Expression Of methyl-CpG-binding Protein 2 Protein Research Articles

USP15 inhibits hypoxia-induced IL-6 signaling by deubiquitinating and stabilizing MeCP2.

Methyl-CpG binding protein 2 (MeCP2) is an important X-linked DNA methylation reader and a key heterochromatin organizer. The expression level of MeCP2 is crucial, as indicated by the observation that loss-of-function mutations of MECP2 cause Rett syndrome, whereas an extra copy spanning the MECP2 locus results in MECP2 duplication syndrome, both being progressive neurodevelopmental disorders. Our previous study demonstrated that MeCP2 protein expression is rapidly induced by renal ischemia-reperfusion injury (IRI) and protects the kidney from IRI through transcriptionally repressing the interleukin-6 (IL-6)/signal transducer and activator of transcription 3 signaling pathway. However, the mechanisms underlying the upregulation of MeCP2 have remained elusive. Here, by using two hypoxia cell models, hypoxia and reoxygenation and cobalt chloride stimulation, we confirmed that the removal of lysine 48-linked ubiquitination from MeCP2 prevented its proteasome-dependent degradation under hypoxic conditions. Through unbiased screening based on a deubiquitinating enzymes library, we identified ubiquitin-specific protease 15 (USP15) as a stabilizer of MeCP2. Further studies revealed that USP15 could attenuate hypoxia-induced MeCP2 degradation by cleaving lysine 48-linked ubiquitin chains from MeCP2, primarily targeting its C-terminal domain. Consistently, USP15 inhibited hypoxia-induced signal transducer and activator of transcription 3 activation, resulting in reduced transcription of IL-6 downstream genes. In summary, our study reveals an important role for USP15 in the maintenance of MeCP2 stability and the regulation of IL-6 signaling.

Methyl-CpG-binding protein 2 regulates CYP27A1-induced myometrial contraction during preterm labor.

Persistent and intense uterine contraction is a risk factor for preterm labor. We previously found that methyl-CpG-binding protein 2 (MeCP2), as a target of infection-related microRNA miR-212-3p, may play an inhibitory role in regulating myometrium contraction. However, the molecular mechanisms by which MeCP2 regulates myometrial contraction are still unknown. In this study, we found that MeCP2 protein expression was lower in myometrial specimens obtained from preterm labor cases, compared to those obtained from term labor cases. Herein, using RNA sequence analysis of global gene expression in human uterine smooth muscle cells (HUSMCs) following siMeCP2, we show that MeCP2 silencing caused dysregulation of the cholesterol metabolism pathway. Notably, MeCP2 silencing resulted in the upregulation of CYP27A1, the key enzyme involved in regulating cholesterol homeostasis, in HUSMCs. Methylation-specific PCR, chromatin immunoprecipitation, and dual luciferase reporter gene technology indicated that MeCP2 could bind to the methylated CYP27A1 promoter region and repress its transcription. Administration of siCYP27A1 in a lipopolysaccharide (LPS)-induced preterm labor mouse model delayed the onset of preterm labor. Human preterm myometrium and the LPS-induced preterm labor mouse model both showed lower expression of MeCP2 and increased expression of CYP27A1. These results demonstrated that aberrant upregulation of CYP27A1 induced by MeCP2 silencing is one of the mechanisms facilitating inappropriate myometrial contraction. CYP27A1 could be exploited as a novel therapeutic target for preterm birth.

Regulation of BDNF transcription by Nrf2 and MeCP2 ameliorates MPTP-induced neurotoxicity

Mounting evidence suggests the key role of brain-derived neurotrophic factor (BDNF) in the dopaminergic neurotoxicity of Parkinson’s disease (PD). Activation of NF-E2-related factor-2 (Nrf2) and inhibition of methyl CpG-binding protein 2 (MeCP2) can regulate BDNF upregulation. However, the regulation of BDNF by Nrf2 and MeCP2 in the PD pathogenesis has not been reported. Here, we revealed that Nrf2/MeCP2 coordinately regulated BDNF transcription, reversing the decreased levels of BDNF expression in 1-methyl-4-phenylpyridinium (MPP+)-treated SH-SY5Y cells and 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-treated mice. Repeated administration of sulforaphane (SFN, an Nrf2 activator) attenuated dopaminergic neurotoxicity in MPTP-treated mice through activation of BDNF and suppression of MeCP2 expression. Furthermore, intracerebroventricular injection of MeCP2-HDO, a DNA/RNA heteroduplex oligonucleotide (HDO) silencing MeCP2 expression, ameliorated dopaminergic neurotoxicity in MPTP-treated mice via activation of Nrf2 and BDNF expression. Moreover, we found decreased levels of Nrf2 and BDNF, and increased levels of MeCP2 protein expression in the striatum of patients with dementia with Lewy bodies (DLB). Interesting, there were correlations between BDNF and Nrf2 (or MeCP2) expression in the striatum from DLB patients. Therefore, it is likely that the activation of BDNF transcription by activation of Nrf2 and/or suppression of MeCP2 could be a new therapeutic approach for PD.

Perinatal exposure to high fat diet alters expression of MeCP2 in the hypothalamus

Obesity is a complex disease that is the result of a number of different factors including genetic, environmental, and endocrine abnormalities. Given that monogenic forms of obesity are rare, it is important to identify other mechanisms that contribute to its etiology. Methyl-Cp-G binding protein 2 (MeCP2) is a neuroepigenetic factor that binds to methylated regions of DNA to influence transcription. Past studies demonstrate that disruption in MeCP2 function produces obesity in mice. Using a diet-induced obesity mouse model, we show that perinatal exposure to high fat diet significantly decreases MeCP2 protein expression in the hypothalamus of female mice, effects not seen when high fat diet is given to mice during adulthood. Moreover, these effects are seen specifically in a subregion of the hypothalamus known as the arcuate nucleus with females having decreased MeCP2 expression in rostral areas and males having decreased MeCP2 expression in intermediate regions of the arcuate nucleus. Interestingly, mice gain more weight when exposed to high fat diet during adulthood relative to mice exposed to high fat diet perinatally, suggesting that perhaps high fat diet exposure during adulthood may be affecting mechanisms independent of MeCP2 function. Collectively, our data demonstrate that there are developmentally sensitive periods in which MeCP2 expression is influenced by high fat diet exposure and this occurs in a sexually dimorphic manner.

Effect of Jieduquyuziyin prescription-treated rat serum on MeCP2 gene expression in Jurkat T cells.

How genomic DNA methylation and methyl CpG-binding protein 2 (MeCP2) gene expression affect the pathogenesis of systemic lupus erythematosus (SLE) remains poorly understood. Traditional Chinese medicine has a unique effect in the treatment of SLE patients. This study aimed to investigate the effect of Jieduquyuziyin prescription (JP)-treated rat serum on the gene expression of MeCP2 in Jurkat T cells and its role in the pathogenesis of SLE. Jurkat T cells were harvested, and drug-containing serum was prepared. The ferulic acid and paeoniflorin content in the drug-containing serum were determined by liquid chromatography-mass spectrometry (LC-MS/MS). 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium (MTS) assays were used to screen the optimal concentration of drug-containing serum. The DNA methylation level in Jurkat T cells was detected with a Methylamp™ Total DNA Methylation Kit. The methylation status of the MeCP2 promoter region was detected using bisulfite modification and methylation-specific PCR (MSP). Real-time PCR was used to measure MeCP2 mRNA expression. Western blotting and flow cytometry were done to detect MeCP2 protein expression in Jurkat cell nuclei. Paeoniflorin and ferulic acid were detected in the drug-containing serum of JP-treated rats. The results showed that cell growth was affected in the high serum-containing drug group. The experimental results showed that JP and prednisone acetate increased the level of genomic DNA methylation and MeCP2 gene promoter region methylation in Jurkat cells. MeCP2 mRNA and protein levels were also increased in the JP and prednisone acetate groups. Furthermore, flow cytometry revealed that the expression of MeCP2 protein in Jurkat T cell nuclei was higher in the drug group than the blank control group, and these results were consistent with the western blot analysis results. Our study found that there is a negative correlation between drug-containing serum and cell survival rate. JP upregulated the levels of DNA methylation, MeCP2 mRNA and protein as effectively as prednisone acetate and thus may activate the MeCP2 gene by increasing the methylation level, thereby inhibiting the pathogenesis of SLE. Therefore, JP may potentially be used to treat SLE patients. The Jurkat T lymphocyte in vitro experiments provided a foundation to study the effects of JP on the lupus mouse CD4+ T cell methylation mechanism and to further explore the pathogenesis of SLE.

Interaction between abnormal expression of fragile histidine triad and methyl-CpG-binding protein 2 on cervical cancerization

Objective: To explore the relationship between abnormal expression of fragile histidine triad (FHIT) gene and methyl-CpG-binding protein 2 (MeCP2) as well as their interaction on cervical cancerization. Methods: A total of 73 patients with cervical squamous cell carcinoma (SCC), 113 patients with cervical intraepithelial neoplasia (CIN Ⅰ, n=45; CINⅡ/Ⅲ, n=68) and 60 women with normal cervix (NC) were included in the study. Real time PCR and Western blot were performed to detect the expression levels of mRNA and protein about FHIT and MeCP2, respectively. The methylation status of FHIT gene CpG island was tested by methylation-specifc PCR (MSP). Kruskal-Wallis H test, χ(2) test, trend χ(2) test and Spearman correlation analysis were conducted with software SPSS 20.0. The interaction was evaluated by generalized multifactor dimensionality reduction (GMDR) model. Results: With the deterioration of cervical lesion, the methylation rates of FHIT gene CpG island (χ(2)=18.64, P<0.001; trend χ(2)=18.08, P<0.001) increased gradually, while the expression levels of FHIT mRNA (H=27.32, P<0.001; trend χ(2)=12.65, P<0.001) and protein (H=47.10, P<0.001; trend χ(2)=29.79, P<0.001) decreased gradually. There was a negative correlation between the methylation rates of FHIT gene CpG island and the expression level of FHIT protein (r=-0.226, P<0.001). The levels of MeCP2 mRNA (H=26.19, P<0.001; trend χ(2)=11.81, P=0.001) and protein (H=69.02, P<0.001; trend χ(2)=47.44, P<0.001) increased gradually with the aggravation of cervical lesions. There was a positive correlation between the expression level of MeCP2 protein and the FHIT mRNA Ct ratio (r=0.254, P<0.001). Expression of proteins were negatively correlated between MeCP2 and FHIT (r=-0.213, P=0.001). The results analyzed by GMDR model showed that there were interactions among high MeCP2 protein expression, the CpG island methylation of FHIT and mRNA and protein expression in CINⅡ/Ⅲ group, and among high MeCP2 mRNA and protein expression, the CpG island methylation of FHIT and low mRNA and protein expression in SCC group. Conclusion: High expression of MeCP2 mRNA and protein, the CpG island methylation and low mRNA and protein expression of FHIT could increase the risk of cervical carcinogenesis, and there might be a synergistic effect on cervical carcinogenesis.

Comprehensive Evaluation on Effect of IMPX977 on Expression of Methyl-CpG-binding Protein 2 in Rats

ObjectiveTo investigate the effect of IMPX977 on methyl-CpG-binding protein 2 (MeCP2) expression in rats. MethodsForty-eight SD rats were randomly divided into four groups: normal control group, olive oil (negative control, 5 mL/kg oil) group, and 10 mg/kg and 30 mg/kg IMPX977 administration groups. All rats were given corresponding dose of drugs each other day and administered orally for two weeks. Tissues including cortex and cerebellum were collected from rats to assay the expression of MeCP2 by quantitative RT-PCR and Western blotting. ResultsThe IMPX977 supplement showed no significant effect on the body weight of rats. In normal rats, MeCP2 was highly expressed in cerebellum, cortex and hippocampus, and less expressed in heart, spleen and lung. In addition to male rats, compared with the control group, the expression of MeCP2 mRNA was significantly increased in cerebellum after 30 mg/kg IMPX977 treatment and contrarily, absolutely decreased in cortex of all treatment groups. Furthermore, in female rats MeCP2 mRNA was reduced in cortex of both olive oil and 30 mg/kg IMPX977 treatment groups compared with control group. Meanwhile, MeCP2 protein level was significantly elevated in cerebellum of treated male rats compared to the control group. In contrast to the control group, the expression of MeCP2 protein in both cerebellum and cortex of female rats in other three groups was increased. ConclusionIMPX977 treatment (10 mg/kg) may elevate the expression of MeCP2, which establishes experimental foundation for the further research on rat models of Rett syndrome.

The Therapeutic Potential of mGlu3 Antagonism in Correcting Hippocampal Long‐term Depression Impairments in a Mouse Model of MECP2 Duplication Syndrome

Precise levels of the transcriptional regulator Methyl CpG Binding Protein 2 (MeCP2) are known to be a key determinant for proper neurological function. Mutations in the MECP2 gene results in a disease known as Rett syndrome; in contrast, genetic duplication of MECP2 leads to a disorder known as MECP2 Duplication syndrome. The latter genetic neurodevelopmental disorder has a wide symptomology including stereotypy, seizures, cognitive deficits, and autism. In rodent models of MECP2 Duplication Syndrome in which MeCP2 is overexpressed, increases in glutamatergic synapse formation in hippocampal neurons occur, as well as impairments in hippocampal synaptic plasticity, a neurological phenomenon thought to be involved in memory and cognition. In accordance with this notion, MeCP2 overexpression causes memory and cognitive deficits in mice. Interestingly, the metabotropic glutamate receptor 3 (mGlu3) has been shown to be involved in regulating synaptic plasticity and cognitive behaviors in mice, and mGlu3 expression appears to correlate with MeCP2 expression levels in the brain. We hypothesized that that an upregulation of mGlu3 leads to an impairment in synaptic plasticity and cognitive deficits in MeCP2 overexpressing mice. To investigate the mechanisms by which MeCP2 overexpression induces neurophysiological impairments, a MeCP2‐Tg1 mouse model was used. Our results indicate that mGlu3 is upregulated the hippocampus of MeCP2‐Tg1 mice, correlating with an increase in MeCP2 protein expression. Electrophysiological experiments found that paired‐pulse facilitation was enhanced and input‐output intensity was reduced at the SC‐CA1 hippocampal synapse in the MeCP2‐Tg1 mice compared to wild‐type controls. Furthermore, (S)‐3,5‐Dihydroxyphenylglycine (DHPG) induced‐long term depression (LTD) was impaired in MeCP2‐Tg1 mice. Interestingly, an mGlu3 negative allosteric modulator, VU0650786, was capable of normalizing DHPG‐induced LTD to the level of that observed in wild‐type controls. These results suggest that overexpression of mGlu3 may contribute to synaptic plasticity impairments within the hippocampus of MeCP2‐Tg1 mice. Future experiments are aimed at elucidating behavioral correlates of these neurophysiological abnormalities and their underlying mechanisms.Support or Funding InformationT32NS007491 (BJS), rettsyndrome.org postdoctoral fellowship (RGG), Weatherstone predoctoral fellowship (BKS), T32 GM07628 (NF), R01 MH099269 (KAE), U54 MH084659 (CWL), R01 NS031373 (PJC), R21 MH102548 (CMN), Autism Speaks Treatment Award (CMN).

Regulation of transient receptor potential vanilloid 1 expression in trigeminal ganglion neurons via methyl-CpG binding protein 2 signaling contributes tongue heat sensitivity and inflammatory hyperalgesia in mice.

BackgroundPain hypoalgesia has been reported in Rett syndrome patients, a severe neurodevelopmental disorder which can be attributed to mutations in the methyl-CpG binding protein 2 (MeCP2). Here, we examined the role of MeCP2 signaling in tongue heat sensitivity in the normal and inflamed state using Mecp2 heterozygous (Mecp2+/−) mice.ResultsHeat hypoalgesia of the tongue occurred in Mecp2+/− mice and submucosal injection of complete Freund’s adjuvant into the tongue produced a long-lasting heat hyperalgesia at the inflamed site in wild-type mice but not in Mecp2+/− mice. Transient receptor potential vanilloid 1 was expressed in a large number of MeCP2-immunoreactive trigeminal ganglion neurons innervating the tongue in both wild-type and Mecp2+/− mice (70.9% in wild type; 72.1% in Mecp2+/−). The number of transient receptor potential vanilloid 1-immunoreactive trigeminal ganglion neurons innervating the tongue was smaller in Mecp2+/− mice relative to wild-type mice (30.5% in wild type; 20.2% in Mecp2+/−). Following complete Freund’s adjuvant injection, the number of transient receptor potential vanilloid 1- and MeCP2-immunoreactive trigeminal ganglion neurons innervating the tongue, as well as MeCP2 protein expression in trigeminal ganglion, was significantly increased in wild-type mice but not in Mecp2+/− mice. Additionally, tongue heat hyperalgesia following complete Freund’s adjuvant injection was completely suppressed by the administration of SB366791, a transient receptor potential vanilloid 1 antagonist, in the tongue.ConclusionsThese findings indicate that tongue heat sensitivity and hypersensitivity are dependent on the expression of transient receptor potential vanilloid 1 which is regulated via MeCP2 signaling in trigeminal ganglion neurons innervating the tongue.

Effect of DNA methyltransferase 1 and methyl-CpG-binding protein 2 abnormal expression on cervical lesions and related interaction

To explore the effect of DNA methyltransferase 1 (DNMT1) and methyl-CpG-binding protein 2 (MeCP2) on cervical cancer and cervix precancerous lesion. 74 patients with cervix squamous cell carcinoma(SCC), 52 patients with cervical intraepithelial neoplasm I (CIN I), 60 patients with cervical intraepithelial neoplasm II - II (CIN II-III)and 58 patients with histologically diagnosed cervix inflammation(CI), were included in this study. Information as demography, reproductive history, life style, HPV infection were collected. Western Blot were used to detect the expression of DNMT1 protein and MeCP2 protein. Real-time PCR was used to detect the expression of DNMT1 and MeCP2 mRNA. Levels of DNMT1 and MeCP2 protein expression increased gradually with the deterioration of cervical lesion (H = 94.33, P < 0.001;F = 21.580, P < 0.001). Along with the deterioration of cervical lesion, levels of DNMT1 and MeCP2 mRNA expression were gradually increasing( F = 4.758, P = 0.003; F = 7.804, P < 0.001). Data from Correlation analysis showed that both protein (r = 0.287, P < 0.001) and mRNA(r = 0.179, P = 0.005)were positive correlated with DNMT1 and MeCP2. of our study indicated that there was an additive interaction between high-expression of DNMT1 protein and high-expression of MeCP2 protein in SCC or CIN II-III. However, there was an additive interaction between high-expression of DNMT1 mRNA and high-expression of MeCP2 mRNA in SCC or CIN II-III. Results from our study revealed the fact that both high expression of DNMT1 protein and high expression of MeCP2 protein could increase the risk of cervix cancerization. According to our findings, there might be a synergistic action existed between DNMT1 and MeCP2 during the progression of cervix cancelation.

Effect of folate in modulating the expression of DNA methyltransferase 1 and methyl-CpG-binding protein 2 in cervical cancer cell lines

To explore the effects of folate on the expression of DNA methyltransferase 1 (DNMT1) and methyl-CpG-binding protein 2 (MeCP2) in cervical cancer cell lines. Experimental study was carried out in vitro. Human cervical cancer cell lines, including C33A cell with HPV negative and Caski cell with HPV16 positive, were treated with different concentration of folate. The expression of DNMT1 and MeCP2 protein (by Western blot) and mRNA (by real-time PCR) were then detected in the two cell lines. It was found that supplement of folate was able to reduce the cell proliferation in C33A cell (r = 0.984, P < 0.001) and Caski cell (r = 0.978, P = 0.002), as well as induced the cell apoptosis (C33A: r = 0.989, P < 0.001; Caski: r = 0.994, P < 0.001). showed that the expression levels of DNMT1 protein (C33A: r = -0.914, P < 0.001; Caski: r = -0.859, P = 0.003) and MeCP2 protein (C33A: r = -0.830, P = 0.005; Caski: r = -0.981, P < 0.001) decreased gradually with the increase of folate concentrations, but the expression of DNMT1 and MeCP2 mRNA was not observed in Caski or C33A cell. When at the same levels of folate, the expression of DNMT1 protein or mRNA was higher in Caski cell than in C33A cell. However, the expression of MeCP2 protein or mRNA was higher in C33A cell than in Caski cell. Our finding indicated that adequate folate could effectively inhibit the proliferation of cervical cancer cells and facilitate their apoptosis in vitro, thus would reverse the aberration protein expression of DNMT1 and MeCP2. That there might be a synergistic action between HPV16 infection and parafunction of DNMT1 in cervical cancer, being noticed.

The expression patterns and correlations of claudin-6, methy-CpG binding protein 2, DNA methyltransferase 1, histone deacetylase 1, acetyl-histone H3 and acetyl-histone H4 and their clinicopathological significance in breast invasive ductal carcinomas.

BackgroundClaudin-6 is a candidate tumor suppressor gene in breast cancer, and has been shown to be regulated by DNA methylation and histone modification in breast cancer lines. However, the expression of claudin-6 in breast invasive ductal carcinomas and correlation with clinical behavior or expression of other markers is unclear. We considered that the expression pattern of claudin-6 might be related to the expression of DNA methylation associated proteins (methyl-CpG binding protein 2 (MeCP2) and DNA methyltransferase 1 (DNMT1)) and histone modification associated proteins (histone deacetylase 1 (HDAC1), acetyl-histone H3 (H3Ac) and acetyl- histone H4 (H4Ac)).MethodsWe have investigated the expression of claudin-6, MeCP2, HDAC1, H3Ac and H4Ac in 100 breast invasive ductal carcinoma tissues and 22 mammary gland fibroadenoma tissues using immunohistochemistry.ResultsClaudin-6 protein expression was reduced in breast invasive ductal carcinomas (P < 0.001). In contrast, expression of MeCP2 (P < 0.001), DNMT1 (P = 0.001), HDAC1 (P < 0.001) and H3Ac (P = 0.004) expressions was increased. Claudin-6 expression was inversely correlated with lymph node metastasis (P = 0.021). Increased expression of HDAC1 was correlated with histological grade (P < 0.001), age (P = 0.004), clinical stage (P = 0.007) and lymph node metastasis (P = 0.001). H3Ac expression was associated with tumor size (P = 0.044) and clinical stage of cancers (P = 0.034). MeCP2, DNMT1 and H4Ac expression levels did not correlate with any of the tested clinicopathological parameters (P > 0.05). We identified a positive correlation between MeCP2 protein expression and H3Ac and H4Ac protein expression.ConclusionsOur results show that claudin-6 protein is significantly down-regulated in breast invasive ductal carcinomas and is an important correlate with lymphatic metastasis, but claudin-6 down-regulation was not correlated with upregulation of the methylation associated proteins (MeCP2, DNMT1) or histone modification associated proteins (HDAC1, H3Ac, H4Ac). Interestingly, the expression of MeCP2 was positively correlated with the expression of H3Ac and H3Ac protein expression was positively correlated with the expression of H4Ac in breast invasive ductal carcinomaVirtual slidesThe virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/4549669866581452

IGF1 as a Potential Treatment for Rett Syndrome: Safety Assessment in Six Rett Patients

Rett syndrome (RTT) is a devastating neurodevelopmental disorder that affects one in ten thousand girls and has no cure. The majority of RTT patients display mutations in the gene that codes for the methyl-CpG-binding protein 2 (MeCP2). Clinical observations and neurobiological analysis of mouse models suggest that defects in the expression of MeCP2 protein compromise the development of the central nervous system, especially synaptic and circuit maturation. Thus, agents that promote brain development and synaptic function, such as insulin-like growth factor 1 (IGF1), are good candidates for ameliorating the symptoms of RTT. IGF1 and its active peptide, (1–3) IGF1, cross the blood brain barrier, and (1–3) IGF1 ameliorates the symptoms of RTT in a mouse model of the disease; therefore they are ideal treatments for neurodevelopmental disorders, including RTT. We performed a pilot study to establish whether there are major risks associated with IGF1 administration in RTT patients. Six young girls with classic RTT received IGF1 subcutaneous injections twice a day for six months, and they were regularly monitored by their primary care physicians and by the unit for RTT in Versilia Hospital (Italy). This study shows that there are no risks associated with IGF1 administration.

Reduced MeCP2 Expression is Frequent in Autism Frontal Cortex and Correlates with Aberrant MECP2 Promoter Methylation

Mutations in MECP2, encoding methyl CpG binding protein 2 (MeCP2), cause most cases of Rett syndrome (RTT), an X-linked neurodevelopmental disorder. Both RTT and autism are “pervasive developmental disorders” and share a loss of social, cognitive and language skills and a gain in repetitive stereotyped behavior, following apparently normal perinatal development. Although MECP2 coding mutations are a rare cause of autism, MeCP2 expression defects were previously found in autism brain. To further study the role of MeCP2 in autism spectrum disorders (ASDs), we determined the frequency of MeCP2 expression defects in brain samples from autism and other ASDs. We also tested the hypotheses that MECP2 promoter mutations or aberrant promoter methylation correlate with reduced expression in cases of idiopathic autism. MeCP2 immunofluorescence in autism and other neurodevelopmental disorders was quantified by laser scanning cytometry and compared with control postmortem cerebral cortex samples on a large tissue microarray. A significant reduction in MeCP2 expression compared to age-matched controls was found in 11/14 autism (79%), 9/9 RTT (100%), 4/4 Angelman syndrome (100%), 3/4 Prader-Willi syndrome (75%), 3/5 Down syndrome (60%), and 2/2 attention deficit hyperactivity disorder (100%) frontal cortex samples. One autism female was heterozygous for a rare MECP2 promoter variant that correlated with reduced MeCP2 expression. A more frequent occurrence was significantly increased MECP2 promoter methylation in autism male frontal cortex compared to controls. Furthermore, percent promoter methylation of MECP2 significantly correlated with reduced MeCP2 protein expression. These results suggest that both genetic and epigenetic defects lead to reduced MeCP2 expression and may be important in the complex etiology of autism.

Expression of the methyl-CpG-binding protein MeCP2 in rat brain. An ontogenetic study

Rett syndrome (RS) is caused by mutations in the gene encoding methyl-CpG-binding protein 2 (MeCP2) and is characterized by arrested postnatal neurodevelopment. We followed the expression of MeCP2 protein in various brain structures of normal rat from birth to 2 years of age. By measuring the amount of protein using the Western blot technique, or by determining the percentage of immunoreactive cells, significant heterogeneity in MeCP2 distribution among various brain areas was observed. Highest expression was found in olfactory bulb and in frontal cortex. In contrast, little expression was detected in caudate-putamen, septum and hippocampus. Except in the olfactive nuclei, very few cells showed detectable MeCP2 protein at birth. The number increased during the first week of age, especially in cortex and nucleus accumbens. Rather than playing a global role in gene transcription, the heterogeneous distribution of MeCP2 transcription factor favors the idea that it has a specialized function in neurons.