Simultaneous Inhibition of Histone Deacetylases and RNA Synthesis Enables Totipotency Reprogramming in Pig SCNT Embryos

by Selleckchem | Jul 14 2023

Combining somatic cell nuclear transfer (SCNT) with genome editing technologies has emerged as a powerful platform for the creation of unique swine lineages for agricultural and biomedical applications. However, successful application of this research platform is still hampered by the low efficiency of these technologies, particularly in attaining complete cell reprogramming for the production of cloned pigs. Treating SCNT embryos with histone deacetylase inhibitors (HDACis), such as Scriptaid, has been routinely used to facilitate chromatin reprogramming after nuclear transfer. While increasing histone acetylation leads to a more relaxed chromatin configuration that facilitates the access of reprogramming factors and DNA repair machinery, it may also promote the expression of genes that are unnecessary or detrimental for normal embryo development. In this study, we evaluated the impact of inhibiting both histone deacetylases and RNA synthesis on pre- and post-implantation development of pig SCNT embryos. Our findings revealed that transcription can be inhibited for up to 40 h of development in porcine embryos, produced either by activation, fertilization or SCNT, without detrimentally affecting their capacity to form a blastocyst and their average number of cells at this developmental stage. Importantly, inhibiting RNA synthesis during HDACi treatment resulted in SCNT blastocysts with a greater number of cells and more abundant transcripts for genes related to embryo genome activation on days 2, 3 and 4 of development, compared to SCNT embryos that were treated with HDACi only. In addition, concomitant inhibition of histone deacetylases and RNA synthesis promoted the full reprograming of somatic cells, as evidenced by the normal fetal and full-term development of SCNT embryos. This combined treatment may improve the efficiency of the genome-editing + SCNT platform in swine, which should be further tested by transferring more SCNT embryos and evaluating the health and growth performance of the cloned pigs.

Comments:

The study you mentioned focuses on improving the efficiency of somatic cell nuclear transfer (SCNT) combined with genome editing technologies for creating unique swine lineages. SCNT involves transferring the nucleus of a somatic cell into an enucleated egg to create a cloned embryo. However, the efficiency of this process is currently low, and researchers have been exploring various approaches to enhance the success rate.

One method commonly used to improve the reprogramming of SCNT embryos is the use of histone deacetylase inhibitors (HDACis) such as Scriptaid. HDACis increase histone acetylation, which relaxes the chromatin structure and allows better access for reprogramming factors and DNA repair machinery. However, increased histone acetylation can also lead to the expression of unnecessary or detrimental genes for normal embryo development.

In this study, the researchers aimed to evaluate the impact of inhibiting both histone deacetylases and RNA synthesis on the development of pig SCNT embryos. They found that inhibiting transcription (RNA synthesis) for up to 40 hours during early development did not negatively affect the ability of the embryos to form blastocysts or their average cell number at this stage. Importantly, the combined treatment of inhibiting histone deacetylases and RNA synthesis resulted in SCNT blastocysts with more cells and increased expression of genes related to embryo genome activation on multiple days of development.

Furthermore, the researchers observed that the combined treatment facilitated the full reprogramming of somatic cells, leading to normal fetal development and full-term development of the cloned pigs. These findings suggest that the combined inhibition of histone deacetylases and RNA synthesis can improve the efficiency of the genome-editing + SCNT platform in swine.

To further validate the effectiveness of this approach, the researchers propose transferring more SCNT embryos and evaluating the health and growth performance of the cloned pigs generated using this method. By doing so, they can assess the long-term effects and confirm the potential benefits of the combined treatment in swine breeding for agricultural and biomedical purposes.