Cardiac hypertrophy and heart failure remain leading causes of death in the United States. Many studies have suggested that, under stress, myocardium releases factors triggering protein synthesis and stimulating myocyte growth. We identified and cloned myotrophin, a 12-kDa protein from hypertrophied human and rat hearts. Myotrophin (whose gene is localized on human chromosome 7q33) stimulates myocyte growth and participates in cellular interaction that initiates cardiac hypertrophy in vitro. In this report, we present data on the pathophysiological significance of myotrophin in vivo, showing the effects of overexpression of cardio-specific myotrophin in transgenic mice in which cardiac hypertrophy occurred by 4 weeks of age and progressed to heart failure by 9-12 months. This hypertrophy was associated with increased expression of proto-oncogenes, hypertrophy marker genes, growth factors, and cytokines, with symptoms that mimicked those of human cardiomyopathy, functionally and morphologically. This model provided a unique opportunity to analyze gene clusters that are differentially up-regulated during initiation of hypertrophy versus transition of hypertrophy to heart failure. Importantly, changes in gene expression observed during initiation of hypertrophy were significantly different from those seen during its transition to heart failure. Our data show that overexpression of myotrophin results in initiation of cardiac hypertrophy that progresses to heart failure, similar to changes in human heart failure. Knowledge of the changes that take place as a result of overexpression of myotrophin at both the cellular and molecular levels will suggest novel strategies for treatment to prevent hypertrophy and its progression to heart failure.

Oxidative stress alters physiological function in most biological tissues and can lead to cell death. In the retina, oxidative stress initiates a cascade of events leading to focal loss of RPE and photoreceptors, which is thought to be a major contributing factor to geographic atrophy. Despite these implications, the molecular regulation of RPE oxidative stress under normal and pathological conditions remains largely unknown. A better understanding of the mechanisms involved in regulating RPE and photoreceptors oxidative stress response is greatly needed. To this end we evaluated photoreceptor and RPE changes in mice deficient in DJ-1, a protein that is thought to be important in protecting cells from oxidative stress. Young (3 months) and aged (18 months) DJ-1 knockout (DJ-1 KO) and age-matched wild-type mice were examined. In both group of aged mice, scanning laser ophthalmoscopy (SLO) showed the presence of a few autofluorescent foci. The 18 month-old DJ-1 KO retinas were also characterized by a noticeable increase in RPE fluorescence to wild-type. Optical coherence tomography (OCT) imaging demonstrated that all retinal layers were present in the eyes of both DJ-1 KO groups. ERG comparisons showed that older DJ-1 KO mice had reduced sensitivity under dark- and light-adapted conditions compared to age-matched control. Histologically, the RPE contained prominent vacuoles in young DJ-1 KO group with the appearance of enlarged irregularly shaped RPE cells in the older group. These were also evident in OCT and in whole mount RPE/choroid preparations labeled with phalloidin. Photoreceptors in the older DJ-1 KO mice displayed decreased immunoreactivity to rhodopsin and localized reduction in cone markers compared to the wild-type control group. Lower levels of activated Nrf2 were evident in retina/RPE lysates in both young and old DJ-1 KO mouse groups compared to wild-type control levels. Conversely, higher levels of protein carbonyl derivatives and iNOS immunoreactivity were detected in retina/RPE lysates from both young and old DJ-1 KO mice. These results demonstrate that DJ-1 KO mice display progressive signs of retinal/RPE degeneration in association with higher levels of oxidative stress markers. Collectively this analysis indicates that DJ-1 plays an important role in protecting photoreceptors and RPE from oxidative damage during aging.

Background DJ-1 is found in many tissues, including the brain, where it has been extensively studied due to its association with Parkinson's disease. DJ-1 functions as a redox-sensitive molecular chaperone and transcription regulator that robustly protects cells from oxidative stress. Methodology Retinal pigment epithelial (RPE) cultures were treated with H2O2 for various times followed by biochemical and immunohistological analysis. Cells were transfected with adenoviruses carrying the full-length human DJ-1 cDNA and a mutant construct, which has the cysteine residues at amino acid 46, 53 and 106 mutated to serine (C to S) prior to stress experiments. DJ-1 localization, levels of expression and reactive oxygen species (ROS) generation were also analyzed in cells expressing exogenous DJ-1 under baseline and oxidative stress conditions. The presence of DJ-1 and oxidized DJ-1 was evaluated in human RPE total lysates. The distribution of DJ-1 was assessed in AMD and non-AMD cryosectionss and in isolated human Bruch's membrane (BM)/choroid from AMD eyes. Principal Findings DJ-1 in RPE cells under baseline conditions, displays a diffuse cytoplasmic and nuclear staining. After oxidative challenge, more DJ-1 was associated with mitochondria. Increasing concentrations of H2O2 resulted in a dose-dependent increase in DJ-1. Overexpression of DJ-1 but not the C to S mutant prior to exposure to oxidative stress led to significant decrease in the generation of ROS. DJ-1 and oxDJ-1 intensity of immunoreactivity was significantly higher in the RPE lysates from AMD eyes. More DJ-1 was localized to RPE cells from AMD donors with geographic atrophy and DJ-1 was also present in isolated human BM/choroid from AMD eyes. Conclusions/Significance DJ-1 regulates RPE responses to oxidative stress. Most importantly, increased DJ-1 expression prior to oxidative stress leads to decreased generation of ROS, which will be relevant for future studies of AMD since oxidative stress is a known factor affecting this disease.

Program Number: 6585 Poster Board Number: D0356 Presentation Time: 11:00 AM–12:45 PM Novel RS1 Mutation in an Irish X-Linked Retinoschisis Cohort Kirk Stephenson1, Matthew Carrigan2, Paul Kenna3, 2, G Jane Farrar2, David Keegan1. 1Ophthalmology, Mater Misericordiae University Hospital, Dublin, Ireland; 2Trinity College Dublin, Dublin, Ireland; 3Ophthalmology, Royal Victoria Eye & Ear Hospital, Dublin, Ireland. Purpose: To describe the phenotype and genotype of a family cohort (observational study, n=6) of X-linked retinoschisis in an Irish population with a novel RS1 mutation. Methods: Patients were recruited as part of the Irish national genetic screening registry for inherited retinal degenerations. This screening program includes clinical history and examination with retinal imaging, electrophysiology, visual field testing and genetic analysis. Six patients (age 62y – 74y) were identified with X-linked retinoschisis (five brothers, one male first cousin). Next generation sequencing (NGS) was performed for each patient. Investigation into the family history revealed 5 grandsons and a further maternal male first cousin that are affected. Results: All had a history of visual acuity and colour vision disturbance from childhood. There was significant phenotypic variability between the six subjects. The youngest and least severely affected patient had one eye enucleated; the remaining eye had a normal macular appearance, with vitreous strands. The eldest and most severely affected patient had advanced macular atrophy. The four patients of intermediate age and severity had a more classic macular retinoschisis pattern of retinal splitting. NGS detected a novel RS1 gene mutation (X chromosome); this was a single base change (c.413C>A) in exon 5. This mutation had not been previously submitted to the Retinoschisis Consortium, but a different mutation at this codon (c.412A>G) has been describe, which leads to a deficiency of the retinoschisin protein. Conclusions: This family has a novel gene mutation in the RS1 gene with clinical retinoschisis. The next step is to investigate the male children of these patients’ daughters for retinoschisis and this RS1 mutation. We aim to collaborate with current research in the development of gene therapy for treatment of RS1 gene mutations. Those with more advanced macular atrophy will have limited potential for improvement; however, the primary beneficiaries of gene therapy are the younger generation. With early clinical and genetic detection of X-linked retinoschisis phenotype/genotype in genetically predisposed individuals, permanent central visual loss may be prevented. Commercial Relationships: Kirk Stephenson, None; Matthew Carrigan, None; Paul Kenna, None; G Jane Farrar, None; David Keegan, None Program Number: 6586 Poster Board Number: D0357 Presentation Time: 11:00 AM–12:45 PM Mutations in Receptor Expression Enhancing Protein 6 (REEP6) Cause Early Onset RP in Humans Smriti Agrawal1, 2, Aiden Eblimit1, 2, Feng Wang1, 2, Mingchu Xu1, 2, Kerry Goetz3, Yumei Li1, 2, Rui Chen1, 2. 1Molecular and Human Genetics, Baylor College of Medicine, Houston, TX; 2Human Genome Sequencing Center, Baylor College of Medicine, Houston, TX; 3Ophthalmic Genetics and Visual Function Branch, National Eye Institute/National Institutes of Health, Bethesda, MD. Purpose: Retinitis pigmentosa is a genetically heterogeneous disorder characterized by rod photoreceptor degeneration and is a leading cause of blindness worldwide. Currently, the genetic basis of about 40% of autosomal recessive (arRP) patients remains unknown. Here we report the identification and characterization of REEP6 (Receptor Expression Enhancing Protein 6) as a novel diseasecausing gene associated with arRP. Methods: Whole exome sequencing (WES) was performed on a cohort of unassigned RP patients previously screened with retinal capture sequencing for mutations in known disease-genes. To test the pathogenicity of the mutation identified in the patient, we used CRISPR/Cas9 mediated targeting to generate knock-in mice carrying the patient mutation. Immunohistochemistry was performed to examine expression and localization of the protein in the retina. To study retinal function, we performed scotopic and photopic retinal electroretinography (ERG). Optical Coherence Tomography (OCT), histological analysis, and immunohistochemistry were performed to further characterize morphological defects. Results: WES data analysis led to the identification of bi-allelic mutations in REEP6 in a patient with early-onset arRP. To confirm the pathogenicity of the patient mutation, we generated corresponding CRISPR-targeted knock-in mice. Immunostaining of WT retina confirmed the previously reported expression of Reep6 specifically in the outer segment (OS) of the rod photoreceptors, the outer nuclear layer (ONL), and the outer plexiform layer (OPL). Consistent with the phenotypes observed in the patient, Reep6 mutant mice exhibit progressive retinal degeneration with abnormal scotopic ERG response starting at 3 months of age, indicative of progressive rod dysfunction. OCT and histological analysis of Reep6 mutant mice show significant thinning of the ONL and photoreceptor degeneration. Conclusions: This study is the first to identify mutations in REEP6 that cause retinitis pigmentosa in humans. Furthermore, we have developed Reep6 knock-in mice that model the human disease, enabling us to gain insights into Reep6 dysfunction in photoreceptor degeneration. Our results suggest that Reep6 plays an important role in preserving proper photoreceptor function and survival. Commercial Relationships: Smriti Agrawal, None; Aiden Eblimit, None; Feng Wang, None; Mingchu Xu, None; Kerry Goetz; Yumei Li, None; Rui Chen, None Support: NEI Grant R01EY022356 and R01EY018571, Foundation Fighting Blindness Grant BR-GE-0613-0618-BCM

DJ-1/PARK7 mutations or deletions cause autosomal recessive early onset Parkinson's disease (PD). Thus, DJ-1 protein has been extensively studied in brain and neurons. PD patients display visual symptoms; however, the visual symptoms specifically attributed to PD patients carrying DJ-1/PARK7 mutations are not known. In this study, we analyzed the structure and physiology of retinas of 3- and 6-month-old DJ-1 knockout (KO) mice to determine how loss of function of DJ-1 specifically contributes to the phenotypes observed in PD patients. As compared to controls, the DJ-1 KO mice displayed an increase in the amplitude of the scotopic ERG b-wave and cone ERG, while the amplitude of a subset of the dc-ERG components was decreased. The main structural changes in the DJ-1 KO retinas were found in the outer plexiform layer (OPL), photoreceptors and retinal pigment epithelium (RPE), which were observed at 3 months and progressively increased at 6 months. RPE thinning and structural changes within the OPL were observed in the retinas in DJ-1 KO mice. DJ-1 KO retinas also exhibited disorganized outer segments, central decrease in red/green cone opsin staining, decreased labeling of ezrin, broader distribution of ribeye labeling, decreased tyrosine hydroxylase in dopaminergic neurons, and increased 7,8-dihydro-8-oxoguanine-labeled DNA oxidation. Accelerated outer retinal atrophy was observed in DJ-1 KO mice after selective oxidative damage induced by a single tail vein injection of NaIO3, exposing increased susceptibility to oxidative stress. Our data indicate that DJ-1-deficient retinas exhibit signs of morphological abnormalities and physiological dysfunction in association with increased oxidative stress. Degeneration of RPE cells in association with oxidative stress is a key hallmark of age-related macular degeneration (AMD). Therefore, in addition to detailing the visual defects that occur as a result of the absence of DJ-1, our data is also relevant to AMD pathogenesis.

BALB/cJ mice housed under normal vivarium lighting conditions can exhibit profound retinal abnormalities, including retinal infoldings, autofluorescent inflammatory cells, and photoreceptor degeneration. To explore the sensitivity of the outer retina to cyclic lighting during aging, a cohort of BALB/cJ mice was evaluated with Scanning Laser Ophthalmoscopy (SLO), Spectral-Domain Optical Coherence Tomography (OCT) and conventional histopathology. Mice were bred and reared in a low-illuminance (extracage/intracage: 13 lx/1 lx) vivarium under cyclic light (14 h light: 10 h dark). Retinal imaging (around postnatal day 70) was performed to screen for any pre-existing abnormalities and to establish a baseline. Mice with normal retinas were separated into groups (A, B, C) and placed on bottom (Groups A & B) or top (Group C) of the cage racks where cage illumination was <10 & 150 lx respectively. Experimental groups B & C were imaged multiple times over a 17 month period. Mice from group A (controls) were imaged only once post-baseline at various times for comparison to groups B & C. Mice were assessed by histology at 8, 15, 20, 36, and 56 weeks and immunohistochemistry at 15 weeks post-baseline. SLO and OCT retinal images were measured and the resulting trends displayed as a function of age and light exposure. Retinal lesions (RL) and autofluorescent foci (AFF) were identified with histology as photoreceptor layer infoldings (IF) and localized microglia/macrophages (MM), respectively. Few RL and AFF were evident at baseline. Retinal infoldings were the earliest changes followed by subjacent punctate autofluorescent MM. The colocalization of IF and MM suggests a causal relationship. The incidence of these pathological features increased in all groups relative to baseline. OCT imaging revealed thinning of the outer nuclear layer (ONL) in all groups at 1 year relative to baseline. ONL thinning followed an exponential rate of change but the decay constant varied depending on intensity of illumination of the groups. Advanced age and top row illuminance conditions resulted in significant photoreceptor cell loss as judged by decreased thickness of the ONL. Photoreceptor loss was preceded by both retinal infoldings and the presence of autofluorescent inflammatory cells in the outer retina, suggesting that these changes are early indicators of light toxicity in the BALB/cJ mouse.

PURPOSE:Ambient light is both a stimulus for visual function and a regulator of photoreceptor physiology. However, it is not known if light can regulate any aspect of photoreceptor development. The purpose of this study was to investigate whether ambient light is required for the development of mouse rod photoreceptors.METHODS:Newborn mouse pups (C57BL/6) were reared in either cyclic light (LD) or constant dark (DD). Pups were collected at postnatal day (P)5, P10, P17, or P24. We performed retinal morphometric and cell death analysis at P5, P10, and P17. Rhodopsin expression was assessed using immunofluorescence, Western blot, and quantitative RT-PCR analysis. Electroretinograms were performed at P17 and P24. Radioimmunoassay and ELISA were used to follow changes in thyroid hormone levels in the serum and vitreous.RESULTS:In the DD pups, the outer nuclear layer was significantly thinner at P10 and there were higher numbers of apoptotic cells at P5 compared to the LD pups. Rhodopsin expression was lower at P10 and P17 in DD pups. Electroretinogram a-waves were reduced in amplitude at P17 in the DD pups. The DD animals had lower levels of circulating thyroid hormones at P10. Light-mediated changes in thyroid hormones occur as early as P5, as we detected lower levels of total triiodothyronine in the vitreous from the DD animals. Drug-induced developmental hypothyroidism resulted in lower rhodopsin expression at P10.CONCLUSIONS:Our data demonstrate that light exposure during postnatal development is required for rod photoreceptor development and that this effect could be mediated by thyroid hormone signaling.

PURPOSE To define the retinal pathology in a 3 year-old eye donor who died from complications of an undiagnosed genetic syndrome. METHODS Eyes were fixed and analyzed using macroscopic fundus photography (MF), confocal scanning laser ophthalmoscopy (cSLO) and spectral-domain optical coherence tomography (SD-OCT). Small areas from the perifovea and periphery were processed for histology and indirect immunofluorescence, using antibodies specific to retinal proteins such as rhodopsin, cone arrestin, RPE65 and others. Available medical records were also reviewed. RESULTS With all three imaging modalities, the affected donor's eyes lacked the distinct morphological detail typically observed with these techniques in postmortem control eyes. MF images showed a "photonegative effect" due to a hypopigmented macula relative to a hyperpigmented retinal background. cSLO imaging demonstrated a weak autofuorescence signal that was largely devoid of the usual retinal structures compared to the control. SD-OCT suggested disorganization of the affected retina, absence of a photoreceptor layer, and degeneration of the choroid in the macular area. Histologic findings indicated a highly disorganized photoreceptor layer in the macula and periphery. The RPE layer displayed thinning in some regions of the periphery and decreased pigmentation in most areas. Rods and cones were significantly reduced in the affected retina but a few cones were detected in the perifovea. Centrin-2 labeling was mostly absent from the connecting cilium of the photoreceptor cells. Medical record review pointed to a possible clinical diagnosis of Joubert syndrome. CONCLUSIONS The retinal degenerative findings, and absence of centrin-2 labeling are compatible with the expected retinal phenotype in patients with Joubert syndrome.

To evaluate the retinal histopathology in donor eyes from patients with autosomal recessive retinitis pigmentosa (arRP) caused by EYS mutations. Eyes from a 72-year-old female (donor 1, family 1), a 91-year-old female (donor 2, family 2), and her 97-year-old sister (donor 3, family 2) were evaluated with macroscopic, scanning laser ophthalmoscopy (SLO) and optical coherence tomography (OCT) imaging. Age-similar normal eyes and an eye donated by donor 1’s asymptomatic mother (donor 4, family 1) were used as controls. The perifovea and peripheral retina were processed for microscopy and immunocytochemistry with markers for cone and rod photoreceptor cells. DNA analysis revealed EYS mutations c.2259 + 1G > A and c.2620C > T (p.Q874X) in family 1, and c.4350_4356del (p.I1451Pfs*3) and c.2739-?_3244 + ?del in family 2. Imaging studies revealed the presence of bone spicule pigment in arRP donor retinas. Histology of all three affected donor eyes showed very thin retinas with little evidence of stratified nuclear layers in the periphery. In contrast, the perifovea displayed a prominent inner nuclear layer. Immunocytochemistry analysis demonstrated advanced retinal degenerative changes in all eyes, with near-total absence of rod photoreceptors. In addition, we found that the perifoveal cones were more preserved in retinas from the donor with the midsize genomic rearrangement (c.4350_4356del (p.I1451Pfs*3) and c.2739-?_3244 + ?del) than in retinas from the donors with the truncating (c.2259 + 1G > A and c.2620C > T (p.Q874X) mutations. Advanced retinal degenerative changes with near-total absence of rods and preservation of some perifoveal cones are observed in arRP donor retinas with EYS mutations.