The Effects of Trichostatin A on mRNA Expression of Chromatin Structure-, DNA Methylation-, and Development-Related Genes in Cloned Mouse Blastocysts

Trichostatin A (TSA) is the most potent histone deacetylase (HDAC) inhibitor known. We previously reported that treatment of mouse somatic cell nuclear-transferred (SCNT) oocytes with TSA significantly increased the blastocyst rate, blastocyst cell number, and full-term development. How TSA enhances the epigenetic remodeling ability of somatic nuclei and the expression of development-related genes, however, is not known. In the present study, we compared the expression patterns of nine genes involved in chromatin structure and DNA methylation, and seven development-related genes in blastocysts developed from SCNT oocytes treated with and without TSA, and in blastocysts developed in vivo and in vitro using real-time reverse transcription-polymerase chain reaction. In vivo-recovered blastocysts and blastocysts developed from TSA-treated SCNT oocytes exhibited similar expression patterns for Hdac1, 2, and 3, CBP, PCAF, and Dnmt3b genes compared with in vitro-developed blastocysts and blastocysts developed from SCNT oocytes without TSA treatment. There were significantly lower expression levels of Hdac1 and Hdac2 transcripts in TSA-treated and in vivo-recovered blastocysts than in TSA-untreated and in vitro-developed blastocysts. The finding that TSA treatment of SCNT oocytes significantly upregulated Sox2 and cMyc transcripts in blastocysts indicated that both transcripts are TSA-responsive genes. Thus, TSA treatment of mouse SCNT oocytes decreased the expression of chromatin structure- and DNA methylation-related genes, and increased the expression of Sox2 and cMyc genes in blastocysts. Such modifications might be a reason for the high developmental potential of mouse SCNT oocytes treated with TSA.