Increased binding of MeCP2 to the GAD1 and RELN promoters may be mediated by an enrichment of 5-hmC in autism spectrum disorder (ASD) cerebellum.
Autism spectrum disorder (ASD) is a neurodevelopmental disorder characterized by symptoms related to altered social interactions/communication and restricted and repetitive behaviors. In addition to genetic risk, epigenetic mechanisms (which include DNA methylation/demethylation) are thought to be important in the etiopathogenesis of ASD. We studied epigenetic mechanisms underlying the transcriptional regulation of candidate genes in cerebella of ASD patients, including the binding of MeCP2 (methyl CpG binding protein-2) to the glutamic acid decarboxylase 67 (GAD1), glutamic acid decarboxylase 65 (GAD2), and Reelin (RELN) promoters and gene bodies. Moreover, we performed methyl DNA immunoprecipitation (MeDIP) and hydroxymethyl DNA immunoprecipitation (hMeDIP) to measure total 5-methylcytosine (5-mC) and 5-hydroxymethylcytosine (5-hmC) in the same regions of these genes. The enrichment of 5-hmC and decrease in 5-mC at the GAD1 or RELN promoters detected by 5-hmC and 5-mC antibodies was confirmed by Tet-assisted bisulfite (TAB) pyrosequencing. The results showed a marked and significant increase in MeCP2 binding to the promoter regions of GAD1 and RELN, but not to the corresponding gene body regions in cerebellar cortex of ASD patients. Moreover, we detected a significant increase in TET1 expression and an enrichment in the level of 5-hmC, but not 5-mC, at the promoters of GAD1 and RELN in ASD when compared with CON. Moreover, there was increased TET1 binding to these promoter regions. These data are consistent with the hypothesis that an increase of 5-hmC (relative to 5-mC) at specific gene domains enhances the binding of MeCP2 to 5-hmC and reduces expression of the corresponding target genes in ASD cerebella.
The Psychiatric Institute, Department of Psychiatry, College of Medicine, University of Illinois at Chicago, Chicago, IL, USA.
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Zhubi
The Psychiatric Institute, Department of Psychiatry, College of Medicine, University of Illinois at Chicago, Chicago, IL, USA.
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Chen
The Psychiatric Institute, Department of Psychiatry, College of Medicine, University of Illinois at Chicago, Chicago, IL, USA.
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Dong
Institute for Juvenile Research, Department of Psychiatry, College of Medicine, University of Illinois at Chicago, Chicago, IL, USA.
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Cook
The Psychiatric Institute, Department of Psychiatry, College of Medicine, University of Illinois at Chicago, Chicago, IL, USA.
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Guidotti
The Psychiatric Institute, Department of Psychiatry, College of Medicine, University of Illinois at Chicago, Chicago, IL, USA.
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Grayson
D044503:5-Methylcytosine / Q000031:analogs & derivatives; D015816:Cell Adhesion Molecules, Neuronal / Q000235:genetics / Q000378:metabolism*; D002525:Cerebellar Cortex / Q000378:metabolism* / Q000473:pathology; D002659:Child Development Disorders, Pervasive / Q000235:genetics / Q000378:metabolism*; D003596:Cytosine / Q000031:analogs & derivatives* / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000378:metabolism; D044127:Epigenesis, Genetic; D016326:Extracellular Matrix Proteins / Q000235:genetics / Q000378:metabolism*; D005968:Glutamate Decarboxylase / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D051783:Methyl-CpG-Binding Protein 2 / Q000378:metabolism*; D006899:Mixed Function Oxygenases; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000378:metabolism*; D011401:Promoter Regions, Genetic; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D000091042:Reelin Protein; D012697:Serine Endopeptidases / Q000235:genetics / Q000378:metabolism*; D014015:Tissue Banks
D015816:Cell Adhesion Molecules, Neuronal; D004268:DNA-Binding Proteins; D016326:Extracellular Matrix Proteins; D051783:Methyl-CpG-Binding Protein 2; D009419:Nerve Tissue Proteins; D011518:Proto-Oncogene Proteins; D000091042:Reelin Protein; C011865:5-hydroxymethylcytosine; D044503:5-Methylcytosine; D003596:Cytosine; D006899:Mixed Function Oxygenases; C462539:TET1 protein, human; C000717127:RELN protein, human; D012697:Serine Endopeptidases; D005968:Glutamate Decarboxylase; C402565:glutamate decarboxylase 1