Characterization of new Ca2+ channels that underpin immunological decision making

描述（由申请人提供）：CD4+ T细胞在协调免疫反应中起基本作用。异常的T淋巴细胞信号是包括自身免疫、哮喘和过敏在内的许多疾病发病机制的基础。因此，揭示控制辅助性T细胞谱系承诺和功能的信号通路对于更好地理解支撑这些疾病状态的分子基础至关重要。细胞内钙离子浓度（[Ca2+]i）的增加是调节许多T细胞功能的重要信号。Ca2+信号模式的振幅和持续时间的变化对淋巴细胞的转录程序有差异调节，但很少有人了解哪些Ca2+通道介导这些信号并因此控制T细胞分化。T型通道CaV3.1以其在脑和心脏功能中的作用而闻名，在中T淋巴细胞上表达，在静息膜电位下调节Ca2+进入，并在Th2分化过程中显著上调。从基因上删除T淋巴细胞中的CaV3.1会降低基线Ca2+内流，对储存操作的Ca2+进入（SOCE）没有影响，并使细胞向Th1分化倾斜。此外，删除CaV3.1会抑制Gata-3的表达，而有利于T-bet的表达。这些观察结果提供了CaV3.1 T型Ca2+通道调节Th1/Th2极化的证据，并提示CaV3.1介导的Ca2+进入在T淋巴细胞分化中的惊人作用。本应用的目的是充分表征CaV3.1的功能，因为它与Th淋巴细胞分化和功能有关。我们提出实验来定义CaV3.1在Th分化中的需求（Aim 1），解剖CaV3.1调节的信号通路（Aim 2），并确定它是否调节Th2反应，这些反应是哮喘和各种过敏等常见免疫疾病的基础（Aim 3）。我们预计，所提出的实验结果将大大提高我们对塑造T细胞分化所需的Ca2+信号事件的分子性质的理解。

DESCRIPTION (provided by applicant): CD4+ T cells play a fundamental role in orchestrating immune responses. Aberrant T lymphocyte signaling underlies the pathogenesis of numerous diseases including autoimmunity, asthma and allergy. Therefore, unraveling the signaling pathways that govern T helper lineage commitment and function is crucial toward gaining a better understanding the molecular basis underpinning these disease states. An increase in intracellular calcium ion concentration ([Ca2+]i) is an essential signal that regulates numerous T cellular functions. Variations in both the amplitude and duration of Ca2+ signaling patterns differentially regulate transcriptional programs in lymphocytes, yet little is understood as to which Ca2+ channels mediate these signals and consequently control T cell differentiation. The T-type channel CaV3.1, best known for its role in brain and cardiac function, is expressed on nave T lymphocytes, regulates a Ca2+ entry at resting membrane potentials and is dramatically up-regulated during Th2 differentiation. Genetically deleting CaV3.1 in T lymphocytes decreases baseline Ca2+ influx, has no impact on store-operated Ca2+ entry (SOCE) and skews the cells towards Th1 differentiation. Moreover, deleting CaV3.1 prevents Gata-3 expression while favoring T-bet expression. These observations provide evidence that CaV3.1 T-type Ca2+ channels regulates Th1/Th2 polarization and suggest a surprising role for CaV3.1- mediated Ca2+ entry in T lymphocyte differentiation. The objective of this application is to fully characterize the function of CaV3.1 as it relates to Th lymphocyte differentiation and function. We propose experiments to define the requirement of CaV3.1 in Th differentiation (Aim 1), dissect the signaling pathways that CaV3.1 regulates (Aim 2) and determine if it regulates Th2 responses that underlie common immune diseases such as asthma and various allergies (Aim 3). We anticipate that the outcomes of the proposed experiments will greatly enhance our understanding of the molecular nature of Ca2+ signaling events required to shape T cell differentiation.