Sultan, Fatima and Parkin, Edward (2022) The Amyloid Precursor Protein Plays Differential Roles in the UVA Resistance and Proliferation of Human Retinal Pigment Epithelial Cells. Protein and Peptide Letters. ISSN 0929-8665
Sultan_and_Parkin_2022.pdf - Accepted Version
Restricted to Repository staff only until 17 February 2023.
Available under License Creative Commons Attribution-NonCommercial.
Download (1MB)
Abstract
Background: Age-related macular degeneration (AMD) can be characterised by degeneration of retinal pigment epithelial (RPE) cells and the accumulation, in retinal drusen deposits, of amyloid beta-peptides proteolytically derived, by secretases, from the amyloid precursor protein (APP). Ultraviolet (UV) light exposure is a risk factor for the development of AMD. Objectives: In the current study, we investigated whether APP and/or its proteolysis are linked to the UVA resistance or proliferation of ARPE-19 human RPE cells. Methods: Cell viability was determined, following UVA exposure, with prior small interfering RNA-mediated APP depletion or secretase inhibitor treatments. APP levels/proteolysis were analysed by immunoblotting. Cells were also grown in the presence/absence of secretase inhibitors to assess their effects on longer-term culture growth. Finally, the effects of APP proteolytic fragments on ARPE-19 cell proliferation were monitored following co-culture with human embryonic kidney cells stably over-expressing these fragments. Results: Endogenous APP was depleted following UVA irradiation and β-secretase, but not -secretase, processing of the protein was reduced. Experimental APP depletion or -secretase (but not - or β-secretase) inhibition ablated the detrimental effect of UVA on cell viability. In contrast, -secretase, and possibly -secretase but not β-secretase activity, appeared to promote the longer-term proliferation of ARPE-19 cells in the absence of UVA irradiation Conclusions: There are clear but differential links between APP expression/proteolysis and the proliferation and UVA resistance of ARPE-19 cells indicating that the protein should be investigated further in relation to the identification of possible drug targets for the treatment of AMD.