Brain histone beta-hydroxybutyrylation couples metabolism with gene expression

Current understanding of how metabolic signals influence gene expression in the brain remains limited. While beta-hydroxybutyrate (BHB) is known as a ketone body, its role as a signaling molecule in epigenetic regulation is less established. Prior research has shown that BHB can act as an inhibitor of histone deacetylases, but its direct impact on histone modifications in the brain has not been fully explored. This gap motivated researchers to investigate whether BHB could modify histone lysine residues in neural tissues. No prior work had resolved the specific molecular mechanisms linking fasting to epigenetic changes in the brain. The study aimed to clarify how metabolic states like fasting might alter histone modifications and gene expression. Existing knowledge suggests that histone modifications are critical for gene regulation, but their connection to metabolic stimuli in the brain is unclear. The research sought to determine if fasting-induced BHB levels could influence histone beta-hydroxybutyrylation and, in turn, affect transcriptional activity. This work addresses a key question in understanding the intersection of metabolism and epigenetics in the brain.

The purpose of this study was to determine how a ketogenic metabolic challenge affects histone beta-hydroxybutyrylation in the brain. Researchers focused on the cerebral cortex of mice after 48 hours of fasting to assess changes in lysine beta-hydroxybutyrylation (K-bhb) levels. They aimed to identify whether fasting alters K-bhb in histone H3 and other proteins. The study also sought to evaluate the functional consequences of these modifications on gene expression. By using chromatin immunoprecipitation sequencing (ChIP-seq), the researchers intended to map K-bhb enrichment across the genome. Transcriptomic analysis was planned to correlate histone modifications with active gene expression. The goal was to determine if fasting-induced BHB influences epigenetic and transcriptional landscapes in the brain. This work aimed to provide insights into how metabolic signals like fasting might regulate neural gene expression through histone modifications.

The study employed a 48-hour fasting protocol in mice to induce a ketogenic metabolic state. Researchers extracted proteins from the cerebral cortex to assess lysine beta-hydroxybutyrylation (K-bhb) levels. ChIP-seq was used to analyze histone H3K9-bhb enrichment across the genome. Transcriptomic profiling was conducted to evaluate gene expression changes in fasting mice. Diurnal oscillation of specific transcripts was measured in the cortex and suprachiasmatic nucleus. Locomotor activity was monitored during re-feeding after fasting to assess behavioral changes. Data analysis focused on identifying correlations between histone modifications and active gene expression. The study combined epigenetic and transcriptional data to evaluate the impact of fasting on the brain's molecular landscape.

Fasting significantly increased K-bhb levels in the cerebral cortex, including histone H3. ChIP-seq revealed that H3K9-bhb was enriched on over 8000 DNA loci following fasting. Transcriptomic analysis showed that H3K9-bhb correlated with active gene expression at enhancers and promoters. Functional annotation identified 'circadian rhythms' as a key enriched category in both epigenetic and transcriptional data. Fasting modulated the diurnal oscillation of specific transcripts in the cortex and suprachiasmatic nucleus. Locomotor activity patterns changed during re-feeding after 48 hours of fasting. These findings suggest that fasting alters the brain's transcriptional and epigenetic landscape. BHB appears to act as an epigenetic regulator in the brain through histone modifications.

The study suggests that fasting influences the brain's transcriptional and epigenetic landscape. BHB may act as an epigenetic regulator in the brain through histone modifications. Fasting-induced H3K9-bhb was observed on over 8000 DNA loci. These modifications correlated with active gene expression at enhancers and promoters. The findings indicate that metabolic states like fasting may modulate gene expression through histone beta-hydroxybutyrylation. Circadian rhythms emerged as a key functional category affected by fasting. Locomotor activity changes during re-feeding suggest behavioral consequences of these epigenetic shifts. The results support the idea that BHB may serve as a signaling molecule in the brain.