Excess S-Adenosylmethionine inhibits methylation via catabolism to adenine

Mouse embryonic fibroblasts were treated with 1mM SAM, 1mM adenine or 10microM, and transcriptome signatures were compared to untreated cells. Cells were cultivated in 3 replicate 10cm Petri dishes per treatment until confluence. Medium was replaced with medium containing either 1mM S-adenosylmethionine (SAM) and 3.3 mM HCl, 1mM adenine and 3.3 mM HCl, 10 microM Deazaneplanocin A (DZ) and 3.3 mM HCl, or 3.3 mM HCl. Since the solvent of adenine was HCl, the same amount of HCl was added to all other dishes.