Anti-silencing factor 1A is associated with genome stability maintenance of mouse preimplantation embryos†

Abstract

Genome stability is critical for the normal development of preimplantation embryos, as DNA damages may result in mutation and even embryo lethality. Anti-silencing factor 1A (ASF1A) is a histone chaperone and enriched in the MII oocytes as a maternal factor, which may be associated with the maintenance of genome stability. Thus, this study was undertaken to explore the role of ASF1A in maintaining the genome stability of early mouse embryos. The ASF1A expressed in the preimplantation embryos and displayed a dynamic pattern throughout the early embryonic development. Inhibition of ASF1A expression decreased embryonic development and increased DNA damages. Overexpression of ASF1A improved the developmental potential and decreased DNA damages. When 293T cells that had been integrated with RGS-NHEJ were co-transfected with plasmids of pcDNA3.1-ASF1A, gRNA-NHEJ, and hCas9, less cells expressed eGFP, indicating that non-homologous end joining was reduced by ASF1A. When 293T cells were co-transfected with plasmids of HR-donor, gRNA-HR, hCas9, and pcDNA3.1-ASF1A, more cells expressed eGFP, indicating that homologous recombination (HR) was enhanced by ASF1A. These results indicate that ASF1A may be associated with the genome stability maintenance of early mouse embryos and this action may be mediated by promoting DNA damage repair through HR pathway.

Distinct role of histone chaperone Asf1a and Asf1b during fertilization and pre-implantation embryonic development in mice

“…To investigate the effect of Asf1a or Asf1b knockdown on pre-implantation development, zygotes (2 hpi) were microinjected with specific MO against Asf1a or Asf1b, respectively, and examined their development rates. In agreement with previous studies [ 33 ], knockdown of Asf1a did not affect developmental rate of embryos at 2-cell and 4-cell stages, but significantly decreased that of the morula and blastocyst stage embryos (Fig. 3 A, C).…”

“…We found that nuclear enrichment of both Asf1a and Asf1b were restricted to fully grown oocyte and early cleavage stage embryos (Fig. 1 A, B), which is consistent with previous reports that Asf1a and Asf1b are abundant in mature oocytes [ 26 , 43 ] and highly expressed after fertilization in zygotes and 2-cell embryos [ 33 ]. Of note, observed cytoplasmic staining of Asf1b in the oocytes and embryos (Fig.…”

“…3 A). Additionally, since down-regulation of H3K56ac also leads to accumulation of DNA damage [ 56 , 57 ] and impairs genomic stability [ 33 , 58 ], the increased DNA damage detected by γH2A.X (Additional file 1 : Fig. S8) might also contribute to the significantly reduced developmental capacity (Fig.…”

Evaluate the developmental competence of human 8-cell embryos by single-cell RNA sequencing

“…Meanwhile, it was also found that several genes such as ASF1b, BEX3, DPPA2, and ORC4 are correlated to the developmental competence of 8-cell embryos. ASF1b is a histone H3-H4 chaperone and plays an essential role in regulating DNA replication, epigenetic modifications and genome stability in different species (Messiaen et al, 2016;Wang et al, 2021;Deng et al, 2020). Meanwhile, brain expressed X-linked 3 gene (BEX3) is identified as an X-linked gene expressed at a high level in preimplantation embryos (Sharov et al, 2003).…”

“…Following fertilization, the activation of the zygote genome is initiated and maternal mRNAs are eliminated (Clift and Schuh, 2013). The research on human, mouse, goat, and bovine have demonstrated that the elimination of maternal transcripts is accomplished by two sequential pathways mediated by maternal or zygotic factors (Xue et al, 2013;Yan et al, 2013;Deng et al, 2020;Bogliotti et al, 2020;Sha et al, 2020).…”