Vascular Endothelial Growth Factor and Erythropoietin Show Different Expression Patterns in the Early and Late Hypoxia Preconditioning Phases and May Correlate with DNA Methylation Status in the Mouse Hippocampus.

Liu, Na, Yanbo Zhang, Pu Zhang, Kerui Gong, Chunyang Zhang, Kai Sun, and Guo Shao. Vascular endothelial growth factor and erythropoietin show different expression patterns in the early and late hypoxia preconditioning phases and may correlate with DNA methylation status in the mouse hippocampus. . 23:361-368, 2022. Vascular endothelial growth factor (VEGF) and erythropoietin (EPO) have been proven to participate in neuroprotection induced by hypoxia preconditioning (HPC), and they can be regulated by hypoxia-inducible factor 1 (HIF-1). It has been reported that DNA methylation can affect VEGF and EPO expression. This study aimed to explore the expression of VEGF and EPO in the early phase and late phase of HPC and whether their expression was affected by DNA methylation. Acute repeated HPC mice were used as the animal model, and detection of molecular changes was performed immediately (early phase) and 1 day (late phase) after HPC treatment. The mRNA and protein expression levels of VEGF, EPO, and DNA methyltransferases (DNMTs) in the hippocampi were measured by real-time polymerase chain reaction and western blotting, respectively. The activity of DNMTs and global methylation levels were analyzed by enzyme-linked immunosorbent assay. DNA methylation levels of VEGF and EPO promoters, which were catalyzed by DNMTs, were determined by bisulfite-modified DNA sequencing. The expression of VEGF was increased in the early phase and late phase of HPC ( < 0.05), whereas the expression of EPO was unchanged in the early phase ( > 0.05) of HPC and was increased in the late phase ( < 0.05). VEGF and EPO expression were negatively correlated with the DNA methylation levels of their promoters. DNMT3A and DNMT3B were decreased in the early phase and late phase ( < 0.05), whereas DNMT1 was unchanged in the early phase and late phase ( > 0.05). Our data demonstrated that DNMTs affect VEGF and EPO expression by regulating the DNA methylation levels of the promoters of VEGF and EPO.