Retinal Disease Research, Department of Biological Sciences, Allergan, Inc., RD3-2D, 2525 Dupont Drive, Irvine, CA 92612-1599, USA.
Exp Eye Res. 2012 Jan;94(1):63-70. doi: 10.1016/j.exer.2011.11.007. Epub 2011 Nov 25.
Efficient phagocytosis of photoreceptor outer segments (POS) by retinal pigment epithelial cells (RPE) plays a key role in biological renewal of these highly peroxidizable structures and in maintenance of retina health. Here, we used an in vitro RPE cell phagocytosis assay to investigate how sub-lethal oxidative stress modifies the key components of the cell phagocytic machinery leading to severe impairment of phagocytosis. Sub-lethal oxidative treatment, induced by hydrogen peroxide (H(2)O(2)), significantly inhibited binding and uptake of POS by RPE cells. However, sub-lethal oxidative stress did not affect cell surface expression of αvβ5 or RPE cell adhesion to αvβ5. Similarly, the enzymatic activity of mature cathepsin D was not altered upon challenge by oxidative stress. In contrast, studies of signaling molecules in the RPE cell phagocytic machinery revealed that sub-lethal oxidative stress inhibits POS-induced activation of FAK and MerTK. Our data demonstrate that sub-lethal oxidative treatment with H(2)O(2) inhibits phagocytic activity of ARPE-19 cells, in part by inhibiting FAK and MerTK.
高效的光感受器外节（POS）被视网膜色素上皮细胞（RPE）吞噬，在这些高度过氧化物结构的生物更新和维持视网膜健康方面起着关键作用。在这里，我们使用体外 RPE 细胞吞噬试验来研究亚致死氧化应激如何改变细胞吞噬机制的关键成分，导致吞噬作用严重受损。由过氧化氢（H2O2）诱导的亚致死氧化处理显著抑制了 RPE 细胞对 POS 的结合和摄取。然而，亚致死氧化应激并不影响 αvβ5 的细胞表面表达或 RPE 细胞与 αvβ5 的粘附。同样，在氧化应激的挑战下，成熟组织蛋白酶 D 的酶活性也没有改变。相比之下，对 RPE 细胞吞噬机制中的信号分子的研究表明，亚致死氧化应激抑制 POS 诱导的 FAK 和 MerTK 的激活。我们的数据表明，用 H2O2 进行亚致死氧化处理抑制了 ARPE-19 细胞的吞噬活性，部分原因是抑制了 FAK 和 MerTK。
