Department of Medical Genetics, University of Wisconsin-Madison, Madison, Wisconsin, United States.
McPherson Eye Research Institute, University of Wisconsin-Madison, Madison, Wisconsin, United States.
Invest Ophthalmol Vis Sci. 2020 Oct 1;61(12):16. doi: 10.1167/iovs.61.12.16.
Aging is a critical risk factor for the development of retinal diseases, but how aging perturbs ocular homeostasis and contributes to disease is unknown. We identified transmembrane protein 135 (Tmem135) as a gene important for regulating retinal aging and mitochondrial dynamics in mice. Overexpression of Tmem135 causes mitochondrial fragmentation and pathologies in the hearts of mice. In this study, we examine the eyes of mice overexpressing wild-type Tmem135 (Tmem135 TG) and compare their phenotype to Tmem135 mutant mice.
Eyes were collected for histology, immunohistochemistry, electron microscopy, quantitative PCR, and Western blot analysis. Before tissue collection, electroretinography (ERG) was performed to assess visual function. Mouse retinal pigmented epithelium (RPE) cultures were established to visualize mitochondria.
Pathologies were observed only in the RPE of Tmem135 TG mice, including degeneration, migratory cells, vacuolization, dysmorphogenesis, cell enlargement, and basal laminar deposit formation despite similar augmented levels of Tmem135 in the eyecup (RPE/choroid/sclera) and neural retina. We observed reduced mitochondria number and size in the Tmem135 TG RPE. ERG amplitudes were decreased in 365-day-old mice overexpressing Tmem135 that correlated with reduced expression of RPE cell markers. In Tmem135 mutant mice, RPE cells are thicker, smaller, and denser than their littermate controls without any signs of degeneration.
Overexpression and mutation of Tmem135 cause contrasting RPE abnormalities in mice that correlate with changes in mitochondrial shape and size (overfragmented in TG vs. overfused in mutant). We conclude proper regulation of mitochondrial homeostasis by TMEM135 is critical for RPE health.
衰老是发生眼部疾病的一个关键危险因素，但衰老如何扰乱眼部稳态并导致疾病尚不清楚。我们鉴定出跨膜蛋白 135（Tmem135）是一个在调节小鼠视网膜衰老和线粒体动力学方面起重要作用的基因。Tmem135 的过表达可导致小鼠的心脏中线粒体碎片化和病变。在本研究中，我们检查了过表达野生型 Tmem135（Tmem135 TG）的小鼠的眼睛，并将其表型与 Tmem135 突变小鼠进行了比较。
收集组织用于组织学、免疫组织化学、电子显微镜、定量 PCR 和 Western blot 分析。在进行组织收集之前，我们进行了视网膜电图（ERG）检查以评估视觉功能。我们建立了小鼠视网膜色素上皮（RPE）细胞培养物以可视化线粒体。
尽管在眼杯（RPE/脉络膜/巩膜）和神经视网膜中观察到 Tmem135 的水平相似，但 Tmem135 TG 小鼠的 RPE 中仅观察到病变，包括变性、迁移细胞、空泡化、畸形发生、细胞增大和基底膜层沉积物形成。我们观察到 Tmem135 TG RPE 中线粒体数量和大小减少。在过表达 Tmem135 的 365 天大鼠中，ERG 幅度降低，与 RPE 细胞标志物的表达降低相关。在 Tmem135 突变小鼠中，RPE 细胞比其同窝对照更厚、更小且更密集，但没有任何退化迹象。
Tmem135 的过表达和突变导致了小鼠 RPE 异常的对比，这与线粒体形态和大小的变化有关（TG 中过度碎片化，而在突变体中过度融合）。我们得出结论，TMEM135 对线粒体动态平衡的适当调节对 RPE 的健康至关重要。
Zotero 插件
