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体。为了正确安装响应，T细胞使用细胞外 受体感知其环境并将信号传递到细胞内信号网络。而很多 建立了与T细胞功能相关的信号通路，对这些途径的了解少知道 调节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。这种知识将有助于控制T细胞激活和分化多个 治疗环境。一个主要信号输入是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。在以前的工作中，我们确定了力量 T细胞受体信号的差异调节AKT/MTOR信号轴。调节TCR信号强度 AKT的磷酸化又控制AKT底物特异性，因此不同的TCR信号强度 参与定性不同的AKT信号网络。虽然这些结果很有趣，但基本的生化 将TCR信号强度与包括差异AKT的下游信号网络相对的机制 激活仍然不明显。一种可以将TCR信号强度与细胞内信号传导相结合的途径 网络是磷脂酰肌醇（PIP）代谢。许多PIP物种具有生物活性和调节信号传导， 转录，代谢和RNA剪接。 PMHC与TCR结合后，PI3K磷酸化PI（4,5）P2至 在细胞膜上产生PIP3。 PIP3引起了兴趣，因为它激活激活激酶对 免疫功能，包括AKT和PDK1。但是，产生了其他生物活性PIP脂质物种，它们的 建立了T细胞中的功能。基于我们构建的计算模型，以研究Akt激活 T细胞，我们的模拟意外预测，不同的TCR信号强度将产生不同的PIP。 在实验上，我们发现除PIP3以外，其他生物活性PIP在相当的水平上生成 T细胞激活，并且不同的TCR信号强度会产生不同的PIP物种。我们的蛋白质组学屏幕 在T细胞中鉴定出与特定PIP结合的蛋白 在T细胞激活过程中参与。 T细胞通过产生TCR信号强度传递TCR信号强度的新型结果 不同的PIP有可能照亮基本的生化机制，用于T细胞如何解释细胞外 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细胞命运决策，强度将通过：1） 识别控制磷脂酰肌醇响应TCR信号的机制 强度和2）确定磷脂酰肌醇的差异产生如何在Treg与T中起作用 助手细胞命运选择，TH1与Th2细胞命运选择。综上所述，这项工作的结果将提供 分子水平上受体信号整合的新型机制，并识别差异的功能 在CD4+ T细胞命运选择的背景下，磷脂酰肌醇的产生。