Molecular Genetics of Age-Dependent Retinal Degeneration

年龄依赖性视网膜变性的分子遗传学

• 批准号: 8689046
• 负责人: AKIHIRO IKEDA
• 金额: $ 47.56万
• 依托单位: UNIVERSITY OF WISCONSIN-MADISON
• 依托单位国家: 美国
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-08-01 至 2015-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8689046
• 关键词: Affect; Aging; Aging-Related Process; Apoptotic; Candidate Disease Gene; Cell Death; Cell physiology; Cells; Characteristics; Chromosome Mapping; Defect; Development; Disease; Ethylnitrosourea; Genes; Genetic Engineering; Genetic screening method; Goals; Human; Integral Membrane Protein; Link; Maps; Mediator of activation protein; Mitochondria; Molecular; Molecular Genetics; Mus; Mutant Strains Mice; Mutation; Neurodegenerative Disorders; Organelles; Oxidative Stress; Pathway interactions; Phenotype; Photoreceptors; Play; Prevention strategy; Proteins; Resolution; Retina; Retinal; Retinal Defect; Retinal Degeneration; Retinal Diseases; Role; Source; Splice-Site Mutation; Stress; Synapses; Synaptic Vesicles; Tail; Testing; Therapeutic; Time; age related; base; early onset; insight; mouse model; mutant; normal aging; overexpression; oxidative damage; photoreceptor degeneration; positional cloning; response

DESCRIPTION (provided by applicant): Our long-term goal is to understand the molecular mechanisms causing retinal defects associated with human retinal diseases and aging. Recent studies have shown that similar synaptic abnormality and gradual photoreceptor cell loss are commonly observed in aging and a number of retinal degenerative diseases. The similarity of retinal abnormalities observed in aging and age-dependent retinal degenerative diseases suggests the link between molecular mechanisms underlying these conditions. Elucidating the molecular mechanisms causing the common age-dependent retinal abnormalities, therefore, should enhance our understanding of age-dependent retinal diseases and aging of the retina. We identified an ENU-induced mutant mouse strain, FUN025, showing early onset of age-dependent abnormalities in the retina. The phenotypes of these mice mimic abnormalities that are observed in normal aging retina, but they appear at the earlier time point. Furthermore, we found that the retina of FUN025 mice is more susceptible to oxidative stress, suggesting that the FUN025 gene is involved in protection of photoreceptor cells from oxidative stress. Following genetic mapping of the FUN025 mutation, we found a splice-site mutation in the transmembrane protein 135 (Tmem135) gene that is in the minimal FUN025 region. We further determined that the TMEM135 protein is localized to mitochondria as well as synaptic vesicles of photoreceptor cells, and its expression is reduced in the normal aging retina. Mitochondria are known as both the source and the target of oxidative damage in cells, as well as the mediator of apoptotic cell death, and are the likely organelle affected by the FUN025 mutation. These findings have led us to our hypothesis that FUN025 has a major role in the mitochondria to protect photoreceptor cells from oxidative stress. In this application, our major focus is to identify genes involved in age-dependent retinal abnormalities, and characterize those molecules. More specifically, in Aim 1, we will test Tmem135 as a strong candidate gene for FUN025, and definitively identify the gene responsible for FUN025 phenotypes. In Aim 2, we will study the role of FUN025 in the mitochondrial functions and cellular responses to oxdative stress. In addition, we will test whether overexpression of the FUN025 gene provides greater protection of photoreceptor cells from oxidative stress. In Aim 3, we will conduct positional cloning of the responsible gene for another mouse mutant showing age-dependent photoreceptor degeneration and synaptic abnormalities, that are identical to those observed in FUN025 mice. Completion of the proposed studies should provide multiple entry points into the molecular mechanisms underlying age-dependent retinal degeneration, and may offer therapeutic strategies for prevention of retinal conditions associated with aging and age-dependent retinal disorders.

描述（由申请人提供）：我们的长期目标是了解导致与人类视网膜疾病和衰老相关的视网膜缺陷的分子机制。最近的研究表明，在衰老和许多视网膜退行性疾病中，通常会观察到类似的突触异常和逐渐的感光细胞丧失。在衰老和年龄依赖性视网膜退行性疾病中观察到的视网膜异常的相似性表明这些疾病的分子机制之间存在联系。因此，阐明导致常见的年龄依赖性视网膜异常的分子机制应该增强我们对年龄依赖性视网膜疾病和视网膜老化的理解。我们鉴定了一种 ENU 诱导的突变小鼠品系 FUN025，该品系显示出早期出现的与年龄相关的视网膜异常。这些小鼠的表型模仿了在正常老化视网膜中观察到的异常，但它们出现在较早的时间点。此外，我们发现FUN025小鼠的视网膜更容易受到氧化应激的影响，这表明FUN025基因参与保护感光细胞免受氧化应激。对 FUN025 突变进行遗传图谱分析后，我们发现位于最小 FUN025 区域的跨膜蛋白 135 (Tmem135) 基因中存在剪接位点突变。我们进一步确定TMEM135蛋白定位于线粒体以及感光细胞的突触小泡，并且其表达在正常老化的视网膜中减少。线粒体被认为是细胞氧化损伤的来源和目标，也是细胞凋亡的介质，并且是可能受 FUN025 突变影响的细胞器。这些发现使我们得出这样的假设：FUN025 在线粒体中发挥着重要作用，可保护感光细胞免受氧化应激。在此应用中，我们的主要重点是识别与年龄依赖性视网膜异常相关的基因，并表征这些分子。更具体地说，在目标 1 中，我们将测试 Tmem135 作为 FUN025 的强大候选基因，并最终确定负责 FUN025 表型的基因。在目标 2 中，我们将研究 FUN025 在线粒体功能和细胞对氧化应激的反应中的作用。此外，我们将测试 FUN025 基因的过度表达是否可以更好地保护感光细胞免受氧化应激。在目标 3 中，我们将对另一种小鼠突变体的相关基因进行位置克隆，该突变体表现出年龄依赖性光感受器变性和突触异常，这与在 FUN025 小鼠中观察到的情况相同。完成拟议的研究将为年龄依赖性视网膜变性的分子机制提供多个切入点，并可能为预防与衰老和年龄依赖性视网膜疾病相关的视网膜疾病提供治疗策略。