Rod metabolic demand drives progression in retinopathies

Lin, Michael K.; Kim, Soo Hyun; Zhang, Lijuan; Tsai, Yi‐Ting; Tsang, Stephen H.

doi:10.1016/j.tjo.2015.06.002

Cited by 15 publications

(12 citation statements)

References 56 publications

(75 reference statements)

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“…In our report, we propose a similar strategy that improves both survival and function of degenerating rods and cones. We hypothesized that Pde6-associated RP provokes a metabolic aberration in the rod cells that forces them to succumb to the consequences of elevated cGMP and Ca 2+ via cyclic nucleotide-gated (CNG) channels and Na + /Ca 2+ -K + exchangers (36)(37)(38)(39). The histone deacetylase sirtuin 6 (SIRT6) is a transcriptional repressor of glycolytic enzymes that has been extensively studied in the context of metabolism and cancer biology (40).…”

Section: Resultsmentioning

confidence: 99%

Reprogramming metabolism by targeting sirtuin 6 attenuates retinal degeneration

Zhang¹,

Du²,

Justus³

et al. 2016

Journal of Clinical Investigation

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Retinitis pigmentosa (RP) encompasses a diverse group of Mendelian disorders leading to progressive degeneration of rods and then cones. For reasons that remain unclear, diseased RP photoreceptors begin to deteriorate, eventually leading to cell death and, consequently, loss of vision. Here, we have hypothesized that RP associated with mutations in phosphodiesterase-6 (PDE6) provokes a metabolic aberration in rod cells that promotes the pathological consequences of elevated cGMP and Ca 2+, which are induced by the Pde6 mutation. Inhibition of sirtuin 6 (SIRT6), a histone deacetylase repressor of glycolytic flux, reprogrammed rods into perpetual glycolysis, thereby driving the accumulation of biosynthetic intermediates, improving outer segment (OS) length, enhancing photoreceptor survival, and preserving vision. In mouse retinae lacking Sirt6, effectors of glycolytic flux were dramatically increased, leading to upregulation of key intermediates in glycolysis, TCA cycle, and glutaminolysis. Both transgenic and AAV2/8 gene therapy-mediated ablation of Sirt6 in rods provided electrophysiological and anatomic rescue of both rod and cone photoreceptors in a preclinical model of RP. Due to the extensive network of downstream effectors of Sirt6, this study motivates further research into the role that these pathways play in retinal degeneration. Because reprogramming metabolism by enhancing glycolysis is not gene specific, this strategy may be applicable to a wide range of neurodegenerative disorders.Reprogramming metabolism by targeting sirtuin 6 attenuates retinal degeneration , were challenging to interpret because of negative effects on synaptic transmission (45). We therefore altered our approach to limit ablation of Sirt6 to rod photoreceptors with an inducible gene disruption strategy. Using this model, we tested whether upregulation of glycolytic flux through Sirt6 knockout can preserve both rod and cone photoreceptors in a preclinical, Pde6-associated RP model. The Journal of Clinical Investigation R E S E A R C H A R T I C L E ResultsGeneration of experimental and control groups. The third most common cause of autosomal recessive RP is deficiency in the PDE6 enzyme, which controls the depolarization state of rods by regulating cGMP levels (9, 46-48). An established preclinical model for RP involves a homozygous point mutation (H620Q) in the gene months by increasing glucose uptake and utilization for NADPH production in 4 different mouse models of RP (11,12). In our report, we propose a similar strategy that improves both survival and function of degenerating rods and cones. We hypothesized that Pde6-associated RP provokes a metabolic aberration in the rod cells that forces them to succumb to the consequences of elevated cGMP and Ca 2+ via cyclic nucleotide-gated (CNG) channels and Na + /Ca 2+ -K + exchangers (36-39). The histone deacetylase sirtuin 6 (SIRT6) is a transcriptional repressor of glycolytic enzymes that has been extensively studied in the context of metabolism and cancer biology (40). Normally, S...

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Section: Resultsmentioning

confidence: 99%

Reprogramming metabolism by targeting sirtuin 6 attenuates retinal degeneration

Zhang¹,

Du²,

Justus³

et al. 2016

Journal of Clinical Investigation

Self Cite

111

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“…( Figure 4) due to subretinal fluid will cause cones to degenerate soon after, [16][17][18] which results in blindness and cannot be treated with gene supplementation therapy. Thus, unless rod transplantation is applied, the ideal time for intervention is as soon as possible after diagnosis or at least before fluid-induced rod cell death.…”

Section: A Retinal Pigmented Epithelial (Rpe) Disorder Bestrophinopamentioning

confidence: 99%

BEST1: the Best Target for Gene and Cell Therapies

Yang

Justus²,

et al. 2015

Molecular Therapy

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A retinal pigmented epithelial (RPE) disorder, bestrophinopathy has recently been proven to be amenable to gene and cell-based therapies in preclinical models. RPE disorders and allied retinal degenerations exhibit significant genetic heterogeneity, and diverse mutations can result in similar disease phenotypes. Several RPE disorders have recently become targets for gene therapies in humans. The year 2011 brought a new advance in cell-based therapies, with the Food and Drug Administration approving clinical trials using embryonic stem cells for an RPE disorder known as age-related macular degeneration. Recent studies on induced pluripotent stem (iPS)-RPE generation indicate strong potential for developing patient-specific disease models in vitro, which could eventually enable personalized treatment. This mini-review will briefly highlight the suitability of the retina for gene and cell therapies, the pathophysiology of bestrophinopathy, and the research and treatment opportunities afforded by stem cell and genetic therapies.

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“…9) in rod photoreceptors, which in turn promotes lipid biosynthesis through parasympathetic mechanisms [15]. Excessive Warburg glycolysis in photoreceptor leads to an increase in retinal pigment epithelium stress and thickening of Bruch’s membrane [16]. Hypoxia-induced metabolic stress in retinal pigment epithelium cells is sufficient to induce photoreceptor degeneration [17].…”

Section: Discussionmentioning

confidence: 99%

Treatment of Macular Degeneration with Sildenafil: Results of a Two-Year Trial

et al. 2018

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Objective: To evaluate PDE5/6 inhibition with sildenafil to reduce choroidal ischemia and treat age-related macular degeneration. Methods: Sildenafil was prescribed to treat participants with macular degenerations or macular dystrophies measured by spectral-domain optical coherence tomography, color fundus photography, enhanced depth imaging, and best-corrected visual acuity. Results: No change in calcified drusen was noted. Vitelliform-type soft drusen were not substantially changed. A participant with Best vitelliform macular dystrophy had a significant improvement in vision as well as in photoreceptor and ellipsoid layers. Conclusions: Our research supports sildenafil as a safe treatment for age-related and vitelliform macular degenerations. Thickened Bruch’s membrane reduces the beneficial effect of perfusion increase, but all eyes appear to benefit from PDE6. Notably, maintenance or improvement in the photoreceptor layer may be the most significant result of sildenafil and is consistent with PDE6 inhibition. Thus, sildenafil treatment of macular degeneration offers significant potential for vision retention and recovery.

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Rod metabolic demand drives progression in retinopathies

Cited by 15 publications

References 56 publications

Reprogramming metabolism by targeting sirtuin 6 attenuates retinal degeneration

Reprogramming metabolism by targeting sirtuin 6 attenuates retinal degeneration

BEST1: the Best Target for Gene and Cell Therapies

Treatment of Macular Degeneration with Sildenafil: Results of a Two-Year Trial

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