Identification of photoreceptor genes affected by PRPF31 mutations associated with autosomal dominant retinitis pigmentosa

Several ubiquitously expressed genes encoding pre-mRNA splicing factors have been associated with autosomal dominant retinitis pigmentosa (adRP), including PRPF31, PRPF3 and PRPF8. Molecular mechanisms by which defects in pre-mRNA splicing factors cause photoreceptor degeneration are not clear. To investigate the role of pre-mRNA splicing in photoreceptor gene expression and function, we have begun to search for photoreceptor genes whose pre-mRNA splicing is affected by mutations in PRPF31. Using an immunoprecipitation-coupled-microarray method, we identified a number of transcripts associated with PRPF31-containing complexes, including peripherin/RDS, FSCN2 and other photoreceptor-expressed genes. We constructed minigenes to study the effects of PRPF31 mutations on the pre-mRNA splicing of these photoreceptor specific genes. Our experiments demonstrated that mutant PRPF31 significantly inhibited pre-mRNA splicing of RDS and FSCN2. These observations suggest a functional link between ubiquitously expressed and retina-specifically expressed adRP genes. Our results indicate that PRPF31 mutations lead to defective pre-mRNA splicing of photoreceptor-specific genes and that the ubiquitously expressed adRP gene, PRPF31, is critical for pre-mRNA splicing of a subset of photoreceptor genes. Our results provide an explanation for the photoreceptor-specific phenotype of PRPF31 mutations.