Mechanisms & Energetics of Transmembrane-induced Signaling of Cytokine Receptors

描述(由申请人提供)：膜蛋白的跨膜(TM)结构域如何通过细胞膜传递信号长期以来一直是生物学中非常感兴趣的主题。最近，细胞因子受体超家族的激活机制发生了范式转变。细胞因子激素与胞外结构域结合的作用现在被认为是预二聚化的TM结构域构象变化的“诱导者”，从而触发随后的细胞内反应。这与其作为“组织者”的传统角色截然不同，后者的唯一功能是启动受体TM二聚体的形成。我们的长期目标是描述TM诱导的各种单程TM受体在配体结合后从无效到活跃转变过程中的信号机制和伴随的能量学。我们的假设是，非活跃的离态构象比活跃的开态构象稳定得多，配体结合的主要作用是破坏锁定在关态结构中的预二聚化(能量稳定的)TM-TM接触，指导(能量不稳定的)开态结构。在这个方案中，我们将使用人生长激素受体(HGHR)和人催乳素受体(HPRLR)作为同源二聚体TM诱导激活的原型模型系统。这项建议的目的是通过创新的、多学科的计算和实验相结合的方法，确定hGHR和hPRLR TM二聚体的界面残基，并阐明激活过程中的构象和能量变化。该项目的成功完成将对该领域产生重大影响，不仅通过阐明TM信号机制和能量学，而且通过提供计算和实验方法，可以用来表征其他细胞因子受体的生物激活过程和大量的其他单通路TM受体，这些都对生物学和人类健康至关重要。 公共卫生相关性：膜蛋白的跨膜区如何通过细胞膜传递信号长期以来一直是生物学中感兴趣的和挑战的主题。本项目不仅试图阐明跨膜信号转导机制和能量学，而且还提供了计算和实验方法，可用于表征其他细胞因子受体的生物激活过程和丰富的其他单程跨膜受体，这些都对生物学和人类健康具有至关重要的意义。

DESCRIPTION (provided by applicant): How transmembrane (TM) domains of membrane proteins transmit the signal across the cell membrane has long been a subject of keen interest in biology. There is a recent paradigm shift in the mechanism of activation for the cytokine receptor superfamily. The role of cytokine hormone binding to the extracellular domain is now recognized as an "inducer" of the conformational change of pre-dimerized TM domains that triggers subsequent intracellular responses. This is drastically different from its traditional role as an "organizer" whose sole function was to initiate the receptor TM dimer formation. Our long-term objective is to delineate the mechanisms and accompanying energetics of TM-induced signaling of various single-pass TM receptors during the inactive to active transition upon ligand binding. Our hypothesis is that the inactive off-state conformation is much more stable than the active on-state one, and the major role of ligand binding is to disrupt the pre-dimerized (energetically stable) TM-TM contact that locks-in the off-state structure, to direct the (energetically unstable) on-state structure. In this proposal, we will use human growth hormone receptor (hGHR) and human prolactin receptor (hPRLR) as prototypical model systems for homodimeric TM-induced activation. The objectives of this proposal are to determine the interfacial residues of hGHR and hPRLR TM dimers and to elucidate the conformational and energetic changes during the activation process by innovative, multidisciplinary combination of versatile computational and experimental approaches. The successful completion of this project will have a significant impact on the field, not only by elucidating the TM signaling mechanism and energetics, but also by providing the computational and experimental methods that can be used to characterize the biological activation process of other cytokine receptors and the plentitude of other single-pass TM receptors, which all have the critical importance to biology and thus, human health. PUBLIC HEALTH RELEVANCE: How transmembrane domains of membrane proteins transmit the signal across the cell membrane has long been a subject of interest and challenge in biology. This project seeks to not only elucidate the transmembrane signaling mechanism and energetics, but also provide the computational and experimental methods that can be used to characterize the biological activation process of other cytokine receptors and the plentitude of other single-pass transmembrane receptors, which all have the critical importance to biology and thus, human health.