Somatic cell-induced hyperacetylation, but not hypomethylation, positively and reversibly affects the efficiency of in vitro cloned blastocyst production in cattle.

5-Aza-2'-deoxycytidine (AzC), trichostatin A (TSA), and its natural mimetic, sodium butyrate (NaB), are antineoplastic drugs that can modify the epigenetic status of donor cells prior to somatic cell nuclear transfer (SCNT). In this study, we used fibroblast cells treated with these drugs to investigate the direct and indirect effects of induced changes in DNA methylation and acetylation of the lysine 9 residue of histone H3 (H3K9). Additionally, we assayed cellular characteristics (cell growth, cell proliferation, cell cycle progression, and apoptosis) and SCNT efficiency in response to these drugs as well as monitoring these effects 24 h after removing the drugs. We observed the following: (1) AzC, TSA, and NaB all showed dose-dependent effects on different cellular characteristics; (2) TSA and NaB induced H3K9 hyperacetylation accompanied by DNA hypermethylation, whereas AzC induced DNA hypomethylation with no effect on H3K9 hyperacetylation; (3) TSA and NaB improved cloning efficiency, whereas AzC reduced it; and (4) unlike AzC, the effects of TSA and NaB on cellular characteristics and SCNT efficiency were reversed following drug removal. Our results indicate that somatic cells treated with TSA and NaB show better survival and recovery rates following the removal of these drugs. Moreover, H3K9 hyperacetylation (induced with TSA and NaB), but not DNA hypomethylation (induced with AzC), favors cloning efficiency.