Molecular Genetics of Age-Dependent Retinal Degeneration

项目摘要 我们的长期目标是了解导致人类疾病的分子机制 衰老。年龄依赖性疾病的一种可能机制是加速衰老过程 环境和遗传因素。我们之前的研究表明，小鼠模型显示出加速衰老 表型是识别视网膜中这些因素的强大工具。ENU诱导的突变小鼠模型， FUN025，显示视网膜加速老化，以及在与年龄相关的视网膜中观察到的某些关键病理 疾病包括视网膜色素上皮(RPE)细胞异常、炎症和感光细胞 变性，这表明负责的基因参与了视网膜衰老的调节，而且它的 损伤会导致年龄相关性视网膜异常的发生。在上一次筹资期间， 我们发现跨膜蛋白135(Tmem135)中的一个突变导致视网膜 FUN025小鼠的异常。我们发现TMEM135定位于线粒体，并参与了 线粒体分裂。培养的Tem135突变细胞和突变细胞对氧化应激的敏感性增加 视网膜，可能是由于线粒体的异常。我们的观察表明，RPE是主要的地点 受Tem135突变的影响。此外，我们还发现野生型Tem135在小鼠中过表达 导致RPE细胞变性。基于这些发现，我们假设线粒体的适当控制 通过TMEM135的动力学对于维持RPE细胞的正常功能和完整性是必不可少的，调节失调 这会导致年龄相关的异常。除了我们自己的发现，有越来越多的证据表明 表明RPE是包括老年性黄斑变性在内的年龄依赖性疾病的靶点。然而， 在这些与年龄相关的疾病中，RPE功能障碍/死亡的病因尚不清楚。在这次更新中 提案中，我们将研究Tmem135引起的线粒体动力学缺陷是如何导致RPE的 功能障碍/退化。具体地说，我们将1)确定Tem135影响的分子途径 在RPE细胞中突变/过表达，2)研究线粒体动力学如何影响RPE细胞的完整性和功能 RPE以及TMEM135如何参与这一过程，以及3)确定RPE细胞的遗传修饰物 Tmem135过度表达引起的退变。该项目的成功完成将揭示 线粒体动力学和Tmem135在RPE细胞增龄变化中的作用及其相关因素的研究 这些过程可能导致针对衰老和与年龄相关的新的补充或治疗选择 视网膜中的疾病。

Project Summary Our long-term goal is to understand the molecular mechanisms causing human diseases associated with aging. One possible mechanism for age-dependent diseases is acceleration of the aging process by environmental and genetic factors. Our previous studies show that mouse models showing accelerated aging phenotypes are powerful tools to identify such factors in the retina. An ENU-induced mutant mouse model, FUN025, displays accelerated retinal aging, as well as certain key pathologies observed in age-related retinal diseases including retinal pigment epithelium (RPE) cell abnormalities, inflammation and photoreceptor cell degeneration, suggesting that the responsible gene is involved in the regulation of retinal aging, and that its impairment leads to development of the age-dependent retinal abnormalities. In the previous funding period, we identified that a mutation in transmembrane protein 135 (Tmem135) is responsible for the retinal abnormalities in FUN025 mice. We found that TMEM135 localizes to mitochondria, and is involved in mitochondrial fission. Sensitivity to oxidative stress increases in cultured Tmem135 mutant cells and mutant retina, likely due to the mitochondrial abnormalities. Our observations indicate that the RPE is the primary site affected by the Tmem135 mutation. In addition, we found that over-expression of wild-type Tmem135 in mice results in RPE cell degeneration. Based on these findings, we hypothesize that proper control of mitochondrial dynamics through TMEM135 is essential to maintain normal function and integrity of RPE cells, dysregulation of which leads to age-dependent abnormalities. In addition to our own findings, there is increasing evidence to show that RPE is the target of age-dependent diseases including age-related macular degeneration. However, the etiology of RPE dysfunction/death in these age-related diseases is not well understood. In this renewal proposal, we will investigate how defective mitochondrial dynamics due to Tmem135 result in RPE dysfunction/degeneration. Specifically, we will 1) determine molecular pathways affected by Tmem135 mutation/over-expression in RPE cells, 2) study how mitochondrial dynamics affect the integrity and function of the RPE and how TMEM135 is involved in this process, and 3) identify genetic modifiers of RPE cell degeneration caused by Tmem135 overexpression. Successful completion of this project will reveal the role of mitochondrial dynamics and Tmem135 in age-dependent changes of RPE cells, and identify factors involved in those processes, which may lead to novel supplementation or treatment options for aging and age-related diseases in the retina.