Identification of an Alternative Splicing Product of the Otx2 Gene Expressed in the Neural Retina and Retinal Pigmented Epithelial Cells.

To investigate the complexity of alternative splicing in the retina, we sequenced and analyzed a total of 115,706 clones from normalized cDNA libraries from mouse neural retina (66,217) and rat retinal pigmented epithelium (49,489). Based upon clustering the cDNAs and mapping them with their respective genomes, the estimated numbers of genes were 9,134 for the mouse neural retina and 12,050 for the rat retinal pigmented epithelium libraries. This unique collection of retinal of messenger RNAs is maintained and accessible through a web-base server to the whole community of retinal biologists for further functional characterization. The analysis revealed 3,248 and 3,202 alternative splice events for mouse neural retina and rat retinal pigmented epithelium, respectively. We focused on transcription factors involved in vision. Among the six candidates suitable for functional analysis, we selected Otx2S, a novel variant of the Otx2 gene with a deletion within the homeodomain sequence. Otx2S is expressed in both the neural retina and retinal pigmented epithelium, and encodes a protein that is targeted to the nucleus. OTX2S exerts transdominant activity on the tyrosinase promoter when tested in the physiological environment of primary RPE cells. By overexpressing OTX2S in primary RPE cells using an adeno associated viral vector, we identified 10 genes whose expression is positively regulated by OTX2S. We find that OTX2S is able to bind to the chromatin at the promoter of the retinal dehydrogenase 10 (RDH10) gene.

Threshold levels of visual field and acuity loss related to significant decreases in the quality of life and emotional states of patients with retinitis pigmentosa.

INTRODUCTION: Retinitis pigmentosa (RP) is an inherited retinal disorder, characterized by photoreceptor degeneration inducing progressive vision loss. This study evaluates its impact on quality of life (QOL) and emotional states of patients affected by RP. METHODS: A cross-sectional study was conducted on 60 RP patients diagnosed with rod-cone dystrophy and on 20 control subjects. The RP population has been divided into 3 groups according to visual field (VF) and visual acuity (VA) impairments. Concurrently, scores of self-reported QOL (25-item National Eye Institute Visual Functioning Questionnaire) and of the Hospital Anxiety and Depression Scale for anxiety/depression assessments were collected. RESULTS: For the QOL composite score, we noticed consistent differences between all VF and VA affected groups and their control group. We also found significant differences between both the most affected VF group (VF1: ØVF <20°) and VA group (VA1: VA <0.3) compared to other VF and VA groups. For anxiety/depression scores, consistent differences have been found between the control group and VF1 and VA1, respectively. CONCLUSIONS: This work determines that, for RP patients, a significant QOL and emotional state deterioration correlates with a residual VF diameter below 20° and a VA lower than 0.3. It introduces, for the first time, thresholds to be used in visual restoration or visual preservation therapies to improve QOL of RP patients.

Rod-derived Cone Viability Factor-2 is a novel bifunctional-thioredoxin-like protein with therapeutic potential.

BACKGROUND: Cone degeneration is the hallmark of the inherited retinal disease retinitis pigmentosa. We have previously identified a trophic factor "Rod-derived Cone Viability Factor (RdCVF) that is secreted by rods and promote cone viability in a mouse model of the disease. RESULTS: Here we report the bioinformatic identification and the experimental analysis of RdCVF2, a second trophic factor belonging to the Rod-derived Cone Viability Factor family. The mouse RdCVF gene is known to be bifunctional, encoding both a long thioredoxin-like isoform (RdCVF-L) and a short isoform with trophic cone photoreceptor viability activity (RdCVF-S). RdCVF2 shares many similarities with RdCVF in terms of gene structure, expression in a rod-dependent manner and protein 3D structure. Furthermore, like RdCVF, the RdCVF2 short isoform exhibits cone rescue activity that is independent of its putative thiol-oxydoreductase activity. CONCLUSION: Taken together, these findings define a new family of bifunctional genes which are: expressed in vertebrate retina, encode trophic cone viability factors, and have major therapeutic potential for human retinal neurodegenerative diseases such as retinitis pigmentosa.