal prenatal stress and infant DNA methylation: A systematic review

Maternal prenatal stress has been linked to a variety of infant postnatal outcomes, partially through alterations in fetal HPA axis functioning; yet the underlying pathobiology remains elusive. Current literature posits DNA methylation as a candidate mechanism through which maternal prenatal stress can influence fetal HPA axis functioning. The goal of this systematic review was to summarize the literature examining the associations among maternal prenatal stress, DNA methylation of commonly studied HPA axis candidate genes, and infant HPA axis functioning. Results from the review provided evidence for a link between various maternal prenatal stressors, NR3C1 methylation, and infant stress reactivity, but findings among other genes were limited, with mixed results. An original study quality review tool revealed that a majority of studies in the review are adequate, and emphasizes the need for future research to consider study quality when interpreting research findings.

Impact of prenatal stress on mother-infant dyadic behavior during the still-face paradigm

BACKGROUND

Mother-infant interaction provides important training for the infant's ability to cope with stress and the development of resilience. Prenatal stress (PS) and its impact on the offspring's development have long been a focus of stress research, with studies highlighting both harmful and beneficial effects. The aim of the current study was to examine the possible influence of both psychological stress and hypothalamic-pituitary-adrenal (HPA) axis activity during pregnancy with mother-child dyadic behavior following stress exposure.

METHODS

The behavior of 164 mother-infant dyads during the still-face situation was filmed at six months postpartum and coded into three dyadic patterns: 1) both positive, 2) infant protesting-mother positive, and 3) infant protesting-mother negative. PS exposure was assessed prenatally according to psychological measures (i.e., psychopathological, perceived and psychosocial PS; n = 164) and HPA axis activity measures (maternal salivary cortisol, i.e., cortisol decline and area under the curve with respect to ground (AUCg); n = 134).

RESULTS

Mother-infant dyads in both the high- and low-stress groups showed decreasing positive and increasing negative dyadic behavior in the reunion episode, which is associated with the well-known "still-face" and "carry-over" effect. Furthermore, mother-infant dyads with higher psychosocial PS exhibited significantly more positive dyadic behavior than the low psychosocial PS group in the first play episode, but not in the reunion episode. Similarly, mother-infant dyads with high HPA axis activity (i.e. high AUCg) but steeper diurnal cortisol decline (i.e. cortisol decline) displayed significantly less negative behavior in the reunion episode than dyads with low HPA axis activity. No significant results were found for psychopathological stress and perceived stress.

CONCLUSIONS

The results suggest a beneficial effect of higher psychosocial PS and higher prenatal maternal HPA axis activity in late gestation, which is in line with "stress inoculation" theories.

Adverse Childhood Experiences and the Consequences on Neurobiological, Psychosocial, and Somatic Conditions Across the Lifespan

Introduction: Adverse childhood experiences (ACE) such as sexual and physical abuse or neglect are frequent in childhood and constitute a massive stressor with long-lasting adverse effects on the brain, mental and physical health.The aim of this qualitative review is to present a concise overview of the present literature on the impact of ACE on neurobiology, mental and somatic health in later adulthood. Methods: The authors reviewed the existing literature on the impact of ACE on neurobiology, mental and somatic health in later adulthood and summarized the results for a concise qualitative overview. Results: In adulthood, the history of ACE can result in complex clinical profiles with several co-occurring mental and somatic disorders such as posttraumatic stress disorder, depression, borderline personality disorder, obesity and diabetes. Although a general stress effect in the development of the disorders and neural alterations can be assumed, the role of type and timing of ACE is of particular interest in terms of prevention and treatment of ACE-related mental and somatic conditions. It has been suggested that during certain vulnerable developmental phases the risk for subsequent ACE-related disorders is increased. Moreover, emerging evidence points to sensitive periods and specificity of ACE-subtypes in the development of neurobiological alterations, e.g., volumetric and functional changes in the amygdala and hippocampus. Conclusion: Longitudinal studies are needed to investigate complex ACE-related characteristics and mechanisms relevant for mental and somatic disorders by integrating state of the art knowledge and methods. By identifying and validating psychosocial and somatic risk factors and diagnostic markers one might improve the development of innovative somatic and psychological treatment options for individuals suffering from ACE-related disorders.

Telomere Length in Newborns is Related to Maternal Stress During Pregnancy

Telomere length (TL) is a marker of biological aging, and numerous studies have shown associations between TL and somatic or psychiatric disorders. Research also indicates an association between maternal stress during pregnancy and TL in the offspring. The present study investigated possible associations between TL and: (1) maternal perceived stress during pregnancy; (2) a maternal lifetime history of psychiatric disorder (lifetime PD); and (3) paternal age. TL was analyzed in 319 newborns and 318 mothers from a predominantly Caucasian sample (n=273 Caucasian newborns and n=274 Caucasian mothers). Two key findings were observed. First, maternal perceived stress during pregnancy was associated with shorter telomeres in newborns but not with maternal TL. Second, maternal lifetime PD was associated with shorter maternal telomeres, but not with TL in newborns. Paternal age was not associated with TL in newborns. The finding that maternal stress during pregnancy is associated with shorter telomeres in newborns supports the results of smaller previous studies. The fact that a relation between maternal prenatal stress and TL was observed in the offspring but not in mothers may be attributable to a high vulnerability to stress during intrauterine development of a maturing organism. To our knowledge, this is the largest study to date to show that maternal stress during pregnancy but not maternal lifetime PD is associated with shorter telomeres in the offspring.

MORC Proteins: Novel Players in Plant and Animal Health

Microrchidia (MORC) proteins comprise a family of proteins that have been identified in prokaryotes and eukaryotes. They are defined by two hallmark domains: a GHKL-type ATPase and an S5 fold. MORC proteins in plants were first discovered via a genetic screen for Arabidopsis mutants compromised for resistance to a viral pathogen. Subsequent studies expanded their role in plant immunity and revealed their involvement in gene silencing and transposable element repression. Emerging data suggest that MORC proteins also participate in pathogen-induced chromatin remodeling and epigenetic gene regulation. In addition, biochemical analyses recently demonstrated that plant MORCs have topoisomerase II (topo II)-like DNA modifying activities that may be important for their function. Interestingly, animal MORC proteins exhibit many parallels with their plant counterparts, as they have been implicated in disease development and gene silencing. In addition, human MORCs, like plant MORCs, bind salicylic acid and this inhibits some of their topo II-like activities. In this review, we will focus primarily on plant MORCs, although relevant comparisons with animal MORCs will be provided.

The epigenetic impacts of social stress: how does social adversity become biologically embedded?

Epigenetic mechanisms are implicated in the processes through which social stressors erode health in humans and other animals. Here I review progress in elucidating the biological pathways underlying the social gradient in health, with particular emphasis on how behavioral stresses influence epigenomic variation linked to health. The evidence that epigenetic changes are involved in embedding of social status-linked chronic stress is reviewed in the context of current knowledge about behavior within animal dominance hierarchies and the impacts of social position on behaviors that affect health. The roles of epigenetic mechanisms in responses to trauma and the evidence for their involvement in intergenerational transmission of the biological impacts of traumatic stress are also considered. Taken together, the emerging insights have important implications for development of strategies to improve societal health and well-being.

Ankyrin-3 as a molecular marker of early-life stress and vulnerability to psychiatric disorders

Exposure to early-life stress (ELS) may heighten the risk for psychopathology at adulthood. Here, in order to identify common genes that may keep the memory of ELS through changes in their methylation status, we intersected methylome analyses performed in different tissues and time points in rats, non-human primates and humans, all characterized by ELS. We identified Ankyrin-3 (Ank3), a scaffolding protein with a strong genetic association for psychiatric disorders, as a gene persistently affected by stress exposure. In rats, Ank3 methylation and mRNA changes displayed a specific temporal profile during the postnatal development. Moreover, exposure to prenatal stress altered the interaction of ankyrin-G, the protein encoded by Ank3 enriched in the post-synaptic compartment, with PSD95. Notably, to model in humans a gene by early stress interplay on brain phenotypes during cognitive performance, we demonstrated an interaction between functional variation in Ank3 gene and obstetric complications on working memory in healthy adult subjects. Our data suggest that alterations of Ank3 expression and function may contribute to the effects of ELS on the development of psychiatric disorders.

The Signature of Maternal Social Rank in Placenta Deoxyribonucleic Acid Methylation Profiles in Rhesus Monkeys

The effects of social status on human health can be modeled in captive cohorts of nonhuman primates. This study shows that maternal social rank is associated with broad changes in DNA methylation in placentae of rhesus monkeys (N = 10). Differentially methylated genes between social ranks are enriched in signaling pathways playing major roles in placenta physiology. Moreover, the authors found significant overlaps with genes whose expression was previously associated with social rank in adult rhesus monkeys (Tung et al., 2012) and whose methylation was associated with perinatal stress in newborn humans and rhesus monkeys (Nieratschker et al., 2014). These results are consistent with the hypothesis that system-wide epigenetic changes in multiple tissues are involved in long-term adaptations to the social environment.

Epigenetic Modifications of Major Depressive Disorder

Major depressive disorder (MDD) is a chronic disease whose neurological basis and pathophysiology remain poorly understood. Initially, it was proposed that genetic variations were responsible for the development of this disease. Nevertheless, several studies within the last decade have provided evidence suggesting that environmental factors play an important role in MDD pathophysiology. Alterations in epigenetics mechanism, such as DNA methylation, histone modification and microRNA expression could favor MDD advance in response to stressful experiences and environmental factors. The aim of this review is to describe genetic alterations, and particularly altered epigenetic mechanisms, that could be determinants for MDD progress, and how these alterations may arise as useful screening, diagnosis and treatment monitoring biomarkers of depressive disorders.

Maternal psychosocial stress during pregnancy alters the epigenetic signature of the glucocorticoid receptor gene promoter in their offspring: a meta-analysis

Prenatal stress has been widely associated with a number of short- and long-term pathological outcomes. Epigenetic mechanisms are thought to partially mediate these environmental insults into the fetal physiology. One of the main targets of developmental programming is the hypothalamic-pituitary-adrenal (HPA) axis as it is the main regulator of the stress response. Accordingly, an increasing number of researchers have recently focused on the putative association between DNA methylation at the glucocorticoid receptor gene (NR3C1) and prenatal stress, among other types of psychosocial stress. The current study aims to systematically review and meta-analyze the existing evidence linking several forms of prenatal stress with DNA methylation at the region 1F of the NR3C1 gene. The inclusion of relevant articles allowed combining empirical evidence from 977 individuals by meta-analytic techniques, whose methylation assessments showed overlap across 5 consecutive CpG sites (GRCh37/hg19 chr5:142,783,607-142,783,639). From this information, methylation levels at CpG site 36 displayed a significant correlation to prenatal stress (r = 0.14, 95% CI: 0.05-0.23, P = 0.002). This result supports the proposed association between a specific CpG site located at the NR3C1 promoter and prenatal stress. Several confounders, such as gender, methylation at other glucocorticoid-related genes, and adjustment for pharmacological treatments during pregnancy, should be taken into account in further studies.

Epigenetic and gene expression changes in the adolescent brain: What have we learned from animal models?

Adolescence is defined as the gradual period of transition between childhood and adulthood that is characterized by significant brain maturation, growth spurts, sexual maturation, and heightened social interaction. Although originally believed to be a uniquely human aspect of development, rodent and non-human primates demonstrate maturational patterns that distinctly support an adolescent stage. As epigenetic processes are essential for development and differentiation, but also transpire in mature cells in response to environmental influences, they are an important aspect of adolescent brain maturation. The purpose of this review article was to examine epigenetic programming in animal models of brain maturation during adolescence. The discussion focuses on animal models to examine three main concepts; epigenetic processes involved in normal adolescent brain maturation, the influence of fetal programming on adolescent brain development and the epigenome, and finally, postnatal experiences such as exercise and drugs that modify epigenetic processes important for adolescent brain maturation. This corollary emphasizes the utility of animal models to further our understanding of complex processes such as epigenetic regulation and brain development.

Stress-induced mechanisms in mental illness: A role for glucocorticoid signalling

Stress represents the main environmental risk factor for mental illness. Exposure to stressful events, particularly early in life, has been associated with increased incidence and susceptibility of major depressive disorders as well as of other psychiatric illnesses. Among the key players in these events are glucocorticoid receptors. Dysfunctional glucocorticoid signalling may indeed contribute to psychopathology through a number of mechanisms that regulate the response to acute or chronic stress and that affect the function of genes and systems known to be relevant for mood disorders. Indeed, exposure to chronic stress early in life as well as in adulthood has been shown to reduce the expression of glucocorticoid receptors (GR), also through epigenetic mechanisms, and to up-regulate the expression of the co-chaperone gene FKBP5, which restrains GR activity by limiting the translocation of the receptor complex to the nucleus. Another mechanism that contributes to changes in GR responsiveness is the state of receptor phosphorylation that controls activation, subcellular localization as well as its transcriptional activity. Moreover, GR phosphorylation may represent an important mechanism for the cross talk between neurotrophic signalling and GR-dependent transcription, bridging two important players for mood disorders. One gene that lies downstream from GR and may contribute to stress-related changes is serum glucocorticoid kinase-1 (SGK1). We have demonstrated that the expression of SGK1 is significantly increased after exposure to chronic stress in rodents as well as in the blood of drug-free depressed patients. We have also shown that SGK1 up-regulation may ultimately reduce hippocampal neurogenesis and contribute to the structural abnormalities that have been reported to occur in depressed patients. In summary, GR signalling may represent a point of convergence as well as of divergence for defects associated with pathologic conditions characterized by heightened vulnerability to stress. The characterization of these abnormalities is crucial to identify novel targets for therapeutic intervention that may counteract more effectively stress-induced neurobiological abnormalities.

Gene expression in major depressive disorder

The search for genetic variants underlying major depressive disorder (MDD) has not yet provided firm leads to its underlying molecular biology. A complementary approach is to study gene expression in relation to MDD. We measured gene expression in peripheral blood from 1848 subjects from The Netherlands Study of Depression and Anxiety. Subjects were divided into current MDD (N=882), remitted MDD (N=635) and control (N=331) groups. MDD status and gene expression were measured again 2 years later in 414 subjects. The strongest gene expression differences were between the current MDD and control groups (129 genes at false-discovery rate, FDR<0.1). Gene expression differences across MDD status were largely unrelated to antidepressant use, inflammatory status and blood cell counts. Genes associated with MDD were enriched for interleukin-6 (IL-6)-signaling and natural killer (NK) cell pathways. We identified 13 gene expression clusters with specific clusters enriched for genes involved in NK cell activation (downregulated in current MDD, FDR=5.8 × 10(-5)) and IL-6 pathways (upregulated in current MDD, FDR=3.2 × 10(-3)). Longitudinal analyses largely confirmed results observed in the cross-sectional data. Comparisons of gene expression results to the Psychiatric Genomics Consortium (PGC) MDD genome-wide association study results revealed overlap with DVL3. In conclusion, multiple gene expression associations with MDD were identified and suggest a measurable impact of current MDD state on gene expression. Identified genes and gene clusters are enriched with immune pathways previously associated with the etiology of MDD, in line with the immune suppression and immune activation hypothesis of MDD.