Biophysics of fluid lipid/protein membrane domains and immune cell signaling

流体脂质/蛋白质膜结构域和免疫细胞信号传导的生物物理学

• 批准号: 7532781
• 负责人: Tobias Baumgart
• 金额: $ 19.1万
• 依托单位: UNIVERSITY OF PENNSYLVANIA
• 依托单位国家: 美国
• 财政年份: 2007
• 资助国家: 美国
• 起止时间: 2007-12-01 至 2010-08-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7532781
• 关键词: Affect; Affinity; Allergens; Allergic; American; Antibodies; Antigens; Area; Basophilic leukemia; Behavior; Binding; Biochemical; Biological; Biophysics; Catalytic Domain; Cell Line; Cell membrane; Cell model; Cells; Cellular Membrane; Complement; Complex; Consensus; Cytolysis; Data; Dependence; Detergents; Development; Effector Cell; Event; Fluorescence; Fluorescence Microscopy; Healthcare Systems; Heterogeneity; Hormonal; Hypersensitivity; IgE; IgE Receptors; Image; Immune; Immune response; Immune system; Inflammation; Jurkat Cells; Label; Lasers; Lateral; Lead; Life; Link; Lipids; Liquid substance; Literature; Lymphocyte; Magic; Mammalian Cell; Mass Spectrum Analysis; Mature B-Lymphocyte; Measures; Mechanics; Mediating; Mediator of activation protein; Membrane; Membrane Proteins; Methods; Microscopic; Modeling; Molecular; Molecular Cloning; NMR Spectroscopy; Optics; Organelles; Partition Coefficient; Pathway interactions; Phase; Physiological; Play; Property; Protein Binding Domain; Proteins; Rattus; Reaction; Regulation; Research; Resolution; Role; Scanning; Signal Pathway; Signal Transduction; Signaling Protein; Symptoms; T-Lymphocyte; Temperature; Tertiary Protein Structure; Testing; Therapeutic; Therapeutic Intervention; Thermodynamics; Transition Temperature; Vesicle; calcium indicator; cost; crosslink; fluorescence imaging; mast cell; mathematical model; membrane model; novel strategies; preference; prevent; protein complex; protein distribution; receptor; response

DESCRIPTION (provided by applicant): The long-term objective of this project is to enhance the understanding of the earliest events in the response of immune system cells towards the presence of allergens (antigens). The initial effector cells in hypersensitive reactions to allergen invasion are mast cells. The signaling pathways in these cells that lead to degranulation and secretion of hormonal mediators causing inflammation and the symptoms of allergic hypersensitivity are well-understood overall, except for the mechanisms involved in initiating these pathways. It is widely accepted that cross-linking by multivalent antigen of IgE antibodies that are bound to the high affinity IgE receptor Fc5RI is necessary for stimulating degranulation by this receptor. How this cross-linking event is recognized at the inner plasma membrane leaflet, however, is not well understood. Biophysical elucidation of transmembrane signal transduction therefore has the potential to contribute to identifying strategies for therapeutic interference with pathological immune cell signaling. A large literature exists emphasizing the role of intra-membrane compositional heterogeneities in cell signaling. Dynamic compositional lateral heterogeneity is a necessary consequence of the non-ideal mixing properties of biological membranes, however, the functional importance of compositional fluctuations, or domains, is unclear. A major hindrance for progress in this important field of research is the conceptual division between the large experimental areas of lipid model membrane and cellular membrane research. We are using a novel approach to examine plasma membrane heterogeneity, consisting of optical microscopic and spectroscopic characterization of micron-sized plasma membrane vesicles obtained from immune cells. Our preliminary data indicate that the membranes of these vesicles can segregate into laterally coexisting fluid domains. Aim #1 is to characterize, by 1H MAS NMR and fluorescence imaging, the biophysics of fluid domain formation in plasma membranes depending on plasma membrane composition and a variety of additional physiologically relevant control parameters, including receptor crosslinking. This characterization will prepare us to achieve Aim #2 where we will quantitatively examine, by confocal fluorescence microscopy, the molecular details of how signaling proteins distribute among membrane domains. The resulting partition coefficients will allow for critical re-examination of current models for transmembrane signaling transduction, as well as motivate the development of mathematical models for the fine tuning of signaling fidelity by dynamic compositional heterogeneities. In Aim #3, we will compare the conditions governing domain formation in plasma membrane vesicles to cell signaling capacities in live cells and will clarify whether membrane composition poised near a mixing/demixing transition is an important principle in amplifying immune response to stimulation. Allergies affect more than 50 million Americans and cause significant suffering and costs to the health care system[1]. The absence of curing treatments is due in part to the lack of understanding how allergens stimulate immune system responses. Our research has the potential to elucidate mechanistic aspects of the earliest molecular events following allergen invasion and could therefore help identify strategies for preventing and treating allergic hypersensitivity.

描述（由申请人提供）：该项目的长期目标是加强对免疫系统细胞对过敏原（抗原）反应的早期事件的理解。在对过敏原侵袭的超敏反应中，最初的效应细胞是肥大细胞。除了启动这些通路的机制外，这些细胞中导致脱颗粒和激素介质分泌引起炎症和过敏性超敏反应症状的信号通路总体上已经得到了很好的理解。人们普遍认为，结合高亲和力IgE受体Fc5RI的IgE抗体的多价抗原交联是刺激该受体脱颗粒的必要条件。然而，这种交联事件是如何在内质膜小叶上被识别的，目前还不清楚。因此，跨膜信号转导的生物物理阐明有可能有助于确定治疗性干预病理性免疫细胞信号的策略。大量文献强调膜内成分异质性在细胞信号传导中的作用。动态成分横向异质性是生物膜非理想混合特性的必然结果，然而，成分波动或结构域的功能重要性尚不清楚。在这一重要研究领域取得进展的主要障碍是脂质模型膜和细胞膜研究的大实验领域之间的概念划分。我们正在使用一种新的方法来检查质膜的异质性，包括从免疫细胞中获得的微米大小的质膜囊泡的光学显微镜和光谱表征。我们的初步数据表明，这些囊泡的膜可以分离成横向共存的流体域。目的1是通过1H MAS NMR和荧光成像来表征质膜中流体域形成的生物物理学，这取决于质膜组成和各种额外的生理相关控制参数，包括受体交联。这种表征将为我们实现目标#2做好准备，我们将通过共聚焦荧光显微镜定量检查信号蛋白在膜结构域之间分布的分子细节。所得的分配系数将允许对跨膜信号转导的当前模型进行批判性的重新检查，并激励数学模型的发展，通过动态组成异质性来微调信号保真度。在Aim #3中，我们将比较控制质膜囊结构域形成的条件与活细胞中的细胞信号传导能力，并将阐明在混合/脱混过渡附近平衡的膜组成是否是放大免疫应答刺激的重要原则。过敏影响了5000多万美国人，给医疗保健系统带来了巨大的痛苦和成本。治疗方法的缺乏部分是由于缺乏对过敏原如何刺激免疫系统反应的了解。我们的研究有可能阐明过敏原入侵后最早分子事件的机制方面，因此可以帮助确定预防和治疗过敏性超敏反应的策略。

项目成果

Temperature-dependent phase behavior and protein partitioning in giant plasma membrane vesicles.

• DOI: 10.1016/j.bbamem.2010.03.009
• 发表时间: 2010-07
• 期刊: BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES
• 影响因子: 3.4
• 作者: Johnson, S. A.;Stinson, B. M.;Go, M. S.;Carmona, L. M.;Reminick, J. I.;Fang, X.;Baumgart, T.
• 通讯作者: Baumgart, T.