Signal transduction in neutrophil chemotaxis

中性粒细胞趋化性中的信号转导

• 批准号: 7139632
• 负责人: Hongbo R Luo
• 金额: $ 31.27万
• 依托单位: BOSTON CHILDREN'S HOSPITAL
• 依托单位国家: 美国
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-08-01 至 2011-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7139632
• 关键词: biological signal transduction; calmodulin; chemotaxis; gene induction /repression; genetic regulation; genetically modified animals; inflammation; inositol phosphates; laboratory mouse; membrane proteins; molecular dynamics; neutrophil; peritonitis; phosphatidylinositol 3 kinase; phosphorylation; protein isoforms; protein localization; protein transport; tissue /cell culture

DESCRIPTION (provided by applicant): Neutrophils are the most abundant cell type among circulating white blood cells and constitute the first line of host defense against invading bacteria and other pathogens. They migrate toward sites of infection or inflammation by responding to gradients of chemoattractants, a process known as chemotaxis. Neutrophil chemotaxis is mediated by chemotactic signal transduction pathways. The long-term goal of this project is to elucidate the molecular basis of the chemotactic signaling. We are particularly interested in the signal pathway mediated by inositol phospholipid Ptdlns(3,4,5)P3. This pathway has proven to be essential for mediating chemotactic responses, while its regulation remains ill defined. Chemoattractant stimulation initiates localized accumulation of Ptdlns(3,4,5)P3 on the plasma membrane at the leading edge of chemotaxing cells. A set of pleckstrin homolog (PH) domain-containing proteins are then translocated onto the membrane via their specific binding to Ptdlns(3,4,5)P3 and subsequently trigger downstream signals leading to chemotaxis. The PH-domain membrane translocation was previously thought to be dependent solely upon concentrations of Ptdlns(3,4,5)P3 in the membrane. Recently, we discovered that an intracellular inositol phosphate, lns(1,3,4,5)P4, competes with Ptdlns(3,4,5)P3 for binding to the PH domain and attenuates PH-domain membrane translocation in neutrophils, providing a novel mode of regulation for PH domain function. This intriguing result led us to hypothesize that lns(1,3,4,5)P4, by suppressing PH- domain translocation, negatively regulates neutrophil chemotaxis. Consistent with this idea, our preliminary data show that lns(1,3,4,5)P4 level is greatly augmented during chemotaxis. In addition, treatment of neutrophils with membrane-permeant lns(1,3,4,5)P4 significantly inhibits their chemotactic movement. To further understand the regulation of Ptdlns(3,4,5)P3 signal by lns(1,3,4,5)P4 in chemotaxis, we will characterize the molecular mechanisms by which the intracellular level of lns(1,3,4,5)P4 is augmented by Chemoattractant stimulation (Aim I). Moreover, the physiological consequences of the chemoattractant- elicited augmentation of lns(1,3,4,5)P4 will be investigated using neutrophils lacking lns(1,3,4,5)P4 (Aim II). Finally, the contribution of lns(1,3,4,5)P4 to neutrophil chemotaxis in live animals will be investigated using a mouse peritonitis model and a dorsal air pouch model (Aim III). Together, these studies will provide a better understanding of the role of lns(1,3,4,5)P4 in neutrophil chemotaxis, with the ultimate goal of establishing lns(1,3,4,5)P4 and related pathways as novel therapeutic targets for modulating neutrophil functions. Accordingly, more efficient and effective therapies could be developed to treat a variety of infectious and inflammatory diseases, such as asthma, multiple sclerosis, and rheumatoid arthritis.

描述（由申请人提供）：中性粒细胞是循环白细胞中最丰富的细胞类型，构成了宿主防御的第一线，以防止入侵细菌和其他病原体。它们通过响应趋化剂的梯度（一种称为趋化性的过程）迁移到感染或炎症部位。中性粒细胞趋化性是由趋化信号转导途径介导的。该项目的长期目标是阐明趋化信号传导的分子基础。我们对由肌醇磷脂PTDLN（3,4,5）P3介导的信号途径特别感兴趣。事实证明，该途径对于介导趋化反应至关重要，而其调节仍未定义。化学吸引剂刺激引发了PTDLN（3,4,5）P3在趋化细胞前缘的质膜上的局部积累。然后，通过特异性结合与PTDLN（3,4,5）P3，将一组含有含蛋白的Pleckstrin同源物（pH）蛋白转移到膜上，然后随后触发导致趋化性的下游信号。以前，pH结构域膜的易位仅取决于膜中PTDLN（3,4,5）P3的浓度。最近，我们发现细胞内肌醇磷酸LNS（1,3,4,5）P4与PTDLNS（3,4,5）P3竞争，以结合pH结构域，并减轻中性粒细胞中的pH膜膜易位，从而提供了一种新型调节模式的pH指导模式。这一有趣的结果使我们假设LNS（1,3,4,5）P4通过抑制ph域易位，对中性粒细胞趋化性进行负调节。与这个想法一致，我们的初步数据表明，在趋化性期间，LNS（1,3,4,5）P4水平大大增加。此外，用膜 - 佩里压：1,3,4,5）P4的中性粒细胞显着抑制其趋化运动。为了进一步了解LNS（1,3,4,5）P4在趋化性中对PTDLN（3,4,5）P3信号的调节，我们将表征LNS内LNS的细胞内水平（1,3,4,5）P4通过化学涂层刺激增强的分子机制（1,3,4,5）。此外，将使用缺乏LNS的中性粒细胞（1,3,4,5）P4（AIM II）研究了趋化剂引起的LNS增强（1,3,4,5）P4的生理后果。最后，将使用小鼠腹膜炎模型和背袋模型（AIM III）研究LNS（1,3,4,5）P4对活动物中性粒细胞趋化性的贡献。总之，这些研究将更好地理解LNS（1,3,4,5）P4在中性粒细胞趋化性中的作用，其最终目的是建立LNS（1,3,4,5）P4及相关途径作为调节中性粒细胞功能的新型治疗靶标。因此，可以开发更有效的疗法来治疗各种感染性和炎症性疾病，例如哮喘，多发性硬化症和类风湿关节炎。