The Ureb-1 ubiquitin ligase in neural stem cells and cancer

神经干细胞和癌症中的 Ureb-1 泛素连接酶

• 批准号: 7648243
• 负责人: ANNA LASORELLA
• 金额: $ 33.26万
• 依托单位: COLUMBIA UNIVERSITY HEALTH SCIENCES
• 依托单位国家: 美国
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-09-01 至 2013-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7648243
• 关键词: Address; Adult; Affect; Alleles; Arts; Behavior; Biochemical; Biochemical Genetics; Bioinformatics; Brain; Brain Neoplasms; Cell Fraction; Cells; Childhood; Data; Defect; Differentiation Inhibitor; Differentiation and Growth; Event; Extracellular Signal Regulated Kinases; Gene Expression Profiling; Genes; Genetic; Glioblastoma; Glioma; Goals; Homeostasis; Human; In Vitro; Laboratories; Lead; Link; Malignant Neoplasms; Malignant neoplasm of brain; Mass Spectrum Analysis; Mediating; Modeling; Modification; Molecular; Mus; Mutate; Mutation; N-Myc Protein; NF1 gene; Nervous system structure; Neuraxis; Neuroepithelial, Perineurial, and Schwann Cell Neoplasm; Neurons; Oncogene Proteins; Oncogenic; Pathway interactions; Phosphorylation; Phosphorylation Site; Post-Translational Regulation; Pregnancy; Process; Property; Protein Kinase; Proteins; Proteomics; Radiation Tolerance; Regulation; Role; Series; Signal Transduction; Specimen; Stem cells; System; Testing; Tumor Stem Cells; Tumor Suppressor Genes; cellular engineering; clinically relevant; design; in vivo; loss of function; mouse development; mutant; neoplastic cell; nerve stem cell; nervous system development; neurodevelopment; novel; progenitor; protein complex; protein degradation; public health relevance; relating to nervous system; research study; self-renewal; stem; stem cell differentiation; tool; tumor; ubiquitin ligase; ubiquitin-protein ligase

DESCRIPTION (provided by applicant): Rapid expansion of neural stem cells is a normal component of central nervous system (CNS) development. However, at mid-gestation of mouse development, neural progenitors exit from active cycling and begin differentiation, a process that is initially directed towards the neuronal and later the astroglial lineages. Unrestrained proliferation and differentiation block are hallmarks of childhood and adult brain cancer, for which neural stem cells and/or immature progenitors have been proposed as cell of origin. Indeed, brain tumors appear to hijack the homeostasis of neural stem cells in that only a small fraction of cells within brain tumors displays stem-like features and retains tumor-initiating capacity (brain tumor stem cells, BTSC). Here we have identified the E3 ubiquitin ligase Ureb1 as a positive regulator of neural differentiation and inhibitor of the stem cell state. The preliminary data for this proposal indicate that Ureb1 exerts these effects primarily through destabilization of the oncoprotein N-Myc, a factor required for the ability of neural stem cells to expand and populate the brain and frequently activated in neural tumors. The model that we will pursue in this proposal predicts that, through the control of N-Myc protein turnover, Ureb1 acts as a restraining factor for the self- renewal and tumor initiating capacity of BTSC derived from glioblastoma multiforme (GBM), the most aggressive form of brain tumor in humans. In GBM, N-Myc is the hub of a molecular network that controls the stem cell state. This proposal will employ powerful biochemical and genetic tools available in the mouse to develop a comprehensive picture of the Ureb1 ubiquitin ligase for the regulation of the homeostasis of neural stem cells and BTSC derived from GBM. First, we will use a series of biochemical approaches to functionally characterize the major levels of post-translational regulation (phosphorylation) of the Ureb1 protein. We will also take advantage of a state-of-the-art mass spectrometry approach to identify the relevant Ureb1-containing protein complexes in neural cells. Second, we will address the function of Ureb1 in normal and tumor cells from the nervous system in mice carrying a conditionally mutant allele of Ureb1 in the neural stem cell compartment. Finally, to directly test the hypothesis that Ureb1 acts as a brake for the stem cell and tumor initiating activity of GBM through N-Myc we will manipulate the activity of Ureb1 and N-My in BTSC derived from human GBM and determine whether the Ureb1 gene is mutated in human high grade gliomas. PUBLIC HEALTH RELEVANCE: Unrestrained proliferation combined with a differentiation block are hallmarks of childhood and adult brain cancer, for which neural stem cells and/or immature progenitors have been proposed as cell of origin. N-Myc, is a very unstable protein involved in neural stem cell state and frequently deregulated in neural cancer. We have identified a new ubiquitin ligase for N-Myc in neural cells and will test whether defects in N-myc turnover affects neural stem cells and initiates cancer in the brain.

描述（由申请人提供）：神经干细胞的快速扩张是中枢神经系统（CNS）发育的正常组成部分。然而，在小鼠发育的中期，神经祖细胞从主动循环中退出并开始分化，该过程最初针对神经元，后来又针对星形胶质细胞谱系。不受约束的增殖和分化块是儿童期和成人脑癌的标志，为此，已经提出了神经干细胞和/或未成熟的祖细胞作为原始细胞。实际上，脑肿瘤似乎劫持了神经干细胞的体内平衡，因为脑肿瘤中只有一小部分细胞显示出类似干燥的特征并保持肿瘤发射能力（脑肿瘤干细胞，BTSC）。在这里，我们确定E3泛素连接酶Ureb1是神经分化和干细胞抑制剂的阳性调节剂。该提案的初步数据表明，UREB1主要通过破坏肿瘤蛋白N-MYC的稳定，这是神经干细胞扩展和填充大脑并经常在神经肿瘤中激活的因素。我们将在该提案中采用的模型预测，通过控制N-MYC蛋白更新，UREB1充当了BTSC的自我更新和肿瘤启动能力的限制因素，它源自胶质母细胞瘤多形（GBM），这是人类脑肿瘤最具侵略性的脑肿瘤形式。在GBM中，N-MYC是控制干细胞态的分子网络的枢纽。该提案将采用小鼠中可用的强大生化和遗传工具来开发Ureb1泛素连接酶的全面图片，以调节神经干细胞的稳态和源自GBM的BTSC的体内稳态。首先，我们将使用一系列生化方法在功能上表征UREB1蛋白的翻译后调节（磷酸化）的主要水平。我们还将利用一种最新的质谱方法来识别神经细胞中含UREB1的相关蛋白质复合物。其次，我们将在神经干细胞室中有条件突变的UREB1的小鼠中，从神经系统中的正常和肿瘤细胞中ureb1的功能。最后，为了直接检验ureb1充当干细胞和肿瘤通过N-MYC启动活性的刹车，我们将操纵源自人类GBM的BTSC中Ureb1和N-MY的活性，并确定UREB1基因在人类高级Gliomas中是否突变。公共卫生相关性：不受限制的增殖与分化区块相结合是儿童和成人脑癌的标志，为此，已经提出了神经干细胞和/或未成熟的祖细胞作为原产性细胞。 N-MYC是一种非常不稳定的蛋白质，参与神经干细胞状态，并且经常在神经癌中失调。我们已经确定了神经细胞中N-MYC的一种新的泛素连接酶，并将测试N-MYC转换中的缺陷是否会影响神经干细胞并引发大脑中的癌症。