Stroke Causes DNA Methylation at Heart Promoter in the Brain Via DNMT1/MeCP2/REST Epigenetic Complex.

BACKGROUND

REST (Repressor-Element 1 [RE1]-silencing transcription factor) inhibits Na/Caexchanger-1 () transcription in neurons through the binding of RE1 site on brain promoter after stroke. We identified a new putative RE1 site in heart promoter sequence (-RE1) that participates in neuronal transcription. Because REST recruits DNA-methyltransferase-1 (DNMT1) and MeCP2 (methyl-CpG binding protein 2) on different neuronal genes, we investigated the role of this complex in transcriptional regulation after stroke.

METHODS AND RESULTS

Luciferase experiments performed in SH-SY5Y cells demonstrated that activity was selectively decreased by REST, whereas activity was reduced by DNMT1, MeCP2, and REST. Notably, site-direct mutagenesis of RE1 prevented REST-dependent downregulation of . Furthermore, in temporoparietal cortex of 8-week-old male wild-type mice (C57BL/6) subjected to transient middle cerebral artery occlusion, DNMT1, MeCP2, and REST binding to promoter was increased, with a consequent DNA promoter hypermethylation. Intracerebroventricular injection of siREST prevented DNMT1/MeCP2 binding to and downregulation, thus causing a reduction in stroke-induced damage. Consistently, in cortical neurons subjected to oxygen and glucose deprivation plus reoxygenation knockdown counteracted neuronal protection induced by the demethylating agent 5-azacytidine. For comparisons between 2 experimental groups, Student's  test was used, whereas for more than 2 experimental groups, 1-way ANOVA was used, followed by Tukey or Newman Keuls. Statistical significance was set at <0.05.

CONCLUSIONS

If the results of this study are confirmed in humans, it could be asserted that DNMT1/MeCP2/REST complex disruption could be a new pharmacological strategy to reduce DNA methylation of in the brain, ameliorating stroke damage.