- Fujitani Y, Fujitani S, Luo H, Qiu F, Burlison J, Long Q, Kawaguchi Y, Edlund H, MacDonald RJ, Furukawa T, Fujikado T, Magnuson MA, Xiang M, Wright CV. Ptf1a determines horizontal and amacrine cell fates during mouse retinal development. Development (Cambridge, England). 2006 Nov;133(22). 4439-50. PMID: 17075007 [PubMed].
The vertebrate neural retina comprises six classes of neurons and one class of glial cells, all derived from a population of multipotent progenitors. There is little information on the molecular mechanisms governing the specification of cell type identity from multipotent progenitors in the developing retina. We report that Ptf1a, a basic-helix-loop-helix (bHLH) transcription factor, is transiently expressed by post-mitotic precursors in the developing mouse retina. Recombination-based lineage tracing analysis in vivo revealed that Ptf1a expression marks retinal precursors with competence to exclusively produce horizontal and amacrine neurons. Inactivation of Ptf1a leads to a fate-switch in these precursors that causes them to adopt a ganglion cell fate. This mis-specification of neurons results in a complete loss of horizontal cells, a profound decrease of amacrine cells and an increase in ganglion cells. Furthermore, we identify Ptf1a as a primary downstream target for Foxn4, a forkhead transcription factor involved in the genesis of horizontal and amacrine neurons. These data, together with the previous findings on Foxn4, provide a model in which the Foxn4-Ptf1a pathway plays a central role in directing the differentiation of retinal progenitors towards horizontal and amacrine cell fates.