Aging of post-mitotic cells is associated with the accumulation of lipofuscin, which
can lead to deleterious changes in the body and increased susceptibility to certain
diseases. This study focused on measuring lipofuscin in the aging retina and determining whether the absence of immunoproteasome affected this age-related
process. We hypothesize that lipofuscin increased with aging and the absence of
immunoproteasomes. To test our hypothesis, RPE cells from mice of different ages,
including wild type and immunoproteasome knockout strains, were used. The cells
were processed for lipid extracts containing lipofuscin. The lipid extracts were then
used to measure lipofuscin content using fluorescence spectroscopy. Here we developed an optimal method for measuring lipofuscin, including homogenization with PBS buffer, and extraction under dark condition. It was found that fluorescence intensity increases with age in knockout mice, but decreases with age in wild type mice. The intensity was also observed to be higher in knockout compared with wild type. Intensity-average-emission-maximum (IAEM) values were found to vary within different age groups. Our method of quantifying lipofuscin could detect differences in content between retinas from mice of different ages and between strains. The higher content of lipofuscin in KO mice supports our hypothesis. Varied IAEM suggests different fluorescent species developed with aging. This study is important
as it might contribute to the aspect of aging theory and, thus, provide insight to
studies associated with degenerative diseases, such as age macular degeneration
This research was supported by the Undergraduate Research Opportunities Program (UROP).
Developing a Quantitative Method for Determining Lipofuscin Content in Mouse Retinal Pigment Epithelium: An Age Comparison of Wild Type and Immunoproteasome Knockout Mice.
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