Structure and Regulation of the TREX1 Exonuclease

描述(申请人提供)：人类TREX1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(FCL)、视网膜血管病伴脑白质营养不良(RVCL)和艾卡迪-古蒂埃综合征(AGS)。二聚体TREX1酶提供了人类细胞中主要的3‘&gt；5’外切酶活性，而不能有效地处理濒死细胞中的DNA和RNA多核苷酸是核酸介导的天然免疫激活和自体炎症疾病的关键驱动因素。致病突变如何影响TREX1的生物学功能，以及它们如何影响TREX1处理不同DNA底物的能力是两个悬而未决的问题，这两个问题对于我们理解TREX1功能障碍如何导致自身免疫性疾病至关重要。我们认为，导致疾病的显性TREX1突变在细胞死亡期间降解双链DNA的能力存在特定缺陷，这可能是免疫激活的细胞机制。这些研究将结合结构和生化实验来确定TREX1在双链DNA复合体中的结构(目标1)，揭示蛋白质二聚体结构调节的生化机制(目标2)，并确定蛋白质泛素化的催化调节机制(目标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).