Fig. 8

a Pou5f3 and Sox19b regulate chromatin accessibility on more enhancers than promoters. Six types of cis-regulatory elements include four types downregulated in the double mutants (Pou5f3-dependent, codependent, redundant, and Sox19b-dependent), one type upregulated in the double mutant (repressed), and unchanged in the double mutant. Percentages of these types for all ARs, promoters, and enhancers are shown b Examples of enhancer types where chromatin accessibility is directly regulated by Pou5f3 or Sox19b, as indicated (mych, vgll4l, etv4, abtb2a) and indirectly repressed enhancer (tbx18a). UCSC genomic browser view, H3K27ac and H3K4me3 are shown as log2 ChIP/input ratio, ATAC-seq and TF binding as normalized reads, motif occurrence as bars. Note the parallel changes in H3K27ac and chromatin accessibility (for MZspg and MZsox19b). MZsox = MZsox19b, double = MZsox19bspg. Source data for a, b are provided as a Dataset ^S3. c The model of dorso-ventral balance at ZGA: Pou5f3 and Sox19b prime ventral and ectodermal genes for activation, activating Pou5f3-dependent, codependent and redundant enhancers (“P”, “P and S”, “P or S”). Dorsal and mesendodermal genes are primed by other maternal TFs via independent enhancers (I) and enhancers indirectly repressed by Pou5f3 and Sox19b (“R”, i.e. noggin1 enhancer on Fig.​Fig.5d).5d). d Scheme: Pou5f3 and Sox19b indirectly repress premature activation of transcription factors involved in organogenesis and differentiation.