Abstract
Purpose: :
Our current study investigates whether two members of the onecut transcription family, Oc1 (also known as Hnf-6) and Oc2, play a role in mouse retinal development.
Methods: :
We performed immunofluorescence staining with anti-Oc1 and anti-Oc2 on mouse retinal sections of different developmental stages and genotypes and examined their relationship with other retinal and cell cycle markers.
Results: :
The onecut transcription factors are defined by a ‘cut’ domain and an atypical homeo domain. There are three onecut members, Oc1, Oc2 and Oc3, in the mouse. They function in the development of the liver, pancreas, intestine and lymphocytes. They have also been reported to be expressed in the central nervous system such as the spinal cord. To investigate whether they regulate retinal development, we performed immunofluorescence staining for Oc1 and Oc2 on mouse retinas of different developmental stages. We found that these two factors had almost identical expression patterns throughout development. Both factors started to be expressed in the retina at around E11.5. At early stages (E11.5 and E12.5), they were expressed in both the progenitor cell layer and ganglion cell layer. As development progressed, their expression diminished in the progenitor cells and became more restricted to the ganglion cell layer. By P5, Oc1 and Oc2 were expressed at very low levels in ganglion cells, but very strongly in horizontal cells. Co-labeling of Oc1 with cell cycle markers showed that Oc1 was expressed in both proliferating retinal progenitors and postmitotic retinal cells. Co-labeling of Oc1 with Math5, Pou4f2 and Isl1, three transcription factors required for ganglion cell development, revealed that Oc1 coincided with Math5 at E11.5 and E12.5, but not at E14.5, in the progenitor cell layer, and overlapped with Pou4f2 and Isl1 in the ganglion cell layer. Furthermore, we found that expression of Oc1 and Oc2 did not change in retinas of Math5-, Pou4f2- and Isl1-null mice as compared to that in wild-type retinas.
Conclusions: :
Oc1 and Oc2 are expressed in developing ganglion cells and their progenitors; they may regulate the formation of ganglion cells in a pathway independent of Math5, Pou4f2 and Isl1. The two factors are also expressed in developing horizontal cells, suggesting that they function in the genesis of horizontal cells as well.
Keywords: ganglion cells • retinal development • transcription factors