Fig. 7.

Pioneer action of Pax7. Cooperative chromatin opening by the pioneer Pax7 and the nonpioneer factor Tpit. The heterochromatin target sites of pituitary Pax7 pioneer action typically contain Pax7 DNA binding sites together with Tpit binding sites within a few hundred bp of each other. a, b Schematic representation of chromatin accessibility (a) assessed by assay for transposase-accessible chromatin using sequencing (ATACseq) at a pituitary melanotrope-specific TAD containing the Pcsk2 gene (red domain). This domain presents multiple ATACseq peaks in wild-type melanotrope of the pituitary intermediate lobe (IL). This chromatin accessibility is not observed in cells of other pituitary lineages or in mutant ILs of single or double mutants for Pax7 and/or Tpit (b). Similar observations were made for the Pcsk2 (Fig. 5g), Drd2 and Grik1 loci (Supplementary Fig. 5g)