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《神经药理学报》
>S5B-3 Selective Deletion of Dnmts in Excitatory Neurons Impairs Recognition Memory and Synaptic Function in Hippocampal Network of Adult Mice
S5B-3 Selective Deletion of Dnmts in Excitatory Neurons Impairs Recognition Memory and Synaptic Function in Hippocampal Network of Adult Mice
Objective:DNA methylation is one of the most important epigenetic modulation,which is catalyzed primarily by three methyltransferases,DNMT1,DNMT3a and DNMT3b.The aim of our study is to investigate the modulatory effect of DNMTs on hippocampus-dependent memory formation,and to explore the underlying molecular,cellular and synaptic mechanisms.Methods:Dnmt1,3a and 3b were selectively deleted in the CA1 region of dorsal hippocampus by Cre/LoxP recombinase systerm,either with virus-mediated Cre expression in CA1 of Dnmtsflox/flox mice or conditionalαCaMKII-Cre;Dnmtsflox/flox mice.Hippocampus-dependent and hippocampus-independent memory performance were evaluated in adult KO and control mice.RNA-seq analysis was conducted to screen differential expression genes in the hippocampus after conditional Dnmts knockout.Real-time qPCR and Western blot analysis were used to confirm the differential expression.We also analyzed the alteration in DNA methylation by Whole Genome Bisulfite Sequencing.Neuronal excitability,synaptic transmission and plasticity were measured in CA1 pyramidal neurons of hippocampal slices.Finally,we checked whether virus-mediated shRNA expression in hippocampal CA1 could ameliorate abnormal synaptic function and memory deficit observed inαCaMKII-Cre;Dnmstflox/flox mice.Results:We found that both Dnmt1flox/floxDnmt3aflox/flox mice and Dnmt3bflox/flox mice receiving AAV-Cre virus infection into CA1 region displayed recognition memory deficit to object place,but normal memory to novel object.All mice showed similar performance in fear memory tests.Also,virus infection and Dnmts deletion did not changed anxiety-or depression-like behavior.The object place recognition memory deficit was also observed in bothαCaMKII-Cre;Dnmt1flox/floxDnmt3aflox/flox mice andαCaMKII-Cre;Dnmt3bflox/flox mice.The Cre expression inαCaMKII-Cre mice was verified to be dominant in hippocampal CA1.RNA-seq based gene expression and followed real-time qPCR and western blot analysis confirmed significant upregulation of certain genes after Dnmts deletion in aCaMKII-expression excitatory neurons in the hippocampus.WGBS analysis showed differentiated DNA methylation in related genes.Normal basal synaptic transmission but impaired LTP was observed in SCCA1 path of bothαCaMKII-Cre;Dnmt1flox/floxDnmt3aflox/flox mice andαCaMKII-Cre;Dnmt3bflox/flox mice.AAV-virus mediated specific shRNA expression in CA1 region of dorsal hippocampus interfered upregulation of candidate genes,rescued abnormal synaptic function,and ameliorated object place cognition impairment in bothαCaMKII-Cre;Dnmt1flox/floxDnmt3aflox/flox mice andαCaMKII-Cre;Dnmt3bflox/flox mice.Virus-mediated shRNA expression in CA1 region of dorsal hippocampus did not affect recognition memory to novel object.Conclusion:In conclusion,our findings suggest that Dnmts in CA1 excitatory neurons plays an important role in regulating synaptic function and hippocampus-dependent recognition memory process by control the expression of certain target genes.
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