title: DNA methyltransferase 1 regulates reelin mRNA expression in mouse primary cortical cultures.
abstract: The polygenic nature of complex psychiatric disorders suggests a common pathway that may be involved in the down-regulation of multiple genes through an epigenetic mechanism. To investigate the role of methylation in down-regulating the expression of mRNAs that may be associated with the schizophrenia phenotype, we have adopted a cell-culture model amenable to this line of investigation. We have administered methionine (2 mM) to primary cultures of cortical neurons prepared from embryonic day 16 mice and show that this treatment down-regulated reelin and glutamic acid decarboxylase 67 (GAD67) mRNA expression but not that corresponding to neuron-specific enolase mRNA. Moreover, methionine increased methylation of the reelin promoter, suggesting a possible mechanism for the observed change. These cultures contain a mixed population of neurons and glia. Approximately 83% of the neurons are GABAergic based on GAD immunoreactivity, and these neurons coexpress high levels of reelin and DNA methyltransferase (Dnmt) 1 immunoreactivity. To examine whether Dnmt1 regulates reelin gene expression, we used an antisense approach to reduce (knock down) Dnmt1 expression. The reduced Dnmt1 mRNA and protein were accompanied by increased reelin mRNA expression. More importantly, the Dnmt1 knockdown blocked the methionine-induced reelin and GAD67 mRNA down-regulation. These data support the hypothesis that the reduced amounts of reelin and GAD67 mRNAs documented in postmortem schizophrenia brain may be the consequence of a Dnmt1-mediated hypermethylation of the corresponding promoters.
authors.affiliation: Psychiatric Institute, Department of Psychiatry, College of Medicine, University of Illinois, 1601 West Taylor Street, Chicago, IL 60612, USA.
authors.forename: Jai Sung
authors.initials: JS
authors.lastname: Noh
authors.forename: Rajiv P
authors.initials: RP
authors.lastname: Sharma
authors.forename: Marin
authors.initials: M
authors.lastname: Veldic
authors.forename: Alain A
authors.initials: AA
authors.lastname: Salvacion
authors.forename: Xiaomei
authors.initials: X
authors.lastname: Jia
authors.forename: Ying
authors.initials: Y
authors.lastname: Chen
authors.forename: Erminio
authors.initials: E
authors.lastname: Costa
authors.forename: Alessandro
authors.initials: A
authors.lastname: Guidotti
authors.forename: Dennis R
authors.initials: DR
authors.lastname: Grayson
mesh_terms: D000818:Animals; D015816:Cell Adhesion Molecules, Neuronal / Q000235:genetics*; D002478:Cells, Cultured; D002540:Cerebral Cortex / Q000196:embryology / Q000502:physiology*; D000076123:DNA (Cytosine-5-)-Methyltransferase 1; D004248:DNA (Cytosine-5-)-Methyltransferases / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D019175:DNA Methylation; D016326:Extracellular Matrix Proteins / Q000235:genetics*; D005786:Gene Expression Regulation; D005865:Gestational Age; D005968:Glutamate Decarboxylase / Q000235:genetics / Q000378:metabolism; D006801:Humans; D007527:Isoenzymes / Q000235:genetics / Q000378:metabolism; D008715:Methionine / Q000494:pharmacology; D051379:Mice; D018345:Mice, Knockout; D023421:Models, Animal; D009419:Nerve Tissue Proteins; D009474:Neurons / Q000502:physiology; D011401:Promoter Regions, Genetic / Q000187:drug effects / Q000235:genetics; D012333:RNA, Messenger / Q000235:genetics*; D000091042:Reelin Protein; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012559:Schizophrenia / Q000235:genetics / Q000378:metabolism; D012697:Serine Endopeptidases
chemical_list: D015816:Cell Adhesion Molecules, Neuronal; D016326:Extracellular Matrix Proteins; D007527:Isoenzymes; D009419:Nerve Tissue Proteins; D012333:RNA, Messenger; D000091042:Reelin Protein; D008715:Methionine; D000076123:DNA (Cytosine-5-)-Methyltransferase 1; D004248:DNA (Cytosine-5-)-Methyltransferases; C000619380:DNMT1 protein, human; C000619381:Dnmt1 protein, mouse; C000717127:RELN protein, human; C000717128:Reln protein, mouse; D012697:Serine Endopeptidases; D005968:Glutamate Decarboxylase; C402565:glutamate decarboxylase 1