Exercise-induced endothelial Mecp2 lactylation suppresses atherosclerosis via the Ereg/MAPK signalling pathway.

BACKGROUND AND AIMS: Lactylation, a recently identified post-translational modification (PTM), plays a central role in the regulation of multiple physiological and pathological processes. Exercise is known to provide protection against cardiovascular disease. However, whether exercise-generated lactate changes lactylation and is involved in the exercise-induced attenuation of atherosclerotic cardiovascular disease (ASCVD) remains unclear. The purpose of this study was to investigate the effects and mechanisms of exercise-induced lactylation on ASCVD. METHODS AND RESULTS: Using the high-fat diet-induced apolipoprotein-deficient mouse model of ASCVD, we found that exercise training promoted Mecp2 lysine lactylation (Mecp2k271la); it also decreased the expression of vascular cell adhesion molecule 1 (Vcam-1), intercellular adhesion molecule 1 (Icam-1), monocyte chemoattractant protein 1 (Mcp-1), interleukin (IL)-1ß, IL-6, and increased the level of endothelial nitric oxide synthase (Enos) in the aortic tissue of mice. To explore the underlying mechanisms, mouse aortic endothelial cells (MAECs) were subjected to RNA-sequencing and CHIP-qPCR, which confirmed that Mecp2k271la repressed the expression of epiregulin (Ereg) by binding to its chromatin, demonstrating Ereg as a key downstream molecule for Mecp2k271la. Furthermore, Ereg altered the mitogen-activated protein kinase (MAPK) signalling pathway through regulating the phosphorylation level of epidermal growth factor receptor, thereby affecting the expression of Vcam-1, Icam-1, Mcp-1, IL-1ß, IL-6, and Enos in ECs, which in turn promoted the regression of atherosclerosis. In addition, increasing the level of Mecp2k271la by exogenous lactate administration in vivo also inhibits the expression of Ereg and the MAPK activity in ECs, resulting in repressed atherosclerotic progression. CONCLUSIONS: In summary, this study provides a mechanistic link between exercise and lactylation modification, offering new insight into the anti-atherosclerotic effects of exercise-induced PTM.

Epigenetic reader MeCP2 repressed WIF1 boosts lung fibroblast proliferation, migration and pulmonary fibrosis.

Epigenetic has been implicated in pulmonary fibrosis. However, there is limited information regarding the biological role of the epigenetic reader MeCP2 in pulmonary fibrosis. The aim of this study was to investigate the role of MeCP2 and its target WIF1 in pulmonary fibrosis. The pathological changes and collagen depositions was analyzed by H&E, Masson's Trichrome Staining and Sirius Red staining. MeCP2, WIF1, α-SMA, Wnt1, ß-catenin, and collagen I expression were analyzed by western blotting, RT-qPCR, immunohistochemistry, immunofluorescence, respectively. The effects of MeCP2 on pulmonary fibrosis involve epigenetic mechanisms, using cultured cells, animal models, and clinical samples. Herein, our results indicated that MeCP2 level was up-regulated, while WIF1 was decreased in Bleomycin (BLM)-induced mice pulmonary fibrosis tissues, patients pulmonary fibrosis tissues and TGF-ß1-induced lung fibroblast. Knockdown of MeCP2 by siRNA can rescue WIF1 downregulation in TGF-ß1-induced lung fibroblast, inhibited lung fibroblast activation. The DNA methylation inhibitor 5-azadC-treated lung fibroblasts have increased WIF1 expression with reduced MeCP2 association. In addition, we found that reduced expression of WIF1 caused by TGF-ß1 is associated with the promoter methylation status of WIF1. Moreover, in vivo studies revealed that knockdown of MeCP2 mice exhibited significantly ameliorated pulmonary fibrosis, decreased interstitial collagen deposition, and increased WIF1 expression. Taken together, our study showed that epigenetic reader MeCP2 repressed WIF1 facilitates lung fibroblast proliferation, migration and pulmonary fibrosis.

A key role of miR-132-5p in the prefrontal cortex for persistent prophylactic actions of (R)-ketamine in mice.

(R,S)-ketamine is known to elicit persistent prophylactic effects in rodent models of depression. However, the precise molecular mechanisms underlying its action remain elusive. Using RNA-sequencing analysis, we searched for novel molecular target(s) that contribute to the prophylactic effects of (R)-ketamine, a more potent enantiomer of (R,S)-ketamine in chronic restraint stress (CRS) model. Pretreatment with (R)-ketamine (10 mg/kg, 1 day before CRS) significantly ameliorated body weight loss, increased immobility time of forced swimming test, and decreased sucrose preference of sucrose preference test in CRS-exposed mice. RNA-sequencing analysis of prefrontal cortex (PFC) revealed that several miRNAs such as miR-132-5p might contribute to sustained prophylactic effects of (R)-ketamine. Methyl CpG binding protein 2 (MeCP2) is known to regulate brain-derived neurotrophic factor (BDNF) expression. Quantitative RT-PCR confirmed that (R)-ketamine significantly attenuated altered expression of miR-132-5p and its regulated genes (Bdnf, Mecp2, Tgfb1, Tgfbr2) in the PFC of CRS-exposed mice. Furthermore, (R)-ketamine significantly attenuated altered expression of BDNF, MeCP2, TGF-ß1 (transforming growth factor ß1), and synaptic proteins (PSD-95, and GluA1) in the PFC of CRS-exposed mice. Administration of agomiR-132-5p decreased the expression of Bdnf and Tgfb1 in the PFC, resulting in depression-like behaviors. In contrast, administration of antagomiR-132-5p blocked the increased expression of miR-132-5p and decreased expression of Bdnf in the PFC of CRS-exposed mice, resulting in antidepressant-like effects. In conclusion, our data show a novel role of miR-132-5p in the PFC underlying depression-like phenotypes in CRS model and the sustained prophylactic effects of (R)-ketamine.

Mecp2 protects kidney from ischemia-reperfusion injury through transcriptional repressing IL-6/STAT3 signaling.

Rationale: Ischemia-reperfusion (IR) induced acute kidney injury (AKI) causes serious clinical problems associated with high morbidity and mortality. Mecp2 is a methyl-CpG binding protein, its mutation or deletion causes a neurodevelopment disease called Rett syndrome. Notably, some Rett syndrome patients present urological dysfunctions. It remains unclear whether and how Mecp2 affects AKI. Methods: Renal tubular cell specific Mecp2 deletion mice challenged with IR injury were used to investigate the effects of Mecp2 on renal tubular damage, function, cell death, fibrosis and inflammation. Cultured renal epithelial cell lines were transfected with wildtype or different domain-deletion mutants of Mecp2 to study the effects of Mecp2 on Il-6/STAT3 signaling. Results: Our results indicated rapidly upregulated Mecp2 upon acute in vivo and in vitro renal injury. Notably, increased tubular MeCP2 staining was also found in the renal sections of AKI patients. Furthermore, ablation of Mecp2 aggravated renal injury, and promoted renal cell death, inflammation, and fibrosis. Mechanistically, through its transcriptional repression domain, Mecp2 bound to the promoter of proinflammatory cytokine Il-6 to negatively regulate its expression, thus inhibiting STAT3 activation. Conclusions: A novel protective role of Mecp2 against AKI via repressing the Il-6/STAT3 axis was suggested.

Computational analysis of memory consolidation following inhibitory avoidance (IA) training in adult and infant rats: Critical roles of CaMKIIα and MeCP2.

Key features of long-term memory (LTM), such as its stability and persistence, are acquired during processes collectively referred to as consolidation. The dynamics of biological changes during consolidation are complex. In adult rodents, consolidation exhibits distinct periods during which the engram is more or less resistant to disruption. Moreover, the ability to consolidate memories differs during developmental periods. Although the molecular mechanisms underlying consolidation are poorly understood, the initial stages rely on interacting signaling pathways that regulate gene expression, including brain-derived neurotrophic factor (BDNF) and Ca2+/calmodulin-dependent protein kinase II α (CaMKIIα) dependent feedback loops. We investigated the ways in which these pathways may contribute to developmental and dynamical features of consolidation. A computational model of molecular processes underlying consolidation following inhibitory avoidance (IA) training in rats was developed. Differential equations described the actions of CaMKIIα, multiple feedback loops regulating BDNF expression, and several transcription factors including methyl-CpG binding protein 2 (MeCP2), histone deacetylase 2 (HDAC2), and SIN3 transcription regulator family member A (Sin3a). This model provides novel explanations for the (apparent) rapid forgetting of infantile memory and the temporal progression of memory consolidation in adults. Simulations predict that dual effects of MeCP2 on the expression of bdnf, and interaction between MeCP2 and CaMKIIα, play critical roles in the rapid forgetting of infantile memory and the progress of memory resistance to disruptions. These insights suggest new potential targets of therapy for memory impairment.

MeCP2 regulates GFAP expression within the developing brain.

Mutations in MECP2 cause Rett syndrome (RTT), an X-linked neurodevelopmental disorder that primarily affects females. Individuals with RTT have increased glial fibrillary acidic protein (GFAP) expression in the brain. GFAP is an intermediate filament protein that is expressed predominately within astrocytes in the CNS. MeCP2 binds to methylated regions of the GFAP promoter region and suppresses GFAP expression in vitro. Therefore, we wanted to determine if transiently reducing MeCP2 expression would increase GFAP expression in the developing rat brain. Male and female rats received infusions of either MeCP2 or control siRNA targeting the amygdala during the first 3 days of postnatal life. Brains were collected after 6h or 2 weeks following the last infusion. MeCP2 siRNA increased GFAP mRNA and protein within the female, but not the male, amygdala on postnatal day (PN) 2. Two weeks following the infusion, levels returned to normal. MeCP2 siRNA targeting the hypothalamus also increases GFAP mRNA within the female hypothalamus on PN2, suggesting that the regulation is not brain region-specific. It appears that MeCP2 does not regulate all astrocyte markers in the developing female brain, but specifically regulates GFAP expression, as levels of S100ß and vimentin were not altered in the female amygdala at either time point. These data contribute to the idea that the role of MeCP2 differs in the developing male versus female brain. Further elucidating the regulation and function of GFAP can contribute to our understanding of MeCP2 function and perhaps RTT etiology.

Neonatal MeCP2 is important for the organization of sex differences in vasopressin expression.

Several neurodevelopmental disorders are marked by atypical Methyl-CpG-binding protein 2 (MeCP2) expression or function; however, the role of MeCP2 is complex and not entirely clear. Interestingly, there are sex differences in some of these disorders, and it appears that MeCP2 has sex-specific roles during development. Specifically, recent data indicate that a transient reduction in MeCP2 within developing amygdala reduces juvenile social play behavior in males to female-typical levels. These data suggest that MeCP2 within the amygdala is involved in programming lasting sex differences in social behavior. In the present study, we infused MeCP2 or control siRNA into the amygdala of male and female rats during the first three days of postnatal life in order to assess the impact of a transient reduction in MeCP2 on arginine vasopressin (AVP), a neural marker that is expressed differentially between males and females and is linked to a number of social behaviors. The expression of AVP, as well as several other genes, was measured in two-week old and adult animals. Two-week old males expressed more AVP and galanin mRNA in the amygdala than females, and a transient reduction in MeCP2 eliminated this sex difference by reducing the expression of both gene products in males. A transient reduction in MeCP2 also decreased androgen receptor (AR) mRNA in two-week old males. In adulthood, control males had more AVP-immunoreactive (AVP-ir) cells than females in the centromedial amygdala (CMA), bed nucleus of the stria terminalis (BST) and in the fibers that project from these cells to the lateral septum (LS). A transient reduction in MeCP2 eliminated this sex difference. Interestingly, there were no lasting differences in galanin or AR levels in adulthood. Reducing MeCP2 levels during development did not alter estrogen receptorα, neurofilament or Foxg1. We conclude that a transient reduction in MeCP2 expression in the developing male amygdala has a transient impact on galanin and AR expression but a lasting impact on AVP expression, highlighting the importance of MeCP2 in organizing sex differences in the amygdala.

Activity-dependent suppression of miniature neurotransmission through the regulation of DNA methylation.

DNA methylation is an epigenetic mechanism that plays a critical role in the repression of gene expression. Here, we show that DNA methyltransferase (DNMT) inhibition in hippocampal neurons results in activity-dependent demethylation of genomic DNA and a parallel decrease in the frequency of miniature EPSCs (mEPSCs), which in turn impacts neuronal excitability and network activity. Treatment with DNMT inhibitors reveals an activity-driven demethylation of brain-derived neurotrophic factor promoter I, which is mediated by synaptic activation of NMDA receptors, because it is susceptible to AP-5, a blocker of NMDA receptors. The specific effect of DNMT inhibition on spontaneous excitatory neurotransmission requires gene transcription and is occluded in the absence of the transcriptional repressor methyl-CpG-binding protein 2 (MeCP2). Interestingly, enhancing excitatory activity, in the absence of DNMT inhibitors, also produces similar decreases in DNA methylation and mEPSC frequency, suggesting a role for DNA methylation in the control of homeostatic synaptic plasticity. Furthermore, adding excess substrate for DNA methylation (S-adenosyl-L-methionine) rescues the suppression of mEPSCs by DNMT inhibitors in wild-type neurons, as well as the defect seen in MeCP2-deficient neurons. These results uncover a means by which NMDA receptor-mediated synaptic activity drives DNA demethylation within mature neurons and suppresses basal synaptic function.

Epigenetic regulation of metallothionein-i gene expression: differential regulation of methylated and unmethylated promoters by DNA methyltransferases and methyl CpG binding proteins.

Metallothioneins (MTs) are a group of cysteine-rich stress response proteins that scavenge reactive oxygen species and heavy metals. Recently, we have shown that MT-I promoter is methylated and suppressed in some solid and liquid tumors and can be robustly activated following treatment with inhibitors of DNA methyltransferase (DNMT) and histone deacetylase (HDAC). Here, we have analyzed MT-I chromatin structure in active, unmethylated (Hepa cells) and in repressed, methylated state (lymphosarcoma cells). Restriction enzyme accessibility assay showed that the MT-I promoter has an open conformation in unmethylated state as opposed to refractory chromatin structure in methylated state. Positioning of nucleosomal arrays on the methylated promoter further confirmed the closed chromatin structure of the methylated promoter. Chromatin immunoprecipitation (ChIP) assay demonstrated that the unmethylated promoter is associated with K9-acetyl, K4-methyl, and S10-phospho histone H3 whereas the methylated promoter is predominantly associated with K9-methyl H3. HP1alpha that recognizes K9-methyl H3 inhibited methylated MT-1 promoter activity whereas closely related HP1gamma repressed the promoter irrespective of its methylation status. Ubiquitously expressed DNA methyltransferase 1 (DNMT1) suppressed MT-I promoter activity irrespective of its methylation status that does not require its catalytic activity. The DNMT1-mediated repression of MT-I promoter was relieved by trichostatin A, an HDAC inhibitor. Among the methyl CpG binding proteins, MBD2 and MBD4 specifically associated with the methylated promoter and inhibited its activity. In contrast, MBD1 and MeCP2 interacted with both promoters and suppressed the promoter activity irrespective of its methylation status. These results demonstrate that the methylated and unmethylated MT-I promoter are differentially regulated by DNA methyltransferase and methyl-CpG binding proteins, and DNMT1 could suppress MT promoter by a transcriptional mechanism independent of its enzymatic function. These studies suggest that the components of epigenetic machinery differentially regulate methylated and unmethylated MT-I gene expression.