Retinal degeneration is a major cause of blindness in the USA and often results from a combination of environmental and genetic influences. While progress has been made in identifying some of the pathological factors, a better understanding of how defects lead to disease will result in better treatment. This proposal is based upon the hypothesis that the alkalization of lysosomes in RPE cells contributes to retinal degeneration. Lysosomal alkalinization is known to impede degradation and increase the accumulation of waste material. However, new findings suggest additional ways that alkalinized lysosomes can contribute to retinal degenerations, and these will be confirmed and extended. For example, oxidized lipids are known to escalate degeneration, and new data showing that lysosomal alkalinization leads to increase lipid oxidation in vitro and in vivo will be probed. Microglia and macrophages are also implicated in the disease process, and experiments will probe how lysosomal alkalinization leads to the release of cytokines and ATP, chemoattractants that can recruit the monocytes to RPE cells. This proposal will also update a model of chloroquine retinopathy and demonstrate that lysosomal alkalinization is sufficient to activate molecular and protein markers of retinal degeneration. The chloroquine approach will be applied to genetic models of retinal degenerations to test if lysosomal alkalinization acts synergistically with genetic defects to speed the onset and increase severity of the pathologies. Finally, acidic nanoparticles will be used to reacidify compromised RPE lysosomes in vivo and prevent the loss of photoreceptors in a model of retinal degeneration. In summary, this proposal will examine the mechanisms linking lysosomal alkalinization to disease, demonstrate that lysosomal alkalinization combines with genetic defects to increase pathology, and show that reacidifying lysosomes with acid nanoparticles can prevent the loss of photoreceptors.

Public Health Relevance

Retinal degenerations are major causes of blindness in the USA. This project will investigate how defective lysosomes in RPE cells can lead to damage in these diseases and test the ability of a new treatment to prevent this loss of sight.

National Institute of Health (NIH)
Research Project (R01)
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Neuhold, Lisa
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University of Pennsylvania
Anatomy/Cell Biology
Schools of Dentistry/Oral Hygn
United States
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Sanderson, Julie; Dartt, Darlene A; Trinkaus-Randall, Vickery et al. (2014) Purines in the eye: recent evidence for the physiological and pathological role of purines in the RPE, retinal neurons, astrocytes, Müller cells, lens, trabecular meshwork, cornea and lacrimal gland. Exp Eye Res 127:270-9
Coffey, E E; Beckel, J M; Laties, A M et al. (2014) Lysosomal alkalization and dysfunction in human fibroblasts with the Alzheimer's disease-linked presenilin 1 A246E mutation can be reversed with cAMP. Neuroscience 263:111-24
Beckel, Jonathan M; Argall, Arthur J; Lim, Jason C et al. (2014) Mechanosensitive release of adenosine 5'-triphosphate through pannexin channels and mechanosensitive upregulation of pannexin channels in optic nerve head astrocytes: a mechanism for purinergic involvement in chronic strain. Glia 62:1486-501
Guha, Sonia; Liu, Ji; Baltazar, Gabe et al. (2014) Rescue of compromised lysosomes enhances degradation of photoreceptor outer segments and reduces lipofuscin-like autofluorescence in retinal pigmented epithelial cells. Adv Exp Med Biol 801:105-11
Guha, Sonia; Coffey, Erin E; Lu, Wennan et al. (2014) Approaches for detecting lysosomal alkalinization and impaired degradation in fresh and cultured RPE cells: evidence for a role in retinal degenerations. Exp Eye Res 126:68-76
Krizaj, David; Ryskamp, Daniel A; Tian, Ning et al. (2014) From mechanosensitivity to inflammatory responses: new players in the pathology of glaucoma. Curr Eye Res 39:105-19
Guha, Sonia; Baltazar, Gabriel C; Coffey, Erin E et al. (2013) Lysosomal alkalinization, lipid oxidation, and reduced phagosome clearance triggered by activation of the P2X7 receptor. FASEB J 27:4500-9
Xia, Jingsheng; Lim, Jason C; Lu, Wennan et al. (2012) Neurons respond directly to mechanical deformation with pannexin-mediated ATP release and autostimulation of P2X7 receptors. J Physiol 590:2285-304
Zhang, Mei; Hu, Huiling; Zhang, Xiulan et al. (2010) The A3 adenosine receptor attenuates the calcium rise triggered by NMDA receptors in retinal ganglion cells. Neurochem Int 56:35-41
Hu, Huiling; Lu, Wennan; Zhang, Mei et al. (2010) Stimulation of the P2X7 receptor kills rat retinal ganglion cells in vivo. Exp Eye Res 91:425-32

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