TY - JOUR T1 - Dynamic changes in Sox2 spatio-temporal expression direct the second cell fate decision through <em>Fgf4/Fgfr2</em> signaling in preimplantation mouse embryos JF - bioRxiv DO - 10.1101/052530 SP - 052530 AU - Tapan Kumar Mistri AU - Wibowo Arindrarto AU - Wei Ping Ng AU - Choayang Wang AU - Leng Hiong Lim AU - Lili Sun AU - Ian Chambers AU - Thorsten Wohland AU - Paul Robson Y1 - 2016/01/01 UR - http://biorxiv.org/content/early/2016/06/22/052530.abstract N2 - Oct4 and Sox2 regulate the expression of target genes such as Nanog, Fgf4 and Utfl, by binding to their respective regulatory motifs. Their functional cooperation is reflected in their ability to heterodimerise on adjacent cis regulatory elements, the composite Sox/Oct motif. Given that Oct4 and Sox2 regulate many developmental genes, a quantitative analysis of their synergistic action on different Sox/Oct motifs would yield valuable insights into the mechanisms of early embryonic development. In this study, we measured binding affinities of Oct4 and Sox2 to different Sox/Oct motifs using fluorescence correlation spectroscopy (FCS). We found that the synergistic binding interaction is driven mainly by the level of Sox2 in the case of the Fgf4’s Sox/Oct motif. Taking into account that Sox2 expression levels fluctuate more than Oct4, our finding could explain how Sox2 controls the segregation of the cells of the inner cell mass (ICM) into the epiblast (EPI) and the primitive endoderm (PE) populations within the developing rodent blastocyst. ER -