A ketogenic diet rescues hippocampal memory defects in a mouse model of Kabuki syndrome

Kabuki syndrome is a Mendelian intellectual disability syndrome caused by mutations in either of two genes (KMT2D and KDM6A) involved in chromatin accessibility. We previously showed that an agent that promotes chromatin opening, the histone deacetylase inhibitor (HDACi) AR-42, ameliorates the deficiency of adult neurogenesis in the granule cell layer of the dentate gyrus, and rescues hippocampal memory defects in a mouse model of Kabuki syndrome (Kmt2d+/βGeo). Unlike a drug, a dietary intervention could be quickly transitioned to the clinic. Therefore, we have explored whether treatment with a ketogenic diet could lead to a similar rescue through increased amounts of beta-hydroxybutyrate, an endogenous HDACi. Here, we report that a ketogenic diet in Kmt2d+/βGeo mice modulates H3ac and H3K4me3 in the granular cell layer, with concomitant rescue of both the neurogenesis defect and hippocampal memory abnormalities seen in Kmt2d+/βGeo mice; similar effects on neurogenesis were observed upon exogenous administration of beta-hydroxybutyrate. These data suggests that dietary modulation of epigenetic modifications through elevation of beta-hydroxybutyrate may provide a feasible strategy to treat the intellectual disability seen in Kabuki syndrome and related disorders. We used microarrays to query global gene expression changes in the hippocampus of wild type and Kmt2d+/βGeo (Kabuki syndrome model) mice on a regular diet to identify specific gene expression abnormalities in the hippocampus of the Kabuki syndrome mouse model. Two different microarray experiments were run using cDNA synthesized using RNA extracted from whole mouse hippocampi. In both, hippocampi were dissected from 1-2 month old wild type and Kmt2d+/βGeo mice (mouse model of Kabuki syndrome) on a standard diet. In the first experiment 4 wild type and 3 Kmt2d+/βGeo were profiled, and in the second experiment 3 wild type and 3 Kmt2d+/βGeo were profiled.