DICER1 deficit induces Alu RNA toxicity in age-related macular degeneration.

Geographic atrophy (GA), an untreatable advanced form of age-related macular degeneration, results from retinal pigmented epithelium (RPE) cell degeneration. Here we show that the microRNA (miRNA)-processing enzyme DICER1 is reduced in the RPE of humans with GA, and that conditional ablation of Dicer1, but not seven other miRNA-processing enzymes, induces RPE degeneration in mice. DICER1 knockdown induces accumulation of Alu RNA in human RPE cells and Alu-like B1 and B2 RNAs in mouse RPE.

Nicotinic acetylcholine receptor subunits in rhesus monkey retina.

Purpose: The purpose of this study was to detect and establish the cellular localizations of nicotinic acetylcholine receptor (nAChR) subunits in Rhesus monkey retina.

Methods: Retinas were dissected from the eyes of monkeys killed after unrelated experiments. RNA was extracted and analyzed by RT-PCR, using primers designed against human sequences of alpha3-alpha7, alpha9, and beta2-beta4 nAChR subunits.

Cone photoreceptor function loss-3, a novel mouse model of achromatopsia due to a mutation in Gnat2.

Purpose: To report a novel mouse model of achromatopsia with a cpfl3 mutation found in the ALS/LtJ strain.

Methods: The effects of a cpfl3 mutation were documented using fundus photography, electroretinography (ERG), and histopathology. Genetic analysis was performed using linkage studies and PCR gene identification.

ABCA4-associated retinal degenerations spare structure and function of the human parapapillary retina.

Purpose: To study the parapapillary retinal region in patients with ABCA4-associated retinal degenerations.

Methods: Patients with Stargardt disease or cone-rod dystrophy and disease-causing variants in the ABCA4 gene were included. Fixation location was determined under fundus visualization, and central cone-mediated vision was measured.

Identifying photoreceptors in blind eyes caused by RPE65 mutations: Prerequisite for human gene therapy success.

Mutations in RPE65, a gene essential to normal operation of the visual (retinoid) cycle, cause the childhood blindness known as Leber congenital amaurosis (LCA). Retinal gene therapy restores vision to blind canine and murine models of LCA. Gene therapy in blind humans with LCA from RPE65 mutations may also have potential for success but only if the retinal photoreceptor layer is intact, as in the early-disease stage-treated animals.

Histopathologic study of X-linked cone-rod dystrophy (CORDX1) caused by a mutation in the RPGR exon ORF15.

Purpose: To evaluate the donor retina of a patient with X-linked cone-rod dystrophy caused by an RPGR exon ORF15 mutation.

Design: Histopathologic study of the retina.

Methods: The eye of a 69-year-old man was fixed at 1.

Cone damage in patients receiving high-dose irofulven treatment.

Objectives: To describe the clinical, perimetric, and electroretinographic (ERG) results of 4 patients with cone dysfunction following irofulven treatment including the histopathologic and immunocytochemical features of one patient's retinas.

Design: Observational case series.

Methods: The patients were examined clinically, including perimetric and ERG evaluations.

Electroretinographic and clinicopathologic correlations of retinal dysfunction in infantile neuronal ceroid lipofuscinosis (infantile Batten disease).

Infantile neuronal ceroid lipofuscinosis (INCL) is an autosomal recessive disease that results from deficiency of palmitoyl-protein thioesterase-1 (PPT1). INCL leads to retinal blindness, neurodegeneration, and early death. We studied the clinical features and electroretinogram (ERG) in three patients and histopathologic and immunofluorescence analyses of the retina in the third patient, who died at 3 years 2 months of age.

Mutation in a short-chain collagen gene, CTRP5, results in extracellular deposit formation in late-onset retinal degeneration: a genetic model for age-related macular degeneration.

A primary feature of age-related macular degeneration (AMD) is the presence of extracellular deposits between the retinal pigment epithelium (RPE) and underlying Bruch's membrane, leading to RPE dysfunction, photoreceptor death and severe visual loss. AMD accounts for about 50% of blind registrations in Western countries and is a common, genetically complex disorder. Very little is known regarding its molecular basis.

Maculas affected by age-related macular degeneration contain increased chelatable iron in the retinal pigment epithelium and Bruch's membrane.

Objective: To investigate whether iron is involved in the pathogenesis of age-related macular degeneration (AMD).

Methods: Postmortem AMD-affected (nonexudative or exudative) and healthy maculas were studied using the 3,3'-diaminobenzidine-enhanced Perls Prussian blue stain. The Perls Prussian blue stain was quantified by computer-assisted analysis of digital images.

Proapoptotic bcl-2 family members, Bax and Bak, are essential for developmental photoreceptor apoptosis.

Purpose: Apoptosis has been implicated in retinal development and degeneration, but the specific apoptotic pathways used are incompletely understood. The purpose of this study was to characterize the roles in retinal development of the proapoptotic Bcl-2 family members Bax and Bak.

Methods: Eyes from mice at postnatal day (P)7, during the peak of developmental apoptosis in the retina, were processed for TdT-dUTP terminal nick-end labeling (TUNEL) to determine whether Bax knockout or double Bax/Bak knockout causes a defect in developmental apoptosis.

Retinal remodeling triggered by photoreceptor degenerations.

Many photoreceptor degenerations initially affect rods, secondarily leading to cone death. It has long been assumed that the surviving neural retina is largely resistant to this sensory deafferentation. New evidence from fast retinal degenerations reveals that subtle plasticities in neuronal form and connectivity emerge early in disease.

Amyloid-beta is found in drusen from some age-related macular degeneration retinas, but not in drusen from normal retinas.

Purpose: Age-related macular degeneration (AMD) is the most common cause of irreversible vision loss in the elderly. Increased understanding of the pathogenesis is necessary. Amyloid-beta (Abeta), a major extracellular deposit in Alzheimer's disease plaques, has recently been found in drusen, the hallmark extracellular deposit in AMD.

Crumbs homolog 1 (CRB1) mutations result in a thick human retina with abnormal lamination.

Mutations in CRB1, the human homolog of Drosophila Crumbs, cause autosomal recessive blinding disorders of the retina. Whereas Crumbs is implicated in apical-basal epithelial polarity and photoreceptor morphogenesis, the role of CRB1 in normal or diseased retina remains unclear. We characterized the retinal organization in vivo of patients with CRB1 mutations and found that, unlike other inherited retinal degenerations studied to date, the CRB1 mutant retinas are remarkably thick in cross-section and lack the distinct layers of normal adult retina.

Activated microglia in human retinitis pigmentosa, late-onset retinal degeneration, and age-related macular degeneration.

Many gaps exist in our knowledge of human retinal microglia in health and disease. We address the hypothesis that primary death of rod photoreceptors leads to activation of resident microglia in human retinas with retinitis pigmentosa (RP), late-onset retinal degeneration (L-ORD), or age-related macular degeneration (AMD). Regions of ongoing photoreceptor cell death were studied by immunocytochemistry with microglia- and other retinal cell-specific markers.

Clinicopathologic effects of mutant GUCY2D in Leber congenital amaurosis.

Purpose: To study the retinal degeneration in an 11 -year-old patient with Leber congenital amaurosis (LCA) caused by mutation in GUCY2D.

Study Design: Comparative human tissue study.

Participants: Two subjects with LCA; postmortem eye from one LCA patient and three normal donors.

Cone deactivation kinetics and GRK1/GRK7 expression in enhanced S cone syndrome caused by mutations in NR2E3.

Purpose: To determine the relationship between cone deactivation kinetics in patients with the enhanced S cone syndrome (ESCS) caused by mutations in NR2E3 and the immunoreactivity to G-protein-coupled receptor kinase 1 (GRK1) and GRK7.

Methods: Electroretinogram (ERG) photoresponses were used to investigate activation kinetics of cones with a model of cone phototransduction. Deactivation kinetics of cones after bright flashes was quantified with a paired-flash ERG paradigm.

The role of apoptosis in age-related macular degeneration.

Objective: To investigate apoptosis in human age-related macular degeneration (AMD).

Methods: Postmortem retinas with AMD and normal retinas were studied by terminal deoxynucleotidyl transferase dUTP nick end-labeling (TUNEL) to identify dying cells, and by immunocytochemistry with cell-specific antibodies to identify rods and cones. Sections were also labeled for Fas, a cell surface receptor that triggers apoptosis in other cell types.

Retinal histopathology of an XLRP carrier with a mutation in the RPGR exon ORF15.

X-linked retinitis pigmentosa comprises the severe forms of RP, with early onset of night blindness, rapid constriction of visual fields and eventual loss of central acuity. Of the five distinct XLRP loci identified on the X chromosome, mutations have been found only in the RP2 and RPGR genes. Of these, mutations in RPGR are more common, particularly in a mutational hot spot that was identified in the newly discovered exon ORF15.

Nature of the cone ON-pathway dysfunction in melanoma-associated retinopathy.

Purpose: To establish the basis for an ON-pathway abnormality of the cone system in melanoma-associated retinopathy (MAR) through analysis of the electroretinogram (ERG) and visual evoked potential (VEP).

Methods: Two patients with MAR syndrome whose sera produced immunolabeling of retinal bipolar cells participated in the study. Full-field ERGs were recorded in response to brief flashes, to rapid-on and rapid-off sawtooth stimuli at a temporal frequency of 8 Hz, and to sine-wave stimuli at temporal frequencies ranging from 8 to 96 Hz.

The nuclear receptor NR2E3 plays a role in human retinal photoreceptor differentiation and degeneration.

Normal human retinal development involves orderly generation of rods and cones by complex mechanisms. Cell-fate specification involves progenitor cell lineage and external signals such as soluble factors and cell-cell interactions. In most inherited human retinal degenerations, including retinitis pigmentosa, a mutant gene causes loss of visual function, death of mature rods, and eventually death of all cone subtypes.

Identification and subcellular localization of the RP1 protein in human and mouse photoreceptors.

Purpose: Mutations in the RP1 gene account for 6% to 10% of autosomal dominant retinitis pigmentosa (adRP). Previous studies have shown that the RP1 gene is expressed specifically in photoreceptor cells. So far, little is known about the RP1 protein or how mutations in RP1 lead to photoreceptor cell death.