Trichostatin A improves histone acetylation in bovine somatic cell nuclear transfer early embryos

Epigenetic aberrancies likely preclude correct and complete nuclear reprogramming following somatic cell nuclear transfer (SCNT), and may underlie the observed reduced viability of cloned embryos. In the present study, we tested the effects of the histone deacetylase inhibitor (HDACi), trichostatin A (TSA), on development and histone acetylation of cloned bovine preimplantation embryos. Our results indicated that treating activated reconstructed SCNT embryos with 50 nM TSA for 13 h produced eight-cell embryos with levels of acetylation of histone H4 at lysine 5 (AcH4K5) similar to fertilized counterparts and significantly greater than in control NT embryos (p < 0.005). Further, TSA treatment resulted in SCNT embryos with preimplantation developmental potential similar to fertilized counterparts, as no difference was observed in cleavage and blastocyst rates or in blastocyst total cell number (p > 0.05). Measurement of eight selected developmentally important genes in single blastocysts showed a similar expression profile among the three treatment groups, with the exception of Nanog, Cdx2, and DNMT3b, whose expression levels were higher in TSA-treated NT than in in vitro fertilized (IVF) embryos. Data presented herein demonstrate that TSA can improve at least one epigenetic mark in early cloned bovine embryos. However, evaluation of development to full-term is necessary to ascertain whether this effect reflects a true increase in developmental potential.