title: DNA hypomethylation perturbs the function and survival of CNS neurons in postnatal animals.
abstract: DNA methyltransferase I (Dnmt1), the maintenance enzyme for DNA cytosine methylation, is expressed at high levels in the CNS during embryogenesis and after birth. Because embryos deficient for Dnmt1 die at gastrulation, the role of Dnmt1 in the development and function of the nervous system could not be studied by using this mutation. We therefore used the cre/loxP system to produce conditional mutants that lack Dnmt1 in neuroblasts of embryonic day 12 embryos or in postmitotic neurons of the postnatal animal. Conditional deletion of the Dnmt1 gene resulted in rapid depletion of Dnmt1 proteins, indicating that the enzyme in postmitotic neurons turns over quickly. Dnmt1 deficiency in postmitotic neurons neither affected levels of global DNA methylation nor influenced cell survival during postnatal life. In contrast, Dnmt1 deficiency in mitotic CNS precursor cells resulted in DNA hypomethylation in daughter cells. Whereas mutant embryos carrying 95% hypomethylated cells in the brain died immediately after birth because of respiratory distress, mosaic animals with 30% hypomethylated CNS cells were viable into adulthood. However, these mutant cells were eliminated quickly from the brain within 3 weeks of postnatal life. Thus, hypomethylated CNS neurons were impaired functionally and were selected against at postnatal stages.
authors.affiliation: Whitehead Institute for Biomedical Research and Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts 02142, USA.
authors.forename: G
authors.initials: G
authors.lastname: Fan
authors.forename: C
authors.initials: C
authors.lastname: Beard
authors.forename: R Z
authors.initials: RZ
authors.lastname: Chen
authors.forename: G
authors.initials: G
authors.lastname: Csankovszki
authors.forename: Y
authors.initials: Y
authors.lastname: Sun
authors.forename: M
authors.initials: M
authors.lastname: Siniaia
authors.forename: D
authors.initials: D
authors.lastname: Biniszkiewicz
authors.forename: B
authors.initials: B
authors.lastname: Bates
authors.forename: P P
authors.initials: PP
authors.lastname: Lee
authors.forename: R
authors.initials: R
authors.lastname: Kuhn
authors.forename: A
authors.initials: A
authors.lastname: Trumpp
authors.forename: C
authors.initials: C
authors.lastname: Poon
authors.forename: C B
authors.initials: CB
authors.lastname: Wilson
authors.forename: R
authors.initials: R
authors.lastname: Jaenisch
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D002452:Cell Count; D016923:Cell Death; D002470:Cell Survival / Q000502:physiology; D002478:Cells, Cultured; D002490:Central Nervous System / Q000254:growth & development / Q000378:metabolism* / Q000473:pathology; D003433:Crosses, Genetic; D000076123:DNA (Cytosine-5-)-Methyltransferase 1; D004248:DNA (Cytosine-5-)-Methyltransferases / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D019175:DNA Methylation; D004594:Electrophysiology; D018390:Gene Targeting; D051379:Mice; D008822:Mice, Transgenic; D009030:Mosaicism / Q000235:genetics; D019636:Neurodegenerative Diseases / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D009474:Neurons / Q000166:cytology / Q000378:metabolism*; D012131:Respiratory Insufficiency / Q000235:genetics; D013234:Stem Cells / Q000166:cytology / Q000378:metabolism
chemical_list: D000076123:DNA (Cytosine-5-)-Methyltransferase 1; D004248:DNA (Cytosine-5-)-Methyltransferases; C000619381:Dnmt1 protein, mouse