Abstract 1492: Epigenetic Control of the eNOS Promoter by DNA Methylation in Vasculogenic Progenitor Cell Populations
DNA methylation has been shown to play an essential role in both the transcriptional regulation and endothelial cell-specific expression of the human endothelial nitric oxide synthase (eNOS) gene. Further, recent data emphasizes an important role of eNOS in stem cell biology in particular with regard to progenitor cell mobilization and vasculoprotective properties. We assessed the hypothesis that stem and vasculogenic progenitor cells will exhibit different DNA methylation patterns of the eNOS promoter region dependent on their vascular fate. Endothelial progenitor cells (EPCs), mesangioblasts, CD34+, HUVECs and microvascular endothelial cells (MVECs) were cultivated and genomic DNA was subjected to sodium bisulfite treatment. The final PCR products were subcloned and sequenced (5–10 clones). Whereas the eNOS proximal promoter was either devoid or very lightly methylated in the human endothelial cell types including HUVECs and MVECs, the promoter was heavily methylated in the examined progenitor and stem cell types namely CD34+ and mesangioblasts. Surprisingly, EPCs also exhibit a profound methylation of the eNOS promoter (see Figure⇓). In conclusion, we have demonstrated that progenitor and stem cells including EPCs, CD34+ and mesangioblasts - although committed to a vascular fate - are in contrast to endothelial cell types heavily methylated in the promoter region of the eNOS gene suggesting epigenetic silencing at this level of maturation. The functional importance of this finding in particular regarding vasculoprotective potency and the modulation of methylation during progenitor cell maturation is subject of future studies.