bioRxiv preprint doi: https://doi.org/10.1101/2019.12.13.874347; this version posted December 13, 2019. The copyright holder for this preprint (which was not certified by peer review) is the author/funder. All rights reserved. No reuse allowed without permission. Epigenetically bistable regions across neuron-specific genes govern neuron eligibility to a coding ensemble in the hippocampus S. C. ODELL1, F. TAKI2, S. KLEIN2, R. J. CHEN1, O. B. LEVINE1, M.J. SKELLY2,A, NABILA1, E. BRINDLEY2, J. GAL TOTH2, F. DÜNDAR3,4, C. K. SHERIDAN5, R. N. FETCHO1, A. ALONSO5, C. LISTON1, D. A. LANDAU5,6, K. E PLEIL2, M. TOTH2* 1 Department of Neuroscience, Weill Cornell Medicine, New York, NY, USA 2 Department of Pharmacology, Weill Cornell Medicine, New York, NY, USA 3 Physiology and Biophysics, Weill Cornell Medicine, New York, NY, USA 4Applied Bioinformatics Core, Weill Cornell Medicine, New York, NY, USA 5Department of Medicine, Weill Cornell Medicine, New York, NY, USA 6New York Genome Center, New York, NY, USA *correspondence:
[email protected] Summary: Episodic memories are stored in distributed neurons but how eligibility of individual neurons to coding ensembles is determined remains elusive. We identified thousands of predominantly bistable (CpG methylated or unmethylated) regions within neuronal gene bodies, established during the development of the mouse hippocampal dentate gyrus. Reducing DNA methylation and the proportion of the methylated epialleles at bistable regions compromised novel context-induced neuronal activation and spatial memory. Conversely, increasing methylation and the frequency of the methylated epialleles at bistable regions enhanced intrinsic excitability and spatial memory but impaired spatial working memory, indicating that the developmentally established methylated-unmethylated epiallelic balance at bistable regions is essential for proper neuronal excitability and hippocampal cognitive functions.