Biologic Activities of the pertusis toxin B-pentamer

描述(申请人提供)：百日咳毒素(PTX)是一种复杂的AB5毒素，由具有酶活性的A亚基(S1)和结合的B寡聚体(PTX-B)组成，由5个亚基S2、S3、S4和S5组成，比例为1：1：2：1。AB毒素的B部分将A亚单位转运到靶细胞的细胞质中，不被认为参与了毒性。然而，PTX-B已被证明除了在促进S1进入细胞质中的作用外，还具有活性。PTX-B可诱导一系列细胞反应，包括即刻细胞死亡、细胞凋亡、细胞聚集，甚至细胞增殖。在这个方案中，我们将确定PTX-B的受体，我们将以T细胞为模型系统来表征PTX-B结合所影响的信号通路，并将表征其对免疫系统其他细胞的毒性。 具体目标1.PTX-B结合元件的特性。PTX-B已被证明与细胞上的多种受体结合。我们将确定必要的PTX-B结合区，作为识别潜在细胞表面受体的前奏。 具体目的2.确定PTX-B减弱趋化因子受体信号和趋化作用的机制。PTX-B影响趋化因子受体活性的机制在很大程度上仍不清楚。我们将扩展我们对PTX-B信号在T细胞中的机制的研究(S)，以趋化因子受体CCR5为模型系统，确定PTX-B是否通过促进趋化因子受体脱敏来阻止淋巴细胞迁移。 具体目标3.表征原代细胞对完整百日咳毒素和PTX-B的反应能力。已发表的报告表明，对PTX-B的反应在老鼠和人类之间是不同的。我们建议表征人和小鼠白细胞对完整百日咳毒素和PTX-B的短期和长期反应。 百日咳毒素是人类百日咳或百日咳的病原体，是百日咳杆菌的主要致病因子。百日咳是一种常见的地方性疾病，消耗了大量的卫生保健资源，是美国唯一一种发病率正在上升的疫苗可预防的疾病。B.百日咳能够感染以前感染或接种过的人，因为它能够阻碍保护性免疫反应的发展，了解百日咳毒素与免疫系统的相互作用对于开发改进的百日咳疫苗和治疗方法很重要。

DESCRIPTION (provided by applicant): Pertussis toxin (PTX) is a complex AB5 toxin, comprised of the enzymatically active, "A" subunit (S1), and the binding, "B" oligomer (PTX-B), composed of five subunits S2, S3, S4, and S5, found in a 1:1:2:1 ratio. The B portions of AB toxins transport the A subunit to the cytoplasm of target cells, and were not thought to participate in toxicity. However PTX-B has been shown to have activity in addition to its role in facilitating entry of S1 into the cytoplasm. PTX-B induces a spectrum of cellular responses, including immediate cell death, development of apoptosis, cellular clustering, and even cellular proliferation. In this proposal we will identify the receptors for PTX-B, we will characterize the signaling pathways that are affected by binding of PTX-B using T cells as a model system, and we will characterize its toxicity to other cells of the immune system. Specific Aim 1. Characterization of the PTX-B binding elements. PTX-B has been shown to bind to multiple receptors on cells. We will identify the essential PTX-B binding regions as a prelude to the identification of potential cell surface receptors. Specific Aim 2. Determine the mechanism by which PTX-B attenuates chemokine receptor signaling and chemotaxis. The mechanism by which PTX-B affects chemokine receptor activity remains largely unknown. We will extend our studies on the mechanism(s) of PTX-B signaling in T-cells to determine if PTX-B blocks lymphocyte migration by promoting chemokine receptor desensitization using the chemokine receptor CCR5 as a model system. Specific Aim 3. Characterize the ability of primary cells to respond to intact pertussis toxin and PTX-B. Published reports suggest that the responses to PTX-B are different between mice and humans. We propose to characterize the short term and long-term responses of human and murine leukocytes both intact pertussis toxin and PTX-B. Pertussis toxin is the major virulence factor of Bordetella pertussis, the causative agent of human whooping cough or pertussis. Whooping cough is common, endemic, and consumes a significant amount of health care resources, and is the only vaccine-preventable disease that is increasing in incidence in the United States. B. pertussis is able to infect previously infected or vaccinated individuals due to its ability to impede the development of a protective immune response, and understanding the interaction of pertussis toxin with the immune system is important for developing improved pertussis vaccines and therapeutics.