Abstract
Purpose: :
Embryonic stem cell (ESC) transplantation is a promising therapeutic approach for the replacement of degenerated retinal cells in patients with age-related macular degeneration (AMD) and other retinal degenerations. Our goal is to use microarray analysis to identify key transcription factors in murine retinal development, and then use ex vivo gene therapy to express these transcription factors in ESC to induce their differentiation into photoreceptors.
Methods: :
Eyes from embryonic day 11 (E11), embryonic day 18 (E18), postnatal day 5 (P5), postnatal day 8 (P8), postnatal day 12 (P12), and adult C57BL/6 mice were removed and retinal tissue isolated. Total RNA was extracted and cRNAs were probed with Affymetrix microarray 430A 2.0 chips (mouse genome) for retinal gene expression at different developmental stages. Genes were identified as transcription factors involved in phototransduction or retinal development using Gene Ontology molecular and biological function data, respectively. Genesifter and several other microarray analysis software systems were used to identify transcription factor expression patterns at different developmental stages.
Results: :
Cluster analysis reveals the upregulation of genes during embryonic day 18 and post-natal day 5 time period that are enriched for Gene Ontology functional categories related to phototransduction with p-values < 10-10. These genes include NRL, NeuroD1, NR2E3 and NeuroD4 which are known to be involved in neural retina and photoreceptor development. These four genes are predominately expressed at P5, which has previously been characterized as a crucial timepoint in retinal and photoreceptor development.
Conclusions: :
Microarray analysis reveals high expression levels of transcriptions factors involved in mouse retinal development, consistent with the previous reports which suggest that the time between embryonic day 18 and post-natal day 5 appears to be critical for photoreceptor differentiation in the neural retina. This work constitutes significant progress in our understanding of neural development and cellular differentiation in general and in our efforts to develop photoreceptor cells from patient-specific tissues. Over-expression of these transcription factors in mouse stem cells may induce pluripotent stem cells to differentiate into neural retina and photoreceptor cells.
Keywords: retina • gene/expression • transcription factors