Structure and Regulation of the TREX1 Exonuclease

描述（由申请人提供）：humanTREX1基因突变可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aicardii - goutieres综合征（AGS）。二聚体TREX1酶在人类细胞中提供主要的3‘->5’外切酶活性，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症疾病的关键驱动因素。引起突变的疾病如何影响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，这是我们理解TREX1功能障碍如何导致自身免疫性疾病的两个关键问题。我们提出，导致疾病的主要TREX1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，这可能指向免疫激活的细胞机制。这些研究将采用结构与生化实验相结合的方法，确定TREX1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TREX1的生化机制（目的2），明确蛋白质泛素化催化调控TREX1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).