An enhancer located in a Pde6c intron drives transient expression in the cone photoreceptors of developing mouse and human retinas.

How cone photoreceptors are formed during retinal development is only partially known. This is in part because we do not fully understand the gene regulatory network responsible for cone genesis. We reasoned that cis-regulatory elements (enhancers) active in nascent cones would be regulated by the same upstream network that controls cone formation.

Initiation of Otx2 expression in the developing mouse retina requires a unique enhancer and either Ascl1 or Neurog2 activity.

During retinal development, a large subset of progenitors upregulates the transcription factor Otx2, which is required for photoreceptor and bipolar cell formation. How these retinal progenitor cells initially activate Otx2 expression is unclear. To address this, we investigated the cis-regulatory network that controls Otx2 expression in mice.