Autophagy in Age-Related Macular Degeneration: A Regulatory Mechanism of Oxidative Stress

Figure 1

The role of oxidative stress in AMD. Light injury, growing age, and oxidants from cigarette smoke (such as HQ) are the risk factors for AMD. Overactive energy metabolism and excessive signal transduction in RPE and photoreceptor cells produce many ROS. Daily phagocytosis of POSs in RPE cells is also an important source of ROS. RPE cells lose the ability of phagocytizing POSs with increasing age, leading to the accumulation of lipid substances, such as lysosomal deposits (also known as lipofuscin). Taken together, ROS are elevated upon exposure to risk factors, and thus, cellular oxidative stress is triggered, causing injuries to proteins, lipids, and DNA and finally the death of RPE and photoreceptor cells. AMD: age-related macular degeneration; HQ: hydroquinone; RPE: retinal pigment epithelial; POSs: photoreceptor outer segments; ROS: reactive oxygen species.