Novel Requirements for Akt1 in T Cell Commitment

T 细胞承诺中对 Akt1 的新要求

基本信息

批准号：
9246741
负责人：
Yina Hsing Huang
金额：
$ 45.73万
依托单位：
DARTMOUTH COLLEGE
依托单位国家：
美国
项目类别：
财政年份：
2011
资助国家：
美国
起止时间：
2011-02-15 至 2021-12-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/9246741
关键词：
1-Phosphatidylinositol 3-Kinase Ablation Acute T Cell Leukemia Adaptive Immune System Address Affect Attention Attenuated B-Lymphocytes Binding CD8B1 gene Cell Line Cell Lineage Cell Survival Cell membrane Cells Couples Cytokine Receptors Defect Dependency Development Disease Dose ES01 Ensure FRAP1 gene Family Feedback Gene Expression Regulation Generations Genes Genetic Transcription Homologous Protein Hyperactive behavior Immunologic Deficiency Syndromes Inositol Investigation Kinetics Lead Ligands Lipids Malignant Epithelial Cell Mediating Membrane Metabolic Metabolism Modeling PDPK1 gene PH Domain PTEN gene Pathologic Pathway interactions Phenotype Phosphoric Monoester Hydrolases Phosphorylation Phosphotransferases Physiological Polyphosphates Protein Isoforms Protein-Serine-Threonine Kinases Proteins Readiness Recruitment Activity Regulatory T-Lymphocyte Role Signal Transduction Surface T cell activating factor T cell regulation T cell transcription factor 1 T-Cell Development T-Cell Receptor T-Lymphocyte Thymocyte Development Thymus Gland Time To specify Transcript Transcription Coactivator Transcriptional Regulation alpha-beta T-Cell Receptor attenuation beta catenin cell growth cell type gene product glucose metabolism member notch protein novel premature progenitor receptor thymocyte transcription factor

项目摘要

ABSTRACT Akt1, Akt2 and Akt3 are members of a family of serine/threonine kinases that are key effectors of PI3K. The Akt family has been well characterized to promote cell survival, glucose metabolism and proliferation in many cell types including developing T cells. Thymocytes express all Akt isoforms to varying degrees. Ablation of single or multiple Akt genes results in differential blocks in T cell development. Loss of all three Akt isoforms leads to an early developmental defect due to decreased survival of CD4–CD8– double negative (DN) thymocytes. Expression of Akt2 or Akt3 alone is sufficient to preserve DN survival; however, DN3 differentiation and DN4 thymocyte proliferation remain defective along with survival of cells at later developmental stages. These distinct phenotypes suggest either that different Akt isoforms regulate distinct functions or that different doses of Akt activity are required to promote stage-specific cell survival, proliferation and differentiation. With no current evidence for isoform-specific functions, we focused our attention on characterizing mechanisms for regulating the dose of Akt activity. Surface receptors, including (pre-)T cell receptor and cytokine receptors, activate PI3K to generate PIP3. Interactions between PIP3 and the Pleckstrin homology (PH) domain of Akt are required to recruit Akt to the plasma membrane for activation. Thus, fine control of PI3K activity and PIP3 availability can directly regulate Akt activation levels. This application addresses an increasingly important alternative mechanism for indirectly controlling Akt activity: via generation of IP4, a soluble inositol polyphosphate that is structurally similar to PIP3. IP4 is generated following (pre)TCR stimulation and competes with PIP3 for binding to the Akt PH domain. Thymocytes deficient in IP4 activate Akt excessively following expression of preTCR at the DN3 and DN4 stages. Strikingly, Akt hyperactivity leads to accelerated β selection, premature reprogramming to glycolytic metabolism and loss of Notch dependency. This leads us to propose the global hypotheses that 1) preTCR- induced IP4 generation restricts Akt-dependent metabolic reprogramming and proliferation to ensure adequate Notch signaling and 2) preTCR and Notch cooperative signaling is required for T cell lineage specification. Successful completion of this study will shift our current understanding of T lineage specification by revealing 1) an unexpected requirement for preTCR in imposing a Notch checkpoint and in co-stimulating Notch function, 2) a novel preTCR feedback mechanism that controls DN thymocyte proliferation/maturation via tuning of Akt activity and metabolic reprogramming; and 3) a non-canonical pathway for activating TCF1-dependent transcription to specify T cell commitment.

抽象的 Akt1、Akt2 和 Akt3 是丝氨酸/苏氨酸激酶家族的成员，是 PI3K 的关键效应子。 Akt 家族已被充分表征，可促进细胞存活、葡萄糖代谢和增殖许多细胞类型，包括发育中的胸腺细胞，都不同程度地表达所有 Akt 亚型。单个或多个 Akt 基因的消融会导致 T 细胞发育的差异性阻断。 Akt 同工型由于 CD4–CD8– 双体存活率降低而导致早期发育缺陷阴性 (DN) 胸腺细胞单独表达 Akt2 或 Akt3 足以维持 DN 存活； DN3 分化和 DN4 胸腺细胞增殖仍然存在缺陷，并且细胞随后存活这些不同的表型表明不同的 Akt 亚型调节不同的作用。功能或需要不同剂量的 Akt 活性来促进特定阶段的细胞存活，由于目前没有同工型特异性功能的证据，我们将重点放在我们的研究上。关注调节 Akt 活性剂量的特征机制，包括表面受体。 (前)T 细胞受体和细胞因子受体激活 PI3K 以产生 PIP3 和 PIP3 之间的相互作用。 Akt 的 Pleckstrin 同源 (PH) 结构域需要将 Akt 招募到质膜上因此，精细控制 PI3K 活性和 PIP3 可用性可以直接调节 Akt 激活水平。该应用程序解决了一种日益重要的间接控制 Akt 的替代机制活性：通过生成IP4，一种可溶性肌醇多磷酸盐，其结构与PIP3相似。 (前)TCR 刺激后产生，并与 PIP3 竞争与 Akt PH 结构域的结合。 IP4 缺陷的胸腺细胞在 DN3 和 DN4 表达 preTCR 后过度激活 Akt 引人注目的是，Akt 过度活跃会加速 β 选择，过早重编程为糖酵解。代谢和Notch依赖性的丧失这导致我们提出以下总体假设：1) preTCR- 诱导的 IP4 生成限制 Akt 依赖性代谢重编程和增殖，以确保 T 细胞谱系需要足够的 Notch 信号传导和 2) preTCR 和 Notch 协同信号传导这项研究的成功完成将改变我们目前对 T 谱系的理解。规范，揭示了 1) 在强加 Notch 检查点时对 preTCR 的意外要求以及共刺激Notch功能，2）控制DN胸腺细胞的新型preTCR反馈机制通过调节 Akt 活性和代谢重编程实现增殖/成熟；3) 非规范性；激活 TCF1 依赖性转录以指定 T 细胞定向的途径。