Abstract
Purpose: :
The forkhead transcription factor FoxN4 is primarily expressed in the developing retinal progenitor cells of Xenous laevis embryos, from specification until maturation. The purpose of our studies is to investigate the role of FoxN4 in Xenopus retinal development.
Methods: :
Morpholino oligonucleotides and synthetic RNAs were injected into 4–celled embryos. Embryos were cultured to desired stages, fixed in paraformaldehyde, and analyzed. Gene expression was visualized by in situ hybridization using antisense riboprobes and whole fixed embryos or sections of paraffin–embedded embryos. Immunocytochemistry was performed using sections of paraffin–embedded embryos and visualized by immunoperoxidase reactions. Histology was visualized by hemotoxylin & eosin staining of sections of paraffin–embedded embryos.
Results: :
Embryos injected with FoxN4 antisense morpholino oligonucleotide exhibited a reduction in eye size and loss of marginal zone progenitor cells. Embryos overexpressing FoxN4 exhibited a variety of phenotypes including reduction in eye size and/or extra or ectopic retinal tissue and neural tubes. Smaller eyes were primarily observed in embryos injected with higher doses of FoxN4 RNA at early stages. Extra retinal tissue was observed within the optic nerve, optic cup and neural tube. In some cases, FoxN4–injected embryos developed whole ectopic eyes. Extra neural tubes were accompanied by ectopic neural progenitor cells.
Conclusions: :
This data suggests that FoxN4 plays a role in the development of neural and retinal progenitor cells in Xenopus.
Keywords: transcription factors • retinal development