Promoter methylation of Egr-1 site contributes to fetal hypoxia-mediated PKCε gene repression in the developing heart

Early growth response-1: Key mediators of cell death and novel targets for cardiovascular disease therapy

Significance

Cardiovascular diseases are seen to be a primary cause of death, and their prevalence has significantly increased across the globe in the past few years. Several studies have shown that cell death is closely linked to the pathogenesis of cardiovascular diseases. Furthermore, many molecular and cellular mechanisms are involved in the pathogenesis of the cardiac cell death mechanism. One of the factors that played a vital role in the pathogenesis of cardiac cell death mechanisms included the early growth response-1 (Egr-1) factor.

Recent Advances

Studies have shown that abnormal Egr-1 expression is linked to different animal and human disorders like heart failure and myocardial infarction. The biosynthesis of Egr-1 regulates its activity. Egr-1 can be triggered by many factors such as serum, cytokines, hormones, growth factors, endotoxins, mechanical injury, hypoxia, and shear stress. It also displays a pro-apoptotic effect on cardiac cells, under varying stress conditions. EGR1 mediates a broad range of biological responses to oxidative stress and cell death by combining the acute changes occurring in the cellular environment with sustained changes in gene expression.

Future Directions

The primary regulatory role played by the Egr-1-targeting DNAzymes, microRNAs, and oligonucleotide decoy strategies in cardiovascular diseases were identified to provide a reference to identify novel therapeutic targets for cardiovascular diseases.

Androgens and Androgen Receptors as Determinants of Vascular Sex Differences Across the Lifespan

Androgens, including testosterone and its more potent metabolite dihydrotestosterone, exert multiple actions in the body. Physiologically, they play a critical role in male sex development. In addition, they influence vascular function, including arterial vasodilation and mediation of myogenic tone. Androgens are produced from 9 weeks' gestation in the human fetal testis, as well as in small amounts by the adrenal glands. Serum concentrations vary according to age and sex. The vasculature is a target for direct actions of androgens, which bind to various sex hormone receptors expressed in endothelial and vascular smooth muscle cells. Androgens exert both vasoprotective and vasoinjurious effects, depending on multiple factors including sex-specific effects of androgens, heterogeneity of the vascular endothelium, differential expression of androgen and sex hormone receptors in endothelial and vascular smooth muscle cells, and the chronicity of androgen administration. Long-term administration of androgens induces vasoconstriction and influences endothelial permeability, whereas acute administration may have opposite effects. At the cellular level, androgens stimulate endothelial cell production of nitric oxide and inhibit proinflammatory signalling pathways, inducing vasorelaxation and vasoprotection. However, androgens also activate endothelial production of vasoconstrictors and stimulate recruitment of endothelial progenitor cells. In humans, both androgen deficiency and androgen excess are associated with increased cardiovascular morbidity and mortality. This review discusses how androgens modulate vascular sex differences across the lifespan by considering the actions and production of androgens in both sexes and describes how cardiovascular risk is altered as levels of androgens change with aging.

Chronic hypoxia alters cardiac mitochondrial complex protein expression and activity in fetal guinea pigs in a sex-selective manner

We hypothesize that intrauterine hypoxia (HPX) alters the mitochondrial phenotype in fetal hearts contributing to developmental programming. Pregnant guinea pigs were exposed to normoxia (NMX) or hypoxia (HPX, 10.5% O2), starting at early [25 days (25d), 39d duration] or late gestation (50d, 14d duration). Near-term (64d) male and female fetuses were delivered by hysterotomy from anesthetized sows, and body/organ weights were measured. Left ventricles of fetal hearts were excised and frozen for measurement of expression of complex (I-V) subunits, fusion (Mfn2/OPA1) and fission (DRP1/Fis1) proteins, and enzymatic rates of I and IV from isolated mitochondrial proteins. Chronic HPX decreased fetal body weight and increased relative placenta weight regardless of timing. Early-onset HPX increased I, III, and V subunit levels, increased complex I but decreased IV activities in males but not females (all P < 0.05). Late-onset HPX decreased (P < 0.05) I, III, and V levels in both sexes but increased I and decreased IV activities in males only. Both HPX conditions decreased cardiac mitochondrial DNA content in males only. Neither early- nor late-onset HPX had any effect on Mfn2 levels but increased OPA1 in both sexes. Both HPX treatments increased DRP1/Fis1 levels in males. In females, early-onset HPX increased DRP1 with no effect on Fis1, whereas late-onset HPX increased Fis1 with no effect on DRP1. We conclude that both early- and late-onset HPX disrupts the expression/activities of select complexes that could reduce respiratory efficiency and shifts dynamics toward fission in fetal hearts. Thus, intrauterine HPX disrupts the mitochondrial phenotype predominantly in male fetal hearts, potentially altering cardiac metabolism and predisposing the offspring to heart dysfunction.

Single molecule characterization of the binding kinetics of a transcription factor and its modulation by DNA sequence and methylation

The interaction of transcription factors with their response elements in DNA is emerging as a highly complex process, whose characterization requires measuring the full distribution of binding and dissociation times in a well-controlled assay. Here, we present a single-molecule assay that exploits the thermal fluctuations of a DNA hairpin to detect the association and dissociation of individual, unlabeled transcription factors. We demonstrate this new approach by following the binding of Egr1 to its consensus motif and the three binding sites found in the promoter of the Lhb gene, and find that both association and dissociation are modulated by the 9 bp core motif and the sequences around it. In addition, CpG methylation modulates the dissociation kinetics in a sequence and position-dependent manner, which can both stabilize or destabilize the complex. Together, our findings show how variations in sequence and methylation patterns synergistically extend the spectrum of a protein's binding properties, and demonstrate how the proposed approach can provide new insights on the function of transcription factors.

DNA Methylation-Reprogrammed Ang II (Angiotensin II) Type 1 Receptor-Early Growth Response Gene 1-Protein Kinase C ε Axis Underlies Vascular Hypercontractility in Antenatal Hypoxic Offspring

As the most common clinical stress during mid and late pregnancy, antenatal hypoxia has profound adverse effects on individual's vascular health later in life, but the underlying mechanisms are still not understood. The purpose of this study was to reveal the mechanisms of the acquired vascular dysfunction in offspring imposed by antenatal hypoxia. Pregnant rats were housed in a normoxic or hypoxic (10.5% oxygen) chamber from gestation day 10 to 21. Male offspring were euthanized at gestational day 21 (fetus) or postnatal 16 weeks old (adult offspring). Mesenteric arteries were collected for examining Ang II (angiotensin II)-mediated vascular contractility, gene expression, and promoter methylation. Antenatal hypoxia increased vascular sensitivity to Ang II, which was resulted by an upregulated AT1R (angiotensin II type 1 receptor). The increased AT1R was correlated with a hypomethylation-mediated activated transcription of Agtr1a (alpha subtype of AT1R). In addition, we presented evidences that there was an AT1R-Egr1 (early growth response gene 1)-PKCε (ε isoform of protein kinase C) axis in vasculature; AT1R could modulate PKCε expression via upregulating Egr1; Egr1 mediated transcription activation of PKCε via Egr1 binding sites in PKCε gene promoter. Overall, antenatal hypoxia activated AT1R-Egr1-PKCε axis in vasculature, eventually predisposed offspring to vascular hypercontractility. This is the first description that antenatal hypoxia resulted in vascular adverse outcomes in postnatal offspring, was strongly associated with reprogrammed gene expression via a DNA methylation-mediated epigenetic mechanism, advancing understanding toward the influence of adverse antenatal factors in early life on long-term vascular health.

Sex differences and the effects of intrauterine hypoxia on growth and in vivo heart function of fetal guinea pigs

We hypothesized that the physiological adaptations of the fetus in response to chronic intrauterine hypoxia depend on its sex and the gestational age of exposure. Pregnant guinea pigs were exposed to room air (normoxia, NMX) or 10.5% O₂ (hypoxia, HPX) at either 25 days (early onset) or 50 days (late onset) of gestation until term (~65 days). We evaluated the effects of HPX on hemodynamic and cardiac function indices using Doppler ultrasound and determined sex-related differences in near-term fetuses. Indices of uterine/umbilical artery pulsatility (PI index) and fetal heart systolic and diastolic function [Tei index and passive filling (E-wave) to filling due to atrial contraction (A-wave) (E/A ratios), respectively] were measured in utero and fetal body (FBW) and organ weights measured from extracted fetuses. Both early- and late-onset HPX decreased FBW in both males and females, had no effect on placenta weights, and increased placenta weight-to-FBW ratios. Early- but not late-onset HPX increased uterine artery PI, but neither HPX condition affected umbilical artery PI. Early-onset HPX increased left ventricle E/A ratios in both males and females, whereas late-onset HPX increased the right ventricle E/A ratio in females only. Hypoxia had no effect on the Tei index in either sex. Early- and late-onset HPX induce placental insufficiency and fetal growth restriction and increase diastolic filling depending on the sex, with female fetuses having a greater capacity than males to compensate for intrauterine hypoxia.

Egr1/p300/ACE signal mediates postnatal osteopenia in female rat offspring induced by prenatal ethanol exposure

Prenatal ethanol exposure induces developmental toxicities of multiple organs in offspring. Here, we investigate the effects of prenatal ethanol exposure on bone mass in postnatal offspring and explore its intrauterine programming mechanism. We found that prenatal ethanol exposure could induce bone dysplasia in fetuses and postnatal osteopenia in female offspring, accompanied by the sustained activation of the local renin-angiotensin systems (RAS) and inhibition of bone formation. Additionally, we also found that histone 3 lysine 9 acetylation (H3K9ac) and H3K27ac levels in the promoter region of angiotensin-converting enzyme (ACE) were increased in female offspring exposed to ethanol during pregnancy. In vitro, ethanol suppressed the formation of mineralized nodules and osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs), which was blocked by enalapril. Furthermore, ethanol promoted the expression and nuclear translocation of early growth response factor 1 (Egr1), which participated in the promotion of histone acetylation of ACE and subsequent RAS activation, by recruiting p300 and binding to the ACE promoter region directly. These findings indicate that the sustained activation of the local RAS might participate in bone dysplasia in fetus and postnatal osteopenia in the female offspring, while the Egr1/p300/ACE signal might be a key promoter of the sustained activation of the local RAS of the long bone.

Cardiovascular Programming During and After Diabetic Pregnancy: Role of Placental Dysfunction and IUGR

Intrauterine growth restriction (IUGR) is a condition whereby a fetus is unable to achieve its genetically determined potential size. IUGR is a global health challenge due to high mortality and morbidity amongst affected neonates. It is a multifactorial condition caused by maternal, fetal, placental, and genetic confounders. Babies born of diabetic pregnancies are usually large for gestational age but under certain conditions whereby prolonged uncontrolled hyperglycemia leads to placental dysfunction, the outcome of the pregnancy is an intrauterine growth restricted fetus with clinical features of malnutrition. Placental dysfunction leads to undernutrition and hypoxia, which triggers gene modification in the developing fetus due to fetal adaptation to adverse utero environmental conditions. Thus, in utero gene modification results in future cardiovascular programming in postnatal and adult life. Ongoing research aims to broaden our understanding of the molecular mechanisms and pathological pathways involved in fetal programming due to IUGR. There is a need for the development of effective preventive and therapeutic strategies for the management of growth-restricted infants. Information on the mechanisms involved with in utero epigenetic modification leading to development of cardiovascular disease in adult life will increase our understanding and allow the identification of susceptible individuals as well as the design of targeted prevention strategies. This article aims to systematically review the latest molecular mechanisms involved in the pathogenesis of IUGR in cardiovascular programming. Animal models of IUGR that used nutrient restriction and hypoxia to mimic the clinical conditions in humans of reduced flow of nutrients and oxygen to the fetus will be discussed in terms of cardiac remodeling and epigenetic programming of cardiovascular disease. Experimental evidence of long-term fetal programming due to IUGR will also be included.

EGR-mediated control of STIM expression and function

Ca²⁺ is a ubiquitous, dynamic and pluripotent second messenger with highly context-dependent roles in complex cellular processes such as differentiation, proliferation, and cell death. These Ca²⁺ signals are generated by Ca²⁺-permeable channels located on the plasma membrane (PM) and endoplasmic reticulum (ER) and shaped by PM- and ER-localized pumps and transporters. Differences in the expression of these Ca²⁺ homeostasis proteins contribute to cell and context-dependent differences in the spatiotemporal organization of Ca²⁺ signals and, ultimately, cell fate. This review focuses on the Early Growth Response (EGR) family of zinc finger transcription factors and their role in the transcriptional regulation of Stromal Interaction Molecule (STIM1), a critical regulator of Ca²⁺ entry in both excitable and non-excitable cells.

Gestational Hypoxia and Developmental Plasticity

Hypoxia is one of the most common and severe challenges to the maintenance of homeostasis. Oxygen sensing is a property of all tissues, and the response to hypoxia is multidimensional involving complicated intracellular networks concerned with the transduction of hypoxia-induced responses. Of all the stresses to which the fetus and newborn infant are subjected, perhaps the most important and clinically relevant is that of hypoxia. Hypoxia during gestation impacts both the mother and fetal development through interactions with an individual's genetic traits acquired over multiple generations by natural selection and changes in gene expression patterns by altering the epigenetic code. Changes in the epigenome determine "genomic plasticity," i.e., the ability of genes to be differentially expressed according to environmental cues. The genomic plasticity defined by epigenomic mechanisms including DNA methylation, histone modifications, and noncoding RNAs during development is the mechanistic substrate for phenotypic programming that determines physiological response and risk for healthy or deleterious outcomes. This review explores the impact of gestational hypoxia on maternal health and fetal development, and epigenetic mechanisms of developmental plasticity with emphasis on the uteroplacental circulation, heart development, cerebral circulation, pulmonary development, and the hypothalamic-pituitary-adrenal axis and adipose tissue. The complex molecular and epigenetic interactions that may impact an individual's physiology and developmental programming of health and disease later in life are discussed.

Chronic hypoxia upregulates DNA methyltransferase and represses large conductance Ca2+-activated K+ channel function in ovine uterine arteries

Chronic hypoxia during gestation suppresses large-conductance Ca2+-activated K+ (BKCa) channel function and impedes uterine arterial adaptation to pregnancy. This study tested the hypothesis that chronic hypoxia has a direct effect in upregulating DNA methyltransferase (DNMT) and epigenetically repressing BKCa channel beta-1 subunit (KCNMB1) expression in uterine arteries. Resistance-sized uterine arteries were isolated from near-term pregnant sheep maintained at ∼300 m above sea level or animals acclimatized to high-altitude (3,801 m) hypoxia for 110 days during gestation. For ex vivo hypoxia treatment, uterine arteries from normoxic animals were treated with 21.0% O2 or 10.5% O2 for 48 h. High-altitude hypoxia significantly upregulated DNMT3b expression and enzyme activity in uterine arteries. Similarly, ex vivo hypoxia treatment upregulated DNMT3b expression and enzyme activity that was blocked by a DNMT inhibitor 5-aza-2'-deoxycytidine (5-Aza). Of importance, 5-Aza inhibited hypoxia-induced hypermethylation of specificity protein (SP) 1 binding site at the KCNMB1 promoter and restored transcription factor binding to the KCNMB1 promoter, resulting in the recovery of KCNMB1 gene expression in uterine arteries. Furthermore, 5-Aza blocked the effect of hypoxia and rescued BKCa channel activity and reversed hypoxia-induced decrease in BKCa channel-mediated relaxations and increase in myogenic tone of uterine arteries. Collectively, these results suggest that chronic hypoxia during gestation upregulates DNMT expression and activity, resulting in hypermethylation and repression of KCNMB1 gene and BKCa channel function, impeding uterine arterial adaptation to pregnancy.

cAMP/PKA/EGR1 signaling mediates the molecular mechanism of ethanol-induced inhibition of placental 11β-HSD2 expression

It is known that inhibiting 11β-hydroxysteroid dehydrogenase type 2 (11β-HSD2) expression in the placenta can cause fetal over-exposure to maternal glucocorticoids and induce intrauterine growth restriction (IUGR); these effects ultimately increase the risk of adult chronic diseases. This study aimed to investigate the molecular mechanism of the prenatal ethanol exposure (PEE)-induced inhibition of placental 11β-HSD2 expression. Pregnant Wistar rats were intragastrically administered ethanol (4 g/kg/d) from gestational days 9 to 20. The levels of maternal and fetal serum corticosterone and placental 11β-HSD2-related gene expression were analyzed. Furthermore, we investigated the mechanism of reduced placental 11β-HSD2 expression induced by ethanol treatment (15-60 mM) in HTR-8/SVneo cells. In vivo, PEE decreased fetal body weights and increased maternal and fetal serum corticosterone and early growth response factor 1 (EGR1) expression levels. Moreover, histone modification changes (decreased acetylation and increased di-methylation of H3K9) to the HSD11B2 promoter and lower 11β-HSD2 expression levels were observed. In vitro, ethanol decreased cAMP/PKA signaling and 11β-HSD2 expression and increased EGR1 expression in a concentration-dependent manner. A cAMP agonist and EGR1 siRNA reversed the ethanol-induced inhibition of 11β-HSD2 expression. Together, PEE reduced placental 11β-HSD2 expression, and the underlying mechanism is associated with ethanol-induced histone modification changes to the HSD11B2 promoter through the cAMP/PKA/EGR1 pathway.

DNA Methylation Variability in a Single Locus of the RXRα Promoter from Umbilical Vein Blood at Term Pregnancy

DNA methylation status of RXRα gene promoter has been correlated with maternal diet during early pregnancy, and associated with offspring's adiposity and bone mineral content. In adult life, increased methylation of RXRα promoter region is associated with myocardium pathologies. Early growth response proteins (EGR) are zinc finger transcription factors associated with several cellular pathways such as inflammation, apoptosis, and cardiopathies. DNA-binding sequences of EGR proteins have been reported in the RXRα gene promoter using chromatin immunoprecipitation methods. Here, we used correlations between the maternal pre-pregnancy body mass index (p-BMI), gestational weight gain (GWG), and birth weight (BW) as indirect indicators of the maternal nutritional status as modifier of DNA methylation in the offspring. DNA methylation status from newborns' umbilical vein blood in full-term pregnancy was evaluated in a short sequence (116 pb) of the RXRα gene promoter that contains the elements of response sequence for EGR proteins. Fifty-three bisulfite-modified DNA samples were assessed through methyl-sensitive high-resolution melting (MS-HRM) analysis. To validate the results, we directly sequenced MS-HRM samples to confirm the presence of CpG-methylated positions. In addition, the RXRα protein levels in extracts of umbilical vein blood were evaluated by western blot. We found differential methylation in a specific locus of the RXRα promoter surrounding the EGR-binding sequence; however, no correlation was found with the level of RXRα protein expression. Variability in the methylation status of the RXRα promoter near the EGR transcription factor binding site in newborn cord blood provides controversial epigenetic insights into RXRα regulation via EGR proteins.

Estrogen receptor β actions in the female cardiovascular system: A systematic review of animal and human studies

Five medical databases were searched for studies that assessed the role of ERβ in the female cardiovascular system and the influence of age and menopause on ERβ functioning. Of 9472 references, 88 studies met our inclusion criteria (71 animal model experimental studies, 15 human model experimental studies and 2 population based studies). ERβ signaling was shown to possess vasodilator and antiangiogenic properties by regulating the activity of nitric oxide, altering membrane ionic permeability in vascular smooth muscle cells, inhibiting vascular smooth muscle cell migration and proliferation and by regulating adrenergic control of the arteries. Also, a possible protective effect of ERβ signaling against left ventricular hypertrophy and ischemia/reperfusion injury via genomic and non-genomic pathways was suggested in 27 studies. Moreover, 5 studies reported that the vascular effects of ERβ may be vessel specific and may differ by age and menopause status. ERβ seems to possess multiple functions in the female cardiovascular system. Further studies are needed to evaluate whether isoform-selective ERβ-ligands might contribute to cardiovascular disease prevention.

The programming of cardiovascular disease

In spite of improving life expectancy over the course of the previous century, the health of the U.S. population is now worsening. Recent increasing rates of type 2 diabetes, obesity and uncontrolled high blood pressure predict a growing incidence of cardiovascular disease and shortened average lifespan. The daily >$1billion current price tag for cardiovascular disease in the United States is expected to double within the next decade or two. Other countries are seeing similar trends. Current popular explanations for these trends are inadequate. Rather, increasingly poor diets in young people and in women during pregnancy are a likely cause of declining health in the U.S. population through a process known as programming. The fetal cardiovascular system is sensitive to poor maternal nutritional conditions during the periconceptional period, in the womb and in early postnatal life. Developmental plasticity accommodates changes in organ systems that lead to endothelial dysfunction, small coronary arteries, stiffer vascular tree, fewer nephrons, fewer cardiomyocytes, coagulopathies and atherogenic blood lipid profiles in fetuses born at the extremes of birthweight. Of equal importance are epigenetic modifications to genes driving important growth regulatory processes. Changes in microRNA, DNA methylation patterns and histone structure have all been implicated in the cardiovascular disease vulnerabilities that cross-generations. Recent experiments offer hope that detrimental epigenetic changes can be prevented or reversed. The large number of studies that provide the foundational concepts for the developmental origins of disease can be traced to the brilliant discoveries of David J.P. Barker.

Structural impact of complete CpG methylation within target DNA on specific complex formation of the inducible transcription factor Egr-1

The inducible transcription factor Egr-1 binds specifically to 9-bp target sequences containing two CpG sites that can potentially be methylated at four cytosine bases. Although it appears that complete CpG methylation would make an unfavorable steric clash in the previous crystal structures of the complexes with unmethylated or partially methylated DNA, our affinity data suggest that DNA recognition by Egr-1 is insensitive to CpG methylation. We have determined, at a 1.4-Å resolution, the crystal structure of the Egr-1 zinc-finger complex with completely methylated target DNA. Structural comparison of the three different methylation states reveals why Egr-1 can recognize the target sequences regardless of CpG methylation.

Estrogen Regulates Angiotensin II Receptor Expression Patterns and Protects the Heart from Ischemic Injury in Female Rats

Previous studies have shown that female offspring are resistant to fetal stress-induced programming of ischemic-sensitive phenotype in the heart; however, the mechanisms responsible remain unclear. The present study tested the hypothesis that estrogen plays a role in protecting females in fetal programming of increased heart vulnerability. Pregnant rats were divided into normoxic and hypoxic (10.5% O2 from Day 15 to 21 of gestation) groups. Ovariectomy (OVX) and estrogen (E2) replacement were performed in 8-wk-old female offspring. Hearts of 4-mo-old females were subjected to ischemia and reperfusion injury in a Langendorff preparation. OVX significantly decreased postischemic recovery of left ventricular function and increased myocardial infarction, and no difference was observed between normoxic and hypoxic groups. The effect of OVX was rescued by E2 replacement. OVX decreased the binding of glucocorticoid receptor (GR) to glucocorticoid response elements at angiotensin II type 1 (Agtr1) and type 2 (Agtr2) receptor promoters, resulting in a decrease in Agtr1 and an increase in Agtr2 in the heart. Additionally, OVX decreased estrogen receptor (ER) expression in the heart and inhibited ER/GR interaction in binding to glucocorticoid response elements at the promoters. Consistent with the changes in Agtrs, OVX significantly decreased Prkce abundance in the heart. These OVX-induced changes were abrogated by E2 replacement. The results indicate that estrogen is not directly responsible for the sex dimorphism in fetal programming of heart ischemic vulnerability but suggest a novel mechanism of estrogen in regulating cardiac Agtr1/Agtr2 expression patterns and protecting female hearts against ischemia and reperfusion injury.

Litter and sex effects on maternal behavior and DNA methylation of the Nr3c1 exon 17 promoter gene in hippocampus and cerebellum

Early life events can alter gene expression through DNA methylation. The methylation status of the exon 17 promoter of the glucocorticoid receptor (Nr3c1 gene) in hippocampus associates with frequency of pup licking. Much of this work was conducted with male rats. Because dams more frequently lick male pups, this may contribute to sex differences in phenotypes through DNA methylation. Modifying litter gender composition (LGC), in which offspring of single-sex litters are compared to mixed-sex litters, alters maternal behavior. Previously, we demonstrated that LGC and sex affected pup licking times as well as anxiety and hippocampal DNA methylation of the Nr3c1 exon 17 promoter gene in adolescence. Now, we expand upon this work by examining effects in cerebellum and measuring mRNA levels. We also re-assessed DNA methylation in hippocampus using pyrosequencing and re-analyzed pup licking with the more commonly used frequency measure. Litters, culled to 8 pups on postnatal day 1 (PN1), were assigned to one of three conditions: all male (n = 10), all female (n = 12), or half of each sex (n = 20). Licking was rated on PN4, 7, and 10. On PN35, hippocampal and cerebellar samples were obtained. Single-sex males were licked the least and mixed-sex males, the most. Hippocampal Nr3c1 mRNA levels were lowest in mixed females with no LGC or Sex effects in DNA methylation. Cerebellar DNA methylation levels were lowest in mixed males with no effect on mRNA levels. Maternal pup licking associated with DNA methylation of the Nr3c1 exon 17 promoter gene in cerebellum and with hippocampal mRNA.

Epigenetic code and potential epigenetic-based therapies against chronic diseases in developmental origins

Accumulated findings have demonstrated that the epigenetic code provides a potential link between prenatal stress and changes in gene expression that could be involved in the developmental programming of various chronic diseases in later life. Meanwhile, based on the fact that epigenetic modifications are reversible and can be manipulated, this provides a unique chance to develop multiple novel epigenetic-based therapeutic strategies against many chronic diseases in early developmental periods. This article will give a short review of recent findings of prenatal insult-induced epigenetic changes in developmental origins of several chronic diseases, and will attempt to provide an overview of the current epigenetic-based strategies applied in the early prevention, diagnosis and possible therapies for human chronic diseases.