The role of methyl‑CpG binding domain 3 in seizures and epileptogenesis.

In Saccharomyces cerevisiae, splicing of HAC1 mRNA is initiated in response to the accumulation of unfolded proteins in the endoplasmic reticulum by the transmembrane kinase-endoribonuclease Ire1p. Spliced Hac1p (Hac1ip) is a negative regulator of differentiation responses to nitrogen starvation, pseudohyphal growth, and meiosis. Here we show that the RPD3-SIN3 histone deacetylase complex (HDAC), its catalytic activity, recruitment of the HDAC to the promoters of early meiotic genes (EMGs) by Ume6p, and the Ume6p DNA-binding site URS1 in the promoters of EMGs are required for nitrogen-mediated negative regulation of EMGs and meiosis by Hac1ip. Co-immunoprecipitation experiments demonstrated that Hac1ip can interact with the HDAC in vivo. Systematic analysis of double deletion strains revealed that HAC1 is a peripheral component of the HDAC. In summary, nitrogen-induced synthesis of Hac1ip and association of Hac1ip with the HDAC are physiological events in the regulation of EMGs by nutrients. These data also define for the first time a gene class that is under negative control by the UPR, and provide the framework for a novel mechanism through which bZIP proteins repress transcription.

The EF‑hand calcium binding protein tescalcin (TESC) is highly expressed in various human and mouse cancer tissues and is therefore considered a potential oncogene. However, the underlying mechanism that governs TESC expression remains unclear. Emerging evidence suggests that TESC expression is under epigenetic regulation. In the present study, the relationship between the epigenetic modification and gene expression of TESC in gastric cancer was investigated. To evaluate the relationship between the methylation and expression of TESC in gastric cancer, the methylation status of CpG sites in the TESC promoter was analyzed using microarray with the Illumina Human Methylation27 BeadChip (HumanMethylation27_270596_v.1.2), gene profiles from the NCBI Dataset that revealed demethylated status were acquired, and real‑time methylation‑specific PCR (MSP) in gastric cancer cells was conducted. In the present study, it was demonstrated that the hypermethylation of TESC led to the downregulation of TESC mRNA/protein expression. In addition, 5‑aza‑2c‑deoxycytidine (5'‑aza‑dC) restored TESC expression in the tested gastric cancer cells except for SNU‑620 cells. ChIP assay further revealed that the methylation of the TESC promoter was associated with methyl‑CpG binding domain protein (MBD)1, histone deacetylase (HDAC)2, and Oct‑1 and that treatment with 5'‑aza‑dC facilitated the dissociation of MBD1, HDAC2, and Oct‑1 from the promoter of TESC. Moreover, silencing of TESC increased MBD1 expression and decreased the H3K4me2/3 level, thereby causing transcriptional repression and suppression of cell survival in NCI‑N87 cells; conversely, overexpression of TESC downregulated MBD1 expression and upregulated the H3K4me2 level associated with active transcription in SNU‑638 cells. These results indicated that the differential expression of TESC via the modification status of the promoter and histone methylation controled cell survival in gastric cancer cells. Overall, the present study provided a novel therapeutic strategy for gastric cancer.

P.1.001 - Altered synaptic gain in amygdala circuits after Grik4 over-expression

Retroviral Vectors Induce Epigenetic Chromatin Modifications and IL-10 Production in Transduced B Cells via Activation of Toll-like Receptor 2

Methyl CpG binding domain 3 (Mbd3) protein belongs to the MBD family of proteins and is responsible for reading the DNA methylation pattern. Our previous study revealed increased levels of Nucleosome Remodeling and Deacetylase (NuRD) complex proteins, including Mbd3, in the brains of epileptic animals. The present study investigated whether the Mbd3 protein level determines the seizure threshold. We demonstrate that seizures induced by pentylenetetrazole (PTZ) cause a transient, brain area-specific increase in Mbd3 protein levels in the entorhinal cortex and amygdala. Overexpression of Mbd3 in the amygdala using AAV decreased anxiety, increased excitability in the open-field test, and accelerated epileptogenesis in the PTZ-kindling model. In vitro, mRNA profiling using RNA-seq in a model of magnesium deficiency-induced epileptiform discharges revealed complex, time- and state-specific changes in gene expression. Genes regulated by Mbd3 overexpression were associated with the Wnt and Notch pathways, potassium channel function, and GABAB receptor signaling. Our findings indicate that increased Mbd3 expression has pro-epileptic properties and contributes to the regulation of multiple pathways potentially involved in seizure development. Significantly, seizures themselves transiently elevate Mbd3 levels, suggesting a potential vicious circle that may aggravate disease progression. Targeting the pro-epileptic effects of Mbd3 could therefore represent a novel therapeutic approach in epilepsy.

Brain circuits between medial prefrontal cortex (mPFC) and amygdala have been implicated in cortical control of emotion, especially anxiety. Studies in recent years focus on differential roles of subregions of mPFC and amygdala, and reciprocal pathways between mPFC and amygdala in regulation of emotional behaviors. It has been shown that, while the projection from ventral mPFC to basomedial amygdala has an anxiolytic effect, the reciprocal projections between dorsal mPFC (dmPFC) and basolateral amygdala (BLA) are generally involved in an anxiogenic effect in various conditions with increased anxiety. However, the function of the projection from dmPFC to BLA in regulation of general emotional behaviors under normal conditions remains unclear. In this study, we used optogenetic analysis to identify how this dmPFC-BLA pathway regulates various emotional behaviors in normal rats. We found that optogenetic stimulation of the dmPFC-BLA pathway promoted a behavioral state of negative emotion, increasing anxiety-like and depressive-like behaviors and producing aversive behavior of place avoidance. Conversely, optogenetic inhibition of this pathway produced opposite effects, reducing anxiety-like and depressive-like behaviors, and inducing behaviors of place preference of reward. These findings suggest that activity of the dmPFC-BLA pathway is sufficient to drive a negative emotion state and the mPFC-amygdala circuit is tonically active in cortical regulation of emotional behaviors.

Decision letter: Prefrontal-amygdalar oscillations related to social behavior in mice

Editor's evaluation: Prefrontal-amygdalar oscillations related to social behavior in mice

The amygdala is central for social and emotional processing and has been implicated in various disorders including autism spectrum disorder (ASD) and Alzheimer's disease (AD). Animal research and some limited research with humans has indicated that widespread alterations in neuronal development or neuronal loss in the basolateral and other amygdala subnuclei may be a contributing factor to variations in social behaviours. Yet, the basolateral amygdala is comprised of three subnuclei, each with a specialized role related to the coordination of emotional regulation. Due to their small size, the nuclei which comprise the basolateral amygdala remain understudied in humans in vivo. In this work, we describe methodology to examine the basolateral amygdala and other subnuclei in human ex vivo medial temporal lobe prosections using ultrahigh-field magnetic resonance imaging (MRI) at 9.4T. Manual segmentations of the amygdala subnuclei on MR images, verified with immunohistochemical data, provide a robust three-dimensional atlas of the human amygdala. The goal is to apply the atlas to in vivo MRI scans to examine basolateral amygdala macrostructural development attributed to social cognitive dysfunction in ASD and other neurodevelopmental disorders. Furthermore, the atlas can be used to examine MRI-based correlates of neuronal loss commonly seen in neurodegenerative disorders.

Involvement of GABAA receptors in the regulation of social preference and emotional behaviors by oxytocin in the central amygdala of female mandarin voles

Paclitaxel is widely used as a first-line chemotherapy agent to treat malignant tumors. However, paclitaxel causes peripheral nerve fiber damage and neuropathic pain in some patients. In addition, patients received paclitaxel chemotherapy are often accompanied by negative emotions such as anxiety. The amygdala is critically involved in regulating pain signals, as well as anxiety. The purpose of this study is to clarify the role of Ca2+/calmodulin-dependent protein kinase II (CaMKII)-positive glutamatergic neurons in the amygdala in paclitaxel-induced pain and negative affective symptoms. Intraperitoneal injection of paclitaxel into mice caused mechanical and thermal allodynia, as measured by Von Frey test and Hargreaves test, and anxiety, as measured by open field test and elevated plus maze test. Immunofluorescence staining revealed that c-fos-positive neurons were significantly more in the basolateral amygdala (BLA) and central amygdala (CeA) in paclitaxel-treated mice than untreated mice. Furthermore, part of c-fos-positive neurons in the BLA were immunoreactive of CaMKII. Engineered Designer receptors exclusively activated by designer drugs (DREADD) receptor hM4Di or hM3Dq was selectively expressed on CaMKII neurons by injection of adeno-associated virus (AAV) vectors containing CaMKII and hM4Di or hM3Dq. Administration of DREADD agonist CNO to selectively inhibit the CaMKII neurons in the BLA significantly increased the paw withdrawal thresholds and paw withdrawal latencies. In addition, selectively inhibition of CaMKII neurons in the BLA alleviated anxiety behavior without affecting the motor activity. In summary, our findings suggest that CaMKII neurons in the amygdala are critical for neuropathic pain and anxiety behaviors induced by paclitaxel chemotherapy.

Introduction: The embryonic development of the vertebrate Central Nervous System (CNS) requires the induction of transcription factors regulating the expression of specific subsets of genes in restricted CNS regions. Among these transcription factors, homeobox-containing proteins play a crucial role, and altered expression of these factors can impact the embryonic as well as adult CNS functions. Importantly, the homeobox-containing genes Otx2, Engrailed-1 (En1), and Engrailed-2 (En2) have been described to crucially regulate differentiation of dopaminergic and serotonergic neurons during vertebrate CNS development. Dopaminergic and serotonergic neurons, located in midbrain and hindbrain regions respectively, diffusely innervate several forebrain areas including limbic system, contributing in regulating several physiological functions. Understanding the embryonic development of these neuronal populations is crucial to elucidate their physiological function including brain excitability in the adult brain. New evidence is emerging about the impact of an altered embryonic development of dopamine and serotonin neurons onto seizure susceptibility in the adult life. Methods: In this mini-review, we summarized our kainic acid (KA) induced seizure susceptibility in adult mutant mouse lines with targeted manipulation of Otx2, En1, and En2 genes. Results: Our results demonstrated that altered development of dopamine (DA) neurons does not interfere with KA seizure susceptibility, while increased serotonin (5-hydroxytryptamine, 5-HT) hyperinnervation leads to resistance to KA-induced seizure. Conclusion: We propose that developmental alterations of serotonergic but not dopaminergic circuits play a crucial role in controlling seizure susceptibility in the adult life

HCN channel activity-dependent modulation of inhibitory synaptic transmission in the rat basolateral amygdala

BackgroundDopaminergic circuits play important roles in the motivational control of behavior and dysfunction in dopaminergic circuits have been implicated in several psychiatric disorders, such as schizophrenia and depression. While these disorders exhibit different incidence rates in men and women, the potential sex differences in the underlying neural circuits are not well-understood. Previous anatomical tracing studies in mammalian species have revealed a prominent circuit projection connecting the dopaminergic midbrain ventral tegmental area (VTA) to the basolateral amygdala (BLA), which is involved in emotional processing and associative learning. However, whether there is any sex difference in this anatomical circuit remains unknown.MethodsTo study the potential sex differences in the VTA-to-BLA dopaminergic circuit, we injected two viral vectors encoding fluorescent reporters of axons and synaptic boutons (AAV–FLEX–tdTomato and AAV–FLEX–SynaptophysinGFP, respectively) into the VTA of a mouse transgenic driver line (tyrosine hydroxylase promoter-driven Cre, or TH-Cre), which restricts the reporter expression to dopaminergic neurons. We then used confocal fluorescent microscopy to image the distribution and density of dopaminergic axons and synaptic boutons in serial sections of both male and female mouse brain.ResultsWe found that the overall labeling intensity of VTA-to-BLA dopaminergic projections is intermediate among forebrain dopaminergic pathways, significantly higher than the projections to the prefrontal cortex, but lower than the projections to the nucleus accumbens. Within the amygdala areas, dopaminergic axons are concentrated in BLA. Although the size of BLA and the density of dopaminergic axons within BLA are similar between male and female mice, the density of dopaminergic synaptic boutons in BLA is significantly higher in male brain than female brain.ConclusionsOur results demonstrate an anatomical sex difference in mouse dopaminergic innervations from the VTA to BLA. This finding may provide a structural foundation to study neural circuit mechanisms underlying sex differences in motivational and emotional behaviors and related psychiatric dysfunctions.

Depression and alcohol dependence are associated with increased plasma ceramide concentrations in humans. Pharmacological increase in C16 ceramide concentrations in the dorsal hippocampus (DH) induced a depressive-like phenotype in naïve mice. However, the effects of C16 ceramide on alcohol consumption and anxiety-like behavior as well as the behavioral effects of other ceramide species are yet unknown. Therefore, we investigated whether repeated infusion of ceramides with different fatty acid chain lengths (C8, C16, and C20) into the DH and the basolateral amygdala (BLA) alter alcohol consumption, emotional behavior, and tissue monoamine levels. Our results revealed that C16, but not C8 and C20, ceramide altered alcohol drinking and emotional behavior in a brain region-specific way without altering tissue noradrenaline, dopamine, and serotonin levels in the prefrontal cortex, ventral striatum, and dorsal mesencephalon. In more detail, C16 ceramide increased alcohol consumption when infused into the BLA, but not when infused into the DH. Furthermore, C16 ceramide induced a depressive-like phenotype when infused into the DH, but a predominantly anxiogenic-like phenotype (in a non-social, but not a social context) when infused into the BLA. In turn, alcohol drinking normalized C16 ceramide-induced depressive-like and anxiogenic-like phenotypes. This study demonstrates a complex ceramide species-specific and brain region-specific modulation of alcohol consumption and emotional behavior in mice and provides the framework for future studies investigating the involvement of distinct ceramide species in the regulation of emotional behavior.