Profiling of methylation and demethylation pathways during brain development and ageing.

Numerous signal pathways are epigenetically controlled during brain development and ageing. Thereby, both 5-methylcytosine (5mC) and the newly described 5-hydroxymethylcytosine (5hmC) are highly exhibited in the brain. As there is an uneven distribution of 5hmC in the brain depending on age and region, there is the need to investigate the underlying mechanisms being responsible for 5hmC generation and decline. The aim of this study was to quantify expression levels of genes that are associated with DNA methylation/demethylation in different brain regions and at different ages. Therefore, we investigated frontal cortex and cerebellum of 40 mice (strain C57BL/6), each eight mice sacrificed at day 0, 7, 15, 30 and 120 after birth. We performed expression profiling of methylation/demethylation genes depending on age and brain region. Interestingly, we see significant expression differences of genes being responsible for methylation/demethylation with a significant reduction of expression levels during ageing. Validating selected expression data on protein level using immunohistochemistry verified the expression data. In conclusion, our findings demonstrate that the regulation of methylation/demethylation pathways is highly controlled depending on brain region and age. Thus our data will help to better understand the complexity and plasticity of the brain epigenome.