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Biochemical Investigations of Macular Degeneration: The Significance of Protein Oxidation including Novel Methods for Its Study Biochemical Investigations of Macular Degeneration: The Significance of Protein Oxidation including Novel Methods for Its Study

by Warburton, Sarah 1981-

Abstract (Summary)
The retinal pigment epithelium (RPE) is a monolayer of cells located directly behind the photoreceptor cells in the retina. These cells are involved in a variety of functions that support the visual process in the eye, namely 1) they form a blood-retina barrier which separates the neural retina from the choroid’s blood supply, 2) the apical processes of RPE cells diurnally phagocytose the outer segments of photoreceptor cells, and 3) they participate in the renewal of the photopigment 11-cis retinal.

Age-related macular degneration (AMD) is the leading cause of blindness in people over the age of 50 years in North America and other developed countries. AMD involves the death of retinal pigment epithelial (RPE) cells in the macula early in the progress of the disease. Like some other postmitotic cells, the RPE accumulates autofluorescent lysosomal storage bodies (lipofuscin) during senescence. Lipofuscin is reported to begin accumulating in the human RPE around age 20 and continues to accumulate throughout an individual’s life. This progressive accumulation of lipofuscin can eventually occupy a substantial fraction of the RPE cytoplasmic volume and may lead to impairment of normal RPE functions, resulting in retinal degeneration and loss of visual function as in AMD. Another autofluorescent granule that accumulates in RPE cells and may contribute to the etiology of AMD is a complex granule exhibiting properties of both melanosomes and lipofuscin granules called melanolipofuscin (MLF). In contrast with the accumulation of LF in the RPE, MLF accumulation has been reported by Feeney-Burns to more closely reflect the onset of AMD.

Although there have been significant advances in our understanding of AMD, knowledge of the mechanisms responsible for its progression remain unclear. This dissertation details experiments that were designed to better understand the factors that may play a causal role in AMD as well as the development of methods to assist in AMD research. Specifically, the protein composition of retinal LF was assessed to elucidate its origin. These findings are reported in chapter 2. The accumulation, composition and phototoxicity of MLF were analyzed to assess MLF’s origin and possible contribution to AMD. These results are reported in chapter 3. Because protein oxidation is possibly a common posttranslational modification to proteins which accumulate in lipofuscin and melanolipofuscin granules, a method for the detection and analysis of oxidized proteins was developed and is reported in chapter 4. Chapter 5 details the proteomic differences between ARPE-19 cells - the only human RPE cell line available for research - in their differentiated and undifferentiated states and compares these to the proteome of human RPE cells. These results are also compared to the phenotypic difference of these cells as observed by transmission electron microscopy.

Bibliographical Information:

Advisor:

School:Brigham Young University

School Location:USA - Utah

Source Type:Master's Thesis

Keywords:age related macular degeneration amd retinal pigment epithelium rpe proteomics oxidation lipofuscin melanolipofuscin mass spectrometry protein biochemistry

ISBN:

Date of Publication:09/05/2006

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