Lysine Crotonylation Acts as an Epigenetic Switch for Glutamate Neurotransmission and Spatial Memory

Histone post-translational modifications (PTMs), particularly lysine acetylation (Kac), are critical epigenetic regulators of transcriptional programs underlying long-term memory consolidation. Beyond Kac, several other non-acetyl acylations have been identified with the ability to regulate transcription; however, their role in memory consolidation remains unknown. Here, we identify histone lysine crotonylation (Kcr) as a molecular switch for long-term memory and glutamatergic neurotransmission. We find that spatial learning induces distinct spatiotemporal patterns of Kcr across hippocampal subregions, and that Kcr stimulates learning-induced gene expression. Through genetic and pharmacological manipulations, we show that reducing hippocampal Kcr levels impairs memory, while increasing Kcr enhances long-term memory. Single-nuclei transcriptome and chromatin accessibility analyses reveals that Kcr facilitates activation of genes regulating glutamate signaling. Cell-cell communication analysis further infers that Kcr enhancement strengthens glutamatergic signaling within principal hippocampal neurons. Real-time fluorescence imaging with genetically encoded sensors functionally validates our multiomics and computational findings--demonstrating the role of Kcr in regulating presynaptic glutamate release and neuronal activity. In summary, our findings elucidate a novel mechanism underlying long-term memory consolidation and excitatory neurotransmission, linking epigenetic events to synaptic function and behavior.