The single-stranded DNA binding protein Ssbp3 promotes trophoblast differentiation of mouse embryonic stem cells

Unlimited self-renewal and developmental pluripotency are hallmarks of embryonic stem cells. Both properties are precisely controlled by the extrinsic signals and intrinsic factors and have been extensively investigated. However, factors capable of converting ES cells to extra-embryonic lineages have been poorly studied. Here we found that overexpression of Ssbp3 dramatically up-regulated trophoblast specific markers. Then we investigated the genome-wide transcriptional effect of ectopic Ssbp3 expression by comparing the whole genome expression profiles of Ssbp3-overexpressing cells with negative control cells using affymetrix microarray.Genetic analysis indicated that overexpression of Ssbp3 drives the trophoblast transcriptional program, induces the expression of early trophectoderm transcription factors such as Cdx2, Gata3 and Elf5, and activates MAPK and TGF-β pathways, which are essential for trophoblast derivation.Our findings identify Ssbp3 as a novel regulator converting ES cells into extra-embryonic trophoblast. The experiment contains two groups of samples, one group is Vector-expressing cells and the other group is Ssbp3-overexpressing cells. Each group contains duplicated biological samples. Vector or Ssbp3 was overexpressed for 96 hours in mouse E14T ES cells. Differentially expressed genes with a cutoff threshold of 2-fold were identified from the whole genome expression profiles of Ssbp3-overexpressing cells vs Vector-overexpressing cells using affymetrix microarray.