Effects of downregulating oct-4 transcript by RNA interference on early development of porcine embryos

Abstract

The objective of this study was to investigate the role of the POU family transcription factor, Oct-4, in the early development of porcine embryos. We attempted Oct-4 downregulation of porcine early embryos by RNA interference, and evaluated Oct-4 suppression of developmental competencies and gene transcripts in porcine embryos. Injection of specific siRNA resulted in a distinct decrease in Oct-4 mRNA and protein expression in porcine embryos until at least the morula stage. Although the porcine embryos injected with Oct-4 siRNA were able to develop to the morula stage, these embryos failed to form blastocysts. Gene transcripts of caudal-like transcription factor (Cdx2) and fibroblast growth factor 4 (Fgf4), which were involved in segregation of the trophectderm and functionalization of the inner cell mass, were unchanged by Oct-4 siRNA injection. Our results indicated that Oct-4 is an important factor for porcine embryos and, in particular, for the regulation of porcine blastocyst formation.

Fig. 1.

Relative abundance (mean ± SEM) of Oct-4 transcripts in uninjected porcine morula stage embryos (n=6) or porcine morula stage embryos treated with control siRNA (n=6), siRNA-1 (n=7) or siRNA-2 (n=6). ^{a, b} Different superscripts indicate a significant difference (P<0.05).

Fig. 2.

Representative photographs of Oct-4 protein expression in porcine embryos. The embryos labeled for Oct-4 (green) and DAPI (blue). (A) Oct-4 signals in control siRNA and siRNA-2-injected embryos at each developmental stage. (B) Oct-4 signals in morula stage embryos obtained without injection (uninjected) or with the control siRNA or the siRNA-2 injection. (C) Oct-4 signals in blastocyst stage embryos obtained with the control siRNA or the siRNA-2 injection.

Fig. 3.

Representative photographs showing the developmental morphology in late culture periods of porcine embryos obtained without injection (uninjected) or the control siRNA or the siRNA-2 injection. The morula stage embryos obtained from each treatment were selected on day 4, and these embryos were cultured continuously until day 6.

Fig. 4.

Relative abundance (mean ± SEM) of (A) Cdx2 and (B) Fgf4 transcripts in uninjected porcine morula stage embryos (n=6), or porcine morula stage embryos treated with the control siRNA (n=6) or with siRNA-2 (n=6).