Host glycosyltransferases in the glycosylation of Toxoplasma proteins

弓形虫蛋白糖基化中的宿主糖基转移酶

基本信息

批准号：
8451142
负责人：
ANTHONY P. SINAI
金额：
$ 18.56万
依托单位：
UNIVERSITY OF KENTUCKY
依托单位国家：
美国
项目类别：
财政年份：
2013
资助国家：
美国
起止时间：
2013-01-18 至 2014-12-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/8451142
关键词：
Acquired Immunodeficiency Syndrome Address Affinity Agglutinins Animals Antibodies Antigens Binding Biogenesis Bioinformatics Biological Assay Biology Blood Brain Cells Chinese Hamster Ovary Cell Competence Cross Presentation Cultured Cells Cyst Defect Detection Disease Dolichos Elements Endoplasmic Reticulum Enzymes Epitopes Event Exhibits Felis catus Funding Mechanisms Genes Genome Glycoproteins Golgi Apparatus Growth HIV Immune Immune response Immune system Immunosuppression Individual Infection Ingestion Integration Host Factors Label Lectin Life Light Link Maintenance Measures Mediating Membrane Modification Molecular Cloning Monoclonal Antibodies Muscle Oocysts Organelles Parasites Pathogenesis Pathway interactions Patients Pattern Peanut Agglutinin Polysaccharides Protein Glycosylation Proteins Recruitment Activity Reporter Research Design Risk Role Sambucus nigra Sialic Acids Sialyltransferases Small Interfering RNA Spatial Distribution Specificity Staining method Stains Sterility System Testing Tissues Toxoplasma Toxoplasma gondii Toxoplasmosis Vacuole Vesicle Viral Tumor Antigens Work base clinically relevant glycosylation glycosyltransferase innovation jacalin microbial mutant novel parasite genome pathogen prevent public health relevance sialylation success sugar tissue culture transmission process

项目摘要

DESCRIPTION (provided by applicant): The protozoan parasite Toxoplasma gondii is an important infection causing life threatening disease in patients with HIV-AIDs and other immune suppressive conditions. Despite the activation of a robust immune response including high antibody titers in infected individuals, sterile cure is not achieved. Rather the parasite differentiates into a relatively metabolically quiescent tissue cyst form. Tissue cysts which establish within muscle and the CNS, are characterized by having a highly glycosylated cyst wall and matrix. A given cyst may contain several hundred individual parasites. Our studies using lectin reactivity have identified the presence of sialic acid containing glycans in the tissu cyst wall and matrix of both brain derived and tissue culture induced cysts. This finding is remarkable in light of the absence of any of the machinery for the synthesis, activation and transfer of sialic acid being found in the parasite genome. The implication of this finding is that host activities may be responsible for the sialylation of the tissue cyst associated glycans. In ths study we explore this radical hypothesis by using established host cell mutants with defects in distinct steps of the sialylation pathway to confirm the contribution of the host cell. In addition specific host activities will also be targeted using siRNA knockdowns to establish the classes of sialyltransferases involved. Finally we will develop as split GFP/Luc based system to address whether fusion of the parasitophorous vacuole membrane and the associated ER as well as the redirection of Golgi associated vesicles is involved in the delivery of cyst modifying glycosylatin enzymes from the host cell. We believe that by hijacking the host's own glycosylation machinery, the parasite may avoid detection by the immune system by effectively "sugar coating" potentially antigenic determinants with "self" sugars rendering them functionally invisible.

描述（由申请人提供）：原生动物寄生虫弓形虫是一种重要的感染，会导致艾滋病毒/艾滋病和其他免疫抑制疾病患者罹患危及生命的疾病。尽管在感染个体中激活了强大的免疫反应，包括高抗体滴度，但仍未实现无菌治愈。相反，寄生虫分化成代谢相对静止的组织囊肿形式。在肌肉和中枢神经系统内建立的组织囊肿的特征是具有高度糖基化的囊肿壁和基质。一个特定的囊肿可能含有数百个单独的寄生虫。我们使用凝集素反应性的研究已经确定，在脑源性和组织培养诱导的囊肿的组织囊肿壁和基质中存在含有聚糖的唾液酸。鉴于寄生虫基因组中不存在任何合成、激活和转移唾液酸的机制，这一发现是引人注目的。这一发现的含义是宿主活动可能与组织囊肿相关聚糖的唾液酸化有关。在这项研究中，我们通过使用在唾液酸化途径的不同步骤中具有缺陷的已建立的宿主细胞突变体来探索这一激进的假设，以确认宿主细胞的贡献。此外，还将使用 siRNA 敲低来靶向特定的宿主活性，以确定所涉及的唾液酸转移酶的类别。最后，我们将开发基于分离 GFP/Luc 的系统，以解决寄生液泡膜和相关 ER 的融合以及高尔基体相关囊泡的重定向是否参与从宿主细胞传递囊肿修饰糖基化酶。我们相信，通过劫持宿主自身的糖基化机制，寄生虫可以通过用“自身”糖有效地“糖衣”潜在抗原决定簇，从而使其在功能上不可见，从而避免被免疫系统检测到。