The Huwe1 ubiquitin ligase regulates mitosis, genomic stability and oncogenesis.

摘要 从未转化的正常细胞到恶性癌细胞的进展需要多个基因变化 在激活癌基因的同时抑制肿瘤抑制因子。这是通过获得基因突变来实现的。 基因拷贝数的变化。整条染色体和节段性非整倍体可以改变 相关的癌基因和抑癌基因以及控制染色保真度的机制的扰动 有丝分裂过程中的一些分离足以通过产生非整倍体来促进肿瘤的发展。 Hect结构域泛素连接酶HUWE1通过以下途径协调蛋白酶体介导的蛋白质降解 在细胞分裂、分化和存活中的关键作用和最近的工作表明，HUWE1的失活 有助于肿瘤的发展。最初，我们建立并研究了条件基因敲除小鼠，在其中HUWE1 灭活的目标是神经系统。我们使用这个小鼠模型来表征HUWE1的作用 在神经发生方面。我们发现，MYCN癌蛋白和MYCN依赖的转录网络的激活- 工程是运行在HUWE1下游的关键事件，其解除管制导致发展 HUWE1零脑区的异常。我们还确定了遗传和表观遗传机制驱动损失- HUWE1基因在相当一部分人脑肿瘤中的功能改变。最近，我们的工作已经 揭示了HUWE1的新的和意想不到的功能，将这种泛素连接酶定义为关键调节因子 有丝分裂的保真度，HUWE1的缺失会导致染色体的错误分离和基因组的不稳定。这个 目前的提案体现了三个具体目标，将调查HUWE1的新功能并将服务于 作为研究HUWE1抑瘤机制的切入点。在目标1中，我们将调查以下事件 由HUWE1控制，以保持有丝分裂的保真度和基因组的完整性。目标2将研究糖果的作用- Date HUWE1底物，我们已经通过无偏的蛋白质组学方法鉴定了积累 HUWE1活性缺失引起的有丝分裂表型。在目标3中，我们将着手全面解决 遗传性损伤与DNA损伤的积累和由 使用睡美人转座酶插入突变启动HUWE1缺失启动脑癌发生。

Abstract Progression from a non-transformed normal cell to a malignant cancer cell requires multiple genetic changes that activate oncogenes while restraining tumor suppressors. This occurs via the acquisition of genetic mutations and changes of gene copy number. Whole chromosome and segmental aneuploidy can alter copy number of relevant oncogenes and tumor suppressors and perturbation of the machinery controlling the fidelity of chromo- some segregation during mitosis is sufficient to promote tumor development via the generation of aneuploidy. The HECT-domain ubiquitin ligase HUWE1 coordinates the proteasomal-mediated degradation of proteins with crucial roles in cell division, differentiation and survival and recent work has shown that inactivation of HUWE1 contributes to tumor development. Initially, we generated and studied conditional knockout mice in which HUWE1 inactivation was targeted to the nervous system. We used this mouse model to characterize the role of HUWE1 in neurogenesis. We found that the activation of MYCN oncoprotein and MYCN-dependent transcriptional net- works are crucial events operating downstream of HUWE1 and whose de-regulation leads to developmental aberrations in the HUWE1-null brain. We also determined that genetic and epigenetic mechanisms drive loss- of-function alterations of HUWE1 in a significant fraction of human brain tumors. More recently, our work has revealed novel and unexpected functions of HUWE1 that have defined this ubiquitin ligase as crucial regulator of mitotic fidelity whereby loss of HUWE1 induces chromosome mis-segregation and an unstable genome. The present proposal embodies three Specific Aims that will investigate the novel functions of HUWE1 and will serve as entry point into the tumor suppressive mechanisms of HUWE1. In Aim 1 we will investigate the events that are controlled by HUWE1 to preserve mitotic fidelity and genome integrity. Aim 2 will examine the role of candi- date HUWE1 substrates that we have identified through unbiased proteomic methods for the accumulation the mitotic phenotype initiated by loss of HUWE1 activity. In Aim 3 we will proceed to address the full scope of genetic lesions that cooperate with the accumulation of DNA damage and the mitotic phenotype triggered by HUWE1 deletion to initiate brain carcinogenesis using the Sleeping Beauty transposase insertional mutagenesis.