This study examined the DNA replication timing patterns of endothelial cell (EC)-enriched genes. We especially focused on a unique set of EC-enriched mRNA transcripts that possess differentially methylated regions (DMRs) within proximal promoters. It was previously shown that this DNA methylation plays an important functional role in regulating EC-enriched patterns of gene expression. Since the maintenance of these silencing marks is necessary for the inheritance of cell identity, the cell should ensure the proper transmission of such marks during mitotic cell cycle. Here we show that EC-enriched genes with DMRs replicate early during S phase in both expressing and non-expressing cell types. EC-enriched genes that do not have DMRs followed the expected trend, being early replicating in expressing cell types and late in non-expressing cell types. The relationship between DNA replication and DNA methylation was also investigated. A delay between DNA replication and DNA methylation was observed.

This study examined the DNA replication timing patterns of endothelial cell (EC)-enriched genes. We especially focused on a unique set of EC-enriched mRNA transcripts that possess differentially methylated regions (DMRs) within proximal promoters. It was previously shown that this DNA methylation plays an important functional role in regulating EC-enriched patterns of gene expression. Since the maintenance of these silencing marks is necessary for the inheritance of cell identity, the cell should ensure the proper transmission of such marks during mitotic cell cycle. Here we show that EC-enriched genes with DMRs replicate early during S phase in both expressing and non-expressing cell types. EC-enriched genes that do not have DMRs followed the expected trend, being early replicating in expressing cell types and late in non-expressing cell types. The relationship between DNA replication and DNA methylation was also investigated. A delay between DNA replication and DNA methylation was observed.