Figure 2.

Hypoxia upregulates H3K9 methylation in placental trophoblasts. To determine if H3K9 methylation status is regulated by oxygen environment, H3K9me1, H3K9me2, H3K9me3 expression were examined in trophoblasts cultured under hypoxia and reoxygenation conditions. Hypoxic condition: HTR-8/SVneo cells were cultured 2%O2 for 24 hours; Hypoxic + Re-oxygen condition: HTR-8/SVneo cells were cultured under 2%O2 for 24 hours and then incubated under 21%O2 for 6 hours. Cells cultured under 21%O2 served as control. (A) Expression of H3K9me1, H3K9me2, and H3K9me3 were significantly upregulated in cells cultured under 2%O2 but returned to the control levels after cells were reoxygenated at 21%O2 condition. (B) The bar graphs show relative expression for H3K9me1, H3K9me2, H3K9me3 after normalized by β-actin expression in each sample. Bar graphs shows mean ± SE from 3 independent experiments. *p<0.05 and **p<0.01: Cells cultured under 2% vs. 21%O2; #p<0.05 and ##p<0.01: 2%O2+ re-oxygen vs. 2%O2 alone. These results indicate oxygen environment could regulate methylation status of H3K9 in placental trophoblasts.