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. Overall design: 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.