Synaptic Pathology, Altered Gene Expression, and Degeneration in Photoreceptors Impacted by Drusen

Johnson, P.T.; Brown, Meghan N; Pulliam, Bryce C; Anderson, Don H.; Johnson, Lincoln V.

doi:10.1167/iovs.05-0767

Cited by 107 publications

(86 citation statements)

References 40 publications

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“…It has been shown that photoreceptor cells in areas impacted by drusen exhibit morphologic and biochemical signs of degeneration, including decreased expression of synapse-associated proteins and increased expression of stress-response molecules. There are also drusen-associated reductions in photoreceptor cell densities, thus suggesting that degenerative changes in photoreceptors ultimately lead to cell death (151,152).…”

Section: Physiological Correlates Of Early Amdmentioning

confidence: 99%

Age‐related macular degeneration—emerging pathogenetic and therapeutic concepts

et al. 2006

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Today, the average life expectancy in developed nations is over 80 years and climbing. And yet, the quality of life during those additional years is often significantly diminished by the effects of age-related, degenerative diseases, including age-related macular degeneration (AMD), the leading cause of blindness in the elderly worldwide. AMD is characterized by a progressive loss of central vision attributable to degenerative and neovascular changes in the macula, a highly specialized region of the ocular retina responsible for fine visual acuity. Estimates gathered from the most recent World Health Organization (WHO) global eye disease survey conservatively indicate that 14 million persons are blind or severely visually impaired because of AMD. The disease has a tremendous impact on the physical and mental health of the geriatric population and their families and is becoming a major public health burden.Currently, there is neither a cure nor a means to prevent AMD. Palliative treatment options for the less prevalent, late-stage 'wet' form of the disease include anti-neovascular agents, photodynamic therapy and thermal laser. There are no current therapies for the more common 'dry' AMD, except for the use of antioxidants that delay progression in 20%-25% of eyes. New discoveries, however, are beginning to provide a much clearer picture of the relevant cellular events, genetic factors, and biochemical processes associated with early AMD. Recently, compelling evidence has emerged that the innate immune system and, more specifically, uncontrolled regulation of the complement alternative pathway plays a central role in the pathobiology of AMD. The complement Factor H gene-which encodes the major inhibitor of the complement alternative pathway-is the first gene identified in multiple independent studies that confers a significant genetic risk for the development of AMD. The emergence of this new paradigm of AMD pathogenesis should hasten the development of novel diagnostic and therapeutic approaches for this disease that will dramatically improve the quality of our prolonged lifespan.

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Section: Physiological Correlates Of Early Amdmentioning

confidence: 99%

Age‐related macular degeneration—emerging pathogenetic and therapeutic concepts

et al. 2006

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“…In comparison, the AMD data and the current study most likely represent a degenerative process at different time scales: our data may represent the initial events whereas stress-response in diverse proteins may be a later event. Synaptic disassembly appears to arise early and is sustained for a long period (Johnson et al, 2005).…”

Section: Opsin Accumulation and Cyclic Illumination Promote Er-stressmentioning

confidence: 99%

Autophagy and ER-stress contribute to photoreceptor degeneration in cultured adult porcine retina

et al. 2014

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Abbreviations: AMD, age-related macular degeneration; BSA, bovine serum albumin; CHOP, C/EBP homology protein; CtBP2, C-terminal binding protein 2; ER, endoplasmic reticulum; GRP78/BiP, glucoseregulated protein 78kDa/Binding immunoglobulin protein, INL, inner nuclear layer; IPL, inner plexiform layer; LC3B, microtubule-associated protein light chain 3B; mTOR, mammalian target of rapamycin; ONL, outer nuclear layer; OPL, outer nuclear layer; PBS, phosphate buffered saline; PNA, peanut agglutinin; p62/SQSTM1; nucleoporin p62/sequestosom 1; PSD-95, postsynaptic density protein 95; rd1, retinal degeneration 1; RPE, retinal pigment epithelium; UPS, ubiquitin-proteasome system; 2 AbstractThe aim of this study was to investigate rod and cone photoreceptor degeneration in organotypic cultures of adult porcine retina. Our hypothesis was that the photoreceptors accumulate opsins, which, together with exposure to cyclic dim light illumination, induce autophagy and endoplasmic reticulum stress (ER-stress) to overcome damaging protein overload. For this purpose, retinas were cultured for 48 h and 72 h during which they were illuminated with dim light for 8 h/day; specimens were analyzed by means of immunohistochemistry, western blot and transmission electron microscopy. ER-stress and photoreceptor degeneration was observed in conventionally cultured retinas. The additional stress in the form of dim light illumination for 8 h/day resulted in increased levels of the ER-stress markers GRP78/BiP and CHOP, as well as increased level of active caspase-12. Increased autophagic processes in cone and rod photoreceptors were detected by LC3B-II increases and occurrence of autophagosomes at the ultrastructural level. Illumination also resulted in altered protein expression for autophagy inducers such as p62 and Beclin-1. Moreover, there was a decrease in phosphorylated mammalian target of rapamycin (mTOR), which further indicate an increase of autophagy. Rod and cone photoreceptors in retinas from a diurnal animal that were exposed to dim light illumination in vitro displayed autophagy and ER-stress processes. In particular, these processes resulted in decreased protein levels for rhodopsin.3

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“…Further, it was found that alpha crystallins accumulated in Bruch's membrane, choroidal connective tissue, and RPE to a greater degree in AMD than in normal non-AMD controls (Nakata et al, 2005, De et al, 2007. Expression of stress related proteins apolipoprotein E and αB crystallin increased in the photoreceptors over Drusen (Johnson et al, 2005).…”

Section: Introductionmentioning

confidence: 98%

Exacerbation of retinal degeneration in the absence of alpha crystallins in an in vivo model of chemically induced hypoxia

Yaung

Kannan

Wawrousek

et al. 2008

Experimental Eye Research

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This study evaluated the role of crystallins in retinal degeneration induced by chemical hypoxia. Wild type, αA-crystallin (−/−), and αB-crystallin (−/−) mice received intravitreal injection of 12 nmol (low dose), 33 nmol (intermediate dose) or 60 nmol (high dose) cobalt chloride (CoCl 2 ). Hematoxylin and eosin and TdT-mediated dUTP nick-end labeling (TUNEL) stains were performed after 24 hours, 96 hours, and 1 week post-injection, while immunofluorescent stains for αA-and αB-crystallin were performed 1 week post-injection. The in vitro effects of CoCl 2 on αB-crystallin expression in ARPE-19 cells were determined by real time RT-PCR, Western blot, and confocal microscopy and studies evaluating subcellular distribution of αB-crystallin in the mitochondria and cytosol were also performed. Histologic studies revealed progressive retinal degeneration with CoCl 2 injection in wild type mice. Retinas of CoCl 2 injected mice showed transient increased expression of HIF-1α which was maximal 24 hours after injection. Intermediate dose CoCl 2 injection was associated with increased retinal immunofluorescence for both αA-and αB-crystallin; however, after high dose injection, increased retinal degeneration was associated with decreased levels of crystallin expression. Injection of CoCl 2 at either intermediate or high dose in αA-crystallin (−/−) and αB-crystallin (−/−) mice resulted in much more severe retinal degeneration compared to wild type eyes. A decrease in ARPE-19 total and cytosolic αB-crystallin expression with increasing CoCl2 treatment and an increase in mitochondrial αB-crystallin were found. We conclude that lack of α-crystallins accentuates retinal degeneration in chemically-induced hypoxia in vivo.

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Synaptic Pathology, Altered Gene Expression, and Degeneration in Photoreceptors Impacted by Drusen

Cited by 107 publications

References 40 publications

Age‐related macular degeneration—emerging pathogenetic and therapeutic concepts

Age‐related macular degeneration—emerging pathogenetic and therapeutic concepts

Autophagy and ER-stress contribute to photoreceptor degeneration in cultured adult porcine retina

Exacerbation of retinal degeneration in the absence of alpha crystallins in an in vivo model of chemically induced hypoxia

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