Functions of Ub-like Proteins & Processing Proteases

描述（由申请人提供）：去泛素化酶（deubiquitination enzyme, DUBs）是一种重要的调节蛋白酶，它处理泛素基因家族的初级基因产物，逆转泛素与细胞蛋白的结合，并分解靶蛋白的多泛素链，以供蛋白酶体降解。因此，它们调节蛋白质水解，从而通过细胞周期、信号转导途径、应激反应、抗原呈递、染色质结构、受体内化和内吞作用进行进展。直到最近才认识到，其他泛素样（Ubl）蛋白对蛋白质的修饰具有类似的靶向功能。这项资助的基本假设是，通过解偶联泛素样蛋白对Ubl通路的调节可能同样重要，在癌症、生长和细胞凋亡的调节中发挥作用。逆转UbI蛋白偶联的酶（泛素样蛋白蛋白酶，ULP）是进一步研究的有吸引力的目标，因为这些修饰的逆转预计会干扰功能。由于它们是蛋白酶，大量的研究工作提出了有效的药物干预方法。此外，通过过表达解偶联酶来干扰这些途径（概念上和实践上）比阻止UbI结构域的附着更容易；一种需要基因敲除或显性阴性方法的方法。理解这些解偶联酶的作用需要我们对这类酶、它们的底物和调控有更多的了解。ulp的一系列抑制剂和底物将被合成并用于测试三个特定的假设。首先，威尔金森博士将验证一个假设，即哺乳动物cop9信号体的一个完整亚基能够逆转cullins的Nedd8修饰。他还将通过识别和干扰逆转这种修饰的酶的功能，来验证ISG15对蛋白质的修饰是干扰素反应的一个组成部分的假设。他将确定促凋亡的Ubl FAT10的偶联是否可逆。最后，他将验证HAUSP和/或SENPI是将SUMO-1从早幼粒细胞白血病蛋白中移除，触发PML分解的Ubl的假设。

DESCRIPTION (provided by applicant): Deubiquitinating enzymes (DUBs, also known as deconjugating enzymes) are important regulatory proteases that process the primary gene products of the ubiquitin gene family, reverse the conjugation of ubiquitin to cellular proteins, and disassemble the polyubiquitin chains that target proteins for degradation by the proteasome. As such, they regulate proteolysis and thereby progression through the cell cycle, signal transduction pathways, the stress response, antigen presentation, chromatin structure, receptor internalization and endocytosis. It has only recently been appreciated that modification of proteins by other ubiquitin-like (Ubl) proteins exerts a similar targeting function. The underlying assumption of this grant is that regulation of the Ubl pathways by deconjugation of ubiquitin-like proteins is likely to be equally important, with roles in cancer, the regulation of growth and apoptosis. The enzymes that reverse the conjugation of UbI proteins (Ubiquitin-like protein proteases, ULP) are attractive targets for further study since the reversal of these modifications is expected to interfere with functions. As they are proteases, a large body of work suggests approaches to effective pharmacological intervention. Additionally, it is easier (conceptually and practically) to interfere with these pathways by overexpressing a deconjugating enzyme than it is to prevent attachment of the UbI domain; an approach that requires gene knock-out or dominant negative approaches. Understanding the role of these deconjugating enzymes requires that we know more about this class of enzymes, their substrates and their regulation. A series of inhibitors and substrates for ULPs will be synthesized and used to test three specific hypotheses. First, Dr. Wilkinson will test the hypothesis that an integral subunit of the mammalian COP9-signalosome is able to reverse the Nedd8 modification of cullins. He also will test the hypothesis that modification of proteins by ISG15 are an integral part of the interferon response by identifying, and interfering with the function of, enzymes which reverse this modification. He will determine if conjugation of the proapoptotic Ubl FAT10 is reversible. Finally, he will test the hypothesis that HAUSP and/or SENPI are the Ubl that removes SUMO-1 from the Promyelocytic leukemia protein, triggering the disassembly of PML.