Chromatin-mediated alternative splicing regulates cocaine reward behavior

Neuronal alternative splicing is a key gene regulatory mechanism in brain. Yet the spliceosome machinery is insufficient to fully specify splicing complexity. In considering the role of the epigenome in activity-dependent alternative splicing, we and others find the histone modification, H3K36me3, to be a putative splicing regulator. In the current study, we found that mouse cocaine self-administration caused widespread differential alternative splicing, concomitant with enrichment of H3K36me3 at differentially spliced junctions. Importantly, only targeted epigenetic editing can distinguish between a direct role of H3K36me3 in splicing and an indirect role via regulation of splice factor expression elsewhere on the genome. We targeted Srsf11, which was both alternatively spliced and H3K36me3 enriched in brain following cocaine self-administration. Results: Epigenetic editing of H3K36me3 at Srsf11 was sufficient to drive its alternative splicing and enhanced cocaine self-administration, establishing the direct causal relevance of H3K36me3 to alternative splicing of Srsf11 and to reward behavior. H3K36me3 ChIP-seq identified H3K36me3 enrichment at splice junctions (N=3) in cocaine samples. H3K36me3 Cut&Run-seq (N=6) of dCas9-SET2-sgRNA transfected N2a cells confirmed increased H3K36me3 enrichment in Srsf11 splice junction. Alternative splicing analysis of dCas9-Set2-Srsf11 targeted NAc (N=4) identified its alternative splicing profile. H3K36me3 ChIP-seq (N=3) and RNA-seq (N=3) in HSV-Set2 transfected NAc assessed how H3K36me3 regulated alternative splicing globally in NAc.