Epigenetic changes in status epilepticus.

Epigenetics refers broadly to processes that influence medium- to long-term expression of genes through changes to the readability and accessibility of the genome to transcription. The mediators include DNA methylation, posttranslational modification of histone proteins, and noncoding RNAs. The present review focuses on recent findings showing epigenetic processes influence susceptibility to and severity of status epilepticus, while status epilepticus in turn drives changes to epigenetic marks that affect the gene expression landscape underlying epileptogenesis. Experimental status epilepticus triggers select, spatiotemporal hypo- and hypermethylation changes throughout the genome. Experimental manipulations that alter DNA methylation after status epilepticus are associated with amelioration of cognitive and hyperexcitability phenotypes. Prolonged seizures also modify chromatin compaction via acetylation and other changes to histones and their expression. Finally, short noncoding RNAs called microRNAs target networks of genes through posttranscriptional and other mechanisms and their modulation can alter status epilepticus as well as serve as potential molecular biomarkers. Long noncoding RNAs have also been targeted to influence expression of genes affecting electrophysiological functions of neurons. In summary, epigenetic processes can modulate status epilepticus, and status epilepticus imposes changes on the epigenome, which together provide novel insight into pathomechanisms, therapy, and biomarkers for status epilepticus. Wiley Periodicals, Inc.