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

摘要 从未转化的正常细胞发展为恶性癌细胞需要多种遗传变化 在抑制肿瘤抑制因子的同时激活癌基因。这是通过获得基因突变发生的 以及基因拷贝数的变化。整条染色体和节段性非整倍体可以改变 相关的癌基因和肿瘤抑制因子以及控制染色体保真度的机制的扰动- 在有丝分裂期间的一些分离足以通过产生非整倍性促进肿瘤发展。 HECT结构域泛素连接酶HUWE 1协调蛋白酶体介导的蛋白质降解， 在细胞分裂、分化和存活中起着至关重要的作用，最近的研究表明HUWE 1的失活 有助于肿瘤的发展。最初，我们产生并研究了条件性基因敲除小鼠，其中HUWE 1 失活靶向神经系统。我们使用这种小鼠模型来表征HUWE 1的作用。 在神经发生中。我们发现MYCN癌蛋白的激活和MYCN依赖的转录网络， 工程是HUWE 1下游运行的关键事件，其放松管制导致发展 HUWE 1-null脑中的畸变。我们还确定了遗传和表观遗传机制会导致损失- HUWE 1在人类脑肿瘤的显著部分中的功能改变。最近，我们的工作 揭示了HUWE 1的新的和意想不到的功能，这些功能将这种泛素连接酶定义为重要的调节因子 有丝分裂保真度，其中HUWE 1的损失诱导染色体错误分离和不稳定的基因组。的 本提案体现了三个具体目标，将研究HUWE 1的新功能，并将服务于 作为HUWE 1肿瘤抑制机制的切入点。在目标1中，我们将调查 由HUWE 1控制，以保持有丝分裂保真度和基因组完整性。目标2将检查candi的作用- 我们通过无偏的蛋白质组学方法确定了HUWE 1底物的日期， 有丝分裂表型由HUWE 1活性丧失引发。在目标3中，我们将着手解决 与DNA损伤的积累和有丝分裂表型协同作用的遗传病变， 使用睡美人转座酶插入诱变的HUWE 1缺失启动脑致癌作用。

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.