Signaling Functions of the Tumor Suppressor CYLD

肿瘤抑制因子 CYLD 的信号传导功能

• 批准号: 7150300
• 负责人: Shao-Cong Sun
• 金额: $ 36.02万
• 依托单位: PENNSYLVANIA STATE UNIV HERSHEY MED 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 2007-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7150300
• 关键词: neoplasm /cancer; phosphorylation

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是最近鉴定的去泛素化酶（DUB），其负调节由免疫受体（如TNF受体（TNFR））介导的信号传导事件。为了了解CYLD的生理功能，我们已经产生了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细胞发育和活化中的关键作用。CYLD缺陷小鼠在产生CD 4和CD 8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，尽管它们的数量较低，但CYLD-/-外周T细胞对TCR刺激具有高度反应性。这些发现表明CYLD在调节胸腺细胞发育和外周T细胞活化中起着关键但独特的作用。 本修订申请的总体目标是了解CYLD调节T细胞发育和活化的分子机制。作为实现这一目标的关键一步，我们已经确定了蛋白酪氨酸激酶LCK作为CYLD的特异性靶点。CYLD与胸腺细胞中的LCK物理相互作用以响应TCR刺激并抑制LCK的泛素化。CYLD调节LCK与其靶ZAP-70的诱导型结合，从而参与TCR近端信号传导事件。这些发现提供了一个重要的洞察机制，CYLD积极调节胸腺细胞的发展。由于CYLD负调节外周T细胞活化，这些发现也提出了一些有趣的问题。CYLD在调节发育和外周T细胞的TCR信号转导中是否具有相反的功能？CYLD是否负调节T细胞共刺激受体，尤其是TNFR家族成员？CYLD是否作为外周T细胞的内在负调节因子或通过调节胸腺细胞发育间接起作用？另一个重要的问题是CYLD的信号功能是如何调节的。在这方面，我们已经表明，CYLD是磷酸化沿着与胸腺细胞和外周T细胞的激活，从而表明有趣的可能性，CYLD的信号转导功能受到其磷酸化的调节。我们将执行三个具体目标，以解决这些问题，并实现我们的总体目标。(1)描述CYLD调节胸腺细胞发育和TCR信号传导的分子机制。(2)检查CYLD如何负调节外周T细胞活化，以及CYLD缺乏是否会导致自身免疫。(3)探讨CYLD磷酸化的生化机制及功能意义。