INHIBITION OF STAT TRANSCRIPTION BY TOXOPLASMA

弓形虫对 STAT 转录的抑制

• 批准号: 9244190
• 负责人: L. David Sibley
• 金额: $ 22.88万
• 依托单位: WASHINGTON UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-12-05 至 2018-11-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9244190
• 关键词: Acute; Adult; Animals; Antibiotic Therapy; Binding; Binding Proteins; Biochemical Genetics; Biological Assay; CRISPR/Cas technology; Cell Nucleus; Cells; Chromatin; Chromatin Structure; Chronic; Complement; Complex; Cyst; Cytokine Receptors; Development; Dimerization; Event; Family; Gene Deletion; Gene Expression; Gene Expression Profiling; Genes; Genetic Transcription; Guanosine Triphosphate Phosphohydrolases; Hela Cells; Hematopoietic; Human; Immune; Immune Response Genes; Immune response; Immune system; Immunity; Immunocompromised Host; Individual; Infection; Infection Control; Interferon Type II; Interferons; Janus kinase; Knowledge; Lead; Life; MHC Class II Genes; Mammalian Cell; Mediating; Methods; Molecular; Mus; NOS2A gene; Natural Immunity; NuRD complex; Nuclear; Nuclear Translocation; Nucleosomes; Parasites; Pathway interactions; Peptide Signal Sequences; Phenotype; Phosphorylation; Proteins; Recruitment Activity; Reporter; Repression; Risk; Rodent; Role; STAT protein; STAT1 gene; Signal Transduction; Technology; Tissues; Toxoplasma; Toxoplasma gondii; Toxoplasmosis; Transcription Coactivator; Up-Regulation; Vacuole; Virulence Factors; Zoonoses; antimicrobial; dimer; guanylate; immune activation; improved; inhibitor/antagonist; killings; prevent; promoter; response; therapy design; trafficking; trait; transcription factor; transmission process

Toxoplasma gondii is a widespread parasite of animals that causes zoonotic infection in humans. Although acute infections in healthy adults are normally resolved without serious consequences, infection of immunocompromised individuals can lead to serious complications. Additionally, because chronic infections are not cleared by the immune system or by normal antibiotic treatment, individuals remain chronically infected for life. The presence of semi-dormant tissue cysts that can reactivate predisposes infected individuals to the risk of complications in the event of waning immunity. One of the key features of T. gondii that enables it to persist in the host is the ability to block immune responses, and thereby prevent clearance of the parasite. Among the pathways that are perturbed by T. gondii infection are the signal transducer and activator of transcription (STAT) family of transcription factors. Control of T. gondii infection relies on activation of STAT1 by IFN-γ, which is essential to upregulate antimicrobial pathways in both hematopoietic and non-hematopoietic cells. However, when cells are infected by T. gondii before encountering IFN-γ, the parasite is able to block STAT1-mediated transcription resulting in reduced control of infection. Global analysis of gene expression reveals that the majority of IFN-γ-activated genes are blocked by prior infection with T. gondii. The block in STAT1 signaling occurs in both rodent and human cells, although the molecular basis for this trait has not been previously identified. In preliminary studies we have identified a T. gondii protein that binds to phosphorylated STAT1 dimers and prevents activation of downstream genes. This effector, known as T. gondii Inhibitor of STAT Transcription (TgIST) blocks IFN-γ-induced gene expression mediated by STAT1. TgIST is both necessary and sufficient for blocking STAT1- mediated transcription in mouse and human cells. TgIST binds to a host repressor complex that alters chromatin structure. The proposed studies will define the role of host chromatin modifiers in modulating STAT1 transcriptional complexes using gene disruption by CRISPR/Cas9 combined with various reporter assays. Additionally, we will implement a variety of cellular, biochemical, and genetic methods to define the domains necessary for export and trafficking of TgIST to the host cell nucleus, where it is active.

弓形虫是一种广泛存在于动物体内的寄生虫， 人类虽然健康成人的急性感染通常在没有 严重后果，免疫功能低下的个体感染可导致严重的 并发症此外，由于慢性感染无法被免疫系统清除， 通过系统或正常的抗生素治疗，个人仍然是终身慢性感染。 存在半休眠组织囊肿，可以重新激活易感染 在免疫力减弱的情况下，个体面临并发症的风险。的一个关键 T.使其能够在宿主中持续存在的是阻断免疫的能力， 反应，从而防止寄生虫的清除。在这些途径中 受T.弓形虫感染是信号转导子和转录激活子 （STAT）转录因子家族。控制T.弓形虫感染依赖于 STAT 1通过IFN-γ，这是必不可少的上调抗菌途径， 造血和非造血细胞。然而，当细胞被T. 在遇到IFN-γ之前，弓形虫能够阻断STAT 1介导的 转录导致感染控制降低。基因表达的全局分析 表明大多数IFN-γ激活的基因被T. 刚地。STAT 1信号传导的阻断发生在啮齿动物和人类细胞中，尽管 这种性状的分子基础以前没有被鉴定。 在初步研究中，我们已经确定了一个T。与磷酸化的 STAT 1二聚体并阻止下游基因的激活。这种效应器被称为T. 弓形虫STAT转录抑制剂阻断IFN-γ诱导的基因表达 由STAT 1介导。TgIST是阻断STAT 1的必要和充分条件。 在小鼠和人类细胞中介导的转录。TgIST与宿主阻遏物结合 改变染色质结构的复合物。拟议的研究将界定东道国的作用， 染色质修饰剂在使用基因调节STAT 1转录复合物中的作用 通过CRISPR/Cas9结合各种报告基因测定进行破坏。此外，我们将 实施各种细胞、生物化学和遗传学方法来定义域 这是TgIST输出和运输到宿主细胞核所必需的，在那里它是有活性的。