Background Childhood maltreatment and early trauma leave lasting imprints on neural mechanisms of cognition and emotion. With a rat model of infant maltreatment by a caregiver, we investigated ...whether early-life adversity leaves lasting epigenetic marks at the brain-derived neurotrophic factor ( BDNF ) gene in the central nervous system. Methods During the first postnatal week, we exposed infant rats to stressed caretakers that predominately displayed abusive behaviors. We then assessed DNA methylation patterns and gene expression throughout the life span as well as DNA methylation patterns in the next generation of infants. Results Early maltreatment produced persisting changes in methylation of BDNF DNA that caused altered BDNF gene expression in the adult prefrontal cortex. Furthermore, we observed altered BDNF DNA methylation in offspring of females that had previously experienced the maltreatment regimen. Conclusions These results highlight an epigenetic molecular mechanism potentially underlying lifelong and transgenerational perpetuation of changes in gene expression and behavior incited by early abuse and neglect.
•Epigenetic mechanisms regulate the memory consolidation and reconsolidation processes.•Epigenetic mechanisms can regulate memory updating during the reconsolidation process.•Epigenetic mechanisms ...may be regulated by NMDA-mediated plasticity during reconsolidation.
Memory consolidation involves transcriptional control of genes in neurons to stabilize a newly formed memory. Following retrieval, a once consolidated memory destabilizes and again requires gene transcription changes in order to restabilize, a process referred to as reconsolidation. Understanding the molecular mechanisms of gene transcription during the consolidation and reconsolidation processes could provide crucial insights into normal memory formation and memory dysfunction associated with psychiatric disorders. In the past decade, modifications of epigenetic markers such as DNA methylation and posttranslational modifications of histone proteins have emerged as critical transcriptional regulators of gene expression during initial memory formation and after retrieval. In light of the rapidly growing literature in this exciting area of research, we here examine the most recent and latest evidence demonstrating how memory acquisition and retrieval trigger epigenetic changes during the consolidation and reconsolidation phases to impact behavior. In particular we focus on the reconsolidation process, where we discuss the already identified epigenetic regulators of gene transcription during memory reconsolidation, while exploring other potential epigenetic modifications that may also be involved, and expand on how these epigenetic modifications may be precisely and temporally controlled by important signaling cascades critical to the reconsolidation process. Finally, we explore the possibility that epigenetic mechanisms may serve to regulate a system or circuit level reconsolidation process and may be involved in retrieval-dependent memory updating. Hence, we propose that epigenetic mechanisms coordinate changes in neuronal gene transcription, not only during the initial memory consolidation phase, but are triggered by retrieval to regulate molecular and cellular processes during memory reconsolidation.
Abstract The transcription of genes that support memory processes are likely to be impacted by the normal aging process. Because Arc is necessary for memory consolidation and enduring synaptic ...plasticity, we examined Arc transcription within the aged hippocampus. Here, we report that Arc transcription is reduced within the aged hippocampus compared to the adult hippocampus during both “off line” periods of rest, and following spatial behavior. This reduction is observed within ensembles of CA1 “place cells”, which make less mRNA per cell, and in the dentate gyrus (DG) where fewer granule cells are activated by behavior. In addition, we present data suggesting that aberrant changes in methylation of the Arc gene may be responsible for age-related decreases in Arc transcription within CA1 and the DG. Given that Arc is necessary for normal memory function, these subregion-specific epigenetic and transcriptional changes may result in less efficient memory storage and retrieval during aging.
It has been established that regulation of chromatin structure through post-translational modification of histone proteins, primarily histone H3 phosphorylation and acetylation, is an important early ...step in the induction of synaptic plasticity and formation of long-term memory. In this study, we investigated the contribution of another histone modification, histone methylation, to memory formation in the adult hippocampus. We found that trimethylation of histone H3 at lysine 4 (H3K4), an active mark for transcription, is upregulated in hippocampus 1 h following contextual fear conditioning. In addition, we found that dimethylation of histone H3 at lysine 9 (H3K9), a molecular mark associated with transcriptional silencing, is increased 1 h after fear conditioning and decreased 24 h after context exposure alone and contextual fear conditioning. Trimethylated H3K4 levels returned to baseline levels at 24 h. We also found that mice deficient in the H3K4-specific histone methyltransferase, Mll, displayed deficits in contextual fear conditioning relative to wild-type animals. This suggests that histone methylation is required for proper long-term consolidation of contextual fear memories. Interestingly, inhibition of histone deacetylases (HDACs) with sodium butyrate (NaB) resulted in increased H3K4 trimethylation and decreased H3K9 dimethylation in hippocampus following contextual fear conditioning. Correspondingly, we found that fear learning triggered increases in H3K4 trimethylation at specific gene promoter regions (Zif268 and bdnf) with altered DNA methylation and MeCP2 DNA binding. Zif268 DNA methylation levels returned to baseline at 24 h. Together, these data demonstrate that histone methylation is actively regulated in the hippocampus and facilitates long-term memory formation.
Highlights • Grin2b / Nr2b and Bdnf DNA methylation is altered in the epileptic hippocampus. • Grin2b / Nr2b and Bdnf gene and protein expression is correlated with DNA methylation. • SE triggered ...early and late increases in DNA methylating and demethylating enzymes. • DNMT inhibition altered SE-induced hippocampal methylation and synaptic plasticity. • DNMT inhibition restored decreases in AP2alpha binding at the Nr2b gene promoter.
It is well established that fear memory formation requires de novo gene transcription in the amygdala. We provide evidence that epigenetic mechanisms in the form of histone lysine methylation in the ...lateral amygdala (LA) are regulated by NMDA receptor (NMDAR) signaling and involved in gene transcription changes necessary for fear memory consolidation. Here we found increases in histone H3 lysine 9 dimethylation (H3K9me2) levels in the LA at 1 h following auditory fear conditioning, which continued to be temporally regulated up to 25 h following behavioral training. Additionally, we demonstrate that inhibiting the H3K9me2 histone lysine methyltransferase G9a (H/KMTs-G9a) in the LA impaired fear memory, while blocking the H3K9me2 histone lysine demethylase LSD1 (H/KDM-LSD1) enhanced fear memory, suggesting that H3K9me2 in the LA can bidirectionally regulate fear memory formation. Furthermore, we show that NMDAR activity differentially regulated the recruitment of H/KMT-G9a, H/KDM-LSD1, and subsequent H3K9me2 levels at a target gene promoter. This was largely regulated by GluN2B- but not GluN2A-containing NMDARs via ERK activation. Moreover, fear memory deficits associated with NMDAR or ERK blockade were successfully rescued through pharmacologically inhibiting LSD1, suggesting that enhancements of H3K9me2 levels within the LA can rescue fear memory impairments that result from hypofunctioning NMDARs or loss of ERK signaling. Together, the present study suggests that histone lysine methylation regulation in the LA via NMDAR-ERK-dependent signaling is involved in fear memory formation.
•This study introduces an improved deer hunting optimization enabled multihop routing (IDHO-MHR) protocol for WSN.•In addition, the IDHO-MHR technique primarily derives a fitness function with the ...inclusion of two major variables namely residual energy (RE) and distance.•The nodes with higher RE and minimum distance have the probability of becoming optimal routes from the networks.
A wireless sensor network (WSN) encompasses a huge set of sensor nodes employed to collect data and transmit it to a base station (BS). Due to its compact, inexpensive, and scalable nature of sensors, WSN finds its applicability in diverse real-time applications. The battery-operated sensor nodes necessitate the design of a multi-hop routing protocol for the effective utilization of available energy in the network. Routing can be considered an optimization problem and can be solved by the design of bioinspired algorithms. This study introduces an improved deer hunting optimization-enabled multihop routing (IDHO-MHR) protocol for WSN. The major intention of the IDHO-MHR approach is to optimally find the routes to the destination in WSN. The IDHO algorithm is initially derived by the incorporation of the Nelder Mead (NM) concept into the traditional DHO algorithm. In addition, the IDHO-MHR technique primarily derives a fitness function with the inclusion of two major variables, namely residual energy (RE) and distance. The nodes with higher RE and minimum distance have the probability of becoming optimal routes from the networks. The performance validation of the IDHO-MHR approach is performed, and the outcomes are inspected in various aspects. The experimental outcomes reported the supremacy of the IDHO-MHR protocol over the other recent approaches.
Diffuse idiopathic skeletal hyperostosis (DISH) is an incompletely defined disease process with no known unifying pathophysiological mechanism.
To our knowledge, no genetic studies have been ...performed in a North American population. To summarize genetic findings from previous studies and to comprehensively test for these associations in a novel and diverse, multi-institutional population.
Cross-sectional, single nucleotide polymorphism (SNP) analysis was performed in 55 of 121 enrolled patients with DISH. Baseline demographic data were available on 100 patients. Based on allele selection from previous studies and related disease conditions, sequencing was performed on COL11A2, COL6A6, fibroblast growth factor 2 gene, LEMD3, TGFB1, and TLR1 genes and compared with global haplotype rates.
Consistent with previous studies, older age (mean 71 years), male sex predominance (80%), a high frequency of type 2 diabetes (54%), and renal disease (17%) were observed. Unique findings included high rates of tobacco use (11% currently smoking, 55% former smoker), a higher predominance of cervical DISH (70%) relative to other locations (30%), and an especially high rate of type 2 diabetes in patients with DISH and ossification of the posterior longitudinal ligament (100%) relative to DISH alone (100% vs 47%, P < .001). Compared with global allele rates, we found higher rates of SNPs in 5 of 9 tested genes ( P < .05).
We identified 5 SNPs in patients with DISH that occurred more frequently than a global reference. We also identified novel environmental associations. We hypothesize that DISH represents a heterogeneous condition with both multiple genetic and environmental influences.
DNA (cytosine-5) methylation represents one of the most widely used mechanisms of enduring cellular memory. Stable patterns of DNA methylation are established during development, resulting in ...creation of persisting cellular phenotypes. There is growing evidence that the nervous system has co-opted a number of cellular mechanisms used during development to subserve the formation of long term memory. In this study, we examined the role DNA (cytosine-5) methyltransferase (DNMT) activity might play in regulating the induction of synaptic plasticity. We found that the DNA within promoters for reelin and brain-derived neurotrophic factor, genes implicated in the induction of synaptic plasticity in the adult hippocampus, exhibited rapid and dramatic changes in cytosine methylation when DNMT activity was inhibited. Moreover, zebularine and 5-aza-2-deoxycytidine, inhibitors of DNMT activity, blocked the induction of long term potentiation at Schaffer collateral synapses. Activation of protein kinase C in the hippocampus decreased reelin promoter methylation and increased DNMT3A gene expression. Interestingly, DNMT activity is required for protein kinase C-induced increases in histone H3 acetylation. Considered together, these results suggest that DNMT activity is dynamically regulated in the adult nervous system and that DNMT may play a role in regulating the induction of synaptic plasticity in the mature CNS.
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