Retinal pigment epithelial (RPE) cells of the eye amass bisretinoid fluorophores with age. This group of pigments, including the founding member A2E, forms in photoreceptor cells due to inadvertent reactions of retinaldehyde. They are deposited in RPE within phagocytosed outer segment membrane and they accumulate as lipofuscin. The damaging effects of these compounds on RPE cells are implicated in a number of age-associated and early-onset forms of macular disease including recessive Stargardt disease, ELOVL4-related disease, best macular dystrophy and age-related macular degeneration. The broad objectives of the studies proposed in this application are to understand mechanisms by which bisretinoids of retina contribute to disease processes that threaten vision. We will address both the bisretinoid pigments constituting RPE lipofuscin and the bisretinoid precursors of these compounds in photoreceptor cells. This work will elucidate therapeutic avenues. Additionally since bisretinoids are the major source of fundus autofluorescence, these studies will contribute to clinical interpretations of fundus autofluorescence images.
In Specific Aim 1, we will investigate our preliminary observation that photo-cleavage of bisretinoid releases the small dicarbonyls (methylglyoxal and glyoxal) that are responsible for advanced glycation end-product (AGE) - modifications of proteins. Proteins in Bruch's membrane and drusen are prone to AGE-modification. Aging changes in Bruch's membrane are also considered to contribute to onset of age-related macular degeneration. We propose that, unlike the case in diabetes, AGE-adducts in Bruch's membrane form as a consequence of dicarbonyl release from overlying RPE.
In Specific Aim 2, we will probe for evidence of photooxidation-associated photodegradation of RPE bisretinoid in vivo.
In Specific Aim 3 we will explore the bisretinoid fluorophores located in photoreceptor cell outer segments that are precursors of RPE lipofuscin. We will probe the propensity for increased formation of bisretinoid in impaired photoreceptor cells;we will test the ability of photoreceptor bisretinoids to mediate oxidation of lipid in photoreceptor cells and photo-damage;and we will demonstrate conditions under which photoreceptor bisretinoids can contribute to hyperautofluorescence in fundus autofluorescence images.
These aims will be achieved by the use of animal and in vitro models and by employing biochemical and histological approaches. Completion of this research will advance our comprehension of drusen formation and will elucidate links between RPE lipofuscin and the aging changes in Bruch's membrane that can be a prelude to AMD. These studies will contribute to an understanding of how light and oxidative mechanisms are factors in photoreceptor cell death in monogenic retinal disorders.

Public Health Relevance

Retinal degeneration remains a major cause of legal blindness. Despite advances in the genetics of retinal degeneration, associated pathogenic processes largely defy elucidation. The work proposed in the application will address disease mechanisms that may be influential in early onset and age-related macular degeneration and in some forms of retinitis pigmentosa;therapeutic avenues are addressed.

National Institute of Health (NIH)
National Eye Institute (NEI)
Research Project (R01)
Project #
Application #
Study Section
Special Emphasis Panel (BVS)
Program Officer
Shen, Grace L
Project Start
Project End
Budget Start
Budget End
Support Year
Fiscal Year
Total Cost
Indirect Cost
Columbia University (N.Y.)
Schools of Medicine
New York
United States
Zip Code
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

Showing the most recent 10 out of 72 publications