Abstract
Abstract: :
Purpose: To evaluate the protein expression levels and immunolabeling patterns of HAP-1 in macular and periphery samples from human retinas. HAP-1 is the human homolog of a novel photoreceptor protein that was initially described in Xenopus laevis retinas. Methods: Fresh and fixed human donor eyes were obtained from the Midsouth Eye Bank and Lions Eye Bank of Oregon. The anterior segment of the eyeballs were surgically removed with the aid of a dissecting microscope. Six millimeter retinal punches were collected from the macular and peripheral regions of each donor eye. The immunolabeling patterns of HAP-1 were evaluated by standard immunohistochemical techniques, and the HAP-1 protein levels were analyzed using 1-D SDS-PAGE followed by Western blotting using the XAP-1 antibody. Blots were captured using a Kodak DC290 camera equipped with a Cybr green filter and data were quantified using Kodak1D software. Results: We have previously demonstrated that the XAP-1 antigen is a novel protein expressed uniquely by healthy photoreceptor cells. The XAP-1 antibody, although generated against Xenopus photoreceptors, recognizes the human homolog, HAP-1 in both the immunohistochemical and Western blot techniques. In the human retina, HAP-1 is localized to the area surrounding the photoreceptor outer segment and the distal inner segment, similar to what we described in Xenopus retinas. Western blot analyses demonstrate that HAP-1 bands can be detected in both the peripheral and macular regions of retina, although a gradient in relative expression was evident with the nasal retina having consistently low expression levels. Conclusion: The localization of HAP-1 suggests it may provide structural support for the formation of outer segment membranes and the normal function of photoreceptor. The gradient in expression levels across the retina also suggests that HAP-1 may play a critical role in specific retinal regions.
Keywords: 517 photoreceptors • 434 immunohistochemistry • 554 retina