Mechanisms of Giardia Iamblia Excystation

贾第鞭毛虫排泄机制

• 批准号: 6576919
• 负责人: FRANCES D. GILLIN
• 金额: $ 39.49万
• 依托单位: UNIVERSITY OF CALIFORNIA, SAN DIEGO
• 依托单位国家: 美国
• 财政年份: 2003
• 资助国家: 美国
• 起止时间: 2003-04-01 至 2008-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6576919
• 关键词: Giardia; binding proteins; calcium flux; calmodulin; cyclic AMP; enzyme linked immunosorbent assay; exocytosis; host organism interaction; intracellular parasitism; mass spectrometry; northern blottings; nucleic acid sequence; phosphorylation; proteomics; second messengers; two dimensional gel electrophoresis

DESCRIPTION (provided by the applicant): Giardia lamblia, an important human pathogen, must successfully excyst in order to infect a new host. Since excystation is too rapid to rely entirely on new gene expression, the unifying hypothesis of this proposal is that second messenger pathways may be central for regulation. While we can reproduce the entire life cycle in vitro, neither the precise stimuli nor the second messenger pathways that regulate excystation are known. Based on extensive Preliminary Data, we propose these Specific Aims: Specific Aim 1 is to define the key physiological excystation stimuli, and to test the hypothesis that Giardia cysts' responses to these signals are mediated by or reflected in changes in cytosolic calcium and/or cyclic AMP. We will ask whether pharmacological release of "caged" Ca 2v and/or cAMP into the cytosol can bypass the corresponding excystation stimulus. Specific Aim 2 is to define the role(s) of calmodulin (CAM) in regulating excystation and to identify specific "downstream" effectors that carry out its function. gCaM co-localizes with protein kinase A to the flagellar basal bodies-centrosomes, suggesting a key role in coordinating these pathways. We will use in vivo cross-linking and genomic data to functionally identify downstream effectors that specifically interact with CaM during excystation. Specific Aim 3 is to test the hypothesis that changes in protein phosphorylation may be important in regulating excystation, compared with de novo protein synthesis. We will compare changes in protein phosphorylation (the "phosphoproteome"), with overall changes in the protein expression in excysting cells. Sequence analyses and genomic data will permit us to identify key excystation proteins. This proteomic approach will test our overall hypothesis and complement the cellular and molecular data of Aims 1 and 2. Our proposed studies will reveal important insights into regulation of G lamblia excystation. Many other parasites have cystic forms whose excystation is required for transmission. Giardia may be a valuable model for understanding parasite differentiation in the intestinal tract. On a basic level, Giardia excystation is a unique model for cellular awakening from dormancy in response to environmental signals in an early-diverging eukaryotes.

描述（由申请方提供）：蓝氏贾第鞭毛虫是一种重要的人类病原体，必须成功脱囊才能感染新宿主。由于脱囊太快，不能完全依赖于新的基因表达，因此该提议的统一假设是第二信使途径可能是调节的中心。虽然我们可以在体外复制整个生命周期，但无论是精确的刺激还是调节脱囊的第二信使途径都是未知的。基于广泛的初步数据，我们提出了这些具体目标：具体目标1是定义关键的生理脱囊刺激，并测试假设贾第鞭毛虫包囊对这些信号的反应是介导的或反映在细胞溶质钙和/或环AMP的变化。我们将问是否药理释放的“笼”钙2 V和/或cAMP进入胞质溶胶可以绕过相应的脱囊刺激。具体目标2是定义钙调蛋白（CAM）在调节脱囊中的作用，并确定执行其功能的特定“下游”效应物。gCaM与蛋白激酶A共定位于鞭毛基体-中心体，表明在协调这些途径中起关键作用。我们将使用在体内的交联和基因组数据，以功能性地确定下游的效应，特别是相互作用的钙调蛋白脱囊。具体目标3是测试的假设，蛋白质磷酸化的变化可能是重要的，在调节脱囊，与从头蛋白质合成相比。我们将比较蛋白质磷酸化（“磷酸化蛋白质组”）的变化，以及脱囊细胞中蛋白质表达的总体变化。序列分析和基因组数据将使我们能够确定关键的脱囊蛋白。这种蛋白质组学方法将检验我们的总体假设，并补充目标1和2的细胞和分子数据。我们提出的研究将揭示重要的见解G lamblia脱囊调节。许多其他寄生虫有囊状的形式，其脱囊是传播所必需的。贾第虫可能是了解肠道寄生虫分化的一个有价值的模型。在一个基本的水平上，贾第鞭毛虫脱囊是一个独特的模式，细胞从休眠中唤醒，在早期分化的真核生物的环境信号。