Functional characterization of SOX2 in bovine preimplantation embryos

Biol Reprod. 2014 Feb 13;90(2):30. doi: 10.1095/biolreprod.113.111526. Print 2014 Feb.


To date, efforts to establish pluripotent embryonic stem cells from bovine embryos have failed. The lack of reliable pluripotency markers is an important drawback when attempting to derive these cells. This study aimed to identify genes upregulated in the inner cell mass (ICM) of bovine blastocysts, and we selected SOX2 for further characterization. Spatial and temporal localization of the SOX2 protein revealed that its expression starts at the 16-cell stage and then becomes restricted to the ICMs of blastocysts. To study the role of SOX2 during the early development of bovine embryos, we designed siRNA to target SOX2. We began by injecting this siRNA into zygotes; the rate at which blastocysts developed declined compared to noninjected or scramble-injected controls. When only one blastomere of a two-cell embryo was injected with SOX2 siRNA, we observed development rates similar to those of controls. Daughter cells of the injected blastomere were tracked by TRITC fluorescence and found to contribute to the ICM, as select cells also lacked SOX2. Gene expression analysis revealed a decrease in SOX2 and NANOG gene expression in siRNA-injected embryos, but OCT4 expression remained unchanged. We conclude that SOX2 localizes exclusively in the ICM of bovine blastocysts, and its downregulation negatively impacts preimplantation development; however, it is still unclear as to why downregulation of SOX2 in one cell of a two-cell embryo does not affect the composition of the ICM.

Keywords: blastocyst; early development; embryo; gene expression.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Blastocyst / cytology
  • Blastocyst / drug effects
  • Blastocyst / metabolism*
  • Blastocyst Inner Cell Mass / drug effects
  • Blastocyst Inner Cell Mass / metabolism
  • Cattle / embryology*
  • Cattle / genetics
  • Cells, Cultured
  • Ectoderm / cytology
  • Ectoderm / drug effects
  • Ectoderm / metabolism
  • Female
  • Gene Expression Regulation, Developmental / drug effects
  • Gene Knockdown Techniques
  • Male
  • Organisms, Genetically Modified
  • RNA, Small Interfering / pharmacology
  • SOXB1 Transcription Factors / antagonists & inhibitors
  • SOXB1 Transcription Factors / genetics*
  • SOXB1 Transcription Factors / metabolism


  • RNA, Small Interfering
  • SOXB1 Transcription Factors