Abnormalities in expression of human retinal mRNA in retinitis pigmentosa

The causative genetic defects of retinitis pigmentosa (RP) might be expected to affect the expression of messenger RNA in the retina. Total cellular RNA from retinas of normal and dystrophic individuals was therefore subjected to (i) in vitro translation and analysis by two-dimensional SDS polyacrylamide gel electrophoresis and (ii) Northern blot analysis using probes specific for ?-tubulin, interphotoreceptor retinoid-binding protein (IRBP) and glial fibrillary acidic protein (GFAP) mRNAs. Both methods revealed quantitative abnormalities in specific mRNA levels in RP. These differences appeared to reflect (i) the loss of photoreceptors in RP (decreased ?-tubulin and IRBP mRNA, and a reduced translation product comigrating with rhodopsin) and (ii) the proliferation of glial elements in the RP retinas (increased GFAP mRNA and its translation product). In addition, translation products of 21 and 39 kDa were consistently increased in RP retinas. These have not been previously detected in gliosis and their characterization may provide insight into the mechanisms of disease in RP.