Gene expression profile normalization in cloned mice by trichostatin A treatment.

Cloning mammals by somatic cell nuclear transfer (SCNT) has become an established procedure, but the success rate remains low and gene expression abnormalities are also observed. In addition, SCNT pups exhibited an abnormal gene expression profile with a high degree of heterogeneity among individuals. Recently, we reported that somatic clones treated with trichostatin A (TSA) exhibited a significantly improved success rate, probably due to its effects on chromatin remodeling and histone modification in early embryos. Here we show that the TSA treatment also improves the long-term consistency of genome-wide gene expression regulation: the total number of genes commonly exhibiting up- or downregulation in the TSA clone pups decreased to half of the conventional SCNT pups, and the variation among individuals observed in the SCNT pups was also reduced to the level of the pups produced by the intracytoplasmic sperm injection (ICSI) method. Interestingly, the total gene expression profile of the TSA clones came to resemble that of the ICSI pups.