The proposed research program endeavors to advance our understanding of the mechanisms by which the lipofuscin that accumulates in retinal pigment epithelial cells (RPE) contributes to disease processes in atrophic macular degeneration, including age-related and juvenile (Stargardt disease and Best vitelliform macular dystrophy) forms. The lipofuscin of RPE cells originates primarily in photoreceptor cells and is generated, in large part, from reactions of all-trans-retinal, which forms when visual pigment absorbs photons of light. To achieve our objectives, we will conduct experiments using cell culture, in vitro assays and mouse models. In light of genetic discoveries linking age-related macular degeneration (AMD) to inflammatory processes, we will investigate photooxidation products of bisretinoid RPE lipofuscin pigments as activators of complement, an element of immune pathways (Aim 1). These studies address four factors posited as being associated with AMD: inflammation, oxidative damage, drusen and RPE lipofuscin. We will also compare known lipofuscin constituents in terms of their propensity for photo-generating reactive forms of oxygen and for photo-induced cleavage (Aim 2). In studies related to Best vitelliform macular dystrophy and other VMD2-associated disorders, we will explore the hypothesis that dysfunctioning of bestrophin-1, the protein product of VMD2, alters intracellular chloride conductances thereby changing pH-dependent rates of photooxidation and equilibria between protonated/conjugated and unprotonated/unconjugated forms of the all-trans-retinal dimer series of RPE lipofuscin pigments. We propose that the shift in equilibrium favors an RPE lipofuscin constituent (unconjugated all-trans-retinal dimer) that is aldehyde-bearing and more photoreactive (Aim 3).
The National Eye Institute has as a 5-year program goal, improved understanding of the molecular and biochemical basis of macular degeneration. AMD affects more than 1.75 million people in the United States. Based on a prevalence of 1/10,000, an additional 30,000 Americans are afflicted with Stargardt disease. Due to the trend toward population aging, the number of cases of AMD could increase to 3 million by 2020. Greater insight into the identities and properties of individual RPE lipofuscin pigments, their adverse behaviors and the factors that influence their formation will facilitate the emergence of novel therapeutic approaches to minimize lipofuscin accumulation and/or neutralize its impact, and thus reduce the incidence and progression of macular degeneration.
|Wu, Li; Ueda, Keiko; Nagasaki, Taka et al. (2014) Light damage in Abca4 and Rpe65rd12 mice. Invest Ophthalmol Vis Sci 55:1910-8|
|Sparrow, Janet R; Blonska, Anna; Flynn, Erin et al. (2013) Quantitative fundus autofluorescence in mice: correlation with HPLC quantitation of RPE lipofuscin and measurement of retina outer nuclear layer thickness. Invest Ophthalmol Vis Sci 54:2812-20|
|Joshi, Dharati; Field, James; Murphy, John et al. (2013) Synthesis of antioxidants for prevention of age-related macular degeneration. J Nat Prod 76:450-4|
|Dobri, Nicoleta; Qin, Qiong; Kong, Jian et al. (2013) A1120, a nonretinoid RBP4 antagonist, inhibits formation of cytotoxic bisretinoids in the animal model of enhanced retinal lipofuscinogenesis. Invest Ophthalmol Vis Sci 54:85-95|
|Sparrow, Janet R; Gregory-Roberts, Emily; Yamamoto, Kazunori et al. (2012) The bisretinoids of retinal pigment epithelium. Prog Retin Eye Res 31:121-35|
|Hunter, Jennifer J; Morgan, Jessica I W; Merigan, William H et al. (2012) The susceptibility of the retina to photochemical damage from visible light. Prog Retin Eye Res 31:28-42|
|Sparrow, Janet R; Yamamoto, Kazunori (2012) The bisretinoids of RPE lipofuscin: a complex mixture. Adv Exp Med Biol 723:761-7|
|Yoon, Kee Dong; Yamamoto, Kazunori; Zhou, Jilin et al. (2011) Photo-products of retinal pigment epithelial bisretinoids react with cellular thiols. Mol Vis 17:1839-49|
|Wu, Yalin; Zhou, Jilin; Fishkin, Nathan et al. (2011) Enzymatic degradation of A2E, a retinal pigment epithelial lipofuscin bisretinoid. J Am Chem Soc 133:849-57|
|Zhou, Jilin; Sparrow, Janet R (2011) Light filtering in a retinal pigment epithelial cell culture model. Optom Vis Sci 88:759-65|
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