Neuronal and glial DNA methylation and gene expression changes in early epileptogenesis

PLoS One. 2019 Dec 30;14(12):e0226575. doi: 10.1371/journal.pone.0226575. eCollection 2019.

Abstract

Background and aims: Mesial Temporal Lobe Epilepsy is characterized by progressive changes of both neurons and glia, also referred to as epileptogenesis. No curative treatment options, apart from surgery, are available. DNA methylation (DNAm) is a potential upstream mechanism in epileptogenesis and may serve as a novel therapeutic target. To our knowledge, this is the first study to investigate epilepsy-related DNAm, gene expression (GE) and their relationship, in neurons and glia.

Methods: We used the intracortical kainic acid injection model to elicit status epilepticus. At 24 hours post injection, hippocampi from eight kainic acid- (KA) and eight saline-injected (SH) mice were extracted and shock frozen. Separation into neurons and glial nuclei was performed by flow cytometry. Changes in DNAm and gene expression were measured with reduced representation bisulfite sequencing (RRBS) and mRNA-sequencing (mRNAseq). Statistical analyses were performed in R with the edgeR package.

Results: We observed fulminant DNAm- and GE changes in both neurons and glia at 24 hours after initiation of status epilepticus. The vast majority of these changes were specific for either neurons or glia. At several epilepsy-related genes, like HDAC11, SPP1, GAL, DRD1 and SV2C, significant differential methylation and differential gene expression coincided.

Conclusion: We found neuron- and glia-specific changes in DNAm and gene expression in early epileptogenesis. We detected single genetic loci in several epilepsy-related genes, where DNAm and GE changes coincide, worth further investigation. Further, our results may serve as an information source for neuronal and glial alterations in both DNAm and GE in early epileptogenesis.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • DNA Methylation*
  • Disease Models, Animal
  • Epigenesis, Genetic
  • Epilepsy, Temporal Lobe / chemically induced
  • Epilepsy, Temporal Lobe / genetics*
  • Galanin / genetics
  • Gene Expression Profiling / methods*
  • Gene Expression Regulation
  • Gene Regulatory Networks*
  • Genetic Predisposition to Disease
  • Histone Deacetylases / genetics
  • Kainic Acid / adverse effects
  • Male
  • Mice
  • Neuroglia / chemistry*
  • Neurons / chemistry*
  • Osteopontin / genetics
  • Receptors, Dopamine D1 / genetics
  • Sequence Analysis, DNA
  • Sequence Analysis, RNA

Substances

  • Drd1 protein, mouse
  • Receptors, Dopamine D1
  • Spp1 protein, mouse
  • Osteopontin
  • Galanin
  • Hdac11 protein, mouse
  • Histone Deacetylases
  • Kainic Acid

Grant support

This project has participated in the European Commission, ERA-NET NEURON, Brain Inflammation, Glia and Epilepsy (K.H.), and has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No 722053 (to K.H.). The project was also funded from South-Eastern Norway Regional Health Authority, No 2014018 (K.K.S.). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.