Epigenetic Regulation of Memory by Acetylation and Methylation of Chromatin: Implications in Neurological Disorders, Aging, and Addiction

Effect of acetate supplementation on traumatic stress-induced behavioral impairments in male rats

Gut microbiota and their metabolites have emerged as key players in the pathogenesis of neuropsychiatric disorders. Recently, we demonstrated that animals susceptible to Single Prolonged Stress (SPS) have an overall pro-inflammatory gut microbiota and significantly lower cecal acetate levels than SPS-resilient rats, which correlated inversely with the anxiety index. Here, we investigated whether the microbial metabolite, acetate, could ameliorate SPS-triggered impairments. Male rats were randomly divided into unstressed controls or groups exposed to SPS. The groups received continued oral supplementation of either 150 mM of sodium acetate or 150 mM of sodium chloride-matched water. Two weeks after SPS, a battery of behavioral tests was performed, and the animals were euthanized the following day. While not affecting the unstressed controls, acetate supplementation reduced the impact of SPS on body weight gain and ameliorated SPS-induced anxiety-like behavior and the impairments in social interaction, but not depressive-like behavior. These changes were accompanied by several beneficial effects of acetate supplementation. Acetate alleviated the stress response by reducing urinary epinephrine levels, induced epigenetic modification by decreasing histone deacetylase (HDAC2) gene expression, inhibited neuroinflammation by reducing the density of Iba1+ cells and the gene expression of IL-1ß in the hippocampus, and increased serum β-hydroxybutyrate levels. The findings reveal a causal relationship between oral acetate treatment and mitigation of several SPS-induced behavioral impairments. Mechanistically, it impacted neuronal and metabolic pathways including changes in stress response, epigenetic modifications, neuroinflammation and showed novel link to ketone body production. The study demonstrates the preventive-therapeutic potential of acetate supplementation to alleviate adverse responses to traumatic stress.

Histone deacetylase 1 regulates haloperidol-induced motor side effects in aged mice

BACKGROUND

Antipsychotic drugs prescribed to elderly patients with neuropsychiatric disorders often experience severe extrapyramidal side effects. Previous studies from our group suggest that changes in histone modifications during aging increase the risk for antipsychotic drug side effects, because co-administration of antipsychotics with class 1 histone deacetylase (HDAC) inhibitors could mitigate the severity of motor side effects in aged mice. However, which HDAC subtype contributes to the age-related sensitivity to antipsychotic drug side effects is unknown.

METHODS

In this study, we overexpressed histone deacetylase type 1(HDAC1) in the striatum of 3-month-old mice and knocked down HDAC 1 in the striatum of 21-month-old mice by microinjection of AAV9-HDAC1-GFP or AAV9-CRISPR/Cas9-HDAC1-GFP vectors. Four weeks after the viral-vector delivery, the typical antipsychotic drug haloperidol was administered daily for 14 days, followed by motor function assessments through the open field, rotarod, and catalepsy behavioral tests.

RESULTS

Young mice with overexpressed HDAC1 showed increased cataleptic behavior induced by haloperidol administration, which is associated with the increased HDAC1 level in the striatum. In contrast, aged mice with HDAC1 knocked down rescued locomotor activity, motor coordination, and decreased cataleptic behavior induced by haloperidol administration, which is associated with decreased HDAC1 level in the striatum.

CONCLUSIONS

Our results suggest that HDAC1 is a critical regulator in haloperidol-induced severe motor side effects in aged mice. Repression of HDAC1 expression in the striatum of aged mice could mitigate typical antipsychotic drug-induced motor side effects.

An enriched environment improves maternal sleep deprivation-induced cognitive deficits and synaptic plasticity via hippocampal histone acetylation

INTRODUCTION

Growing evidence clearly demonstrates that maternal rodents exposure to sleep deprivation (SD) during late pregnancy impairs learning and memory in their offspring. Epigenetic mechanisms, particularly histone acetylation, are known to be involved in synaptic plasticity, learning, and memory. We hypothesize that the cognitive decline induced by SD during late pregnancy is associated with histone acetylation dysfunction, and this effect could be reversed by an enriched environment (EE).

METHODS

In the present study, pregnant CD-1 mice were exposed to SD during the third trimester of pregnancy. After weaning, all offspring were randomly assigned to two subgroups in either a standard environment or an EE. When offspring were 3 months old, the Morris water maze was used to evaluate hippocampal-dependent learning and memory ability. Molecular biological techniques, including western blot and real-time fluorescence quantitative polymerase chain reaction, were used to examine the histone acetylation pathway and synaptic plasticity markers in the hippocampus of offspring.

RESULTS

The results showed that the following were all reversed by EE treatment: maternal SD (MSD)-induced cognitive deficits including spatial learning and memory; histone acetylation dysfunction including increased histone deacetylase 2 (HDAC2) and decreased histone acetyltransferase (CBP), and the acetylation levels of H3K9 and H4K12; synaptic plasticity dysfunction including decreased brain-derived neurotrophic factor; and postsynaptic density protein-95.

CONCLUSIONS

Our findings suggested that MSD could damage learning ability and memory in offspring via the histone acetylation pathway. This effect could be reversed by EE treatment.

Role of posttranslational modifications in memory and cognitive impairments caused by neonatal sevoflurane exposure

With the advancement of technology, increasingly many newborns are receiving general anesthesia at a young age for surgery, other interventions, or clinical assessment. Anesthetics cause neurotoxicity and apoptosis of nerve cells, leading to memory and cognitive impairments. The most frequently used anesthetic in infants is sevoflurane; however, it has the potential to be neurotoxic. A single, short bout of sevoflurane exposure has little impact on cognitive function, but prolonged or recurrent exposure to general anesthetics can impair memory and cognitive function. However, the mechanisms underlying this association remain unknown. Posttranslational modifications (PTMs), which can be described roughly as the regulation of gene expression, protein activity, and protein function, have sparked enormous interest in neuroscience. Posttranslational modifications are a critical mechanism mediating anesthesia-induced long-term modifications in gene transcription and protein functional deficits in memory and cognition in children, according to a growing body of studies in recent years. Based on these recent findings, our paper reviews the effects of sevoflurane on memory loss and cognitive impairment, discusses how posttranslational modifications mechanisms can contribute to sevoflurane-induced neurotoxicity, and provides new insights into the prevention of sevoflurane-induced memory and cognitive impairments.

Crosstalk between epigenetics and mTOR as a gateway to new insights in pathophysiology and treatment of Alzheimer's disease

Epigenetics in the current times has become a gateway to acquire answers to questions that were left unanswered by classical and modern genetics, be it resolving the complex mystery behind neurodegenerative disorders or understanding the complexity behind life-threatening cancers. It has presented to the world an entirely new dimension and has added a dynamic angle to an otherwise static field of genetics. Alzheimer's disease is one of the most prevalent neurodegenerative disorders is largely found to be a result of alterations in epigenetic pathways. These changes majorly comprise an imbalance in DNA methylation levels and altered acetylation and methylation of histones. They are often seen to cross-link with metabolic regulatory pathways such as that of mTOR, contributing significantly to the pathophysiology of AD. This review focusses on the study of the interplay of the mTOR regulatory pathway with that of epigenetic machinery that may elevate the rate of early diagnosis and prove to be a gateway to the development of an efficient and novel therapeutic strategy for the treatment of Alzheimer's disease at an early stage.

Dose Effects of Histone Deacetylase Inhibitor Tacedinaline (CI-994) on Antipsychotic Haloperidol-Induced Motor and Memory Side Effects in Aged Mice

Background: Elderly patients treated with antipsychotic drugs often experience increased severity and frequency of side effects, yet the mechanisms are not well understood. Studies from our group indicate age-related histone modifications at drug targeted receptor gene promoters may contribute to the increased side effects, and histone deacetylase (HDAC) inhibitors entinostat (MS-275) and valproic acid (VPA) could reverse typical antipsychotic haloperidol (HAL) induced motor-side effects. However, whether such effects could be dose dependent and whether HDAC inhibitors could improve memory function in aged mice is unknown. Methods: We co-treated selective class 1 HDAC inhibitor tacedinaline (CI-994) at different doses (10, 20, and 30 mg/kg) with HAL (0.05 mg/kg) in young (3 months) and aged (21 months) mice for 14 consecutive days, then motor and memory behavioral tests were conducted, followed by biochemical measurements. Results: CI-994 at doses of 10 and 20 mg/kg could decrease HAL-induced cataleptic episodes but only 20 mg/kg was sufficient to improve motor coordination in aged mice. Additionally, CI-994 at 10 and 20 mg/kg mitigate HAL-induced memory impairment in aged mice. Biochemical analyses showed increased acetylation of histone marks H3K27ac and H3K18ac at the dopamine 2 receptor (D2R) gene (Drd2) promoter and increased expression of the Drd2 mRNA and D2R protein in the striatum of aged mice after administration of CI-994 at 20 mg/kg. Conclusions: Our results suggest CI-994 can reduce HAL-induced motor and memory side effects in aged mice. These effects may act through an increase of acetylation at the Drd2 promoter, thereby restoring D2R expression and improving antipsychotic drug action.

The Effect of Histone Deacetylase Inhibitors Panobinostat or Entinostat on Motor Recovery in Mice After Ischemic Stroke

Using rigorous and clinically relevant experimental design and analysis standards, in this study, we investigated the potential of histone deacetylase (HDAC) inhibitors panobinostat and entinostat to enhance recovery of motor function after photothrombotic stroke in male mice. Panobinostat, a pan-HDAC inhibitor, is a FDA-approved drug for certain cancers, whereas entinostat is a class-I HDAC inhibitor in late stage of clinical investigation. The drugs were administered every other day (panobinostat-3 or 10 mg/kg; entinostat-1.7 or 5 mg/kg) starting from day 5 to 15 after stroke. To imitate the current standard of care in stroke survivors, i.e., physical rehabilitation, the animals run on wheels (2 h daily) from post-stroke day 9 to 41. The predetermined primary end point was motor recovery measured in two tasks of spontaneous motor behaviors in grid-walking and cylinder tests. In addition, we evaluated the running distance and speed throughout the study, and the number of parvalbumin-positive neurons in medial agranular cortex (AGm) and infarct volumes at the end of the study. Both sensorimotor tests revealed that combination of physical exercise with either drug did not substantially affect motor recovery in mice after stroke. This was accompanied by negligible changes of parvalbumin-positive neurons recorded in AGm and comparable infarct volumes among experimental groups, while dose-dependent increase in acetylated histone 3 was observed in peri-infarct cortex of drug-treated animals. Our observations suggest that add-on panobinostat or entinostat therapy coupled with limited physical rehabilitation is unlikely to offer therapeutic modality for stroke survivors who have motor dysfunction.

Identification of 4-hydroxynonenal-modified proteins in human osteoarthritic chondrocytes

The α,β-unsaturated aldehyde 4-hydroxynonenal (HNE) is formed through lipid peroxidation during oxidative stress. As a highly reactive electrophile, it is able to form adducts with various biomolecules, including proteins. These protein modifications could modulate many signaling pathways, as well as cell differentiation and proliferation, and thus could be highly important in the context of the extracellular matrix and degradation of articular cartilage. This study specifically investigated the role of HNE as a bioactive molecule in chondrocytes of osteoarthritis (OA) patients. Chondrocyte extracts of OA and non-OA patients were analyzed for HNE binding using Western blot and bottom-up LC-MS/MS analyses. HNE-modified histones, H2A and H2B, and histone deacetylase were identified using anti-HNE antibodies. Furthermore, peptide sequencing and database searching revealed 95 distinct HNE-modified proteins and their exact modification sites, with 88 protein adducts being unique to OA chondrocytes. HNE-proteins of specific interest included histone H2A, H2B and H4, collagen alpha-3(VI) chain, eukaryotic initiation factor 4A-I, and nucleolar RNA helicase 2. Comparing their MS/MS spectra to those of HNE-modified standard peptides further validated the six HNE-proteins. SIGNIFICANCE: HNE binding to proteins has been shown to result in multiple abnormalities of chondrocyte phenotype and function, suggesting its contribution in OA development. Considering the increased levels of HNE in OA cartilage, this reactive aldehyde could play a role in OA. This work represents a clinically-relevant in vivo study to demonstrate the pathophysiological role of HNE in human OA. Since HNE binding can alter protein conformation and function, it remains highly relevant to study the effects of this modification in OA.

Synthesis and Evaluation of 18F-INER-1577-3 as a Central Nervous System (CNS) Histone Deacetylase Imaging Agent

BACKGROUND

Epigenetic dysfunction is implicated in many neurologic, psychiatric and oncologic diseases. Consequently, histone deacetylases (HDACs) inhibitors have been developed as therapeutic and imaging agents for these diseases. However, only a few radiotracers have been developed as HDACs imaging agents for the central nervous system (CNS). We report herein the synthesis and evaluation of [¹⁸F]INER-1577-3 ([¹⁸F]5) as an HDACs imaging agent for CNS.

METHODS

[¹⁸F]INER-1577-3 ([¹⁸F]5) was synthesized by two methods: one-step (A) and two-step (B) methods. Briefly, radiofluorination of the corresponding precursors (11, 12) with K[¹⁸F]/K2.2.2 followed by purifications with HPLC gave ([¹⁸F]5). The quality of [¹⁸F]INER- 1577-3 synthesized by these methods was verified by HPLC and TLC as compared to an authentic sample. The inhibitions of [¹⁸F]INER-1577-3 and related HDACs inhibitors on tumor cells growth were carried out with breast cancer cell line 4T1 and MCF-7. The whole-body and brain uptake of [¹⁸F]INER-1577-3 in rats and AD mice were determined using a micro-PET scanner and the data was analyzed using PMOD.

RESULTS

The radiochemical yield of [¹⁸F]INER-1577-3 synthesized by these two methods was 1.4 % (Method A) and 8.8% (Method B) (EOB), respectively. The synthesis time was 115 min and 100 min, respectively, from EOB. The inhibition studies showed that INER-1577-3 has a significant inhibitory effect in HDAC6 and HDAC8 but not HDAC2. PET studies in rats and AD mice showed a maximum at about 15 min postinjection for the whole brain of a rat (0.47 ± 0.03 %ID/g), SAMP8 mice (5.63 ± 1.09 %ID/g) and SAMR1 mice (7.23 ± 1.21 %ID/g).

CONCLUSION

This study showed that INER-1577-3 can inhibit tumor cell growth and is one of a few HDACs inhibitors that can penetrate the blood-brain barrier (BBB) and monitor HDAC activities in AD mice. Thus, [¹⁸F]INER-1577-3 may be a potent HDACs imaging agent, especially for CNS.

Microglial memory of early life stress and inflammation: Susceptibility to neurodegeneration in adulthood

We review evidence supporting the role of early life programming in the susceptibility for adult neurodegenerative diseases while highlighting questions and proposing avenues for future research to advance our understanding of this fundamental process. The key elements of this phenomenon are chronic stress, neuroinflammation triggering microglial polarization, microglial memory and their connection to neurodegeneration. We review the mediating mechanisms which may function as early biomarkers of increased susceptibility for neurodegeneration. Can we devise novel early life modifying interventions to steer developmental trajectories to their optimum?

The Influence of Physical Activity and Epigenomics On Cognitive Function and Brain Health in Breast Cancer

The risk of breast cancer increases with age, with the majority of women diagnosed with breast cancer being postmenopausal. It has been estimated that 25-75% of women with breast cancer experience changes in cognitive function (CF) related to disease and treatment, which compromises psychological well-being, decision making, ability to perform daily activities, and adherence to cancer therapy. Unfortunately, the mechanisms that underlie neurocognitive changes in women with breast cancer remain poorly understood, which in turn limits the development of effective treatments and prevention strategies. Exercise has great potential as a non-pharmaceutical intervention to mitigate the decline in CF in women with breast cancer. Evidence suggests that DNA methylation, an epigenetic mechanism for gene regulation, impacts CF and brain health (BH), that exercise influences DNA methylation, and that exercise impacts CF and BH. Although investigating DNA methylation has the potential to uncover the biologic foundations for understanding neurocognitive changes within the context of breast cancer and its treatment as well as the ability to understand how exercise mitigates these changes, there is a dearth of research on this topic. The purpose of this review article is to compile the research in these areas and to recommend potential areas of opportunity for investigation.

Role of Post-translational Modifications in Alzheimer's Disease

The global burden of Alzheimer's disease (AD) is growing. Valiant efforts to develop clinical candidates for treatment have continuously met with failure. Currently available palliative treatments are temporary and there is a constant need to search for reliable disease pathways, biomarkers and drug targets for developing diagnostic and therapeutic tools to address the unmet medical needs of AD. Challenges in drug-discovery efforts raise further questions about the strategies of current conventional diagnosis; drug design; and understanding of disease pathways, biomarkers and targets. In this context, post-translational modifications (PTMs) regulate protein trafficking, function and degradation, and their in-depth study plays a significant role in the identification of novel biomarkers and drug targets. Aberrant PTMs of disease-relevant proteins could trigger pathological pathways, leading to disease progression. Advancements in proteomics enable the generation of patterns or signatures of such modifications, and thus, provide a versatile platform to develop biomarkers based on PTMs. In addition, understanding and targeting the aberrant PTMs of various proteins provide viable avenues for addressing AD drug-discovery challenges. This review highlights numerous PTMs of proteins relevant to AD and provides an overview of their adverse effects on the protein structure, function and aggregation propensity that contribute to the disease pathology. A critical discussion offers suggestions of methods to develop PTM signatures and interfere with aberrant PTMs to develop viable diagnostic and therapeutic interventions in AD.

Long-term epigenetic changes in offspring mice exposed to alcohol during gestation and lactation

BACKGROUND

Alcohol exposure impairs brain development and leads to a range of behavioural and cognitive dysfunctions, termed as foetal alcohol spectrum disorders. Although different mechanisms have been proposed to participate in foetal alcohol spectrum disorders, the molecular insights of such effects are still uncertain. Using a mouse model of foetal alcohol spectrum disorder, we have previously shown that maternal binge-like alcohol drinking causes persistent effects on motor, cognitive and emotional-related behaviours associated with neuroimmune dysfunctions.

AIMS

In this study, we sought to evaluate whether the long-term behavioural alterations found in offspring with early exposure to alcohol are associated with epigenetic changes in the hippocampus and prefrontal cortex.

METHODS

Pregnant C57BL/6 female mice underwent a model procedure for binge alcohol drinking throughout both the gestation and lactation periods. Subsequently, adult offspring were assessed for their cognitive function in a reversal learning task and brain areas were extracted for epigenetic analyses.

RESULTS

The results demonstrated that early binge alcohol exposure induces long-term behavioural effects along with alterations in histone acetylation (histone H4 lysine 5 and histone H4 lysine 12) in the hippocampus and prefrontal cortex. The epigenetic effects were linked with an imbalance in histone acetyltransferase activity that was found to be increased in the prefrontal cortex of mice exposed to alcohol.

CONCLUSIONS

In conclusion, our results reveal that maternal binge-like alcohol consumption induces persistent epigenetic modifications, effects that might be associated with the long-term cognitive and behavioural impairments observed in foetal alcohol spectrum disorder models.

Sirtuin 2 Inhibition Attenuates Sevoflurane-Induced Learning and Memory Deficits in Developing Rats via Modulating Microglial Activation

Sevoflurane is a widely used inhalational anesthetic in pediatric medicine that has been reported to have deleterious effects on the developing brain. Strategies to mitigate these detrimental effects are lacking. Sirtuin 2 (SIRT2) is a member of nicotinamide adenine dinucleotide (NAD⁺)-dependent protein deacetylases involved in a wide range of pathophysiological processes. SIRT2 inhibition has emerged as a promising treatment for an array of neurological disorders. However, the direct effects of SIRT2 on anesthesia-induced damage to the immature brain are unclear. Neonatal rats were exposed to 3% sevoflurane or 30% oxygen for 2 h daily with or without SIRT2 inhibitor AK7 pretreatment from postnatal day 7 (P7) to P9. One cohort of rats were euthanized 6, 12, and/or 24 h after the last gas exposure, and brain tissues were harvested for biochemical analysis and/or immunohistochemical examination. Cognitive functions were evaluated using the open field and Morris water maze tests on P25 and P28-32, respectively. SIRT2 was significantly up-regulated in neonatal rat hippocampus at 6 and 12 h post-anesthesia. Pretreatment with SIRT2 inhibitor AK7 reversed sevoflurane-induced hippocampus-dependent cognitive impairments. Furthermore, AK7 administration mitigated sevoflurane-induced neuroinflammation and microglial activation. Concomitantly, AK7 inhibited pro-inflammatory/M1-related markers and increased anti-inflammatory/M2-related markers in microglia. AK7 might prevent sevoflurane-induced neuroinflammation by switching microglia from the M1 to M2 phenotype. Downregulation of SIRT2 may be a novel therapeutic target for alleviating anesthesia-induced developmental neurotoxicity.

Neuroinflammation & pre-mature aging in the context of chronic HIV infection and drug abuse: Role of dysregulated autophagy

In the era of combined antiretroviral therapy (cART), HIV-1 infection has transformed from adeath sentenceto a manageable, chronic disease. Although the lifeexpectancy of HIV+ individuals is comparable to that of the uninfectedsubjects paradoxically, there is increased prevalence ofage-associatedcomorbidities such asatherosclerosis, diabetes, osteoporosis & neurological deficits in the context of HIV infection. Drug abuse is a commoncomorbidityofHIV infection andis often associated withincreased neurological complications. Chronic neuroinflammation (abnormal microglial and astrocyte activation) and neuronal synaptodendritic injury are the features of CNS pathology observed inHIV (+) individualsthat are takingcART & that abuse drugs. Neuroinflammation is thedrivingforceunderlying prematureaging associated with HIV (+) infection, cART and drugs of abuse. Autophagy is a highly conserved process critical for maintaining cellular homeostasis. Dysregulated autophagyhas been shown to be linked with abnormal immune responses & aging. Recent emerging evidence implicatesthe role ofHIV/HIV proteins, cART, & abused drugsin disrupting theautophagy process in brain cells such as microglia, astrocytes, and neurons. It can thus be envisioned that co-exposure of CNS cells to HIV proteins, cART and/or abused drugs couldhavesynergistic effects on theautophagy process, thereby leading to exaggerated microglial/astrocyte activation, ultimately, promotingthe aging process. Restoration of autophagic functioncould thusprovide an alternative therapeuticstrategy formitigating neuroinflammation & ameliorating the premature aging process. The current review aims to unravel the role of dysregulated autophagy in the context of single or co-exposure of microglia, astrocytes, and neurons to HIV/HIV proteins, drugs of abuse &/or cART and will also discuss the pathways involved in dysregulated autophagy-mediated neuroinflammation.

Compulsive methamphetamine taking and abstinence in the presence of adverse consequences: Epigenetic and transcriptional consequences in the rat brain

Methamphetamine addiction is characterized by compulsive binges of drug intake despite adverse life consequences. A model of methamphetamine self-administration that includes contingent footshocks to constitute adverse consequences has helped to segregate rats that reduce or stop lever pressing for methamphetamine (sensitive) from those that continue to lever press for the drug (resistant) in the presence of negative outcomes. We have observed differential DNA hydroxymethylation and increased expression of potassium channel mRNAs in the nucleus accumbens of sensitive compared to resistant rats, suggesting a role of these channels in suppressing methamphetamine intake. There were also significant increases in nerve growth factor (NGF) expression and activation of its downstream signaling pathway (NGF-TrkA and p75NTR/MAPK signaling) in only the dorsal striatum of sensitive rats after a month of abstinence. In contrast, oxytocin mRNA expression was increased in only the nucleus accumbens of resistant rats compared to sensitive rats euthanized after that time. These results indicate that footshocks can differentiate two behavioral phenotypes with differential biochemical and epigenetic consequences in the ventral and dorsal striatum.

Brain and Cognition for Addiction Medicine: From Prevention to Recovery Neural Substrates for Treatment of Psychostimulant-Induced Cognitive Deficits

Addiction to psychostimulants like cocaine, methamphetamine, and nicotine poses a continuing medical and social challenge both in the United States and all over the world. Despite a desire to quit drug use, return to drug use after a period of abstinence is a common problem among individuals dependent on psychostimulants. Recovery for psychostimulant drug-dependent individuals is particularly challenging because psychostimulant drugs induce significant changes in brain regions associated with cognitive functions leading to cognitive deficits. These cognitive deficits include impairments in learning/memory, poor decision making, and impaired control of behavioral output. Importantly, these drug-induced cognitive deficits often impact adherence to addiction treatment programs and predispose abstinent addicts to drug use relapse. Additionally, these cognitive deficits impact effective social and professional rehabilitation of abstinent addicts. The goal of this paper is to review neural substrates based on animal studies that could be pharmacologically targeted to reverse psychostimulant-induced cognitive deficits such as impulsivity and impairment in learning and memory. Further, the review will discuss neural substrates that could be used to facilitate extinction learning and thus reduce emotional and behavioral responses to drug-associated cues. Moreover, the review will discuss some non-pharmacological approaches that could be used either alone or in combination with pharmacological compounds to treat the above-mentioned cognitive deficits. Psychostimulant addiction treatment, which includes treatment for cognitive deficits, will help promote abstinence and allow for better rehabilitation and integration of abstinent individuals into society.

Dietary Modulation of the Epigenome

Epigenetics is the study of heritable mechanisms that can modify gene activity and phenotype without modifying the genetic code. The basis for the concept of epigenetics originated more than 2,000 yr ago as a theory to explain organismal development. However, the definition of epigenetics continues to evolve as we identify more of the components that make up the epigenome and dissect the complex manner by which they regulate and are regulated by cellular functions. A substantial and growing body of research shows that nutrition plays a significant role in regulating the epigenome. Here, we critically assess this diverse body of evidence elucidating the role of nutrition in modulating the epigenome and summarize the impact such changes have on molecular and physiological outcomes with regards to human health.

Epigenome Interactions with Patterned Neuronal Activity

The temporal coding of action potential activity is fundamental to nervous system function. Here we consider how gene expression in neurons is regulated by specific patterns of action potential firing, with an emphasis on new information on epigenetic regulation of gene expression. Patterned action potential activity activates intracellular signaling networks selectively in accordance with the kinetics of activation and inactivation of second messengers, phosphorylation and dephosphorylation of protein kinases, and cytoplasmic and nuclear calcium dynamics, which differentially activate specific transcription factors. Increasing evidence also implicates activity-dependent regulation of epigenetic mechanisms to alter chromatin architecture. Changes in three-dimensional chromatin structure, including chromatin compaction, looping, double-stranded DNA breaks, histone and DNA modification, are altered by action potential activity to selectively inhibit or promote transcription of specific genes. These mechanisms of activity-dependent regulation of gene expression are important in neural development, plasticity, and in neurological and psychological disorders.

Epigenetic Alterations in Anesthesia-Induced Neurotoxicity in the Developing Brain

Before birth and early in life, the developing brain is particularly sensitive to environmental and pharmacological influences. Increasing experimental evidence suggests that an association exists between exposure to anesthesia during a vulnerable period of brain development and subsequent poor neurodevelopmental outcomes. However, the mechanisms underlying this association are not fully understood. Epigenetics, broadly defined as the regulation of gene expression without alterations of DNA sequence, has become a field of tremendous interest in neuroscience. In recent years, a growing body of literature suggests that anesthesia-induced long-term changes in gene transcription and functional deficits in learning and behavior later in life are mediated via epigenetic modifications. This brief review provides an overview of epigenetic mechanisms and highlights the emerging roles played by epigenetic dysfunctions in the processes of anesthesia-induced neurotoxicity in the developing brain. Epigenetic targeting of DNA methyltransferases and/or histone deacetylases may have some therapeutic value. Epigenetics may lead to the identification of novel markers that contribute toward considerable translational significance in the field of neuroprotection.

Differential effects of MDMA and cocaine on inhibitory avoidance and object recognition tests in rodents

INTRODUCTION

Drug addiction continues being a major public problem faced by modern societies with different social, health and legal consequences for the consumers. Consumption of psychostimulants, like cocaine or MDMA (known as ecstasy) are highly prevalent and cognitive and memory impairments have been related with the abuse of these drugs.

AIM

The aim of this work was to review the most important data of the literature in the last 10 years about the effects of cocaine and MDMA on inhibitory avoidance and object recognition tests in rodents.

DEVELOPMENT

The object recognition and the inhibitory avoidance tests are popular procedures used to assess different types of memory. We compare the effects of cocaine and MDMA administration in these tests, taking in consideration different factors such as the period of life development of the animals (prenatal, adolescence and adult age), the presence of polydrug consumption or the role of environmental variables. Brain structures involved in the effects of cocaine and MDMA on memory are also described.

CONCLUSIONS

Cocaine and MDMA induced similar impairing effects on the object recognition test during critical periods of lifetime or after abstinence of prolonged consumption in adulthood. Deficits of inhibitory avoidance memory are observed only in adult rodents exposed to MDMA. Psychostimulant abuse is a potential factor to induce memory impairments and could facilitate the development of future neurodegenerative disorders.

New insights into molecular mechanisms of epigenetic regulation in kidney disease

The number of patients with kidney failure has increased in recent years. Different factors contribute to the progression of chronic kidney disease, including glomerular sclerosis, atherosclerosis of the renal arteries and tubulointerstitial fibrosis. Tubulointerstitial injury is induced by hypoxia and other inflammatory signals, leading to fibroblast activation. Technological advances using high-throughput sequencing has enabled the determination of the expression profile of almost all genes, revealing that gene expression is intricately regulated by DNA methylation, histone modification, changes in chromosome conformation, long non-coding RNAs and microRNAs. These epigenetic modifications are stored as cellular epigenetic memory. Epigenetic memory leads to adult-onset disease or ageing in the long term and may possibly play an important role in the kidney disease process. Herein we emphasize the importance of clarifying the molecular mechanisms underlying epigenetic modifications because this may lead to the development of new therapeutic targets in kidney disease.

Histone deacetylases (HDACs) as therapeutic target for depressive disorders

Major depressive disorder (MDD) represents approximately 40% of the disability caused by mental illnesses globally. The poorly understood pathophysiology and limited efficiency of pharmacological treatment (based primarily on the principles of the monoaminergic hypothesis) make depression a serious medical, public and socio-economical problem. An increasing number of studies suggest that epigenetic modifications (alterations in gene expression that are not due to changes in DNA sequence) in certain brain regions and neural circuits represent a key mechanism through which environmental factors interact with individual's genetic constitution to affect risk of mental disorders. Accordingly, chromatin-based epigenetic regulation seems to be a promising direction for the development of new, more effective antidepressant drugs. Recently, several inhibitors of histone deacetylases (HDAC) have been extensively studied in the context of antidepressant action. So far, none of them has been used to treat depression in humans due to the low selectivity for specific HDAC isoforms, and consequently, a risk of serious adverse events. In this review, we focus on the HDAC inhibitors (HDACi) with the greatest antidepressant efficacy and their activity in the preclinical studies. Moreover, we discuss their potential therapeutic usefulness in depression and the main limitations.

Histone deacetylase inhibitors reverse age-related increases in side effects of haloperidol in mice

BACKGROUND

Older patients can be especially susceptible to antipsychotic-induced side effects, and the pharmacodynamic mechanism underlying this phenomenon remains unclear. We hypothesized that age-related epigenetic alterations lead to decreased expression and functionality of the dopamine D2 receptor (D2R), contributing to this susceptibility.

METHODS

In this study, we treated young (2-3 months old) and aged (22-24 months old) C57BL/6 mice with the D2R antagonist haloperidol (HAL) once a day for 14 days to evaluate HAL-induced motor side effects. In addition, we pretreated separate groups of young and aged mice with histone deacetylase (HDAC) inhibitors valproic acid (VPA) or entinostat (MS-275) and then administered HAL.

RESULTS

Our results show that the motor side effects of HAL are exaggerated in aged mice as compared to young mice and that HDAC inhibitors are able to reverse the severity of these deficits. HAL-induced motor deficits in aged mice are associated with an age- and drug-dependent decrease in striatal D2R protein levels and functionality. Further, histone acetylation was reduced while histone tri-methylation was increased at specific lysine residues of H3 and H4 within the Drd2 promoter in the striatum of aged mice. HDAC inhibitors, particularly VPA, restored striatal D2R protein levels and functionality and reversed age- and drug-related histone modifications at the Drd2 promoter.

CONCLUSIONS

These results suggest that epigenetic changes at the striatal Drd2 promoter drive age-related increases in antipsychotic side effect susceptibility, and HDAC inhibitors may be an effective adjunct treatment strategy to reduce side effects in aged populations.

[Anti-ageing therapies in Alzheimer's disease]

Alzheimer's disease is the most common cause of dementia in the elderly population. Currently, there are no effective treatments to prevent or delay the natural course of the disease. Numerous studies have provided information about the molecular processes underlying biological ageing and, perhaps more importantly, potential interventions to slow ageing and promote healthy longevity in laboratory model systems. The main issue addressed in this review is whether an intervention that has anti-ageing properties can alter the appearance and/or progression of Alzheimer's disease, a disease in which age is the biggest risk factor. Different anti-ageing interventions have been shown to prevent (and in some cases possibly restore) several parameters recognised as central symptoms to the development of Alzheimer's disease. In addition, they are taking the first steps towards translating these laboratory discoveries into clinical applications.

Dynamic Expression Changes in the Transcriptome of the Prefrontal Cortex after Repeated Exposure to Cocaine in Mice

Prefrontal cortex (PFC)-dependent functions, such as executive function, explicit learning, and memory, are negatively affected in cocaine abusers and experimental animal models of cocaine treatment. However, its molecular mechanisms are less understood. In the present study, we performed transcriptome profiling of the dynamic changes in the PFC after repeated cocaine administration in mice. We found 463, 14, and 535 differentially expressed genes (DEGs) at 2 h, 24 h, and 7 days, respectively, after the withdrawal of chronic cocaine treatment. Time-series correlation analysis identified 5 clusters of statistically significant expression patterns. The expression levels of DEGs in Clusters 1 and 5 exhibited a gradual or fluctuant decrease, Cluster 2 exhibited an initial increase followed by a decrease or return to the baseline level, and Clusters 3 and 4 exhibited a fluctuant increase in the expression of DEGs. The Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis revealed that genes related to oxidative phosphorylation, ribosomes, and neurodegenerative disorder were enriched in Cluster 1; genes related to the mitogen activated protein kinase (MAPK), transforming growth factor (TGF)-β, insulin signaling, and circadian pathways were enriched in Cluster 2; genes related to plasticity-related pathways were enriched in Clusters 3 and 4; and genes related to the proteasome were enriched in Cluster 5. Our results suggest that maladaptive neural plasticity associated with psychostimulant dependence may be an ongoing degenerative process with dynamic changes in the gene network at different stages of withdrawal. Furthermore, it could be helpful to develop new therapeutic approaches according to different periods of abstinence.

Stress and the Emerging Roles of Chromatin Remodeling in Signal Integration and Stable Transmission of Reversible Phenotypes

The influence of early life experience and degree of parental-infant attachment on emotional development in children and adolescents has been comprehensively studied. Structural and mechanistic insight into the biological foundation and maintenance of mammalian defensive systems (metabolic, immune, nervous and behavioral) is slowly advancing through the emerging field of developmental molecular (epi)genetics. Initial evidence revealed that differential nurture early in life generates stable differences in offspring hypothalamic-pituitary-adrenal (HPA) regulation, in part, through chromatin remodeling and changes in DNA methylation of specific genes expressed in the brain, revealing physical, biochemical and molecular paths for the epidemiological concept of gene-environment interactions. Herein, a primary molecular mechanism underpinning the early developmental programming and lifelong maintenance of defensive (emotional) responses in the offspring is the alteration of chromatin domains of specific genomic regions from a condensed state (heterochromatin) to a transcriptionally accessible state (euchromatin). Conversely, DNA methylation promotes the formation of heterochromatin, which is essential for gene silencing, genomic integrity and chromosome segregation. Therefore, inter-individual differences in chromatin modifications and DNA methylation marks hold great potential for assessing the impact of both early life experience and effectiveness of intervention programs—from guided psychosocial strategies focused on changing behavior to pharmacological treatments that target chromatin remodeling and DNA methylation enzymes to dietary approaches that alter cellular pools of metabolic intermediates and methyl donors to affect nutrient bioavailability and metabolism. In this review article, we discuss the potential molecular mechanism(s) of gene regulation associated with chromatin modeling and programming of endocrine (e.g., HPA and metabolic or cardiovascular) and behavioral (e.g., fearfulness, vigilance) responses to stress, including alterations in DNA methylation and the role of DNA repair machinery. From parental history (e.g., drugs, housing, illness, nutrition, socialization) to maternal-offspring exchanges of nutrition, microbiota, antibodies and stimulation, the nature of nurture provides not only mechanistic insight into how experiences propagate from external to internal variables, but also identifies a composite therapeutic target, chromatin modeling, for gestational/prenatal stress, adolescent anxiety/depression and adult-onset neuropsychiatric disease.

Assessing histone demethylase inhibitors in cells: lessons learned

BACKGROUND

Histone lysine demethylases (KDMs) are of interest as drug targets due to their regulatory roles in chromatin organization and their tight associations with diseases including cancer and mental disorders. The first KDM inhibitors for KDM1 have entered clinical trials, and efforts are ongoing to develop potent, selective and cell-active 'probe' molecules for this target class. Robust cellular assays to assess the specific engagement of KDM inhibitors in cells as well as their cellular selectivity are a prerequisite for the development of high-quality inhibitors. Here we describe the use of a high-content cellular immunofluorescence assay as a method for demonstrating target engagement in cells.

RESULTS

A panel of assays for the Jumonji C subfamily of KDMs was developed to encompass all major branches of the JmjC phylogenetic tree. These assays compare compound activity against wild-type KDM proteins to a catalytically inactive version of the KDM, in which residues involved in the active-site iron coordination are mutated to inactivate the enzyme activity. These mutants are critical for assessing the specific effect of KDM inhibitors and for revealing indirect effects on histone methylation status. The reported assays make use of ectopically expressed demethylases, and we demonstrate their use to profile several recently identified classes of KDM inhibitors and their structurally matched inactive controls. The generated data correlate well with assay results assessing endogenous KDM inhibition and confirm the selectivity observed in biochemical assays with isolated enzymes. We find that both cellular permeability and competition with 2-oxoglutarate affect the translation of biochemical activity to cellular inhibition.

CONCLUSIONS

High-content-based immunofluorescence assays have been established for eight KDM members of the 2-oxoglutarate-dependent oxygenases covering all major branches of the JmjC-KDM phylogenetic tree. The usage of both full-length, wild-type and catalytically inactive mutant ectopically expressed protein, as well as structure-matched inactive control compounds, allowed for detection of nonspecific effects causing changes in histone methylation as a result of compound toxicity. The developed assays offer a histone lysine demethylase family-wide tool for assessing KDM inhibitors for cell activity and on-target efficacy. In addition, the presented data may inform further studies to assess the cell-based activity of histone lysine methylation inhibitors.

Neurosteroids Involvement in the Epigenetic Control of Memory Formation and Storage

Memory is our ability to store and remember past experiences; it is the result of changes in neuronal circuits of specific brain areas as the hippocampus. During memory formation, neurons integrate their functions and increase the strength of their connections, so that synaptic plasticity is improved and consolidated. All these processes recruit several proteins at the synapses, whose expression is highly regulated by DNA methylation and histone tails posttranslational modifications. Steroids are known to influence memory process, and, among them, neurosteroids are implicated in neurodegenerative disease related to memory loss and cognitive impairment. The epigenetic control of neurosteroids involvement in memory formation and maintenance could represent the basis for neuroregenerative therapies.

Isoflurane-induced inactivation of CREB through histone deacetylase 4 is responsible for cognitive impairment in developing brain

Anesthetics including isoflurane are known to induce neuronal dysfunction in the developing brain, however, the underlying mechanism is mostly unknown. The transcriptional activation of CREB (cyclic AMP response element binding protein) and the alterations in acetylation of histones modulated by several histone deacetylases such as HDAC4 (histone deacetylase 4) are known to contribute to synaptic plasticity in the brain. Here we have shown that administration of isoflurane (1.4%) for 2h leads to transcriptional inactivation of CREB which results in loss of dendritic outgrowth and decreased expression level of proteins essential for memory and cognitive functions, such as BDNF, and c-fos in the developing brain of mice at postnatal day 7 (PND7). To elucidate the molecular mechanism, we found that exposure to isoflurane leads to an increase in nuclear translocation of HDAC4, which interacts with CREB in the nucleus. This event, in turn, results in a decrease in interaction between an acetyltransferase, CBP, and CREB that ultimately leads to transcriptional inactivation of CREB. As a result, the expression level of BDNF, and c-fos were significantly down-regulated after administration of isoflurane in PND7 brain. Depletion of HDAC4 in PND7 brain rescues the transcriptional activation of CREB along with augmentation in the level of the expression level of BDNF and c-fos. Moreover, administration of lentiviral particles of HDAC4 RNAi in primary neurons rescues neurite outgrowth following isoflurane treatment. Taken together, our study suggests that HDAC4-induced transcriptional inactivation of CREB is responsible for isoflurane-induced cognitive dysfunction in the brain.

Expression Profiles of SIRT1 and APP Genes in Human Neuroblastoma SK-N-SH Cells Treated with Two Epigenetic Agents

In our previous studies, significant hypermethylation of the sirtuin 1 (SIRT1) gene and demethylation of the β-amyloid precursor protein (APP) gene were found in patients with Alzheimer's disease (AD) compared with the normal population. Moreover, the expression of SIRT1 was significantly decreased while that of APP was increased in AD patients. These results indicated a correlation of DNA methylation with gene expression levels in AD patients. To further investigate the epigenetic mechanism of gene modulation in AD, we used two epigenetic drugs, the DNA methylation inhibitor 5-aza-2'-deoxycytidine (DAC) and the histone deacetylase inhibitor trichostatin A (TSA), to treat human neuroblastoma SK-N-SH cells in the presence of amyloid β-peptide Aβ25-35(Aβ25-35). We found that DAC and TSA had different effects on the expression trends of SIRT1 and APP in the cell model of amyloid toxicity. Although other genes, such as microtubule-associated protein τ, presenilin 1, presenilin 2, and apolipoprotein E, were up-regulated after Aβ25-35 treatment, no significant differences were found after DAC and/or TSA treatment. These results support the evidence in AD patients and reveal a strong correlation of SIRT1/APP expression with DNA methylation and/or histone modification, which may help understand the pathogenesis of AD.

Different Patterns of Acetylation and Dimethylation of Histone H3 between Young and Aged Cases with Chronic Tonsillitis: Influences of Inflammation and Aging

INTRODUCTION

Epigenetics is now considered to be crucially involved in normal genetics and differentiation and in pathological conditions, such as cancer, aging, and inflammation. Epigenetic mechanisms involve DNA methylation and histone modifications. The purpose of this study was to investigate the effects of inflammation on epigenetics in young subjects and the effect of aging.

MATERIALS AND METHODS

The palatine tonsils were extracted from child and adult patients with chronic tonsillitis. Hematoxylin-eosin staining was performed to examine the morphology of the palatine tonsils. A fluorescence immunological examination was also performed to detect acetyl-histone H3 or dimethyl-histone H3. Confocal scanning microscopy was used for observations.

RESULTS

Acetylated histone H3 was detected in tonsils from child patients but not from adult patients. Dimethylated histone H3 was not detected in tonsils from either group of patients. Degeneration of the tonsillar structures was apparent in tonsils from adult patients.

DISCUSSION

The differential expression of acetylated histone H3 Lys9 may reflect immunological differences between young and aged tonsils. The decrease observed in the activity of histone methyltransferase induced the down-regulated expression of methylated histone H3.

CONCLUSION

Our results suggest that epigenetic changes participate in chronic inflammation and aging in the palatine tonsils. Although the results do not lead to a direct treatment, the epigenetic pathogenesis of chronic inflammation, such as immunoglobulin A nephropathy, by focal infections will be described in greater detail in future studies, which will lead to new treatments being developed.

Epigenetics in Legg-Calvé-Perthes disease: A study of global DNA methylation

OBJECTIVE

To examine the global methylation status of DNA in blood cells of children with Legg-Calvé-Perthes disease (LCPD), since the aetiopathogenesis of LCPD remains unclear, and many factors closely associated with DNA methylation may be linked to the occurrence of LCPD.

METHODS

Children with LCPD and age-, sex- and body mass index-matched controls were evaluated. Methylation levels of the long interspersed nuclear element 1 (LINE-1), a biomarker of global DNA methylation, were quantified by methylation-specific polymerase chain reaction.

RESULTS

Of 82 children with LCPD (68 male/14 female) and 120 matched controls (98 male/22 female), methylation of the LINE-1 promoter was significantly lower in patients with LCPD compared with controls. Subgroup analyses showed that methylation of the LINE-1 promoter was significantly lower in male patients with LCPD compared with male controls. No significant between-group differences were observed in female participants.

CONCLUSIONS

Reduced global DNA methylation may be associated with increased risk of LCPD in male children. Further research is required to understand whether detection of global DNA methylation may provide a basis for clinical diagnosis and early intervention of LCPD.

The Molecular Neurobiology of Twelve Steps Program & Fellowship: Connecting the Dots for Recovery

There are some who suggest that alcoholism and drug abuse are not diseases at all and that they are not consequences of a brain disorder as espoused recently by the American Society of Addiction Medicine (ASAM). Some would argue that addicts can quit on their own and moderate their alcohol and drug intake. When they present to a treatment program or enter the 12 Step Program & Fellowship, many addicts finally achieve complete abstinence. However, when controlled drinking fails, there may be successful alternatives that fit particular groups of individuals. In this expert opinion, we attempt to identify personal differences in recovery, by clarifying the molecular neurobiological basis of each step of the 12 Step Program. We explore the impact that the molecular neurobiological basis of the 12 steps can have on Reward Deficiency Syndrome (RDS) despite addiction risk gene polymorphisms. This exploration has already been accomplished in part by Blum and others in a 2013 Springer Neuroscience Brief. The purpose of this expert opinion is to briefly, outline the molecular neurobiological and genetic links, especially as they relate to the role of epigenetic changes that are possible in individuals who regularly attend AA meetings. It begs the question as to whether "12 steps programs and fellowship" does induce neuroplasticity and continued dopamine D2 receptor proliferation despite carrying hypodopaminergic type polymorphisms such as DRD2 A1 allele. "Like-minded" doctors of ASAM are cognizant that patients in treatment without the "psycho-social-spiritual trio," may not be obtaining the important benefits afforded by adopting 12-step doctrines. Are we better off with coupling medical assisted treatment (MAT) that favors combining dopamine agonist modalities (DAM) as possible histone-deacetylase activators with the 12 steps followed by a program that embraces either one or the other? While there are many unanswered questions, at least we have reached a time when "science meets recovery," and in doing so, can further redeem joy in recovery.

Histone-mediated epigenetics in addiction

Many of the brain regions, neurotransmitter systems, and behavioral changes that occur after occasional drug use in healthy subjects and after chronic drug abuse in addicted patients are well characterized. An emerging literature suggests that epigenetic processes, those processes that regulate the accessibility of DNA to regulatory proteins within the nucleus, are keys to how addiction develops and how it may be treated. Investigations of the regulation of chromatin, the organizational system of DNA, by histone modification are leading to a new understanding of the cellular and behavioral alterations that occur after drug use. We will describe how, when, and where histone tails are modified and how some of the most recognized histone regulation patterns are involved in the cycle of addiction, including initial and chronic drug intake, withdrawal, abstinence, and relapse. Finally, we consider how an approach that targets histone modifications may promote successful treatment.

The glucagon-like peptide-1 receptor as a potential treatment target in alcohol use disorder: evidence from human genetic association studies and a mouse model of alcohol dependence

The hormone glucagon-like peptide-1 (GLP-1) regulates appetite and food intake. GLP-1 receptor (GLP-1R) activation also attenuates the reinforcing properties of alcohol in rodents. The present translational study is based on four human genetic association studies and one preclinical study providing data that support the hypothesis that GLP-1R may have a role in the pathophysiology of alcohol use disorder (AUD). Case-control analysis (N = 908) was performed on a sample of individuals enrolled in the National Institute on Alcohol Abuse and Alcoholism (NIAAA) intramural research program. The Study of Addiction: Genetics and Environment (SAGE) sample (N = 3803) was used for confirmation purposes. Post hoc analyses were carried out on data from a human laboratory study of intravenous alcohol self-administration (IV-ASA; N = 81) in social drinkers and from a functional magnetic resonance imaging study in alcohol-dependent individuals (N = 22) subjected to a Monetary Incentive Delay task. In the preclinical study, a GLP-1R agonist was evaluated in a mouse model of alcohol dependence to demonstrate the role of GLP-1R for alcohol consumption. The previously reported functional allele 168Ser (rs6923761) was nominally associated with AUD (P = 0.004) in the NIAAA sample, which was partially replicated in males of the SAGE sample (P = 0.033). The 168 Ser/Ser genotype was further associated with increased alcohol administration and breath alcohol measures in the IV-ASA experiment and with higher BOLD response in the right globus pallidus when receiving notification of outcome for high monetary reward. Finally, GLP-1R agonism significantly reduced alcohol consumption in a mouse model of alcohol dependence. These convergent findings suggest that the GLP-1R may be an attractive target for personalized pharmacotherapy treatment of AUD.

A Neuronal Activity-Dependent Dual Function Chromatin-Modifying Complex Regulates Arc Expression

Chromatin modification is an important epigenetic mechanism underlying neuroplasticity. Histone methylation and acetylation have both been shown to modulate gene expression, but the machinery responsible for mediating these changes in neurons has remained elusive. Here we identify a chromatin-modifying complex containing the histone demethylase PHF8 and the acetyltransferase TIP60 as a key regulator of the activity-induced expression of Arc, an important mediator of synaptic plasticity. Clinically, mutations in PHF8 cause X-linked mental retardation while TIP60 has been implicated in the pathogenesis of Alzheimer's disease. Within minutes of increased synaptic activity, this dual function complex is rapidly recruited to the Arc promoter, where it specifically counteracts the transcriptionally repressive histone mark H3K9me2 to facilitate the formation of the transcriptionally permissive H3K9acS10P, thereby favoring transcriptional activation. Consequently, gain-of-function of the PHF8-TIP60 complex in primary rat hippocampal neurons has a positive effect on early activity-induced Arc gene expression, whereas interfering with the function of this complex abrogates it. A global proteomics screen revealed that the majority of common interactors of PHF8 and TIP60 were involved in mRNA processing, including PSF, an important molecule involved in neuronal gene regulation. Finally, we proceeded to show, using super-resolution microscopy, that PHF8 and TIP60 interact at the single molecule level with PSF, thereby situating this chromatin modifying complex at the crossroads of transcriptional activation. These findings point toward a mechanism by which an epigenetic pathway can regulate neuronal activity-dependent gene transcription, which has implications in the development of novel therapeutics for disorders of learning and memory.

Melatonin regulates aging and neurodegeneration through energy metabolism, epigenetics, autophagy and circadian rhythm pathways

Brain aging is linked to certain types of neurodegenerative diseases and identifying new therapeutic targets has become critical. Melatonin, a pineal hormone, associates with molecules and signaling pathways that sense and influence energy metabolism, autophagy, and circadian rhythms, including insulin-like growth factor 1 (IGF-1), Forkhead box O (FoxOs), sirtuins and mammalian target of rapamycin (mTOR) signaling pathways. This review summarizes the current understanding of how melatonin, together with molecular, cellular and systemic energy metabolisms, regulates epigenetic processes in the neurons. This information will lead to a greater understanding of molecular epigenetic aging of the brain and anti-aging mechanisms to increase lifespan under healthy conditions.

Superior pattern processing is the essence of the evolved human brain

Humans have long pondered the nature of their mind/brain and, particularly why its capacities for reasoning, communication and abstract thought are far superior to other species, including closely related anthropoids. This article considers superior pattern processing (SPP) as the fundamental basis of most, if not all, unique features of the human brain including intelligence, language, imagination, invention, and the belief in imaginary entities such as ghosts and gods. SPP involves the electrochemical, neuronal network-based, encoding, integration, and transfer to other individuals of perceived or mentally-fabricated patterns. During human evolution, pattern processing capabilities became increasingly sophisticated as the result of expansion of the cerebral cortex, particularly the prefrontal cortex and regions involved in processing of images. Specific patterns, real or imagined, are reinforced by emotional experiences, indoctrination and even psychedelic drugs. Impaired or dysregulated SPP is fundamental to cognitive and psychiatric disorders. A broader understanding of SPP mechanisms, and their roles in normal and abnormal function of the human brain, may enable the development of interventions that reduce irrational decisions and destructive behaviors.