PRPF31 alternative splicing and expression in human retina.
OBJECTIVE
To provide a mechanistic link between mutations in PRPF31, and essential and ubiquitously expressed gene, and retinitis pigmentosa, a disorder restricted to the eye.


METHODS
We investigated the existence of retina-specific PRPF31 isoforms and the expression of this gene in human retina and other tissues, as well as in cultured human cell lines. PRPF31 transcripts were examined by RT-PCR, quantitative PCR, cloning and sequencing.


RESULTS
Database searching revealed the presence of a retina-specific PRPF31 isoform in mouse. However, this isoform could not be experimentally identified in transcripts from human retina or from a human whole eye. Nevertheless, four different PRPF31 isoforms, that were common to all analyzed tissues and cell lines, were isolated. Three of these harbored the full-length PRPF31 coding sequence, whereas the fourth was very short and probably non-coding. The amount of PRPF31 mRNA was previously found to be lower in patients with mutations in this gene than in healthy individuals, making it likely that retinal cells are more sensitive to variation in PRPF31 expression. However, quantitative PCR experiments revealed that PRPF31 mRNA levels in human retina were comparable to those detected in other tissues.


CONCLUSIONS
Our results show that the retina-restricted phenotype caused by PRPF31 mutations cannot be explained by the presence of tissue-specific isoforms, or by differential expression of PRPF31 in the retina. As a consequence, the etiology of PRPF31-associated retinitis pigmentosa likely relies on other, probably more subtle molecular mechanisms.
Department of Medical Genetics, University of Lausanne, Lausanne, Switzerland.
Goranka
G
Tanackovic
Carlo
C
Rivolta
D000328:Adult; D017398:Alternative Splicing / Q000235:genetics*; D000818:Animals; D015153:Blotting, Western; D002478:Cells, Cultured; D003001:Cloning, Molecular; D005136:Eye Proteins / Q000235:genetics*; D005260:Female; D015870:Gene Expression; D006801:Humans; D008297:Male; D051379:Mice; D008875:Middle Aged; D009154:Mutation; D020033:Protein Isoforms / Q000235:genetics; D012333:RNA, Messenger / Q000378:metabolism; D012160:Retina / Q000378:metabolism; D012174:Retinitis Pigmentosa / Q000235:genetics*; D020133:Reverse Transcriptase Polymerase Chain Reaction
D005136:Eye Proteins; C454222:PRPF31 protein, human; D020033:Protein Isoforms; D012333:RNA, Messenger