DNA hypomethylation restricted to the murine forebrain induces cortical degeneration and impairs postnatal neuronal maturation.
DNA methylation is a major epigenetic factor regulating genome reprogramming, cell differentiation and developmental gene expression. To understand the role of DNA methylation in central nervous system (CNS) neurons, we generated conditional Dnmt1 mutant mice that possess approximately 90% hypomethylated cortical and hippocampal cells in the dorsal forebrain from E13.5 on. The mutant mice were viable with a normal lifespan, but displayed severe neuronal cell death between E14.5 and three weeks postnatally. Accompanied with the striking cortical and hippocampal degeneration, adult mutant mice exhibited neurobehavioral defects in learning and memory in adulthood. Unexpectedly, a fraction of Dnmt1(-/-) cortical neurons survived throughout postnatal development, so that the residual cortex in mutant mice contained 20-30% of hypomethylated neurons across the lifespan. Hypomethylated excitatory neurons exhibited multiple defects in postnatal maturation including abnormal dendritic arborization and impaired neuronal excitability. The mutant phenotypes are coupled with deregulation of those genes involved in neuronal layer-specification, cell death and the function of ion channels. Our results suggest that DNA methylation, through its role in modulating neuronal gene expression, plays multiple roles in regulating cell survival and neuronal maturation in the CNS.
Department of Human Genetics, David Geffen School of Medicine, University of California at Los Angeles, 695 Charles Young Drive South, Los Angeles, CA 90095, USA.
Leah K
LK
Hutnick
Peyman
P
Golshani
Masakasu
M
Namihira
Zhigang
Z
Xue
Anna
A
Matynia
X William
XW
Yang
Alcino J
AJ
Silva
Felix E
FE
Schweizer
Guoping
G
Fan
D000818:Animals; D002540:Cerebral Cortex / Q000196:embryology / Q000254:growth & development / Q000502:physiology*; D000076123:DNA (Cytosine-5-)-Methyltransferase 1; D004248:DNA (Cytosine-5-)-Methyltransferases / Q000235:genetics / Q000378:metabolism; D019175:DNA Methylation; D006624:Hippocampus / Q000196:embryology / Q000254:growth & development / Q000502:physiology; D051379:Mice; D018345:Mice, Knockout; D055495:Neurogenesis; D009474:Neurons / Q000502:physiology*; D016548:Prosencephalon / Q000196:embryology / Q000254:growth & development / Q000502:physiology*
D000076123:DNA (Cytosine-5-)-Methyltransferase 1; D004248:DNA (Cytosine-5-)-Methyltransferases; C000619381:Dnmt1 protein, mouse