Expression of Pax-6 mRNA in the retinal degeneration (rd) mouse.

The homeobox gene Pax-6 is expressed during eye development in both the retina and lens, and Pax-6 mutations cause ocular abnormalities including retinal defects. We investigated the pattern of Pax-6 gene expression in the rd/rd mouse model of inherited retinal degeneration in comparison with nondegenerative controls, using Northern blot, reverse-transcription (RT)-PCR and in situ hybridization analysis. We observed an increased level of Pax-6 mRNA expression in the degenerative state, which appeared to affect equally the major Pax-6 exon 5a transcriptional splice variants as detected by RT-PCR. By in situ hybridization, Pax-6 mRNA was localized to the inner nuclear and ganglion cell layers of nondegenerative retina, but showed a more diffuse signal pattern in the rd/rd retina. This modulation of Pax-6 mRNA levels and localization is suggestive of activation of expression in retinal glial cells and may reflect reorganization of cellular interactions in response to the degenerative processes.