Ophthalmic Genetics and Visual Function Branch, Section on Epithelial and Retinal Physiology and Disease, National Eye Institute, National Institutes of Health, Bethesda, MD USA.
Genetic Engineering Facility, National Eye Institute, National Institutes of Health, Bethesda, MD, USA.
Hum Mol Genet. 2019 Oct 15;28(20):3355-3368. doi: 10.1093/hmg/ddz171.
MicroRNA-204 (miR-204) is expressed in pulmonary, renal, mammary and eye tissue, and its reduction can result in multiple diseases including cancer. We first generated miR-204-/- mice to study the impact of miR-204 loss on retinal and retinal pigment epithelium (RPE) structure and function. The RPE is fundamentally important for maintaining the health and integrity of the retinal photoreceptors. miR-204-/- eyes evidenced areas of hyper-autofluorescence and defective photoreceptor digestion, along with increased microglia migration to the RPE. Migratory Iba1+ microglial cells were localized to the RPE apical surface where they participated in the phagocytosis of photoreceptor outer segments (POSs) and contributed to a persistent build-up of rhodopsin. These structural, molecular and cellular outcomes were accompanied by decreased light-evoked electrical responses from the retina and RPE. In parallel experiments, we suppressed miR-204 expression in primary cultures of human RPE using anti-miR-204. In vitro suppression of miR-204 in human RPE similarly showed abnormal POS clearance and altered expression of autophagy-related proteins and Rab22a, a regulator of endosome maturation. Together, these in vitro and in vivo experiments suggest that the normally high levels of miR-204 in RPE can mitigate disease onset by preventing generation of oxidative stress and inflammation originating from intracellular accumulation of undigested photoreactive POS lipids. More generally, these results implicate RPE miR-204-mediated regulation of autophagy and endolysosomal interaction as a critical determinant of normal RPE/retina structure and function.
miR-204（微小 RNA-204）在肺部、肾脏、乳腺和眼部组织中表达，其减少可导致包括癌症在内的多种疾病。我们首先生成 miR-204-/- 小鼠，以研究 miR-204 缺失对视网膜和视网膜色素上皮（RPE）结构和功能的影响。RPE 对于维持视网膜光感受器的健康和完整性至关重要。miR-204-/- 眼睛出现了高自发荧光区域和感光细胞消化缺陷，以及小胶质细胞向 RPE 的迁移增加。迁移的 Iba1+小胶质细胞定位于 RPE 的顶端表面，在那里它们参与光感受器外节（POS）的吞噬作用，并导致视紫红质的持续积累。这些结构、分子和细胞结果伴随着视网膜和 RPE 的光诱发电反应减少。在平行实验中，我们使用抗 miR-204 在人 RPE 的原代培养物中抑制 miR-204 的表达。体外抑制人 RPE 中的 miR-204 同样显示出异常的 POS 清除和自噬相关蛋白表达的改变，以及内体成熟调节剂 Rab22a。总之，这些体内和体外实验表明，RPE 中正常高水平的 miR-204 可以通过防止未消化的光反应性 POS 脂质在细胞内积累引起的氧化应激和炎症的产生，来减轻疾病的发生。更一般地说，这些结果表明，RPE 中 miR-204 介导的自噬和内溶酶体相互作用的调节是正常 RPE/视网膜结构和功能的关键决定因素。
