Figure 1.

Methylation status of ERα upstream-untranslated exons changes during development. A, Schematic of known ERα upstream-untranslated exons (A). All exons are spliced to a common splice site just before the translational start site and yield the same ERα gene product. B, There was an increase in methylation of mouse ERα exons A and C across early postnatal development. Genomic DNA was extracted from female and male mouse cortex at PND 4, 10, 18, and 25. DNA was treated with sodium bisulfite and amplified using primers specific for methylated or unmethylated regions of promoter A and promoter C. There was differential methylation of both promoters across early postnatal development, but no gender difference across postnatal days. Methylation was increased starting at PND 10. Experiments were repeated at least three times, and samples were analyzed using control unmethylated β-actin primers.