Esg1, expressed exclusively in preimplantation embryos, germline, and embryonic stem cells, is a putative RNA-binding protein with broad RNA targets

Dev Growth Differ. 2006 Aug;48(6):381-90. doi: 10.1111/j.1440-169X.2006.00875.x.


In our earlier attempt to identify genes involved in the maintenance of cellular pluripotency, we found that KH-domain protein Embryonal stem cell-specific gene 1 (Esg1) showed similar expression patterns to those of Oct3/4 (Pou5f1), whereas the forced repression of Oct3/4 in mouse embryonic stem cells immediately downregulated the expression of Esg1. Here we further confirm this overlap by in situ hybridization and immunohistochemical analyses. Both Esg1 transcript and protein exist in the egg and preimplantation embryos. At embryonic day 3.5, blastocyst stage, however, ESG1 protein was more abundant in the inner cell mass (ICM) than in trophectoderm (TE), whereas Esg1 transcript was detected in both the ICM and the TE, particularly in the polar trophectoderm. The presence of an RNA-binding KH-domain in ESG1 led us to search for and identify 902 target transcripts by microarray analysis of immunoprecipitated ESG1 complex. Interaction of 20 target mRNA with ESG1, including Cdc25a, Cdc42, Ezh2, Nfyc and Nr5a2, was further validated by reverse transcriptase-polymerase chain reaction of the immunoprecipitation material, supporting the notion that ESG1 is an RNA-binding protein which associates with specific target transcripts.

Publication types

  • Research Support, N.I.H., Intramural

MeSH terms

  • Animals
  • Basic Helix-Loop-Helix Transcription Factors / analysis
  • Basic Helix-Loop-Helix Transcription Factors / genetics*
  • Basic Helix-Loop-Helix Transcription Factors / metabolism
  • Blastocyst / chemistry
  • Blastocyst / metabolism*
  • Blotting, Northern
  • Cell Proliferation
  • Female
  • Gene Expression Profiling
  • Gene Expression Regulation, Developmental / genetics
  • Immunoblotting
  • Immunohistochemistry
  • In Situ Hybridization / methods
  • Male
  • Mice
  • Mice, Inbred C57BL
  • Mice, Inbred Strains
  • Models, Biological
  • Morula / chemistry
  • Morula / cytology
  • Morula / metabolism
  • Octamer Transcription Factor-3 / analysis
  • Octamer Transcription Factor-3 / genetics
  • Oligonucleotide Array Sequence Analysis / methods
  • RNA / genetics
  • RNA / metabolism*
  • RNA-Binding Proteins / analysis
  • RNA-Binding Proteins / genetics*
  • RNA-Binding Proteins / metabolism
  • Stem Cells / metabolism*
  • Transcription Factors / analysis
  • Transcription Factors / genetics
  • Transcription Factors / metabolism


  • Basic Helix-Loop-Helix Transcription Factors
  • Enhancer of Split Groucho protein, mouse
  • Octamer Transcription Factor-3
  • RNA-Binding Proteins
  • Transcription Factors
  • RNA