背景:年龄相关性黄斑变性(AMD)是发达国家老年人失明的主要原因,到2040年,受影响的人数预计将几乎翻一番。视网膜是我们体内最高的代谢需求之一,部分或完全由神经视网膜和视网膜色素上皮(RPE)中的线粒体满足。分别。连同其有丝分裂后的状态和来自入射光的持续光氧化损伤,视网膜需要一个涉及自噬的严密调控的内务系统.天然多酚尿石素A(UA)在衰老和年龄相关疾病的几种模型中显示出神经保护作用,主要归因于其诱导线粒体自噬和线粒体生物合成的能力。碘酸钠(SI)给药概括了AMD的晚期阶段,包括地理萎缩和感光细胞死亡。
方法:体外,使用离体和体内模型来测试SI模型中UA的神经保护潜能。功能测定(OCT,ERGs),细胞分析(流式细胞术,qPCR)和精细共聚焦显微镜(免疫组织化学,串联选择性自噬记者)帮助解决了这个问题。
结果:UA减轻了SI治疗小鼠的神经变性并保留了视觉功能。同时,我们在SI损伤诱导后观察到严重的蛋白质停滞缺陷,包括自噬体积累,在接受UA的动物中得到解决。UA治疗可恢复自噬通量并触发PINK1/Parkin依赖性线粒体自噬,正如文献中先前报道的那样。由SI引起的自噬阻断是由严重的溶酶体膜透化引起的。虽然UA不诱导溶酶体生物发生,它确实通过嗜血恢复了透化溶酶体的上循环。在SI处理的细胞中,细胞自噬适配器SQSTM1/p62的敲低消除了UA的生存力挽救,加剧溶酶体缺陷并抑制自噬。
结论:总的来说,这些数据突出显示了UA在AMD治疗中的一种新的推定应用,即它通过促进p62依赖性的细胞自噬来维持蛋白质抑制,从而绕过溶酶体缺陷.
BACKGROUND: Age-related macular degeneration (AMD) is the leading cause of blindness in elderly people in the developed world, and the number of people affected is expected to almost double by 2040. The retina presents one of the highest metabolic demands in our bodies that is partially or fully fulfilled by mitochondria in the neuroretina and retinal pigment epithelium (RPE), respectively. Together with its post-mitotic status and constant photooxidative damage from incoming light, the retina requires a tightly-regulated housekeeping system that involves autophagy. The natural polyphenol Urolithin A (UA) has shown neuroprotective benefits in several models of aging and age-associated disorders, mostly attributed to its ability to induce mitophagy and mitochondrial biogenesis. Sodium iodate (SI) administration recapitulates the late stages of AMD, including geographic atrophy and photoreceptor cell death.
METHODS: A combination of in vitro, ex vivo and in vivo models were used to test the neuroprotective potential of UA in the SI model. Functional assays (OCT, ERGs), cellular analysis (flow cytometry, qPCR) and fine confocal microscopy (immunohistochemistry, tandem selective autophagy reporters) helped address this question.
RESULTS: UA alleviated neurodegeneration and preserved visual function in SI-treated mice. Simultaneously, we observed severe proteostasis defects upon SI damage induction, including autophagosome accumulation, that were resolved in animals that received UA. Treatment with UA restored autophagic flux and triggered PINK1/Parkin-dependent mitophagy, as previously reported in the literature. Autophagy blockage caused by SI was caused by severe lysosomal membrane permeabilization. While UA did not induce lysosomal biogenesis, it did restore upcycling of permeabilized lysosomes through lysophagy. Knockdown of the lysophagy adaptor SQSTM1/p62 abrogated viability rescue by UA in SI-treated cells, exacerbated lysosomal defects and inhibited lysophagy.
CONCLUSIONS: Collectively, these data highlight a novel putative application of UA in the treatment of AMD whereby it bypasses lysosomal defects by promoting p62-dependent lysophagy to sustain proteostasis.