Genome-scale methylation analysis of Parkinson's disease patients' brains reveals DNA hypomethylation and increased mRNA expression of cytochrome P450 2E1

Multiple lines of evidence suggest a link between environmental toxins and Parkinson's disease (PD). Although numerous studies reported associations of genetic variants in de-toxifying enzymes, i.e. cytochrome genes, with PD. Epigenetic modifications of genes and subsequent altered expression may confer a yet unappreciated level of susceptibility. We present a genome-wide methylation analysis of PD with quantitative DNA methylation levels of 27.500 CpG sites representing 14.495 genes. We found decreased methylation of the cytochrome P450 2E1 gene and increased expression of CYP2E1 messenger RNA in PD patients' brains, suggesting that epigenetic variants of this cytochrome contribute to PD susceptibility.     

颞叶癫痫microRNA基因甲基化模式分析及机制探究

目的重注释甲基化数据并构建microRNA(miRNA)基因甲基化谱,探究差异甲基化miRNA在颞叶癫痫(TLE)发生发展及耐药机制中的作用。方法收集TLE患者以及健康对照外周血,提取DNA进行全基因组DNA甲基化检测。将甲基化数据重注释至miRNA基因,统计分析筛选病例组与对照组以及临床亚组之间的差异甲基化miRNA,运用生物信息学方法对差异甲基化miRNA功能分析。结果 TLE和对照组间有82个miRNA基因甲基化存在差异(FDR5%),其中甲基化升高的70个。临床亚组间也存在差异甲基化miRNA基因(P0.01)。差异甲基化miRNA基因参与MAPK信号通路、神经营养信号通路等多条生物学通路。结论 TLE患者外周血miRNA基因组甲基化存在异常,以甲基化程度升高为主。差异甲基化miRNA基因参与多条生物学通路,可能在TLE发病及耐药机制中起到重要作用。     

Fracture risk is increased in epilepsy

OBJECTIVES: To study fracture rates and risk factors for fractures in non-institutionalized patients with epilepsy. MATERIAL AND METHODS: Historical follow-up. Self-administered questionnaires were issued to 755 patients with epilepsy (ICD 10: G40.0 to G40.9) and 1000 randomly selected controls from the background population. RESULTS: A total of 345 patients (median age: 45, range 17-80 years) and 654 control subjects (median age: 43, range 19-93 years) returned the questionnaire. Before epilepsy was diagnosed there was no difference in overall fracture rate between patients and controls (RR = 1.0, 95% CI: 0.8-1.3). After the diagnosis the overall fracture rate was significantly higher in the patients (RR = 2.0, 95% CI: 1.6-2.5). Fractures of the spine, forearms, femurs, lower legs, and feet and toes were significantly increased. Fractures related to seizures accounted for 33.9% (95% CI: 25.3-43.5%) of all fractures. After elimination of seizure related fractures the increase in fracture frequency was only borderline significant: RR = 1.3 (95% CI: 1.0-1.7, P = 0.042). No difference in fracture energy between patients and controls was observed (low energy fractures: 1.7/1.4%, medium energy fractures: 59.8/52.0%, and high energy fractures: 38.3/46.6%). Use of phenytoin (OR = 2.4, 95% CI: 1.1-5.4) and a family fracture history (OR = 2.4, 95% CI: 1.3-4.6) was associated with an increased fracture risk. CONCLUSIONS: Fractures were more common in epileptics than in controls especially among users of phenytoin. Most of the increase in fracture frequency was related to seizures and not to low bone biomechanical competence.     

Deep brain stimulation in epilepsy.

Since the pioneering studies of Cooper et al. to influence epilepsy by cerebellar stimulation, numerous attempts have been made to reduce seizure frequency by stimulation of deep brain structures. Evidence from experimental animal studies suggests the existence of a nigral control of the epilepsy system. It is hypothesized that the dorsal midbrain anticonvulsant zone in the superior colliculi is under inhibitory control of efferents from the substantia nigra pars reticulata. Inhibition of the subthalamic nucleus (STN) could release the inhibitory effect of the substantia nigra pars reticulata on the dorsal midbrain anticonvulsant zone and thus activate the latter, raising the seizure threshold. Modulation of the seizure threshold by stimulation of deep brain structures-in particular, of the STN-is a promising future treatment option for patients with pharmacologically intractable epilepsy. Experimental studies supporting the existence of the nigral control of epilepsy system and preliminary results of STN stimulation in animals and humans are reviewed, and alternative mechanisms of seizure suppression by STN stimulation are discussed.     

艾司西酞普兰对慢性应激大鼠海马脑源性神经营养因子基因外显子表达及DNA甲基化的影响

目的 探讨艾司西酞普兰对成年慢性应激大鼠海马脑源性神经营养因子(BDNF)基因不同外显子表达及DNA甲基化的影响.方法 以慢性不可预测温和应激(chronic unpredictablemild stress,CUMS)建立应激抑郁模型并予艾司西酞普兰干预.56只雄性Sprague-Dawley大鼠随机分为CUMS+水组、CUMS+药组、对照+水组及对照+药组,每组14只,以蔗糖水偏好试验评估大鼠抑郁样行为;模型建立第3周后分别检测上述各组大鼠海马BDNF基因第Ⅰ、Ⅱ、Ⅳ、Ⅵ外显子mRNA及BDNF总mRNA(第Ⅸ外显子)表达和第Ⅳ启动子区DNA甲基化水平.结果 (1)蔗糖水偏好试验:模型建立第2,3周,CUMS+水组[(34±21)％,(63±21)％]蔗糖水偏好均低于对照+水组[(67±15)％,(80±15)％],差异均有统计学意义(事后检验,P均＜0.05);而CUMS+药组[(58士19)％,(80±14)％]与对照+水组间的差异均无统计学意义(事后检验,P均＞0.05).(2)BDNF外显子表达:模型建立第3周,第Ⅳ外显子mRNA为BDNF总mRNA(第Ⅸ外显子)表达中的最主要者.CUMS+水组BDNF第Ⅳ及Ⅸ外显子mRNA水平[(4.64±0.65)×10-3,(5.73±0.79) ×10-3]均低于对照+水组[ (6.14±0.87)×10-3,(6.82±0.35)×10-3],差异均有统计学意义(事后检验,P均＜0.05);而CUMS+药组[(5.69±0.18)×10-3,(6.91±0.98)×10-3]与对照+水组间的差异均无统计学意义(事后检验,P均＞0.05).(3)DNA甲基化:各组大鼠海马BDNF第Ⅳ启动子区DNA均未发生甲基化.结论 艾司西酞普兰主要调节BDNF第Ⅳ外显子转录阻止CUMS成年大鼠海马的该基因表达下降,艾司西酞普兰第Ⅳ启动子区DNA甲基化无影响.     

Chronic cerebrovascular hypoperfusion affects global DNA methylation and histone acetylation in rat brain

DNA methylation and histone acetylation can be modified by various pathological or physiological factors such as hypoxia,thus influencing gene expression.In this study,we investigated the changes of global DNA methylation and histone acetylation and the related enzymes in rat brain after chronic cerebrovascular hypoperfusion by bilateral common carotid occlusion（2-VO） surgery.Colorimetric and immunohistochemistry staining were used to evaluate the global DNA methylation and histone acetylation levels,respectively.The expressions of DNA methyltransferase 1/3a（DNMT1/3a）,methyl-CpG binding domain protein 2（MBD2）,histone deacetylase 3（HDAC3） and acetyltransferase（HAT） were assessed by Western blot.We found that the level of global DNA methylation was decreased to 31.7%（P ＆lt;0.01） of the sham-operated group at 10 days and increased by 30%（P ＆lt;0.01） compared with the sham group at 90 days after 2-VO surgery.DNMT3a expression was down-regulated to 75.7% of the sham group,while MBD2 expression was up-regulated by 95% compared with sham group at 90 days after 2-VO.The histone H3 acetylation level was markedly decreased to 75.3% of the sham group at 10 days and 73.5% at 90 days after 2-VO,while no significant change was found for histone H4 acetylation.HDAC3 expression was markedly down-regulated to 36% of the sham group,whereas cAMP-response element binding protein expression was up-regulated by 33.6% compared with the sham group at 90 days after 2-VO.These results suggest that chronic cerebrovascular hypoperfusion influences global DNA methylation and histone acetylation levels through the related enzymes,and therefore might contribute to several neurodegenerative diseases.     

Peripheral serotonin transporter DNA methylation is linked to increased salience network connectivity in females with anorexia nervosa

BackgroundEpigenetic variation in the serotonin transporter gene (SLC6A4) has been shown to modulate the functioning of brain circuitry associated with the salience network and may heighten the risk for mental illness. This study is, to our knowledge, the first to test this epigenome–brain–behaviour pathway in patients with anorexia nervosa.MethodsWe obtained resting-state functional connectivity (rsFC) data and blood samples from 55 acutely underweight female patients with anorexia nervosa and 55 age-matched female healthy controls. We decomposed imaging data using independent component analysis. We used bisulfite pyrosequencing to analyze blood DNA methylation within the promoter region of SLC6A4. We then explored salience network rsFC patterns in the group × methylation interaction.ResultsWe identified a positive relationship between SLC6A4 methylation levels and rsFC between the dorsolateral prefrontal cortex and the salience network in patients with anorexia nervosa compared to healthy controls. Increased rsFC in the salience network mediated the link between SLC6A4 methylation and eating disorder symptoms in patients with anorexia nervosa. We confirmed findings of rsFC alterations for CpG-specific methylation at a locus with evidence of methylation correspondence between brain and blood tissue.Limitations: This study was cross-sectional in nature, the sample size was modest for the method and methylation levels were measured peripherally, so findings cannot be fully generalized to brain tissue.ConclusionThis study sheds light on the neurobiological process of how epigenetic variation in the SLC6A4 gene may relate to rsFC in the salience network that is linked to psychopathology in anorexia nervosa.     

Identification of chronic stress-activated regions reveals a potential recruited circuit in rat brain

Chronic stress induces presynaptic and postsynaptic modifications in the paraventricular nucleus of the hypothalamus that are consistent with enhanced excitatory hypothalamo-pituitary-adrenocortical (HPA) axis drive. The brain regions mediating these molecular modifications are not known. We hypothesized that chronic variable stress (CVS) tonically activates stress-excitatory regions that interact with the paraventricular nucleus of the hypothalamus, culminating in stress facilitation. In order to identify chronically activated brain regions, ΔFosB, a documented marker of tonic neuronal activation, was assessed in known stress regulatory limbic and brainstem sites. Four experimental groups were included: CVS, repeated restraint (RR) (control for HPA habituation), animals weight-matched (WM) to CVS animals (control for changes in circulating metabolic factors due to reduced weight gain), and non-handled controls. CVS, (but not RR or WM) induced adrenal hypertrophy, indicating that sustained HPA axis drive only occurred in the CVS group. CVS (but not RR or WM) selectively increased the number of FosB/ΔFosB nuclei in the nucleus of the solitary tract, posterior hypothalamic nucleus, and both the infralimbic and prelimbic divisions of the medial prefrontal cortex, indicating an involvement of these regions in chronic drive of the HPA axis. Increases in FosB/ΔFosB-immunoreactive cells were observed following both RR and CVS in the other regions (e.g. the dorsomedial hypothalamus), suggesting activation by both habituating and non-habituating stress conditions. The data suggest that unpredictable stress uniquely activates interconnected cortical, hypothalamic, and brainstem nuclei, potentially revealing the existence of a recruited circuitry mediating chronic drive of brain stress effector systems.     

PTSD is associated with increased DNA methylation across regions of HLA-DPB1 and SPATC1L

Posttraumatic stress disorder (PTSD) is characterized by intrusive thoughts, avoidance, negative alterations in cognitions and mood, and arousal symptoms that adversely affect mental and physical health. Recent evidence links changes in DNA methylation of CpG cites to PTSD. Since clusters of proximal CpGs share similar methylation signatures, identification of PTSD-associated differentially methylated regions (DMRs) may elucidate the pathways defining differential risk and resilience of PTSD. Here we aimed to identify epigenetic differences associated with PTSD. DNA methylation data profiled from blood samples using the MethylationEPIC BeadChip were used to perform a DMR analysis in 187 PTSD cases and 367 trauma-exposed controls from the Grady Trauma Project (GTP). DMRs were assessed with R package bumphunter. We identified two regions that associate with PTSD after multiple test correction. These regions were in the gene body of HLA-DPB1 and in the promoter of SPATC1L. The DMR in HLA-DPB1 was associated with PTSD in an independent cohort. Both DMRs included CpGs whose methylation associated with nearby sequence variation (meQTL) and that associated with expression of their respective genes (eQTM). This study supports an emerging literature linking PTSD risk to genetic and epigenetic variation in the HLA region.     

Gene expression profiling by mRNA sequencing reveals increased expression of immune/inflammation-related genes in the hippocampus of individuals with schizophrenia

Whole-genome expression profiling in postmortem brain tissue has recently provided insight into the pathophysiology of schizophrenia. Previous microarray and RNA-Seq studies identified several biological processes including synaptic function, mitochondrial function and immune/inflammation response as altered in the cortex of subjects with schizophrenia. Now using RNA-Seq data from the hippocampus, we have identified 144 differentially expressed genes in schizophrenia cases as compared with unaffected controls. Immune/inflammation response was the main biological process over-represented in these genes. The upregulation of several of these genes, IFITM1, IFITM2, IFITM3, APOL1 (Apolipoprotein L1), ADORA2A (adenosine receptor 2A), IGFBP4 and CD163 were validated in the schizophrenia subjects using data from the SNCID database and with quantitative RT-PCR. We identified a co-expression module associated with schizophrenia that includes the majority of differentially expressed genes related to immune/inflammation response as well as with the density of parvalbumin-containing neurons in the hippocampus. The results indicate that abnormal immune/inflammation response in the hippocampus may underlie the pathophysiology of schizophrenia and may be associated with abnormalities in the parvalbumin-containing neurons that lead to the cognitive deficits of the disease.