Extended Data Fig. 8: Depletion of OBOX led to Pol II preconfiguration defects and ectopic activation of 1C Pol II targets.

a, Pol II binding, CG density, and OBOX motif enrichment at 1C-specific, shared, and L2C-specific Pol II peaks in WT and Obox mzKO embryos. Red and blue arrows indicate L2C-specific Pol II binding and enrichment of the OBOX motif, respectively. b, Top, OBOX binding at example genes in WT embryos. OBOX motif and CG density are shown. Middle, Pol II binding and ATAC enrichment in WT and Obox mzKO embryos (2 biological replicates). P (+/−), promoter with or without the OBOX motif; D (+), distal enhancer with the OBOX motif. Bottom, bar charts showing gene expression (2 biological replicates for MII and 3 for L2C). Error bars, mean ± SE. c, Hierarchical clustering based on Pol II Stacc-seq (2 biological replicates). d, Percentages of Pol II or ATAC peaks with OBOX motif at the promoters or distal regions at L2C. e, Box plot showing RNA levels of ectopically activated genes, major ZGA genes, and maternal genes. n, gene number. Centre line, median; box, 25th and 75th percentiles; whiskers, 1.5 × IQR. f, Percentages of ectopically activated genes or all genes (control) that are 1C-specific Pol II targets or Polycomb targets (PcG). P-values, two-sided Fisher’s exact test. g, RNA levels in WT oocytes and embryos for ectopically activated genes (left). GO terms and example genes are shown (right). Centre line, median; box, 25th and 75th percentiles; whiskers, 1.5 × IQR. h, Heatmap showing gene expression in ICM (inner cell mass), TE (trophectoderm), and the ratio of TE/ICM in WT embryos for ectopically activated ICM and TE genes in Obox knockout embryos. Gene expression for W and Obox mzKO MII oocytes (2 biological replicates) and embryos (3 biological replicates) is mapped. n indicates gene number. 4C*, the stage when WT developed to 4C and Obox mzKO embryos arrested at 2-4C. i, Bar chart showing gene expression of example ICM and TE genes from h.

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