Coll-Tane, M. | Search bioRxiv

bioRxiv2026

The evolutionarily conserved EHMT1/G9a histone methyltransferase family regulates sleep maintenance through ROS homeostasis in insulin-producing cells

Sleep disturbances are a common, still poorly characterized feature of Kleefstra syndrome (KLEFS1), a neurodevelopmental disorder caused by rare variants in the epigenetic regulator EHMT1. The gap in understanding the characteristics and origin of these sleep disturbances poses a major barrier for therapy development. In this cross-species study, we reveal that 70% of individuals with KLEFS1 experience severe sleep maintenance insomnia, marked by fragmented sleep due to frequent night awakenings. Furthermore, common genetic variation at the EHMT1 locus was associated with short sleep and insomnia symptoms in the general population. Drosophila mutants of the EHMT1 orthologue G9a recapitulate these phenotypes, exhibiting reduced and fragmented sleep. We show that G9a is required in insulin-producing cells (IPCs) and the fat body, in the latter during development, to ensure adult sleep integrity. Untargeted metabolomics revealed widespread metabolic dysregulation in G9a mutants, particularly affecting methionine metabolism. Mutants exhibited reduced methionine and elevated methionine sulfoxide (Met-SO), pointing to increased reactive oxygen species (ROS). Redox sensors revealed increased H2O2-dependent oxidation in the larval brain and an elevated glutathione redox potential in IPCs during development but not in adulthood. IPC-specific knockdown of MsrA, the enzyme that reduces Met-SO back to methionine, reproduced sleep fragmentation. Developmental, but not acute, antioxidant treatment fully restored adult sleep consolidation, demonstrating that G9a safeguards sleep via ROS homeostasis in early life. Finally, we show that a Drosophila sleep-restriction paradigm based on human sleep-restriction therapy can override the developmental defects and restore sleep continuity in adulthood. Our findings establish an evolutionarily conserved role for EHMT1/G9a in sleep regulation and provide a mechanistic framework to understand and treat sleep disturbances in KLEFS1.

genetics↗

bioRxiv2025

A conserved epilepsy-associated gene co-expression module identifies increased metabolic rate as a shared pathomechanism

Epilepsy is a mechanistically complex, incompletely understood neurological disorder. To uncover novel converging mechanisms in epilepsy, we used Drosophila whole-brain single-cell RNA-sequencing to refine and characterize a previously proposed human epilepsy-associated gene co-expression network (GCN). We identified a conserved co-expressed module of 26 genes, which comprises fly orthologs of 13 epilepsy-associated genes and integrates synaptic and metabolic functions. Over one-third of the Drosophila pan-neuronal knockdown models targeting this module exhibited altered seizure-like behaviors in response to mechanical or heat stress. These recapitulated seizures associated with four epilepsy-associated genes, identified two novel epilepsy candidate genes, and three genes knockdown of which conferred seizure protection. Most knockdown models with altered seizure susceptibility showed changes in metabolic rate and levels of phosphorylated adenosine monophosphate-activated protein kinase (AMPK), a key regulator of cellular energy homeostasis. Enhancing AMPK activity increased seizure resistance in a dose-dependent manner. Our findings show that Drosophila single-cell expression data and behavior can aid functional validation of human GCNs and highlight a role for metabolism in modifying seizure susceptibility. SUMMARY STATEMENTIntegrating Drosophila single-cell RNA-sequencing data with seizure-like behavior and metabolic rate assays, we functionally characterized a human epilepsy-associated gene network, revealing metabolic regulation as a critical factor underlying seizure susceptibilities.

neuroscience↗