Improved development of mouse somatic cell nuclear transfer embryos by chlamydocin analogues, class I and IIa histone deacetylase inhibitors†

Abstract

In mammalian cloning by somatic cell nuclear transfer (SCNT), treatment of reconstructed embryos with histone deacetylase (HDAC) inhibitors improves efficiency. So far, most of those used for SCNT are hydroxamic acid derivatives—such as trichostatin A—characterized by their broad inhibitory spectrum. Here, we examined whether mouse SCNT efficiency could be improved using chlamydocin analogues, a family of newly designed agents that specifically inhibit Class I and IIa HDACs. Development of SCNT-derived embryos in vitro and in vivo revealed that four out of five chlamydocin analogues tested could promote the development of cloned embryos. The highest pup rates (7.1 to 7.2%) were obtained with Ky-9, similar to those achieved with trichostatin A (7.2 to 7.3%). Thus, inhibition of Class I and/or IIa HDACs in SCNT-derived embryos is enough for significant improvements in full-term development. In mouse SCNT, the exposure of reconstructed oocytes to HDAC inhibitors is limited to 8–10 h because longer inhibition with Class I inhibitors causes a 2-cell developmental block. Therefore, we used Ky-29, with higher selectivity for Class IIa than Class I HDACs for longer treatment of SCNT-derived embryos. As expected, 24-h treatment with Ky-29 up to the 2-cell stage did not induce a developmental block, but the pup rate was not improved. This suggests that the 1-cell stage is a critical period for improving SCNT cloning using HDAC inhibitors. Thus, chlamydocin analogues appear promising for understanding and improving the epigenetic status of mammalian SCNT-derived embryos through their specific inhibitory effects on HDACs.

Cellular and Molecular Nature of Fragmentation of Human Embryos

“…It is beyond any doubt that, in the near future, a wide panel of the investigations from the fields of experimental and applied embryology should have been targeted at the precisely identifying and comprehensively exploring a broad spectrum of morphological, ultrastructural, biochemical, and molecular determinants responsible for increased incidence of the processes leading to initiation and progression of embryo fragmentation. The thorough characterization of the aforementioned determinants seems to be strongly justified in order to recognize the highly predictable biomarkers related to diminishments in not only molecular quality parameters, but also the extracorporeal and peri-implantation developmental capabilities of the ex vivo produced embryos created by such modern ARTs as in vitro fertilization and intracytoplasmic sperm injection in humans and other mammalian species and somatic cell nuclear transfer (SCNT)-mediated cloning in other mammalian species [114][115][116][117][118][119].…”

Effects of Crotonylation on Reprogramming of Cashmere Goat Somatic Cells with Different Differentiation Degrees

“…In 2009, Yamanaka [ 29 ] proposed that the Kac level in the donor cell genome appeared to be positively correlated with the development rate of SCNT embryos of miniature pigs. Previous studies showed that Kac modification was enhanced by adding HDACi to the somatic cells to improve the developmental competence of mouse SCNT embryos [ 30 ]. In our study, when MDSCs, FFCs, and EFCs were treated with 10 mM NaCr for 24 h, the Kac levels of the three types of somatic cells were not markedly decreased or increased.…”

Strategies to Improve the Efficiency of Somatic Cell Nuclear Transfer

“…Recently, mouse cloning efficiency could be improved by chlamydocin analogues, which are a family of newly designed agents that specifically inhibit Class I and IIa HDACs. The results showed that one of the chlamydocin analogues, Ky-9, strongly promoted the development of cloned mouse embryos to a level similar to that of TSA [141].…”