Dnmt3a knockout in excitatory neurons impairs postnatal synapse maturation and increases the repressive histone modification H3K27me3

• DOI: 10.7554/elife.66909
• Publication Date: 2022-05-23T12:00:47Z
• Authors: Junhao Li; Antonio Pinto-Duarte; Mark Zander; Michael S Cuoco; Chi-Yu Lai; Julia Osteen; Linjing Fang; Chongyuan Luo; Jacinta D Lucero; Rosa Gomez-Castanon; Joseph R Nery; Isai Silva-Garcia; Yan Pang; Terrence J Sejnowski; Susan B Powell; Joseph R Ecker; Eran A Mukamel; M Margarita Behrens
• Keywords: 0301 basic medicine; 570; Mouse; QH301-705.5; 1.1 Normal biological development and functioning; Knockout; H3K27me3; Science; brain development; Dnmt3a; DNA Methyltransferase 3A; neuroscience; Histones; Mice; 03 medical and health sciences; Underpinning research; synapse; Genetics; genomics; Animals; genetics; Biology (General); mouse; Pediatric; Mice, Knockout; Neurons; DNA methylation; epigenetics; Animal; Human Genome; Q; Neurosciences; R; Polycomb Repressive Complex 2; 500; Brain; Genetics and Genomics; Histone Code; Disease Models, Animal; Neurological; Disease Models; Synapses; Medicine; Biochemistry and Cell Biology

Two epigenetic pathways of transcriptional repression, DNA methylation and polycomb repressive complex 2 (PRC2), are known to regulate neuronal development and function. However, their respective contributions to brain maturation are unknown. We found that conditional loss of the de novo DNA methyltransferase Dnmt3a in mouse excitatory neurons altered expression of synapse-related genes, stunted synapse maturation, and impaired working memory and social interest. At the genomic level, loss of Dnmt3a abolished postnatal accumulation of CG and non-CG DNA methylation, leaving adult neurons with an unmethylated, fetal-like epigenomic pattern at ~222,000 genomic regions. The PRC2-associated histone modification, H3K27me3, increased at many of these sites. Our data support a dynamic interaction between two fundamental modes of epigenetic repression during postnatal maturation of excitatory neurons, which together confer robustness on neuronal regulation.