Blood-Brain Barrier Integrity Is Perturbed in a Mecp2-Null Mouse Model of Rett Syndrome.

Rett syndrome (RTT, online MIM 312750) is a devastating neurodevelopmental disorder characterized by motor and cognitive disabilities. It is mainly caused by pathogenetic variants in the X-linked MECP2 gene, encoding an epigenetic factor crucial for brain functioning. Despite intensive studies, the RTT pathogenetic mechanism remains to be fully elucidated. Impaired vascular function has been previously reported in RTT mouse models; however, whether an altered brain vascular homeostasis and the subsequent blood-brain barrier (BBB) breakdown occur in RTT and contribute to the disease-related cognitive impairment is still unknown. Interestingly, in symptomatic Mecp2-null (Mecp2-/y, Mecp2tm1.1Bird) mice, we found enhanced BBB permeability associated with an aberrant expression of the tight junction proteins Ocln and Cldn-5 in different brain areas, in terms of both transcript and protein levels. Additionally, Mecp2-null mice showed an altered expression of different genes encoding factors with a role in the BBB structure and function, such as Cldn3, Cldn12, Mpdz, Jam2, and Aqp4. With this study, we provide the first evidence of impaired BBB integrity in RTT and highlight a potential new molecular hallmark of the disease that might open new perspectives for the setting-up of novel therapeutic strategies.

Transcriptomic profiles of the ruminal wall in Italian Mediterranean dairy buffaloes fed green forage.

BACKGROUND: Green feed diet in ruminants exerts a beneficial effect on rumen metabolism and enhances the content of milk nutraceutical quality. At present, a comprehensive analysis focused on the identification of genes, and therefore, biological processes modulated by the green feed in buffalo rumen has never been reported. We performed RNA-sequencing in the rumen of buffaloes fed a total mixed ration (TMR) + the inclusion of 30% of ryegrass green feed (treated) or TMR (control), and identified differentially expressed genes (DEGs) using EdgeR and NOISeq tools. RESULTS: We found 155 DEGs using EdgeR (p-values < 0.05) and 61 DEGs using NOISeq (prob ≥0.8), 30 of which are shared. The rt-qPCR validation suggested a higher reliability of EdgeR results as compared with NOISeq data, in our biological context. Gene Ontology analysis of DEGs identified using EdgeR revealed that green feed modulates biological processes relevant for the rumen physiology and, then, health and well-being of buffaloes, such as lipid metabolism, response to the oxidative stress, immune response, and muscle structure and function. Accordingly, we found: (i) up-regulation of HSD17B13, LOC102410803 (or PSAT1) and HYKK, and down-regulation of CDO1, SELENBP1 and PEMT, encoding factors involved in energy, lipid and amino acid metabolism; (ii) enhanced expression of SIM2 and TRIM14, whose products are implicated in the immune response and defense against infections, and reduced expression of LOC112585166 (or SAAL1), ROR2, SMOC2, and S100A11, encoding pro-inflammatory factors; (iii) up-regulation of NUDT18, DNAJA4 and HSF4, whose products counteract stressful conditions, and down-regulation of LOC102396388 (or UGT1A9) and LOC102413340 (or MRP4/ABCC4), encoding detoxifying factors; (iv) increased expression of KCNK10, CACNG4, and ATP2B4, encoding proteins modulating Ca2+ homeostasis, and reduced expression of the cytoskeleton-related MYH11 and DES. CONCLUSION: Although statistically unpowered, this study suggests that green feed modulates the expression of genes involved in biological processes relevant for rumen functionality and physiology, and thus, for welfare and quality production in Italian Mediterranean dairy buffaloes. These findings, that need to be further confirmed through the validation of additional DEGs, allow to speculate a role of green feed in the production of nutraceutical molecules, whose levels might be enhanced also in milk.

The aberrant epigenome of DNMT3B-mutated ICF1 patient iPSCs is amenable to correction, with the exception of a subset of regions with H3K4me3- and/or CTCF-based epigenetic memory.

Bi-allelic hypomorphic mutations in DNMT3B disrupt DNA methyltransferase activity and lead to immunodeficiency, centromeric instability, facial anomalies syndrome, type 1 (ICF1). Although several ICF1 phenotypes have been linked to abnormally hypomethylated repetitive regions, the unique genomic regions responsible for the remaining disease phenotypes remain largely uncharacterized. Here we explored two ICF1 patient-derived induced pluripotent stem cells (iPSCs) and their CRISPR-Cas9-corrected clones to determine whether DNMT3B correction can globally overcome DNA methylation defects and related changes in the epigenome. Hypomethylated regions throughout the genome are highly comparable between ICF1 iPSCs carrying different DNMT3B variants, and significantly overlap with those in ICF1 patient peripheral blood and lymphoblastoid cell lines. These regions include large CpG island domains, as well as promoters and enhancers of several lineage-specific genes, in particular immune-related, suggesting that they are premarked during early development. CRISPR-corrected ICF1 iPSCs reveal that the majority of phenotype-related hypomethylated regions reacquire normal DNA methylation levels following editing. However, at the most severely hypomethylated regions in ICF1 iPSCs, which also display the highest increases in H3K4me3 levels and/or abnormal CTCF binding, the epigenetic memory persists, and hypomethylation remains uncorrected. Overall, we demonstrate that restoring the catalytic activity of DNMT3B can reverse the majority of the aberrant ICF1 epigenome. However, a small fraction of the genome is resilient to this rescue, highlighting the challenge of reverting disease states that are due to genome-wide epigenetic perturbations. Uncovering the basis for the persistent epigenetic memory will promote the development of strategies to overcome this obstacle.

NPPA/atrial natriuretic peptide is an extracellular modulator of autophagy in the heart.

NPPA/atrial natriuretic peptide (natriuretic peptide type A) exerts critical pleiotropic effects in the cardiovascular system, limiting cardiomyocyte hypertrophy and death, reducing cardiac fibrosis and promoting vascular integrity. However, the molecular mechanisms underlying these beneficial effects still need to be clarified. We demonstrated for the first time that macroautophagy/autophagy is involved in the local protective effects of NPPA in cardiomyocytes (CMs), both in vitro and in vivo. Exogenous NPPA rapidly activates autophagy in CMs through NPR1/type A natriuretic peptide receptor and PRKG/protein kinase G signaling and also increases cardiac autophagy in mice. Remarkably, endogenous NPPA is secreted by CMs in response to glucose deprivation or hypoxia, thereby stimulating autophagy through autocrine/paracrine mechanisms. NPPA preserves cell viability and reduces hypertrophy in response to stress through autophagy activation. In vivo, we found that Nppa knockout mice undergoing ischemia-reperfusion (I/R) show increased infarct size and reduced autophagy. Reactivation of autophagy by Tat-Beclin D11 limits I/R injury. We also found that the protective effects of NPPA in reducing infarct size are abrogated in the presence of autophagy inhibition. Mechanistically, we found that NPPA stimulates autophagy through the activation of TFEB (transcription factor EB). Our data suggest that NPPA is a novel extracellular regulator of autophagy in the heart.

Multi-omics data integration provides insights into the post-harvest biology of a long shelf-life tomato landrace.

In this study we investigated the transcriptome and epigenome dynamics of the tomato fruit during post-harvest in a landrace belonging to a group of tomatoes (Solanum lycopersicum L.) collectively known as "Piennolo del Vesuvio", all characterized by a long shelf-life. Expression of protein-coding genes and microRNAs as well as DNA methylation patterns and histone modifications were analysed in distinct post-harvest phases. Multi-omics data integration contributed to the elucidation of the molecular mechanisms underlying processes leading to long shelf-life. We unveiled global changes in transcriptome and epigenome. DNA methylation increased and the repressive histone mark H3K27me3 was lost as the fruit progressed from red ripe to 150 days post-harvest. Thousands of genes were differentially expressed, about half of which were potentially epi-regulated as they were engaged in at least one epi-mark change in addition to being microRNA targets in ~5% of cases. Down-regulation of the ripening regulator MADS-RIN and of genes involved in ethylene response and cell wall degradation was consistent with the delayed fruit softening. Large-scale epigenome reprogramming that occurred in the fruit during post-harvest likely contributed to delayed fruit senescence.

Transcriptomic and Epigenomic Landscape in Rett Syndrome.

Rett syndrome (RTT) is an extremely invalidating, cureless, developmental disorder, and it is considered one of the leading causes of intellectual disability in female individuals. The vast majority of RTT cases are caused by de novo mutations in the X-linked Methyl-CpG binding protein 2 (MECP2) gene, which encodes a multifunctional reader of methylated DNA. MeCP2 is a master epigenetic modulator of gene expression, with a role in the organization of global chromatin architecture. Based on its interaction with multiple molecular partners and the diverse epigenetic scenario, MeCP2 triggers several downstream mechanisms, also influencing the epigenetic context, and thus leading to transcriptional activation or repression. In this frame, it is conceivable that defects in such a multifaceted factor as MeCP2 lead to large-scale alterations of the epigenome, ranging from an unbalanced deposition of epigenetic modifications to a transcriptional alteration of both protein-coding and non-coding genes, with critical consequences on multiple downstream biological processes. In this review, we provide an overview of the current knowledge concerning the transcriptomic and epigenomic alterations found in RTT patients and animal models.

Zfp57 inactivation illustrates the role of ICR methylation in imprinted gene expression during neural differentiation of mouse ESCs.

ZFP57 is required to maintain the germline-marked differential methylation at imprinting control regions (ICRs) in mouse embryonic stem cells (ESCs). Although DNA methylation has a key role in genomic imprinting, several imprinted genes are controlled by different mechanisms, and a comprehensive study of the relationship between DMR methylation and imprinted gene expression is lacking. To address the latter issue, we differentiated wild-type and Zfp57-/- hybrid mouse ESCs into neural precursor cells (NPCs) and evaluated allelic expression of imprinted genes. In mutant NPCs, we observed a reduction of allelic bias of all the 32 genes that were imprinted in wild-type cells, demonstrating that ZFP57-dependent methylation is required for maintaining or acquiring imprinted gene expression during differentiation. Analysis of expression levels showed that imprinted genes expressed from the non-methylated chromosome were generally up-regulated, and those expressed from the methylated chromosome were down-regulated in mutant cells. However, expression levels of several imprinted genes acquiring biallelic expression were not affected, suggesting the existence of compensatory mechanisms that control their RNA level. Since neural differentiation was partially impaired in Zfp57-mutant cells, this study also indicates that imprinted genes and/or non-imprinted ZFP57-target genes are required for proper neurogenesis in cultured ESCs.

MeCP2 and Major Satellite Forward RNA Cooperate for Pericentric Heterochromatin Organization.

Methyl-CpG binding protein 2 (MeCP2) has historically been linked to heterochromatin organization, and in mouse cells it accumulates at pericentric heterochromatin (PCH), closely following major satellite (MajSat) DNA distribution. However, little is known about the specific function of MeCP2 in these regions. We describe the first evidence of a role in neurons for MeCP2 and MajSat forward (MajSat-fw) RNA in reciprocal targeting to PCH through their physical interaction. Moreover, MeCP2 contributes to maintenance of PCH by promoting deposition of H3K9me3 and H4K20me3. We highlight that the MeCP2B isoform is required for correct higher-order PCH organization, and underline involvement of the methyl-binding and transcriptional repression domains. The T158 residue, which is commonly mutated in Rett patients, is directly involved in this process. Our findings support the hypothesis that MeCP2 and the MajSat-fw transcript are mutually dependent for PCH organization, and contribute to clarify MeCP2 function in the regulation of chromatin architecture.

Epigenetic Factors That Control Pericentric Heterochromatin Organization in Mammals.

Pericentric heterochromatin (PCH) is a particular form of constitutive heterochromatin that is localized to both sides of centromeres and that forms silent compartments enriched in repressive marks. These genomic regions contain species-specific repetitive satellite DNA that differs in terms of nucleotide sequences and repeat lengths. In spite of this sequence diversity, PCH is involved in many biological phenomena that are conserved among species, including centromere function, the preservation of genome integrity, the suppression of spurious recombination during meiosis, and the organization of genomic silent compartments in the nucleus. PCH organization and maintenance of its repressive state is tightly regulated by a plethora of factors, including enzymes (e.g., DNA methyltransferases, histone deacetylases, and histone methyltransferases), DNA and histone methylation binding factors (e.g., MECP2 and HP1), chromatin remodeling proteins (e.g., ATRX and DAXX), and non-coding RNAs. This evidence helps us to understand how PCH organization is crucial for genome integrity. It then follows that alterations to the molecular signature of PCH might contribute to the onset of many genetic pathologies and to cancer progression. Here, we describe the most recent updates on the molecular mechanisms known to underlie PCH organization and function.

Interpretation of the Epigenetic Signature of Facioscapulohumeral Muscular Dystrophy in Light of Genotype-Phenotype Studies.

Facioscapulohumeral muscular dystrophy (FSHD) is characterized by incomplete penetrance and intra-familial clinical variability. The disease has been associated with the genetic and epigenetic features of the D4Z4 repetitive elements at 4q35. Recently, D4Z4 hypomethylation has been proposed as a reliable marker in the FSHD diagnosis. We exploited the Italian Registry for FSHD, in which FSHD families are classified using the Clinical Comprehensive Evaluation Form (CCEF). A total of 122 index cases showing a classical FSHD phenotype (CCEF, category A) and 110 relatives were selected to test with the receiver operating characteristic (ROC) curve, the diagnostic and predictive value of D4Z4 methylation. Moreover, we performed DNA methylation analysis in selected large families with reduced penetrance characterized by the co-presence of subjects carriers of one D4Z4 reduced allele with no signs of disease or presenting the classic FSHD clinical phenotype. We observed a wide variability in the D4Z4 methylation levels among index cases revealing no association with clinical manifestation or disease severity. By extending the analysis to family members, we revealed the low predictive value of D4Z4 methylation in detecting the affected condition. In view of the variability in D4Z4 methylation profiles observed in our large cohort, we conclude that D4Z4 methylation does not mirror the clinical expression of FSHD. We recommend that measurement of this epigenetic mark must be interpreted with caution in clinical practice.

Inflammatory response in repeat breeder buffaloes.

The aim of this study was to investigate the repeat breeding condition in Italian Mediterranean buffaloes that failed to conceive after at least 300 days in milk. The trial was carried out on 40 pluriparous Italian Mediterranean buffaloes with more than 300 days in milk. All the animals underwent ultrasound examination to assess endometrial thickness and oestrus synchronization by the Ovsynch-TAI Program. On the day of oestrus, blood samples were collected for the haemocytometric cell count and biochemical assay, and the animals were slaughtered in a local abattoir. A post-mortem uterine flushing was performed using sterile saline for microbiological analyses. Furthermore, uterine biopsies were carried out for histopathological assessment. Finally, endometrial samples were used for real-time PCR (RT-PCR) analysis to evaluate the expression of genes involved in innate immune recognition of pathogens and the inflammatory response, such as Toll-like receptor (TLR)1, TLR8, interleukin (IL)-1ß, IL-6, IL-8, COL4A2, connective tissue growth factor (CTGF), and cysteine-rich angiogenic inducer 61 (CYR61). Statistical analysis was performed by one-way ANOVA. Based on the infiltration of lymphocytes and plasma cells or endometrial gland, lymphatic, and blood vessel ectasia recorded in the histopathological examination, the animals were classified into three groups: healthy (H Group; n = 5), moderate endometritis (M Group; n = 25), and severe endometritis (S Group; n = 10). A significantly greater (P < 0.01) endometrial thickness was recorded in the S Group compared to that in the H and M Group (1.07 ± 0.03 vs. 0.70 ± 0.07 and 0.81 ± 0.04 cm in the S, H, and M Group, respectively). The white blood cell count was lower in the H Group compared to that in the M and S Group (6.3 ± 0.6 vs. 9.3 ± 0.4 and 10.5 ± 0.5 in the H, M, and S Group, respectively). To perform RT-PCR analysis, five animals from groups M and S were randomly selected in order to have balanced results. A higher (P < 0.01) expression of TLR1, together with a lower expression of COL4A2, IL-1ß, IL-6, IL-8, and CYR61, was recorded in the H Group, compared to both the M and S Groups. In conclusion, about 90% of repeat breeder buffaloes show moderate or severe endometritis, associated with an altered histopathological endometrial profile and altered mRNA expression of pro-inflammatory and fibrotic factors.

ATRX Contributes to MeCP2-Mediated Pericentric Heterochromatin Organization during Neural Differentiation.

Methyl-CpG binding protein 2 (MeCP2) is a multi-function factor involved in locus-specific transcriptional modulation and the regulation of genome architecture, e.g., pericentric heterochromatin (PCH) organization. MECP2 mutations are responsible for Rett syndrome (RTT), a devastating postnatal neurodevelopmental disorder, the pathogenetic mechanisms of which are still unknown. MeCP2, together with Alpha-thalassemia/mental retardation syndrome X-linked protein (ATRX), accumulates at chromocenters, which are repressive PCH domains. As with MECP2, mutations in ATRX cause ATR-X syndrome which is associated with severe intellectual disability. We exploited two murine embryonic stem cell lines, in which the expression of MeCP2 or ATRX is abolished. Through immunostaining, chromatin immunoprecipitation and western blot, we show that MeCP2 and ATRX are reciprocally dependent both for their expression and targeting to chromocenters. Moreover, ATRX plays a role in the accumulation of members of the heterochromatin protein 1 (HP1) family at PCH and, as MeCP2, modulates their expression. Furthermore, ATRX and HP1 targeting to chromocenters depends on an RNA component. 3D-DNA fluorescence in situ hybridization (FISH) highlighted, for the first time, a contribution of ATRX in MeCP2-mediated chromocenter clustering during neural differentiation. Overall, we provide a detailed dissection of the functional interplay between MeCP2 and ATRX in higher-order PCH organization in neurons. Our findings suggest molecular defects common to RTT and ATR-X syndrome, including an alteration in PCH.

Evaluation of factors involved in the failure of ovum capture in superovulated buffaloes.

The aim of this work was to evaluate factors affecting ovum capture in superovulated buffaloes, by comparing the morphological features of pre-ovulatory follicles and oocytes, the intrafollicular and plasmatic steroid profile, as well as the expression of genes involved in cumulus expansion and steroid cascade in granulosa cells (GCs) and that of genes involved in contraction-relaxation of the oviduct between superovulated and synchronized buffaloes. Italian Mediterranean Buffalo cows were either synchronized by Ovsynch (n = 25) and superovulated (n = 10) with conventional FSH protocol and sacrificed 18 h after last GnRH. Antral follicular count, recovery rate and oocyte quality were recorded, and plasma and follicular fluid were collected for steroid profile determination. In addition, in 10 animals (5/group), GCs were collected to analyse the mRNA expression of gonadotropin receptors (LHR and FSHR) and genes involved in steroid synthesis, as the cytochrome P450 family 19 (CYP19A1) and the steroidogenic acute regulatory protein (STAR). Moreover, oviducts were collected to evaluate the mRNA expression of estrogen receptor 1 (ER1) and the progesterone receptor (PGR), the vascular endothelial growth factor (VEGF) and the VEGF receptors, i.e. the kinase insert domain receptor (FLK1) and the fms related tyrosine kinase 1 (FLT1). No differences were recorded in steroids plasma concentration between synchronized and superovulated animals whereas intrafollicular E2 and P4 concentrations decreased in superovulated group (63.2 ±â€¯10.6 vs 30.3 ±â€¯5.9 ng/mL of E2 and 130.1 ±â€¯19.8 vs 71.6 ±â€¯8.5 ng/mL of P4, respectively in synchronized and superovulated animals; P < 0.05). Interestingly, both the recovery rate (85.7% vs 56.6%, respectively in synchronized and in superovulated animals; P < 0.05) and the percentage of oocytes exhibiting proper cumulus expansion (75% vs 28.1%, respectively in synchronized and in superovulated animals; P < 0.01) decreased in superovulated animals. In addition, the expression of FSHR and CYP19A1 increased while the expression of STAR in GCs decreased (P < 0.05). Finally, in superovulated buffaloes a decreased expression of PGR, ER1, VEGF and its receptor FLK1 in the oviduct was observed. The results suggest that the exogenous FSH treatment impairs steroidogenesis, affecting both the oviduct and the ovarian function, accounting for the failure of ovum capture in superovulated buffaloes.

Glycosphingolipid metabolic reprogramming drives neural differentiation.

Neural development is accomplished by differentiation events leading to metabolic reprogramming. Glycosphingolipid metabolism is reprogrammed during neural development with a switch from globo- to ganglio-series glycosphingolipid production. Failure to execute this glycosphingolipid switch leads to neurodevelopmental disorders in humans, indicating that glycosphingolipids are key players in this process. Nevertheless, both the molecular mechanisms that control the glycosphingolipid switch and its function in neurodevelopment are poorly understood. Here, we describe a self-contained circuit that controls glycosphingolipid reprogramming and neural differentiation. We find that globo-series glycosphingolipids repress the epigenetic regulator of neuronal gene expression AUTS2. AUTS2 in turn binds and activates the promoter of the first and rate-limiting ganglioside-producing enzyme GM3 synthase, thus fostering the synthesis of gangliosides. By this mechanism, the globo-AUTS2 axis controls glycosphingolipid reprogramming and neural gene expression during neural differentiation, which involves this circuit in neurodevelopment and its defects in neuropathology.

Reduced brain UCP2 expression mediated by microRNA-503 contributes to increased stroke susceptibility in the high-salt fed stroke-prone spontaneously hypertensive rat.

UCP2 maps nearby the lod score peak of STR1-stroke QTL in the SHRSP rat strain. We explored the potential contribution of UCP2 to the high-salt diet (JD)-dependent increased stroke susceptibility of SHRSP. Male SHRSP, SHRSR, two reciprocal SHRSR/SHRSP-STR1/QTL stroke congenic lines received JD for 4 weeks to detect brain UCP2 gene/protein modulation as compared with regular diet (RD). Brains were also analyzed for NF-κB protein expression, oxidative stress level and UCP2-targeted microRNAs expression level. Next, based on knowledge that fenofibrate and Brassica Oleracea (BO) stimulate UCP2 expression through PPARα activation, we monitored stroke occurrence in SHRSP receiving JD plus fenofibrate versus vehicle, JD plus BO juice versus BO juice plus PPARα inhibitor. Brain UCP2 expression was markedly reduced by JD in SHRSP and in the (SHRsr.SHRsp-(D1Rat134-Mt1pa)) congenic line, whereas NF-κB expression and oxidative stress level increased. The opposite phenomenon was observed in the SHRSR and in the (SHRsp.SHRsr-(D1Rat134-Mt1pa)) reciprocal congenic line. Interestingly, the UCP2-targeted rno-microRNA-503 was significantly upregulated in SHRSP and decreased in SHRSR upon JD, with consistent changes in the two reciprocal congenic lines. Both fenofibrate and BO significantly decreased brain microRNA-503 level, upregulated UCP2 expression and protected SHRSP from stroke occurrence. In vitro overexpression of microRNA-503 in endothelial cells suppressed UCP2 expression and led to a significant increase of cell mortality with decreased cell viability. Brain UCP2 downregulation is a determinant of increased stroke predisposition in high-salt-fed SHRSP. In this context, UCP2 can be modulated by both pharmacological and nutraceutical agents. The microRNA-503 significantly contributes to mediate brain UCP2 downregulation in JD-fed SHRSP.

MECP2, a multi-talented modulator of chromatin architecture.

It has been a long trip from 1992, the year of the discovery of MECP2, to the present day. What is surprising is that some of the pivotal roles of MeCP2 were already postulated at that time, such as repression of inappropriate expression from repetitive elements and the regulation of pericentric heterochromatin condensation. However, MeCP2 performs many more functions. MeCP2 is a reader of epigenetic information contained in methylated (and hydroxymethylated) DNA, moving from the 'classical' CpG doublet to the more complex view addressed by the non-CpG methylation, which is a feature of the postnatal brain. MECP2 is a transcriptional repressor, although when it forms complexes with the appropriate molecules, it can become a transcriptional activator. For all of these aspects, Rett syndrome, which is caused by MECP2 mutations, is considered a paradigmatic example of a 'chromatin disorder'. Even if the hunt for bona-fide MECP2 target genes is far from concluded today, the role of MeCP2 in the maintenance of chromatin architecture appears to be clearly established. Taking a cue from the non-scientific literature, we can firmly attest that MeCP2 is a player with 'a great future behind it'*.*V. Gassmann 'Un grande avvenire dietro le spalle'. TEA Eds.

X inactivation and reactivation in X-linked diseases.

X chromosome inactivation (XCI) is the phenomenon by which mammals compensate for dosage of X-linked genes in females (XX) versus males (XY). XCI patterns can be random or show extreme skewing, and can modify the mode of inheritance of X-driven phenotypes, which contributes to the variability of human pathologies. Recent findings have shown reversibility of the XCI process, which has opened new avenues in the approaches used for the treatment of X-linked diseases.

Experience-dependent DNA methylation regulates plasticity in the developing visual cortex.

DNA methylation is an epigenetic repressor mark for transcription dynamically regulated in neurons. We analyzed visual experience regulation of DNA methylation in mice and its involvement in ocular dominance plasticity of the developing visual cortex. Monocular deprivation modulated the expression of factors controlling DNA methylation and exerted opposite effects on DNA methylation and hydroxymethylation in specific plasticity genes. Inhibition of DNA methyltrasferase (DNMT) blocked molecular and functional effects of monocular deprivation, partially reversing the monocular deprivation transcriptional program.

Oxidative brain damage in Mecp2-mutant murine models of Rett syndrome.

Rett syndrome (RTT) is a rare neurodevelopmental disorder affecting almost exclusively females, caused in the overwhelming majority of the cases by loss-of-function mutations in the gene encoding methyl-CpG binding protein 2 (MECP2). High circulating levels of oxidative stress (OS) markers in patients suggest the involvement of OS in the RTT pathogenesis. To investigate the occurrence of oxidative brain damage in Mecp2 mutant mouse models, several OS markers were evaluated in whole brains of Mecp2-null (pre-symptomatic, symptomatic, and rescued) and Mecp2-308 mutated (pre-symptomatic and symptomatic) mice, and compared to those of wild type littermates. Selected OS markers included non-protein-bound iron, isoprostanes (F2-isoprostanes, F4-neuroprostanes, F2-dihomo-isoprostanes) and 4-hydroxy-2-nonenal protein adducts. Our findings indicate that oxidative brain damage 1) occurs in both Mecp2-null (both -/y and stop/y) and Mecp2-308 (both 308/y males and 308/+ females) mouse models of RTT; 2) precedes the onset of symptoms in both Mecp2-null and Mecp2-308 models; and 3) is rescued by Mecp2 brain specific gene reactivation. Our data provide direct evidence of the link between Mecp2 deficiency, oxidative stress and RTT pathology, as demonstrated by the rescue of the brain oxidative homeostasis following brain-specifically Mecp2-reactivated mice. The present study indicates that oxidative brain damage is a previously unrecognized hallmark feature of murine RTT, and suggests that Mecp2 is involved in the protection of the brain from oxidative stress.

Non-coding RNAs in chromatin disease involving neurological defects.

Novel classes of small and long non-coding RNAs (ncRNAs) are increasingly becoming apparent, being engaged in diverse structural, functional and regulatory activities. They take part in target gene silencing, play roles in transcriptional, post-transcriptional and epigenetic processes, such as chromatin remodeling, nuclear reorganization with the formation of silent compartments and fine-tuning of gene recruitment into them. Among their functions, non-coding RNAs are thought to act either as guide or scaffold for epigenetic modifiers that write, erase, and read the epigenetic signature over the genome. Studies on human disorders caused by defects in epigenetic modifiers and involving neurological phenotypes highlight the disruption of diverse classes of non-coding RNAs. Noteworthy, these molecules mediate a wide spectrum of neuronal functions, including brain development, and synaptic plasticity. These findings imply a significant contribution of ncRNAs in pathophysiology of the aforesaid diseases and provide new concepts for potential therapeutic applications.