KDM5C binding profile in hippocampal chromatin
Loss or reduced expression of lysine demethylases (KDMs) is linked to neurodevelopmental disorders and intellectual disability. Given the phenotypic similarities between KDM1A and KDM5C deficient mice, and the convergence of both enzymes in maintaining a repressive state via H3K4 demethylation, we examined their functional interaction using double-inducible, forebrain-specific knockouts (dKDM-ifKOs). These mice showed transcriptional and epigenetic dysregulation beyond the additive effects of individual knockouts, including stronger ectopic expression of non-neuronal genes in hippocampal neurons. Thousands of de novo H3K4me3-enriched regions emerged, indicating synergistic disruption of chromatin regulation. In line with these molecular changes, dKDM-ifKOs displayed more severe behavioral impairments than the single ifKOs, along with altered hippocampal expression of ion channels and increased excitability of CA1 pyramidal neurons. These findings underscore the joint role of ID-linked KDMs in regulating cell-type-specific gene silencing and H3K4 methylation levels to safeguard neuronal identity and responsiveness, as well as cognitive function Overall design: Kdm5cf/f, and CamKIIa-CreERT2 mouse strains are available at public repositories (MMRRC stock 066789-UCD; and EMMA EM:02125, respectively). Mice were maintained on a C57BL/6J genetic background. The recombinant protein CreERT2 is dependent on tamoxifen (TMX) administration, and its expression is restricted to principal neurons of the forebrain, where CamKIIa is expressed. CaMKIIa–driven, TMX induced Cre recombination results in the elimination of exons 11 and 12 in Kdm5cf/f . Mice were 2 to 3-month-old at the time of TMX administration.