Defining how T cells measure the strength of T cell receptor signals

定义 T 细胞如何测量 T 细胞受体信号的强度

• 批准号: 9895949
• 负责人: William Francis Hawse
• 金额: $ 19.45万
• 依托单位: UNIVERSITY OF PITTSBURGH AT PITTSBURGH
• 依托单位国家: 美国
• 财政年份: 2020
• 资助国家: 美国
• 起止时间: 2020-03-13 至 2022-02-28
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9895949
• 关键词: Antigens; Autoimmune Diseases; Binding; Biochemical; Biochemical Pathway; CD4 Positive T Lymphocytes; Cell membrane; Cell physiology; Cells; Computer Models; Coupling; Cytokine Signaling; Data; Development; Disease; Dose; Environment; Enzymes; FOXP3 gene; FRAP1 gene; Fostering; Generations; Genetic Transcription; Health; Helper-Inducer T-Lymphocyte; Immunity; Infection; Knowledge; Lead; Lipids; Maintenance; Measures; Mediator of activation protein; Metabolism; Modeling; Molecular; Output; PDPK1 gene; PTEN gene; Pathway interactions; Peptide/MHC Complex; Phosphatidylinositols; Phosphoric Monoester Hydrolases; Phosphorylation; Phosphotransferases; Positioning Attribute; Proteins; Proteomics; Proto-Oncogene Proteins c-akt; RNA Splicing; Receptor Activation; Receptor Signaling; Regulatory T-Lymphocyte; Role; Self Tolerance; Signal Pathway; Signal Transduction; Stimulus; Substrate Specificity; T cell differentiation; T cell response; T-Cell Activation; T-Cell Receptor; T-Lymphocyte; Testing; Th2 Cells; Therapeutic; Thymus Gland; Work; adaptive immune response; base; cell type; cellular transduction; chemical genetics; cytokine; engineered T cells; extracellular; genetic approach; immune function; interest; knowledge base; novel; phosphoinositide-3,4-bisphosphate; programs; receptor; response; simulation; tool

Abstract T cells are mediators of the adaptive immune response. To properly mount a response, T cells use extracellular receptors to sense their environment and transduce signals to intracellular signaling networks. While many signaling pathways relevant to T cell function are established, less is known about how these pathways are modulated to discriminate between different types of signals and thus represents a significant gap in our knowledge base. Such knowledge would aid in controlling T cell activation and differentiation in multiple therapeutic settings. One dominant signaling input is T cell receptor (TCR) signaling strength, which regulates T cell differentiation, thymic development and cytokine signaling. In previous work, we identified that the strength of the T cell receptor signal differentially regulated the AKT/mTOR signaling axis. TCR signal strength regulated the phosphorylation of AKT which in turn controls AKT substrate specificity so that different TCR signal strengths engage qualitatively different AKT signaling networks. While these results are intriguing, the basic biochemical mechanisms that couple TCR signal strength to downstream signaling networks including differential AKT activation remains ill defined. One pathway that could couple TCR signal strength to intracellular signaling networks is phosphatidylinositol (PIP) metabolism. Many PIP species are bioactive and regulate signaling, transcription, metabolism and RNA splicing. Following pMHC binding to TCR, PI3K phosphorylates PI(4,5)P2 to generate PIP3 at the cell membrane. PIP3 has garnered interest because it activates kinases important for immune function, including AKT and PDK1. However, other bioactive PIP lipid species are generated and their functions in T cells are ill established. Based on a computational model we built to study the AKT activation in a T cell, our simulation unexpectedly predicted that different TCR signal strengths would generate different PIPs. Experimentally, we found that other bioactive PIPs in addition to PIP3 are generated at appreciable levels during T cell activation and that different TCR signal strengths generate different PIP species. Our proteomic screen identified proteins in a T cell that bind to specific PIPs, which positions us to identify novel pathways that are engaged during T cell activation. The novel result that T cells transduce TCR signal strength by generating different PIPs has the potential to illuminate a basic biochemical mechanism for how T cell interprets extracellular signals. These preliminary data serve as the basis of our central hypothesis that T cells encode TCR signal strength by generating different phosphatidylinositols to control T cell fate decisions, which will be tested by: 1) identifying mechanisms that control differential generation of phosphatidylinositols in response to TCR signal strength and 2) identifying how differential generation of phosphatidylinositols functions in the Treg versus T helper cell fate choice and the Th1 versus Th2 cell fate choice. Taken together, results from this work will provide novel mechanisms of receptor signal integration at the molecular level and identify functions of differential phosphatidylinositol generation in the context of CD4+ T cell fate choices.

摘要 T细胞是适应性免疫应答的介质。为了正确地建立反应，T细胞使用细胞外 受体感知其环境并将信号传递给细胞内信号网络。虽然许多 虽然与T细胞功能相关的信号通路已经建立，但关于这些通路如何被激活的知之甚少。 调制以区分不同类型的信号，因此代表了我们的研究中的重大差距。 知识库这样的知识将有助于控制T细胞的活化和分化，在多个细胞中。 治疗环境。一个主要的信号输入是T细胞受体（TCR）信号强度，其调节T细胞受体（TCR）信号强度。 细胞分化、胸腺发育和细胞因子信号传导。在以前的工作中，我们发现， T细胞受体信号的差异调节AKT/mTOR信号轴。TCR信号强度调节 AKT磷酸化反过来控制AKT底物特异性， 参与不同性质的AKT信号网络。虽然这些结果很有趣，但基本的生物化学 将TCR信号强度耦合到包括差分AKT的下游信令网络的机制 激活仍然不明确。一种可以将TCR信号强度与细胞内信号传导结合的途径 磷脂酰肌醇（PIP）代谢。许多PIP物质具有生物活性并调节信号传导， 转录、代谢和RNA剪接。在pMHC与TCR结合后，PI 3 K将PI（4，5）P2磷酸化， 在细胞膜上产生PIP 3。PIP 3已经引起了人们的兴趣，因为它激活了对 免疫功能，包括AKT和PDK 1。然而，产生了其他生物活性PIP脂质种类，并且它们的生物活性也是如此。 T细胞的功能不健全。基于我们建立的一个计算模型来研究AKT激活， T细胞，我们的模拟出乎意料地预测不同的TCR信号强度将产生不同的PIP。 在实验上，我们发现除了PIP 3之外，其他生物活性PIPs在细胞周期中也以可观的水平产生。 T细胞活化和不同的TCR信号强度产生不同的PIP种类。我们的蛋白质组筛选 在T细胞中发现了与特定PIP结合的蛋白质，这使我们能够确定新的途径， 在T细胞活化过程中参与。新的结果是T细胞通过产生TCR信号强度， 不同的PIP有可能阐明T细胞如何翻译细胞外信号的基本生化机制， 信号.这些初步数据作为我们的中心假设的基础，即T细胞编码TCR信号 通过产生不同的磷脂酰肌醇来控制T细胞命运决定，这将通过以下方式进行测试：1） 识别响应TCR信号控制磷脂酰肌醇差异产生的机制 强度和2）鉴定磷脂酰肌醇的差异产生如何在Treg与T细胞中起作用 辅助细胞命运选择和Th 1对Th 2细胞命运选择。总之，这项工作的结果将提供 在分子水平上研究受体信号整合的新机制， 在CD 4 + T细胞命运选择的背景下磷脂酰肌醇的产生。