bHLH-dependent and -independent modes of Ath5 gene regulation during retinal development.

In a wide range of vertebrate species, the bHLH transcription factor Ath5 is tightly associated with both the initiation of neurogenesis in the retina and the genesis of retinal ganglion cells. Here, we describe at least two modes of regulating the expression of Ath5 during retinal development. We have found that a proximal cis-regulatory region of the Xenopus Ath5 gene (Xath5) is highly conserved across vertebrate species and is sufficient to drive retinal-specific reporter gene expression in transgenic Xenopus embryos.