Angiogenesis Laboratory, Retina Service, Department of Ophthalmology, Massachusetts Eye and Ear Infirmary, Harvard Medical School, Boston, MA, USA; Department of Ophthalmology, Kaohsiung Chang Gung Memorial Hospital, Kaohsiung, Taiwan.
Angiogenesis Laboratory, Retina Service, Department of Ophthalmology, Massachusetts Eye and Ear Infirmary, Harvard Medical School, Boston, MA, USA.
Biochem Biophys Res Commun. 2020 Jan 8;521(2):414-419. doi: 10.1016/j.bbrc.2019.10.138. Epub 2019 Oct 28.
Lysosome-associated membrane protein-2 (LAMP2), is a highly glycosylated lysosomal membrane protein involved in chaperone mediated autophagy. Mutations of LAMP2 cause the classic triad of myopathy, cardiomyopathy and encephalopathy of Danon disease (DD). Additionally, retinopathy has also been observed in young DD patients, leading to vision loss. Emerging evidence show LAMP2-deficiency to be involved in oxidative stress (ROS) but the mechanism remains obscure. In the present study, we found that tert-butyl hydroperoxide or antimycin A induced more cell death in LAMP2 knockdown (LAMP2-KD) than in control ARPE-19 cells. Mechanistically, LAMP2-KD reduced the concentration of cytosolic cysteine, resulting in low glutathione (GSH), inferior antioxidant capability and mitochondrial lipid peroxidation. ROS induced RPE cell death through ferroptosis. Inhibition of glutathione peroxidase 4 (GPx4) increased lethality in LAMP2-KD cells compared to controls. Cysteine and glutamine supplementation restored GSH and prevented ROS-induced cell death of LAMP2-KD RPE cells.
溶酶体相关膜蛋白 2（LAMP2）是一种高度糖基化的溶酶体膜蛋白，参与伴侣介导的自噬。LAMP2 的突变导致 Danon 病（DD）的经典三联征肌病、心肌病和脑病。此外，年轻的 DD 患者还观察到视网膜病变，导致视力丧失。新出现的证据表明 LAMP2 缺乏与氧化应激（ROS）有关，但机制尚不清楚。在本研究中，我们发现叔丁基过氧化氢或抗霉素 A 诱导的 LAMP2 敲低（LAMP2-KD）比对照 ARPE-19 细胞的细胞死亡更多。在机制上，LAMP2-KD 降低了细胞质半胱氨酸的浓度，导致谷胱甘肽（GSH）水平降低、抗氧化能力下降和线粒体脂质过氧化。ROS 通过铁死亡诱导 RPE 细胞死亡。与对照组相比，谷胱甘肽过氧化物酶 4（GPx4）的抑制增加了 LAMP2-KD 细胞的致死率。半胱氨酸和谷氨酰胺的补充恢复了 GSH，并防止了 ROS 诱导的 LAMP2-KD RPE 细胞死亡。
