Transcriptional Networks in Mouse Trophoblast Stem Cell Self-Renewal

Trophoblast stem cells (TS cells), derived from the trophectoderm (TE) of blastocysts, require transcription factors (TFs) and external signals (Fgf4, Activin/Nodal/Tgfb) for self-renewal. While many reports have focused on TF networks that regulate embryonic stem cell (ES cell) self-renewal and pluripotency, little is know about TF networks that regulate self-renewal in TS cells. To further understand transcriptional networks in TS cells we used chromatin immunopreciptiation and DNA microarray analysis (ChIP-chip) to investigate targets of TFs Ap-2g (Tcfap2c), Eomes, Ets2, and Gata3, and a chromatin remodeling factor, Brg1 (Smarca4). We then evaluated the transcriptional states of target genes using transcriptome analysis and genome-wide analysis of histone H3 acetylation (AcH3). Our results describe previously unknown transcriptional networks in TS cells, including TF occupancy of genes involved in ES cell self-renewal and pluripotency, co-occupancy of multiple TFs at target genes, and transcriptional regulatory circuitry within the 5 factors. Through genome-wide mapping and global expression analysis of 5 TF target genes, our data provide a comprehensive analysis of transcriptional networks that regulate TS cell self-renewal. RNA was harvested at 7 time points from TS cells cultured without Fgf4 over two weeks for transcriptome analysis. RNA was collected from undifferentiated TS cells at T=0hr, and differentiated TS cells cultured without Fgf4 for 24-hrs, 48-hrs, 72-hrs, 6 days, 10 days, and 14 days. Mouse TS cells were ChIPed with antibodies specific to Ap-2g (Tcfap2c), Brg1 (Smarca4), Eomes, Ets2, and Gata3 vs. Input DNA from TS cells