Differential transcriptional regulation of the NANOG gene in chicken primordial germ cells and embryonic stem cells

Abstract

AbstractBackgroundNANOGis a core transcription factor (TF) in embryonic stem cells (ESCs) and primordial germ cells (PGCs). Regulation of theNANOGgene by TFs, epigenetic factors, and autoregulatory factors is well characterized in ESCs, and transcriptional regulation ofNANOGis well established in these cells. AlthoughNANOGplays a key role in germ cells, the molecular mechanism underlying its transcriptional regulation in PGCs has not been studied. Therefore, we investigated the mechanism that regulates transcription of the chickenNANOG(cNANOG)gene in PGCs and ESCs.ResultsWe first identified the transcription start site ofcNANOGby 5′-rapid amplification of cDNA ends PCR analysis. Then, we measured the promoter activity of various 5′ flanking regions ofcNANOGin chicken PGCs and ESCs using the luciferase reporter assay.cNANOGexpression required transcriptional regulatory elements, which were positively regulated byPOU5F3(OCT4)andSOX2and negatively regulated byTP53in PGCs. The proximal region of thecNANOGpromoter contains a positive transcriptional regulatory element (CCAAT/enhancer-binding protein (CEBP)-binding site) in ESCs. Furthermore, small interfering RNA-mediated knockdown demonstrated thatPOU5F3,SOX2, andCEBPplayed a role in cell type-specific transcription ofcNANOG.ConclusionsWe show for the first time that differenttrans-regulatory elements control transcription ofcNANOGin a cell type-specific manner. This finding might help to elucidate the mechanism that regulatescNANOGexpression in PGCs and ESCs.