Foxl2 preserves chromatin accessibility at a distal super-enhancer which regulates the Fshb-Kcna4 locus

Expression of Fshb and Kcna4 was strongly inhibited by JQ-1, which represses super-enhancer activity, and the region displays super-enhancer characteristics. The sites of open chromatin were seen, in chromatin immunoprecipitation (ChIP), to bind Brd4 and Med1, most notably at a site -67 kb from the Fshb gene, as well as binding Ctcf further upstream (-123 kbp), all of which were increased following activin exposure.

The locus is transcribed to chromatin-associated lncRNAs whose levels correlate with Fshb and Kcna4 mRNA levels in vivo and in cultured gonadotrope cells, indicating coordinated regulation. CRISPR interference (CRISPRi) confirmed distinct functions for each element and, together with the 3C data, indicate that the -67 kb locus mediates basal and activin-stimulated Fshb expression, while the site at -59 kb contributes to activin-stimulation of both genes.