DIFFERENTIAL EXPRESSION OF PHOTORECEPTOR-SPECIFIC PROTEINS DURING DISEASE AND DEGENERATION IN THE PROGRESSIVE ROD-CONE DEGENERATION (PRCD) RETINA

Progressive rod-cone degeneration (prcd) is a late-onset hereditary re tinal degeneration characterized by normal development of photorecepto rs prior to degeneration and death of visual cells. We reported previo usly that expression of opsin mRNA and protein decreases prior to visu al cell degeneration. To examine the specificity of this reduction, we have used immunocytochemistry to correlate photoreceptor-specific pro tein expression with visual cell disease progression, Eyes from light- adapted age-matched control and prcd-affected dogs were fixed in paraf ormaldehyde, embedded in diethylene glycol distearate (DGD) wax, and r eacted with antibodies specific to interphotoreceptor retinoid-binding protein (IRBP), S-antigen, opsin, phosducin, gamma-phosphodiesterase (gamma-PDE), and beta(1)-transducin. While IRBP expression did not cha nge with disease progression, immunoreactivity to other proteins varie d. For S-antigen and opsin, immunoreactivity decreased dramatically wi th the transition from photoreceptor disease to degeneration; gamma-PD E immunolabeling in rods also decreased, but the reduction was less ab rupt. However, for two other proteins (phosducin and beta(1)-transduci n), immunoreactivity increased initially and was redistributed (partic ularly to the rod outer segment) in early disease (stage 1). Our resul ts show that there is a differential expression of photoreceptor-speci fic proteins with disease and degeneration that is not uniform for all the gene products examined; expression can be decreased, altered in d istribution or remain unchanged, It is clear that the decrease of opsi n expression described previously is not an isolated phenomenon in the progression of prcd, but is part of a more generalized degenerative p rocess which eventually culminates in cell death, (C) 1997 Academic Pr ess Limited.