Signaling Functions of the Tumor Suppressor CYLD

肿瘤抑制因子 CYLD 的信号传导功能

• 批准号: 7493501
• 负责人: Shao-Cong Sun
• 金额: $ 36.67万
• 依托单位: UNIVERSITY OF TX MD ANDERSON CAN CTR
• 依托单位国家: 美国
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-07-01 至 2010-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7493501
• 关键词: Address; Autoimmunity; Binding; Biochemical; Biological Process; CD8B1 gene; Cell Count; Cell Line; Data; Defect; Deubiquitinating Enzyme; Development; Event; Experimental Autoimmune Encephalomyelitis; Family; Family member; Genetic; Immune response; Immunologic Receptors; Knockout Mice; Laboratories; Limb structure; Localized; Mature Thymocyte; Mediating; Mitogens; Molecular; Mus; Numbers; Peripheral; Phenotype; Phosphorylation; Phosphorylation Site; Phosphotransferases; Physiological; Play; Positioning Attribute; Protein Tyrosine Kinase; Proteins; Publishing; Regulation; Research Personnel; Role; Serine; Signal Transduction; Site; Solid; Staging; Symptoms; T-Cell Activation; T-Cell Development; T-Lymphocyte; Tail; Thymocyte Development; Thymocyte Selection; Tumor Necrosis Factor Receptor; Tumor Suppressor Proteins; Tyrosine Phosphorylation; Ubiquitin-Conjugating Enzymes; Ubiquitination; Work; ZAP-70 Gene; base; enzyme activity; insight; novel; programs; receptor; response; thymocyte

DESCRIPTION (provided by applicant): CYLD is a recently identified deubiquitinating enzyme (DUB) that negatively regulates the signaling events mediated by immune receptors, such as TNF receptors (TNFRs). To understand the physiological function of CYLD, we have generated CYLD knockout mice and undertaken extensive characterization analyses. These genetic studies have revealed a critical role for CYLD in regulating T-cell development and activation. CYLD-deficient mice have a severe defect in generating CD4 and CD8 mature thymocytes, resulting in more than 50% reduction in peripheral T-cell numbers. Interestingly, despite their lower numbers, the CYLD-/- peripheral T cells are hyper-responsive to TCR stimulation. These findings suggest that CYLD plays critical but distinct roles in regulating thymocyte development and peripheral T-cell activation. The overall objective of this revised application is to understand the molecular mechanism by which CYLD regulates T-cell development and activation. As a critical step towards achieving this objective, we have identified the protein tyrosine kinase LCK as a specific target of CYLD. CYLD physically interacts with LCK in thymocytes in response to TCR stimulation and inhibits the ubiquitination of LCK. CYLD regulates the inducible binding of LCK to its target ZAP-70, thereby participating in TCR-proximal signaling events. These findings provide an important insight into the mechanism by which CYLD positively regulates thymocyte development. Since CYLD negatively regulates peripheral T-cell activation, these findings also raise a number of intriguing questions. Does CYLD possess opposing functions in regulating TCR signaling of developing and peripheral T cells? Does CYLD negatively regulate T-cell costimulatory receptors, especially TNFR family members? Does CYLD serve as an intrinsic negative regulator of peripheral T cells or act indirectly through regulating thymocyte development? Another important question is how the signaling function of CYLD is regulated. In this regard, we have shown that CYLD is phosphorylated along with the activation of both thymocytes and peripheral T cells, thus suggesting the intriguing possibility that the signaling function of CYLD is subject to regulation by its phosphorylation. We will perform three specific aims to address these questions and to achieve our overall objective. (1) Characterize the molecular mechanism by which CYLD regulates thymocyte development and TCR signaling. (2) Examine how CYLD negatively regulates peripheral T-cell activation and whether the CYLD deficiency causes autoimmunity. (3) Investigate the biochemical mechanism and functional significance of CYLD phosphorylation.

描述（由申请人提供）：CYLD 是一种最近鉴定的去泛素化酶（DUB），它对免疫受体（例如 TNF 受体（TNFR））介导的信号事件进行负调节。为了了解 CYLD 的生理功能，我们培育了 CYLD 敲除小鼠并进行了广泛的表征分析。这些遗传学研究揭示了 CYLD 在调节 T 细胞发育和激活中的关键作用。 CYLD缺陷小鼠在生成CD4和CD8成熟胸腺细胞方面存在严重缺陷，导致外周T细胞数量减少50%以上。有趣的是，尽管 CYLD-/- 外周 T 细胞数量较少，但它们对 TCR 刺激反应过度。这些发现表明 CYLD 在调节胸腺细胞发育和外周 T 细胞激活中发挥着关键但独特的作用。 此次修订的申请的总体目标是了解 CYLD 调节 T 细胞发育和激活的分子机制。作为实现这一目标的关键一步，我们已确定蛋白酪氨酸激酶 LCK 作为 CYLD 的特定靶点。 CYLD 响应 TCR 刺激与胸腺细胞中的 LCK 发生物理相互作用，并抑制 LCK 的泛素化。 CYLD 调节 LCK 与其靶标 ZAP-70 的诱导性结合，从而参与 TCR 近端信号传导事件。这些发现为 CYLD 积极调节胸腺细胞发育的机制提供了重要的见解。由于 CYLD 负向调节外周 T 细胞激活，这些发现也提出了许多有趣的问题。 CYLD 在调节发育中 T 细胞和外周 T 细胞的 TCR 信号传导方面是否具有相反的功能？ CYLD 是否负向调节 T 细胞共刺激受体，尤其是 TNFR 家族成员？ CYLD 是作为外周 T 细胞的内在负调节因子还是通过调节胸腺细胞发育间接发挥作用？另一个重要问题是CYLD的信号功能是如何调控的。在这方面，我们已经证明CYLD随着胸腺细胞和外周T细胞的激活而被磷酸化，从而表明CYLD的信号传导功能可能受到其磷酸化的调节。我们将实现三个具体目标来解决这些问题并实现我们的总体目标。 (1) 表征CYLD调节胸腺细胞发育和TCR信号传导的分子机制。 (2)检查CYLD如何负向调节外周T细胞活化以及CYLD缺陷是否导致自身免疫。 (3)研究CYLD磷酸化的生化机制及功能意义。