title: Dual DNA methylation patterns in the CNS reveal developmentally poised chromatin and monoallelic expression of critical genes.
abstract: As a first step towards discovery of genes expressed from only one allele in the CNS, we used a tiling array assay for DNA sequences that are both methylated and unmethylated (the MAUD assay). We analyzed regulatory regions of the entire mouse brain transcriptome, and found that approximately 10% of the genes assayed showed dual DNA methylation patterns. They include a large subset of genes that display marks of both active and silent, i.e., poised, chromatin during development, consistent with a link between differential DNA methylation and lineage-specific differentiation within the CNS. Sixty-five of the MAUD hits and 57 other genes whose function is of relevance to CNS development and/or disorders were tested for allele-specific expression in F(1) hybrid clonal neural stem cell (NSC) lines. Eight MAUD hits and one additional gene showed such expression. They include Lgi1, which causes a subtype of inherited epilepsy that displays autosomal dominance with incomplete penetrance; Gfra2, a receptor for glial cell line-derived neurotrophic factor GDNF that has been linked to kindling epilepsy; Unc5a, a netrin-1 receptor important in neurodevelopment; and Cspg4, a membrane chondroitin sulfate proteoglycan associated with malignant melanoma and astrocytoma in human. Three of the genes, Camk2a, Kcnc4, and Unc5a, show preferential expression of the same allele in all clonal NSC lines tested. The other six genes show a stochastic pattern of monoallelic expression in some NSC lines and bi-allelic expression in others. These results support the estimate that 1-2% of genes expressed in the CNS may be subject to allelic exclusion, and demonstrate that the group includes genes implicated in major disorders of the CNS as well as neurodevelopment.
authors.affiliation: Division of Biology, Beckman Research Institute, City of Hope National Medical Center, Duarte, California, United States of America.
authors.forename: Jinhui
authors.initials: J
authors.lastname: Wang
authors.forename: Zuzana
authors.initials: Z
authors.lastname: Valo
authors.forename: Chauncey W
authors.initials: CW
authors.lastname: Bowers
authors.forename: David D
authors.initials: DD
authors.lastname: Smith
authors.forename: Zheng
authors.initials: Z
authors.lastname: Liu
authors.forename: Judith
authors.initials: J
authors.lastname: Singer-Sam
mesh_terms: D000483:Alleles; D000818:Animals; D000941:Antigens / Q000235:genetics; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2 / Q000235:genetics; D002454:Cell Differentiation / Q000235:genetics; D002460:Cell Line; D002490:Central Nervous System / Q000254:growth & development / Q000378:metabolism*; D002843:Chromatin / Q000235:genetics*; D019175:DNA Methylation; D005260:Female; D020869:Gene Expression Profiling; D018507:Gene Expression Regulation, Developmental; D051097:Glial Cell Line-Derived Neurotrophic Factor Receptors / Q000235:genetics; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D000075386:Netrin Receptors; D058953:Neural Stem Cells / Q000166:cytology / Q000378:metabolism; D020411:Oligonucleotide Array Sequence Analysis; D011401:Promoter Regions, Genetic / Q000235:genetics; D016548:Prosencephalon / Q000254:growth & development / Q000378:metabolism; D011506:Proteins / Q000235:genetics; D011509:Proteoglycans / Q000235:genetics; D011956:Receptors, Cell Surface / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D051670:Shaw Potassium Channels / Q000235:genetics; D000099216:Chondroitin Sulfate Proteoglycan 4
chemical_list: D000941:Antigens; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2; D002843:Chromatin; D051097:Glial Cell Line-Derived Neurotrophic Factor Receptors; D047908:Intracellular Signaling Peptides and Proteins; D000075386:Netrin Receptors; D011506:Proteins; D011509:Proteoglycans; D011956:Receptors, Cell Surface; D051670:Shaw Potassium Channels; D000099216:Chondroitin Sulfate Proteoglycan 4; C494991:Gfra2 protein, mouse; C115399:Kcnc4 protein, mouse; C492120:Lgi1 protein, mouse; C000617308:Unc5A protein, mouse; C517671:Camk2a protein, mouse