Retinal pigment epithelium degeneration caused by aggregation of PRPF31 and the role of HSP70 family of proteins

Background Mutations in pre-mRNA splicing factor PRPF31 can lead to retinitis pigmentosa (RP). Although the exact disease mechanism remains unknown, it has been hypothesized that haploinsufficiency might be involved in the pathophysiology of the disease. Methods In this study, we have analyzed a mouse model containing the p.A216P mutation in Prpf31 gene. Results We found that mutant Prpf31 protein produces cytoplasmic aggregates in the retinal pigment epithelium and decreasing the protein levels of this splicing factor in the nucleus. Additionally, normal protein was recruited in insoluble aggregates when the mutant protein was overexpressed in vitro. In response to protein aggregation, Hspa4l is overexpressed. This member of the HSP70 family of chaperones might contribute to the correct folding and solubilization of the mutant protein, allowing its translocation to the nucleus. Conclusions Our data suggests that a mechanism haploinsufficiency and dominant-negative is involved in retinal degeneration due to mutations in PRPF31. HSP70 over-expression might be a new therapeutic target for the treatment of retinal degeneration due to PRPF31 mutations.This project has been financed through a) The ISCIII (Miguel Servet-I, 2015), co-financed by the European Regional Development Fund (ERDF), No CP15/00071. b) The European Union’s Horizon 2020 research and innovation program, under grant agreement No 634479. c) Regional Ministry of Economy, Innovation and Science of the Junta de Andalucía, No P09-CTS-04967.info:eu-repo/semantics/publishedVersio

Cone-Rod Dystrophy Due to Mutations in a Novel Photoreceptor-Specific Homeobox Gene (CRX) Essential for Maintenance of the Photoreceptor

Genes associated with inherited retinal degeneration have been found to encode proteins required for phototransduction, metabolism, or structural support of photoreceptors. Here we show that mutations in a novel photoreceptor-specific homeodomain transcription factor gene (CRX) cause an autosomal dominant form of cone-rod dystrophy (adCRD) at the CORD2 locus on chromosome 19q13. In affected members of a CORD2-linked family, the highly conserved glutamic acid at the first position of the recognition helix is replaced by alanine (E80A). In another CRD family, a 1 bp deletion (E168 [delta1 bp]) within a novel sequence, the WSP motif, predicts truncation of the C-terminal 132 residues of CRX. Mutations in the CRX gene cause adCRD either by haploinsufficiency or by a dominant negative effect and demonstrate that CRX is essential for the maintenance of mammalian photoreceptorsThis work was supported by the RP Foundation of Canada (R. R. M.), the Foundation Fighting Blindness (R. R. M. and S. G. J.), the Canadian Genetic Disease Network (R. R. M. and A. D.), the Medical Research Council of Canada (R. R. M.), The Wellcome Trust (043825/Z/95) and the Human Genome Mapping Resource Centre (C. Y. G.-E. and S. S. B.), the Howard Hughes Medical Institute and NIH R01 EY0 8064 (C. L. C.), the Canadian Genome Analysis and Technology Genome Resource Facility (S. W. S. and L.-C. T.), the NIH/NEI (EY05627) (S. G. J.), and the Greek National Scholarship Foundation (M. P.). R. R. M. and L.-C. T. are International Research Scholars of the Howard Hughes Medical Institute

Effect of Gene Therapy on Visual Function in Leber's Congenital Amaurosis

Early-onset, severe retinal dystrophy caused by mutations in the gene encoding retinal pigment epithelium–specific 65-kD protein (RPE65) is associated with poor vision at birth and complete loss of vision in early adulthood. We administered to three young adult patients subretinal injections of recombinant adeno-associated virus vector 2/2 expressing RPE65 complementary DNA (cDNA) under the control of a human RPE65 promoter. There were no serious adverse events. There was no clinically significant change in visual acuity or in peripheral visual fields on Goldmann perimetry in any of the three patients. We detected no change in retinal responses on electroretinography. One patient had significant improvement in visual function on microperimetry and on dark-adapted perimetry. This patient also showed improvement in a subjective test of visual mobility. These findings provide support for further clinical studies of this experimental approach in other patients with mutant RPE65. (ClinicalTrials.gov number, NCT00643747.)Supported by grants from the U.K. Department of Health, the British Retinitis Pigmentosa Society, and the Special Trustees of Moorfields Eye Hospital, and by the Sir Jules Thorn Charitable Trust, the Wellcome Trust, the European Union (EVI-Genoret and Clinigene programs), the Medical Research Council, Foundation Fighting Blindness, Fight for Sight, the Ulverscroft Foundation, Fighting Blindness (Ireland), Moorfields Eye Hospital, and Institute of Ophthalmology Biomedical Research Centre for Ophthalmology, University College London

Hypoxia enhances the generation of retinal progenitor cells from human induced pluripotent and embryonic stem cells

et al.The efficient differentiation of retinal cells from human pluripotent stem cells remains a major challenge for the development of successful and cost-effective cellular therapies for various forms of blindness. Current differentiation strategies rely on exposing pluripotent stem cells to soluble growth factors that play key roles during early development (such as DKK-1, Noggin, and IGF-1) at 20% oxygen (O 2). This O 2 tension is, however, considerably higher than O 2 levels during organogenesis and may impair the differentiation process. In this study, we examined the effect of mimicking the physiological O 2 tension (2%) on the generation of retinal progenitor cells (RPCs) from human induced pluripotent stem cells (iPSCs) and human embryonic stem cells (hESCs). Both cell types were induced to differentiate into RPCs at 20% and 2% O 2. After 3 days in suspension culture as embryoid bodies (EBs), 2% O 2 caused the activation of hypoxia inducible factor responsive genes VEGF and LDHA and was accompanied by elevated expression levels of the early eye field genes Six3 and Lhx2. Twenty-one days after plating EBs in an adherent culture, we observed more RPCs co-expressing Pax6 and Chx10 at 2% O 2. Quantitative polymerase chain reaction analysis confirmed that lowering O 2 tension had caused a rise in the expression of both genes compared with 20% O 2. Our results indicate that mimicking physiological O 2 is a favorable condition for the efficient generation of RPCs from both hiPSCs and hESCs. © Copyright 2012, Mary Ann Liebert, Inc.D.B would like to thank the Department of Biochemical Engineering of University College London (UCL) for a studentship. P.M.T would like to thank the Mexican Science and Technology Agency (CONACyT) and UCL for the award of a doctoral fellowship. D.H is in receipt of a Technology Strategy Board grant.Peer Reviewe

DNA polymorphisms, identified by an X-chromosome short-arm probe L 1.28 (DXS7), in different racial groups

Restriction fragment length polymorphisms of the L1.28 probe which is closely linked to X-linked disorders, retinitis pigmentosa and Norrie disease, were studied in samples from England, India and Nigeria. The frequency of the A2 allele (9-kb fragment) was 0.23, 0.55 and 0.46 in England, India and Nigeria, respectively. The differences between the English and Indian populations were highly significant

A case of disputed maternity

It has been alleged that two Gujarati Muslim boys are not the sons of the woman who brought them to the United Kingdom, claiming them to be her sons. The father has recently died, but blood samples from the mother and her four daughters (whose parentage is not in doubt) allowed the paternal genotype to be deduced. Samples were tested for 9 blood-group systems (12 gene loci), 9 red-cell-enzyme systems, 6 serum protein types, 2 HLA loci, and 5 X-chromosome probes. There was no evidence of non-maternity of the two boys in any of these systems. The odds that the woman who claims to be the boys' mother, rather than any random Gujarati Muslim woman, is indeed the mother of the older boy are fourteen million to one, and that she is the mother of the younger boy five million to one

Effects of ouabain on sodium uptake by frog heart and skeletal muscle

Effects of ouabain (10(-3)-10(-12) M) on frog heart and skeletal muscle net uptake of Na from a K-free Conway-Ringer solution at 0-2 degrees C were investigated. Under these circumstances Na pumps are inactive and fibers are gaining Na even without ouabain. Changes in K, H2O, and solids were also measured. Na gains and K losses were increased by ouabain at greater than 10(-6) and greater than 10(-7) M, respectively, and decreased in heart muscle at less than or equal to 10(-8) M. It is suggested that these effects are due to actions on membrane permeability. Implications for mechanisms of positive inotropic effect of glycosides and for treatment are discussed