Abstract
DNA methylation, one of the mechanisms of epigenetic regulation, has been suggested to be related with epilepsy. RASgrf1 is a paternally imprinted gene and has a differentially methylated region (DMR) at the promoter that can silence gene expression. We have previously observed the down-regulation of RASgrf1 in the temporal neocortex of epilepsy patients and in the hippocampus of epileptic animals. Here, we further explored the dynamic change (1-day acute period, 10-day latent period and 45-day chronic phase) of DNA methylation and RASgrf1 expression after acute epileptic seizures in kainic acid (KA)-treated mice, and we observed the impact of N-phthalyl-L-tryptophan (RG108), a DNA methyltransferase (DNMT) inhibitor, on an acute epileptic model by polymerase chain reaction (PCR), western blotting, and bisulfite sequencing PCR (BSP). The results directly showed that the methylation of the RASgrf1 promoter gradually increased and reached a maximal level at the latent period, with subsequent suppression of RASgrf1 mRNA and protein expression levels, which reached a minimum level in the chronic phase. RG108 inhibited the increased methylation of the RASgrf1 gene, with significant inhibition occurring at the latent period, and restored RASgrf1 expression levels in the chronic phase. In addition, we demonstrated that RG108 could suppress acute epileptic seizures in KA-treated mice and epileptic discharges in 4-aminopyridine (4-AP)-treated hippocampal slices. These findings demonstrate that RASgrf1 is closely associated with epilepsy via the aberrant methylation of RASgrf1, and regulating the methylation status of relevant genes might be an intriguing topic in future research on epilepsy.
Highlights
DNA methylation is an important epigenetic modification that can regulate gene expression
The results directly showed that the methylation of the RASgrf1 promoter gradually increased and reached a maximal level at the latent period, with subsequent suppression of RASgrf1 mRNA and protein expression levels, which reached a minimum level in the chronic phase
In human temporal lobe epilepsy (TLE), Miller-Delaney reported that differential DNA methylation profiles of coding and non-coding genes define hippocampal sclerosis [11]; we found DNA methylation profiles in human refractory epilepsy and some genes regulated by methylation or demethylation [12]
Summary
DNA methylation is an important epigenetic modification that can regulate gene expression. Genome-wide DNA methylation changes were reported in the hippocampi after status epilepticus (SE) in kainic acid (KA)-treated mice [6]. A similar increase in DNA methylation was demonstrated in the hippocampi of different epileptic animals [7]. In a rat model of chronic epilepsy, a prominent increase in DNA methylation was observed [8, 9]. Hypermethylation of the SCN3A and GRIA2 gene promoters in animal hippocampi was identified under seizure conditions [9, 10]. Increased methylation www.impactjournals.com/oncotarget of the reelin promoter [4] and increased expression of DNA methyltransferase (DNMT) 1 and 3a [13] were found in TLE. The inhibition of DNMTs was able to affect excitatory neurotransmission in the hippocampus [17, 18]
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
