An insufficient supply of visual chromophore due to dysfunction of key proteins involved in its regeneration has devastating effects on rod-mediated vision, and comprises a leading cause of irreversible blindness in humans. Early signs of such blinding diseases are delayed rod cell-mediated dark adaptation and difficulty with night vision. The decline in recovery of visual sensitivity is likely caused by inadequate Rho regeneration with accumulation of chromophore-free opsin that constitutively activates the signaling cascade and accelerates retinal degeneration. Although such free opsin activity can be reduced by exogenous retinal chromophore, this fails to prevent the buildup of toxic retinoid photo-products when their clearance is defective. Thus, an alternative therapeutic approach is urgently needed for combating vision loss under such conditions. Here we propose to investigate the effects of new visual pigments, retinyl-opsins regenerated with novel chromophore analogs, retinyl chlorides on retina physiology in context of potential therapeutic strategy to protect retinal healh in retinal degenerative diseases associated with compromised Rho regeneration. First, we will study the biochemical and functional properties of different retinyl chloride isomers in vitro (Aim 1), and then test the effects of selected retinyl chlorides in both Abca4-/-Rdh8-/- mice, a model of early onset human Stargardt disease and in Lrat-/- mice, a model of Leber congenital amaurosis (LCA) (Aim 2). Finally, we will assess the capability of the RBP4 carrier to increase the ocular delivery of these compounds, and thereby alleviate progressive retinal degeneration in these mouse models (Aim 3).

Public Health Relevance

Attenuated dark adaptation after exposure to intense light is caused by incomplete desensitization of rod photoreceptors. Manifested in various retinal degenerative conditions, this phenomenon results from inadequate rhodopsin (Rho) regeneration and accumulation of constitutively active opsin. Non-hydrolysable analogs of retinal chromophore could be used to inhibit such opsin activity. A non-reversible covalent attachment of retinal would prevent chromophore release upon light illumination eliminating buildups of toxic byproducts of retinoid photoisomerization. Proposed herein comprehensive biochemical and animal studies of these new chromophore analogs will evaluate their potential as new class of therapeutics for degenerative retinopathies.

National Institute of Health (NIH)
National Eye Institute (NEI)
Research Project (R01)
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Biology of the Visual System Study Section (BVS)
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Shen, Grace L
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Case Western Reserve University
Schools of Medicine
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Gao, Songqi; Parmar, Tanu; Palczewska, Grazyna et al. (2018) Protective Effect of a Locked Retinal Chromophore Analog against Light-Induced Retinal Degeneration. Mol Pharmacol 94:1132-1144
Chen, Yuanyuan; Chen, Yu; Jastrzebska, Beata et al. (2018) A novel small molecule chaperone of rod opsin and its potential therapy for retinal degeneration. Nat Commun 9:1976
Mallory, D Paul; Gutierrez, Elizabeth; Pinkevitch, Margaret et al. (2018) The Retinitis Pigmentosa-Linked Mutations in Transmembrane Helix 5 of Rhodopsin Disrupt Cellular Trafficking Regardless of Oligomerization State. Biochemistry 57:5188-5201
Gulati, Sahil; Jastrzebska, Beata; Banerjee, Surajit et al. (2017) Photocyclic behavior of rhodopsin induced by an atypical isomerization mechanism. Proc Natl Acad Sci U S A 114:E2608-E2615
Alexander, Nathan S; Katayama, Kota; Sun, Wenyu et al. (2017) Complex binding pathways determine the regeneration of mammalian green cone opsin with a locked retinal analogue. J Biol Chem 292:10983-10997
Jastrzebska, Beata; Comar, William D; Kaliszewski, Megan J et al. (2017) A G Protein-Coupled Receptor Dimerization Interface in Human Cone Opsins. Biochemistry 56:61-72