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着重要作用。T淋巴细胞信号异常是许多疾病的基础，包括自身免疫、哮喘和过敏。因此，解开支配T辅助细胞系承诺和功能的信号通路对于更好地了解支撑这些疾病状态的分子基础是至关重要的。细胞内钙离子浓度([Ca~(2+)]i)升高是调节多种T细胞功能的重要信号。钙信号模式的幅度和持续时间的变化对淋巴细胞的转录程序有不同的调节作用，但关于哪些钙通道介导这些信号并因此控制T细胞分化，人们知之甚少。T通道CaV3.1以其在大脑和心脏功能中的作用而闻名，它表达在NAVE T淋巴细胞上，调节静息膜电位下的钙离子进入，并在Th2分化过程中显著上调。T淋巴细胞中CaV3.1的基因缺失降低了基线的钙离子内流，对存储操作的钙内流(SOCE)没有影响，并使细胞偏向Th1分化。此外，删除CaV3.1抑制了GATA-3的表达，同时有利于T-bet的表达。这些观察结果提供了CaV3.1 T型钙通道调节Th1/Th2极化的证据，并提示CaV3.1介导的钙离子进入T淋巴细胞分化中具有令人惊讶的作用。本应用的目的是全面研究CaV3.1与Th淋巴细胞分化和功能相关的功能。我们建议通过实验来定义CaV3.1在Th分化中的要求(目标1)，剖析CaV3.1调节的信号通路(目标2)，并确定它是否调节导致常见免疫疾病如哮喘和各种过敏的Th2反应(目标3)。我们预计，拟议的实验结果将极大地增强我们对塑造T细胞分化所需的钙信号事件的分子本质的理解。

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.