Cellular Models of a Monogenic Small Vessel Disease of the Brain

项目摘要 VCID（血管对认知障碍和痴呆的贡献）越来越多地被认为是 是痴呆症的主要原因，也是痴呆症的次要原因，如阿尔茨海默氏症 病理VCID最常见的进展，积累损伤由于小血管疾病的大脑 （SVD）。虽然有几个风险因素与SVD相关，但驱动其启动和 进展尚未得到很好的表征。视网膜血管病变伴脑白质脑病及 系统性表现（RVCL-S）是一种罕见的单基因晚发型疾病，具有显著的临床和 与脑小血管疾病的病理相似性。我们的目标是促进新的 通过对RVCL-S的研究，探讨预防和治疗散发性SVD的方法。 RVCL-S是由常染色体基因TREX 1的显性突变引起的，TREX 1编码主要的 胞内3' DNA外切核酸酶。TREX 1蛋白具有两个主要的功能结构域：氨基末端 结构域是核酸外切酶，而羧基末端结构域将蛋白定位在内质网中 (ER)膜，将DNA酶结构域延伸到胞质溶胶中，在那里它在抑制细胞增殖中起关键作用。 对胞质自身DNA的先天免疫应答。RVCL-S是由完全外显移码突变引起的， TREX 1基因，每个产生携带功能性核酸外切酶结构域的蛋白质，但缺乏 将完整蛋白锚定到ER膜上，导致TREX 1核酸外切酶的非典型定位 遍布细胞质和细胞核。重要的是，截短核酸外切酶内TREX 1的突变 编码区，导致蛋白质缺乏DNA酶活性和ER膜系链，不是致病性的 在杂合状态下，表明RVCL-S是由未拴系的 核酸外切酶我们认为细胞核中TREX 1核酸外切酶的异常活性干扰了DNA 复制/修复以及密切协调的细胞周期调节信号蛋白的活性。我们长久以来- 长期目标是确定突变核酸外切酶的关键有害影响，并制定策略 以减轻这些影响。为此，我们提出以下具体目标： 1.检测RVCL-S基因型对DNA损伤反应和细胞周期调控的影响。 2.采用RNA干扰抑制RVCL-S相关TREX 1移码突变体的表达。 影响：成功完成本研究将提供1）疾病预防策略; 2）生物标志物， 疾病监测;和3）新的治疗方法，将适用于RVCL-S，很可能 适用于偶发SVD。

Project Summary VCID (Vascular contributions to cognitive impairment and dementia) is increasingly recognized as both a primary cause of dementia and as a secondary contributor to dementia, as in the setting of Alzheimer’s pathology. VCID most commonly progresses from accumulated injury due to small vessel disease of the brain (SVD). While several risk factors are associated with SVD, the mechanisms that drive its initiation and progression have not been well characterized. Retinal Vasculopathy with Cerebral Leukoencephalopathy and Systemic Manifestations (RVCL-S) is a rare monogenic late onset condition that bears striking clinical and pathological similarities to small vessel disease of the brain. Our goal is to facilitate the development of new methods for the prevention and treatment of sporadic SVD through an investigation of RVCL-S. RVCL-S is caused by dominant mutations in the autosomal gene TREX1 which encodes the major intracellular 3’ DNA exonuclease. TREX1 protein harbors two major functional domains: the amino-terminal domain is the exonuclease while the carboxy-terminal domain positions the protein in the endoplasmic reticulum (ER) membrane, extending the DNAse domain into the cytosol where it plays a critical role in dampening the innate immune response to cytosolic self-DNA. RVCL-S is caused by fully penetrant frameshift mutations in TREX1 gene, each producing a protein that carries a functional exonuclease domain but lacks the domain that anchors the complete protein to the ER membrane resulting in atypical localization of TREX1 exonuclease throughout the cytosol and the nucleus. Importantly, mutations that truncate TREX1 within the exonuclease coding region, resulting in proteins lacking both DNase activity and the ER membrane tether, are not pathogenic in the heterozygous state, suggesting that RVCL-S is caused by a toxic gain-of-function of the untethered exonuclease. We propose that aberrant activity of TREX1 exonuclease in the cell nucleus interferes with DNA replication/repair as well as the activity of closely coordinated cell cycle regulatory signaling proteins. Our long- term objectives are to identify the critical detrimental effects of the mutant exonuclease and to develop strategies to abate these effects. To that end we propose the following specific aims: 1. Examine the effects of the RVCL-S genotype on the DNA damage response and cell cycle regulation. 2. Employ RNA interference to suppress expression of the RVCL-S associated TREX1 frameshift mutant. Impact: Successful completion of this study will provide 1) strategies for disease prevention; 2) biomarkers for disease monitoring; and 3) novel therapeutic approaches that will be applicable to RVCL-S and very likely applicable to sporadic SVD.