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是最近确定的去泛素化酶（DUB），对免疫受体（例如TNF受体（TNFRS））介导的信号事件负调节。为了了解CYLD的生理功能，我们已经产生了CYLD基因敲除小鼠并进行了广泛的特征分析。这些遗传研究揭示了CYLD在调节T细胞发育和激活中的关键作用。 CYLD缺陷小鼠在产生CD4和CD8成熟的胸腺细胞时具有严重的缺陷，导致周围T细胞数量降低了50％以上。有趣的是，尽管数量较低，但CYLD - / - 周围T细胞对TCR刺激具有超反应性。这些发现表明，CYLD在调节胸腺细胞发育和周围T细胞激活中起着至关重要但独特的作用。 该修订后的应用的总体目的是了解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步骤，我们已经将蛋白质酪氨酸激酶LCK确定为CYLD的特定靶标。 Cyld响应TCR刺激而在胸腺细胞中与LCK物理相互作用，并抑制LCK的泛素化。 CYLD调节LCK与其靶标ZAP-70的诱导结合，从而参与TCR-Proximal信号传导事件。这些发现提供了对CYLD积极调节胸腺细胞发育的机制的重要见解。由于CYLD对周围T细胞激活进行负面调节，因此这些发现也引发了许多有趣的问题。 CYLD在调节发育和周围T细胞的TCR信号传导方面是否具有相反的功能？ CYLD会对T细胞共刺激受体，尤其是TNFR家族成员负面调节？ CYLD是外周T细胞的固有负调节剂还是通过调节胸腺细胞发育而间接起作用？另一个重要的问题是如何调节CYLD的信号传导函数。在这方面，我们表明CYLD与胸腺细胞和外围T细胞的激活一起被磷酸化，因此表明CYLD的信号传导功能受其磷酸化的调节可能引起的可能性。我们将执行三个特定的目标，以解决这些问题并实现我们的整体目标。 （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如何负面调节周围T细胞激活以及CYLD缺乏是否引起自身免疫性。 （3）研究CYLD磷酸化的生化机制和功能意义。