UBIQUITYLATION AND THE REGULATION OF IMMUNE HOMOSTASIS

这个子项目是许多利用资源的研究子项目之一 由NIH/NCRR资助的中心赠款提供。子项目的主要支持 子项目的主要研究者可能是由其他来源提供的， 包括其它NIH来源。 列出的子项目总成本可能 表示子项目使用的中心基础设施的估计数量， NCRR赠款不直接向子项目或子项目工作人员提供资金。 真核细胞上的Toll样受体（TLR）介导微生物分子的识别并调节宿主对微生物病原体的应答。TLR信号的适当调节不仅限制炎症反应的强度和持续时间，而且还可以维持肠道中的免疫稳态，其中过多的微生物病原体与宿主细胞共存。我们实验室最近的研究表明，A20是一种新的蛋白质，它是终止髓系细胞上TLR诱导的信号和防止体内过度炎症反应所必需的。我们的初步数据表明，A20是必要的限制TLR信号在体内。此外，我们的研究结果表明，A20可能是一种新的酶，通过直接调节TLR信号蛋白如TRAF 6的泛素化状态来执行这一关键功能。这些修饰可能导致TLR信号传导蛋白的失活和降解。这些令人兴奋的初步发现为我们提供了独特的机会来测试我们的中心假设，即A20调节信号蛋白，TLR信号和免疫稳态的泛素化。该申请代表了Ma实验室的遗传和细胞专业知识与Pickart实验室的生物化学专业知识之间的协同努力，以确定：（i）A20是否是调节小鼠TLR反应所必需的;（ii）A20是否调节关键TLR信号蛋白的泛素化;（iii）A20是否调节关键TLR信号蛋白的泛素化。以及（iii）A20如何识别泛素化蛋白质并可能同时作为去泛素化酶和E3发挥功能。在后一种方法中，质谱分析对于理解A20如何修饰泛素化蛋白质至关重要。选定的TLR信号传导蛋白将作为推定的底物进行检查，A20的去泛素化和泛素化功能将在候选底物上进行评估。这些研究的结果有望对A20如何将泛素化调控与疾病联系起来产生重要的见解。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. Toll like receptors (TLRs) on eukaryotic cells mediate the recognition of microbial molecules and regulate host responses to microbial pathogens. Proper regulation of TLR signals not only restricts the intensity and duration of inflammatory responses, but may also maintain immune homeostasis in the intestine, where a plethora of microbial pathogens co-exist with host cells. Recent studies from our labs indicate that A20 is a novel protein that is required for terminating TLR induced signals on myeloid cells and for preventing excessive inflammatory responses in vivo. Our preliminary data suggest that A20 is essential for restricting TLR signals in vivo. Moreover, our findings suggest that A20 may be a novel enzyme that performs this critical function by directly modulating the ubiquitylation status of TLR signaling proteins such as TRAF6. These modifications may cause both de-activation and degradation of TLR signaling proteins. These exciting preliminary findings provide us with unique opportunities to test our central hypothesis that A20 regulates ubiquitylation of signaling proteins, TLR signals, and immune homeostasis. This application represents a synergistic effort between the genetic and cellular expertises of the Ma lab and the biochemical expertise of the Pickart lab to determine: (i) whether A20 is essential for regulating TLR responses in mice; (ii) whether A20 regulates ubiquitylation of critical TLR signaling proteins; and (iii) how A20 recognizes ubiquitylated proteins and may function as both a de-ubiquitylating enzyme and an E3. In the latter approach, mass spectroscopic analysis will be essential for understanding how A20 modifies ubiquitylated proteins. Selected TLR signaling proteins will be examined as putative substrates, and both A20's de-ubiquitylating and ubiquitylating functions will be assessed on candidate substrates. Results from these studies promise to yield significant insights into how A20 links the regulation of ubiquitylation with disease.