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Jiying Wang, Kyoko Ohno-Matsui, Ikuo Morita; Amyloid β enhances expression and activity of HTRA1 in retinal pigment epithelial cells, a mechanism of wet age-related macular degeneration development from drusen. Invest. Ophthalmol. Vis. Sci. 2013;54(15):335.
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Single nucleotide polymorphism of high-temperature requirement factor A1 (HTRA1) has been shown strongly associated with increased risk for developing wet age-related macular degeneration (AMD). We have proved previously that amyloid β (Aβ) is a key component of drusen to trigger AMD. In this study, we investigated the effect of Aβ on expression and activity of HTRA1 in retinal pigment epithelial (RPE) cells.
Primarily cultured human RPE cells were stimulated with 25 μM and 50 μM Aβ for 24 hours. HTRA1 mRNA expression and protein production in the supernatant were analyzed by real-time PCR and western blot. The binding between Aβ and HTRA1 was determined by co-immunoprecipitation. Activity of HTRA1 preincubated with/without 50 μM Aβ for 1 hour was measured by activity assay using β-casein substrate.
Aβ treatment induced a significant dose-dependent increase of HTRA1 mRNA expression and protein production in the supernatant of cultured human RPE cells. Aβ could efficiently bind to HTRA1 in vitro in co-immunoprecipiation analysis. In activity assay, HTRA1 preincubated with Aβ could more intensely degrade β-casein compared to HTRA1 preincubated without Aβ.
These results suggest the mechanism that Aβ accumulated in drusen causes over-expression and enhanced activity of HTRA1 in subretinal space. This phenomenon might be an important process for the development of wet AMD.
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