Abstract
Purpose::
To examine the gene expression patterns of retinal progenitor cells (RPCs) transplanted to S334ter-line-3 (line-3) rats, a transgenic model of retinal photoreceptor degeneration, in comparison with the photoreceptor layer of normal donor hPAP/GFP rats.
Methods::
Retinal tissue derived from embryonic day 19 (E19) hPAP/GFP rats was placed within the subretinal space of 27-31 day old line-3 rats. Using a Zeiss/P.A.L.M. laser microdissection system, the photoreceptor layer of a 388 day old hPAP/GFP rat and transplanted layers of RPCs from 258-339 day old transplanted line-3 rats were harvested. Total RNA was purified (RNeasy Micro Kit, Qiagen, Valencia, Ca). cDNA was produced after amplification of total RNA and subsequently labeled with biotin for microarray analysis (Ovation System, Nugen, San Carlos, Ca). Gene expression profiles were generated for transplanted RPCs and the hPAP/GFP control with a rat genome (28,757 functional genes) microarray (Rat Genome 230 2.0 Array, Affymetrix Inc., Santa Clara, Ca). Data analysis was performed using the S-score algorithm to determine statistical significance. The Gene Ontology Database was used to determine the biological significance of a selection of differentially expressed genes.
Results::
Setting a p-value < 10-5, which represents the highest level of stringency, 213 genes or probe sets were selected. The following biological processes were overly represented in the differentially expressed group of genes: (1) detection of light stimulus; (2) detection of external stimulus; (3) detection of abiotic stimulus; (4) response to light stimulus; (5) response to radiation. Some of the genes that were differentially expressed include: glutamate receptor (GRIA2), cadherin 11 (CDH11), retinal outer segment membrane protein 1 (ROM1), retinal degeneration slow (RDS), retinol dehydrogenase 11 (RDH11). Notch homolog 2 (NOTCH2).
Conclusions::
Differences in gene expression between transplanted retinal progenitor cells and normal photoreceptors suggest that specific biological processes differ between RPCs and photoreceptors.
Keywords: retina • gene/expression • gene microarray