Structure and Regulation of the TREX1 Exonuclease

描述（由申请人提供）：人类TREX 1基因突变导致一系列自身免疫性疾病，包括系统性红斑狼疮（SLE）、家族性冻疮狼疮（FCL）、视网膜血管病变伴脑白质营养不良（RVCL）和Aicardi-Goutieres综合征（AGS）。二聚体TREX 1酶在人细胞中提供主要的3 '->5'外切核酸酶活性，并且不能有效地处理来自垂死细胞的DNA和RNA多核苷酸是核酸介导的先天免疫激活和自身炎性疾病的关键驱动因素。致病突变如何影响TREX 1的生物学功能，以及它们如何影响TREX 1处理不同DNA底物的能力是两个悬而未决的问题，这对我们理解TREX 1功能障碍如何导致自身免疫性疾病至关重要。我们提出，导致疾病的显性TREX 1突变在细胞死亡期间降解双链DNA的能力方面存在特异性缺陷，这指向了免疫激活的可能细胞机制。这些研究将结合结构和生化实验来确定TREX 1与双链DNA复合物的结构（目的1），揭示蛋白质二聚体结构调控的生化机制（目的2），并定义蛋白质泛素化催化调控的机制（目的3）。

DESCRIPTION (provided by applicant): Mutations in the humanTREX1 gene contribute to disease in a spectrum of autoimmune disorders including systemic lupus erythematosus (SLE), familial chilblain lupus (FCL), retinal vasculopathy with cerebral leukodystrophy (RVCL) and Aicardi-Goutieres syndrome (AGS). The dimeric TREX1 enzyme provides the major 3'->5' exonuclease activity in human cells, and failure to efficiently dispose of DNA and RNA polynucleotides from dying cells is a key driver of nucleic acid-mediated innate immune activation and autoinflammatory disease. How the disease causing mutations affect the biological function of TREX1, and how they affect the ability of TREX1 to process different DNA substrates are two open questions that are critical to our understanding of how TREX1 dysfunction leads to autoimmune disease. We propose that the dominant TREX1 mutations leading to disease are specifically defective in their ability to degrade double- stranded DNA during cell death, pointing to the likely cellular mechanism of immune activation. These studies will use a combination of structural and biochemical experiments to determine the structure of TREX1 in complex with double-stranded DNA (aim 1), uncover the biochemical mechanism of regulation by the dimeric structure of the protein (aim 2), and define the mechanism of catalytic regulation by protein ubiquitination (aim 3).