regulation of the cullin family E3 ubiquitin ligases

描述（由申请人提供）：在阐明基于cullin的E3泛素连接酶在真核细胞中广泛的生物过程中的关键调节作用方面已经取得了相当大的进展。然而，我们远未了解它们的复杂性，我们才刚刚开始了解它们复杂的监管网络。虽然cullin依赖性蛋白水解途径的缺陷调节在包括癌症在内的人类疾病中是明显的，但由于对这些过程的机制理解不足，我们在开发有效的药理学药物方面仍处于起步阶段。因此，如果我们要了解异常生长，我们必须了解cullin如何介导蛋白质水解以及这些过程是如何调节的。 最近，我们已经确定了一个新的cullin蛋白家族成员称为CUL 7，含有cullin和DOC签名域。值得注意的是，CUL 7组装SCF样E3 Ub连接酶复合物，由Skp 1，CUL 7，ROC 1和以前未表征的F-box蛋白Fbx 29组成。我们建议通过鉴定Fbx 29的底物来阐明基于CUL 7/Fbx 29的E3样复合物在介导蛋白质降解中的生物学功能。 Nedd 8是一种特异性cullin修饰剂，其上调基于cullin的E3 Ub连接酶的活性。最近，我们已经克隆了一个潜在的调节Nedd 8途径称为hDEN-1，一种新的Nedd 8异肽酶。我们将通过评估hDEN-1在哺乳动物细胞中调节Nedd 8依赖性SCF活性的功能，以及通过使用S. pombe和Drosophila模型系统。 pVHL肿瘤抑制因子通过组装含cullin 2的E3连接酶发挥功能，该连接酶靶向HIF-1 α进行泛素化和降解。最近的研究表明，一种新的翻译后修饰，脯氨酰羟基化，在调节pVHL/HIF-1通路中起着核心作用。HIF-1 α在脯氨酸残基564处被PHO 1/SM 20家族脯氨酰羟化酶羟基化，这是HIF-1 α与pVHL相互作用以启动泛素化所必需的。最近，我们已经确定了刺激PHD 1/SM 20脯氨酰羟化酶功能的细胞活性。我们建议确定这种新活性的分子身份，这可能被证明是pVHL/HIF-1途径的另一个关键调节因子。

DESCRIPTION (provided by applicant): Considerable progress has been made in elucidating the critical regulatory role of cullin-based E3 ubiquitin ligases over a wide array of biological processes in eukaryotic cells. However, we are far from understanding their intricacies and we have only begun to appreciate their complex regulatory networks. While defective regulation of the cullin-dependent proteolysis pathways is manifest in human diseases including cancers, we are still in our infancy with respect to developing effective pharmacologic agents due to insufficient mechanistic understanding of these processes. Thus, if we are to understand aberrant growth, we must have fundamental knowledge of how cullins mediate proteolysis and how these processes are regulated. Recently, we have identified a novel member of the cullin protein family called CUL7, containing both the cullin and DOC signature domains. Remarkably, CUL7 assembles an SCF-like E3 Ub ligase complex composed of Skp1, CUL7, ROC1, and a previously uncharacterized F-box protein, Fbx29. We propose to elucidate the biological function of the CUL7/Fbx29-based E3-1ike complex in mediating protein degradation by identifying substrate(s) of Fbx29. Nedd8 is a specific cullin modifier that up-regulates the activity of cullin-based E3 Ub ligases. Recently, we have cloned a potential regulator of the Nedd8 pathway called hDEN-1, a novel Nedd8 isopeptidase. We will investigate the biological function of hDEN-1 in Ub-dependent protein degradation pathways by assessing the function of hDEN-1 in regulating Nedd8-dependent SCF activities in mammalian cells, as well as by examining the biological role of this novel protease using S. pombe and Drosophila model systems. The pVHL tumor suppressor functions by assembling a cullin 2-containing E3 ligase that targets HIF-1alpha for ubiquitination and degradation. Recent studies have revealed that a novel post-translational modification, prolyl hydroxylation, plays a central role in regulating the pVHL/HIF-1 pathway. Hydroxylation of HIF-1alpha at proline residue 564, by the PHO1/SM20 family prolyl hydroxylase, is required for its interaction with pVHL to initiate the ubiquitination. More recently, we have identified a cellular activity that stimulates the function of the PHD1/SM20 prolyl hydroxylase. We propose to determine the molecular identity of this novel activity, which may prove to be yet another critical regulator of the pVHL/HIF-1 pathway.