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UBC Theses and Dissertations

Exploring the role of P2X receptors in age-related macular degeneration Youn, Sena


Purinergic signaling via ATP-activated P2X receptors has been studied in age-related macular degeneration (AMD), where retinal pigment epithelium (RPE) cells release ATP and contribute to inflammation and apoptosis. This study focuses on the less-explored P2X4 receptor alongside the well-studied P2X7 receptor in cultured RPE cells, human post-mortem eyes, and mouse eyes to investigate their potential roles in AMD. Immunocytochemistry indicated expression of P2X4 and P2X7 receptors in cultured ARPE-19 cells (cell surface and intracellular), particularly when permeabilized with Triton X-100. Immunohistochemistry on human post-mortem eyes showed that the P2X4 receptor subtype was the most immunoreactive in the RPE of eyes with soft drusen among the five donor groups. In contrast, the P2X7 receptor subtype was the least immunoreactive in the RPE of eyes with soft drusen among the five donor groups. In support of this, RT-qPCR revealed the presence of P2X4 and P2X7 mRNA in ARPE-19 cells, with P2X4 mRNA showing greater upregulation than P2X7 mRNA. Double immunolabeling using Fab fragments in human post-mortem eyes demonstrated co-localization of P2X4 and P2X7 receptors, particularly within and around choroidal cell nuclei. Spectral unmixing for RPE autofluorescence demonstrated co-localization of P2X4 and P2X7 receptors in the RPE of human post-mortem eyes, particularly within and around RPE cell nuclei. Immunohistochemistry on mouse eyes showed P2X4 and P2X7 immunolabeling in the RPE, choroid, and neuroretina. These findings suggest that P2X4 and P2X7 receptors are co-localized in human and mouse retina, but their expression profiles vary with age, donor group/mouse strain, and retinal degeneration. P2X4 receptors potentially play a role in RPE cells, warranting further investigation into their function and interaction with P2X7 receptors in AMD.

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