Nrl expression and promoter activity in developing cone photoreceptors

The MAF family transcription factor Nrl is known as a master regulator for rod photoreceptor differentiation, with prior evidence from mouse transgenic models relying on a transcriptional promoter element. The authors now show that Nrl expression and promoter activity are also present in developing cones, suggesting the rod-versus-cone fate decision is not as binary as previously thought. These findings could revise current models of photoreceptor lineage commitment and have implications for retinal development and regeneration studies.