Shared cis-regulatory modules control expression of the tandem paralogs midline and H15 in the follicular epithelium.

The posterior end of the follicular epithelium is patterned by midline (MID) and its paralog H15, the Drosophila homologs of the mammalian Tbx20 transcription factor. We have previously identified two cis-regulatory modules (CRMs) that recapitulate the endogenous pattern of mid in the follicular epithelium. Here, using CRISPR/Cas9 genome editing, we demonstrate redundant activity of these mid CRMs.

The ETS-transcription factor Pointed is sufficient to regulate the posterior fate of the follicular epithelium.

The Janus-kinase/signal transducer and activator of transcription (JAK/STAT) pathway regulates the anterior posterior axis of the follicle cells. In the anterior, it activates the bone morphogenetic protein (BMP) signaling pathway through expression of the BMP ligand (). In the posterior, JAK/STAT works with the epidermal growth factor receptor (EGFR) pathway to express the T-box transcription factor ().