Abstracts (poster) - Wissenschaft Online

Maja Klug, Sven Heinz, Lucia Schwarzfischer, Sabine Pape, Michael Rehli
Active demethylation of promoter CpGs in post-mitotic cells
Within the last decades, it has become increasingly evident that the epigenetic code,
including chromatin structure, DNA methylation, as well as histone modifications, plays
an important role in regulating gene expression. The dynamics of DNA methylation, in
particular the regulated, active removal of methyl-CpG marks, has remained a mystery,
partly due to the lack of appropriate model systems. The differentiation of human blood
monocytes into macrophages or dendritic cells proceeds without proliferation,
representing an excellent model system for analyzing active demethylation processes in
post-mitotic cells. In earlier studies, we observed the strong up-regulation of the CCL13
gene specifically in monocyte-derived dendritic cells. The transcriptional activation
coincides with the demethylation of three defined CpG residues in the CCL13-promoter
during differentiation of monocytes into dendritic cells, whereas the promoter remains
methylated and silent in monocyte-derived macrophages. Here we present a detailed
time-course analysis of the epigenetic/chromatin status of the CCL13 promoter by
quantitative mRNA expression analysis, chromatin immunoprecipitation, methyl-CpG
immunoprecipitation and MNase-hypersensitivity, and restriction enzyme accessibility
assays. We detected a strong correlation between active DNA demethylation,
nucleosome remodeling, Histone H3 lysine 4 methylation and transcription of the CCL13
gene during dendritic cell differentiation. Our data suggest that active demethylation
proceeds in parallel with chromatin remodeling and gene activation.
contact:
Dipl Maja Klug
Uniklinikum Regensburg
Hämatologie/Onkologie
maja.klug@klinik.uni-regensburg.de
Franz-Josef-Strauss Allee 11
93053 Regensurg (Deutschland)