Immune control and genomic instability at micronuclei

项目总结 染色体不稳定(CIN)是以高染色体错分率为特征的癌症的标志。 细胞分裂过程中的细胞分裂。CIN可产生称为微核的核畸形，当染色体或 染色体片段在后期滞后，未能与形成初级染色体的主要染色质团结合。 RY核。微核招募核膜但结构缺陷导致频繁破裂、丢失 间隔化，以及蛋白质和小泡与细胞质的不受调控的交换。我- 核膜破裂会导致广泛的功能障碍，并与广泛的DNA损伤和 基因组重排，包括丛生突变现象，如嗜铬细胞症和卡特吉斯病， 通常在癌症基因组中观察到。破裂的微核还可以激活促炎因子- Ry-cGAS-STING通路，在抗肿瘤免疫中起重要作用。这些观察结果表明 微核可能是癌症基因组进化和免疫激活的关键平台。机甲- 在微核中驱动DNA损伤和免疫激活的核反应机制知之甚少。实验室分布在- 涵盖了内质网(ER)相关的核酸外切酶TREX1，它在各种 包括艾卡迪-古蒂埃综合征在内的人类免疫疾病，在微核上聚集。 透明的包膜破裂，切除微核DNA，限制cGAS刺活性。因此， TREX1在人类健康和疾病中具有不同的作用，在关键通路中占有中心地位。简而言之- 通常，有很强的理论基础来理解TREX1活性和与胞浆接触的机制 DNA该实验室的长期目标是确定DNA损伤的机制，集群突变- Nesis，以及核膜破裂部位的免疫激活。这项建议的具体目标是1) 阐明TREX1结构和功能的机制，2)确定TREX1如何被招募到微核， (3)微核DNA损伤途径的解剖。每个目标都有广泛的初步支持 数据。目标1将专注于TREX1中一个以前未描述的区域，该区域对于其去核能力至关重要。 对胞浆DNA进行分级，并抑制cGAS活性。目标2将建立在显示TREX1 DNA结合的结果的基础上 功能对于微核的定位是可有可无的，而与内质网的结合则是必不可少的。目标3 将使用一种新的方法来纯化微核，以解剖微核DNA损伤的来源。加在一起， 这些数据将提供对癌症基因组进化的基本见解，解释以前不具个性的- 命名的TREX1突变导致艾卡迪-古蒂埃综合征，并可能确定新的策略，以提高抗- 肿瘤免疫。

PROJECT SUMMARY Chromosomal instability (CIN) is a hallmark of cancer characterized by high rates of chromosome mis-segre- gation during cell division. CIN can generate nuclear aberrations termed micronuclei when a chromosome or chromosome fragment lags during anaphase and fails to join the main chromatin mass that will form the prima- ry nucleus. Micronuclei recruit nuclear envelopes but defects in construction lead to frequent rupturing, loss of compartmentalization, and an unregulated exchange of proteins and small vesicles with the cytoplasm. Mi- cronuclear envelope rupturing causes broad dysfunction and is associated with extensive DNA damage and genomic rearrangements, including clustered mutational phenomena such as chromothripsis and kataegis, which are commonly observed in cancer genomes. Ruptured micronuclei can also activate the pro-inflammato- ry cGAS-STING pathway, which plays essential roles in anti-tumor immunity. These observations suggest that micronuclei may represent key platforms for genome evolution and immune activation in cancer. The mecha- nisms driving DNA damage and immune activation at micronuclei are poorly understood. The laboratory dis- covered that the endoplasmic reticulum (ER)-associated exonuclease TREX1, which is mutated in a variety of human immune diseases including Aicardi-Goutières Syndrome, accumulates at micronuclei upon micronu- clear envelope rupture where it resects micronuclear DNA and limits cGAS-STING activation. Therefore, TREX1 occupies central positions in key pathways with diverse roles in human health and disease. Conse- quently, there is strong rationale to understand mechanisms of TREX1 activity and engagement with cytosolic DNA. The long-term goals of the laboratory are to determine mechanisms of DNA damage, clustered mutage- nesis, and immune activation at sites of nuclear envelope rupture. The specific Aims of this proposal are to 1) Elucidate mechanisms of TREX1 structure and function, 2) Determine how TREX1 is recruited to micronuclei, and 3) Dissect pathways of micronuclear DNA damage. Each objective is supported by extensive preliminary data. Aim 1 will focus on a previously uncharacterized region in TREX1, which is essential for its ability to de- grade cytosolic DNA and inhibit cGAS activation. Aim 2 will build on results showing that TREX1 DNA binding function is dispensable for its localization to micronuclei, while its association with the ER is essential. Aim 3 will use a new method to purify micronuclei to dissect sources of micronuclear DNA damage. Taken together, these data will provide fundamental insights into cancer genome evolution, explain how previously uncharac- terized TREX1 mutations cause Aicardi-Goutières syndrome, and may identify new strategies to improve anti- tumor immunity.