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个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，显示加速老化的小鼠模型 表型是鉴定视网膜中这些因子的有力工具。ENU诱导的突变小鼠模型， FUN 025显示加速的视网膜老化，以及在年龄相关的视网膜病变中观察到的某些关键病理。 包括视网膜色素上皮（RPE）细胞异常、炎症和感光细胞 退化，这表明负责基因参与视网膜老化的调节，其 损伤导致年龄依赖性视网膜异常的发展。在上一个供资期间， 我们发现，跨膜蛋白135（Tmem 135）的突变是导致视网膜病变的原因。 FUN 025小鼠的异常。我们发现TMEM 135定位于线粒体，并参与 线粒体分裂培养的Tmem 135突变细胞和突变体对氧化应激的敏感性增加 视网膜，可能是由于线粒体异常。我们的观察表明，RPE是主要的网站， 受Tmem 135突变的影响此外，我们发现野生型Tmem 135在小鼠中的过表达， 导致RPE细胞变性。基于这些发现，我们假设适当控制线粒体 通过TMEM 135的动力学对于维持RPE细胞的正常功能和完整性、调节异常 导致年龄依赖性异常。除了我们自己的发现，还有越来越多的证据表明， 显示RPE是包括年龄相关性黄斑变性在内的年龄依赖性疾病的靶点。然而，在这方面， 在这些与年龄相关的疾病中RPE功能障碍/死亡的病因学还不清楚。在这次更新中， 我们将研究由于Tmem 135导致的线粒体动力学缺陷如何导致RPE 功能障碍/退化。具体来说，我们将1）确定受Tmem 135影响的分子途径 2）研究线粒体动力学如何影响视网膜色素上皮细胞的完整性和功能， RPE以及TMEM 135如何参与这一过程，以及3）鉴定RPE细胞遗传修饰剂 由Tmem 135过度表达引起的变性。该项目的成功完成将揭示 线粒体动力学和Tmem 135在RPE细胞的年龄依赖性变化，并确定参与因素 这些过程可能会导致新的补充或治疗方案，以应对衰老和年龄相关的疾病。 视网膜疾病

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.