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.

抽象的 T 细胞是适应性免疫反应的介质。为了正确地产生反应，T 细胞使用细胞外 受体感知环境并将信号转导至细胞内信号网络。虽然很多 与 T 细胞功能相关的信号通路已建立，但人们对这些通路的具体机制知之甚少 调制以区分不同类型的信号，因此代表了我们的显着差距 知识库。这些知识将有助于控制多种 T 细胞的激活和分化。 治疗设置。一种主要的信号输入是 T 细胞受体 (TCR) 信号强度，它调节 T 细胞分化、胸腺发育和细胞因子信号传导。在之前的工作中，我们确定了强度 T 细胞受体信号的差异性调节 AKT/mTOR 信号轴。 TCR 信号强度调节 AKT 的磷酸化反过来控制 AKT 底物特异性，从而产生不同的 TCR 信号强度 参与质量不同的 AKT 信号网络。虽然这些结果很有趣，但基本的生化 将 TCR 信号强度耦合到下游信号网络（包括差分 AKT）的机制 激活仍然不明确。一种将 TCR 信号强度与细胞内信号传导耦合的途径 网络是磷脂酰肌醇（PIP）代谢。许多 PIP 物种具有生物活性并调节信号传导， 转录、代谢和RNA剪接。 pMHC 与 TCR 结合后，PI3K 磷酸化 PI(4,5)P2 在细胞膜上生成 PIP3。 PIP3 引起了人们的兴趣，因为它可以激活对生命至关重要的激酶。 免疫功能，包括AKT和PDK1。然而，会产生其他生物活性 PIP 脂质种类，并且它们的 T 细胞的功能尚未确定。基于我们为研究 AKT 激活而建立的计算模型 T细胞，我们的模拟意外地预测到不同的TCR信号强度会产生不同的PIP。 通过实验，我们发现除 PIP3 之外的其他生物活性 PIP 在 T 细胞激活和不同的 TCR 信号强度会产生不同的 PIP 种类。我们的蛋白质组筛选 鉴定了 T 细胞中与特定 PIP 结合的蛋白质，这使我们能够鉴定新的途径 T 细胞激活期间参与。 T细胞通过产生信号转导TCR信号强度的新结果 不同的 PIP 有可能阐明 T 细胞如何解释细胞外的基本生化机制 信号。这些初步数据是我们中心假设的基础，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 细胞命运决定的强度，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生成的机制 强度和 2) 确定磷脂酰肌醇的差异生成如何在 Treg 与 T 中发挥作用 辅助细胞命运选择和 Th1 与 Th2 细胞命运选择。总而言之，这项工作的结果将提供 分子水平上受体信号整合的新机制并确定差异的功能 CD4+ T 细胞命运选择背景下磷脂酰肌醇的生成。