Elucidating the Numb Signaling Pathway

阐明麻木信号通路

• 批准号: 8269686
• 负责人: WEIMIN ZHONG
• 金额: $ 35.48万
• 依托单位: YALE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-06-15 至 2015-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8269686
• 关键词: Address; Adopted; Aging; Behavior; Biological Models; Cell Cycle; Cell Cycle Progression; Cell division; Cells; Daughter; Defect; Development; Disease; Drosophila genus; Enhancers; Equilibrium; Genes; Genetic Screening; Goals; Golgi Apparatus; Homeostasis; Homologous Gene; Individual; Injury; Invertebrates; Knowledge; Maintenance; Mammals; Mediating; Molecular; Mus; N-terminal; Neuraxis; Neurons; Organogenesis; Population; Process; Production; Protein Binding; Proteins; Signal Pathway; Signal Transduction; Signaling Molecule; Signaling Protein; Source; Specific qualifier value; Stem Cell Research; Stem cells; Therapeutic Uses; Time; Tissues; To specify; Variant; cancer stem cell; cell fate specification; daughter cell; dosage; gain of function; insight; interest; meetings; mouse Numb protein; mutant; nerve stem cell; neurogenesis; novel; numb protein; precursor cell; progenitor; public health relevance; reconstitution; relating to nervous system; response; self-renewal; stem; tissue repair

DESCRIPTION (provided by applicant): Asymmetric cell division, a process by which a cell divides to produce two different daughter cells, is essential for generating cellular diversity during development. Such divisions are also an attractive means for stem cells to balance the competing needs of self-renewal and differentiation during organogenesis and tissue maintenance, by producing one daughter that remains as a stem cell and the other that differentiates. In Drosophila, Numb, a cytoplasmic signaling protein, localizes asymmetrically in dividing precursor cells and segregates primarily into one daughter cell. This asymmetric Numb inheritance is essential for the two daughter cells to adopt different fates. We have been using the mammalian numb proteins, Numb and Numbl, as an entry point, and neurogenesis in mice as a model system, to probe the contribution of two modes of cell division - symmetric vs. asymmetric - in regulating the behavior of stem cells. Neurons in the mammalian central nervous system are generated over an extended period of time during development, requiring neural stem (progenitor) cells to self-renew while generating neurons at the same time. We have postulated that neural progenitor cells balance self-renewal and differentiation during mouse neurogenesis by segregating Numb and Numbl asymmetrically to promote progenitor over neuronal fates in asymmetric divisions that produce another progenitor and a neuron. Indeed, neural progenitor cells lose their ability to self-renew in the absence of Numb and Numbl, whereas forcing them to segregate numb symmetrically inhibits neuron production by forcing their daughter cells to both choose self-renewal over differentiation. We have also identified an essential Numb and Numbl partner, ACBD3, and a novel mechanism that regulates the timing of numb activity in cell-fate specification by using the process of Golgi fragmentation and reconstitution during cell cycle to change the subcellular distribution of ACBD3. Here we seek to address how numb asymmetric localization and numb activity are regulated by combining studies using mice and Drosophila. We hypothesize that the essential regulators of numb signaling are evolutionarily conserved but differentially used in mice and Drosophila to meet their specific demands of neurogenesis. We intend to elucidate how mammalian numb proteins are asymmetrically segregated by neural progenitor cells, by first examining different Numbl protein variants for their ability to mediate asymmetric cell division during mouse neurogenesis and then identifying and characterizing the proteins binding specifically to the Numbl variant that segregates asymmetrically. Mammalian numb and ACBD3 proteins, when introduced into Drosophila, can act synergistically in a dosage-dependent manner to specify cell fates. Thus, we seek to identify novel components of the numb signaling pathway by performing a genetic screen in Drosophila to search for enhancers and suppressors of Numb-ACBD3 activity. We also seek to determine the function of the Drosophila ACBD3 homologue. Through the proposed studies, we hope to achieve a better understanding of how numb proteins specify neural progenitor fates and use the knowledge as entry points to elucidate the essential mechanisms that regulate the behavior of neural stem cells in mammals. A better understanding of how stem cells are regulated will provide novel insights for their therapeutic use to repair tissues damaged by disease, injury or aging. PUBLIC HEALTH RELEVANCE: We seek to identify novel regulators of numb proteins, which are evolutionarily conserved signaling molecules that segregate asymmetrically to allow the two daughter cells to adopt different fates after an asymmetric cell division. We have been using the mammalian numb proteins, Numb and Numbl, to probe the contribution of two modes of cell division - symmetric vs. asymmetric - by stem cells during neurogenesis in mice. Our studies have revealed an essential requirement for numb-mediated asymmetric cell division in allowing neural stem/progenitor cells to balance self-renewal and differentiation as well as a previously unrecognized homeostasis mechanism that strictly controls the number of stem cells during neurogenesis. Whereas asymmetric division allows stem cells to balance self-renewal and differentiation during organogenesis and tissue maintenance, stem cells can use symmetric divisions to expand their population, for example, in response to tissue injury. It is also likely that cancer stem cells are sustained by self-renewing symmetric divisions. Thus, a better understanding of numb function may yield novel insights for achieving a key goal of stem-cell research, which is to repair tissues damaged by disease, injury or aging by introducing stem cells from external sources or expanding the endogenous populations.

描述（由申请人提供）：不对称细胞分裂是细胞分裂产生两个不同子细胞的过程，对于发育过程中产生细胞多样性至关重要。这种分裂对于干细胞来说也是一种有吸引力的手段，可以通过产生一个保留为干细胞的子细胞和另一个分化的子细胞来平衡器官发生和组织维持过程中自我更新和分化的竞争需求。在果蝇中，Numb 是一种细胞质信号蛋白，不对称地定位于分裂的前体细胞中，并主要分离到一个子细胞中。这种不对称的 Numb 遗传对于两个子细胞采取不同的命运至关重要。我们一直使用哺乳动物麻木蛋白 Numb 和 Numbl 作为切入点，并使用小鼠神经发生作为模型系统，以探讨两种细胞分裂模式（对称与不对称）在调节干细胞行为中的贡献。哺乳动物中枢神经系统中的神经元是在发育过程中经过很长一段时间产生的，需要神经干（祖）细胞在自我更新的同时产生神经元。我们假设神经祖细胞在小鼠神经发生过程中通过不对称地分离 Numb 和 Numbl 来平衡自我更新和分化，从而在产生另一个祖细胞和神经元的不对称分裂中促进祖细胞相对于神经元命运。事实上，在没有 Numb 和 Numbl 的情况下，神经祖细胞会失去自我更新的能力，而强迫它们对称地分离 numb 会通过迫使它们的子细胞选择自我更新而不是分化来抑制神经元的产生。我们还确定了一个重要的 Numb 和 Numbl 伙伴 ACBD3，以及一种新机制，该机制通过利用细胞周期期间高尔基体断裂和重建过程来改变 ACBD3 的亚细胞分布，从而调节细胞命运规范中麻木活动的时间。在这里，我们试图通过结合小鼠和果蝇的研究来解决麻木不对称定位和麻木活动是如何调节的。我们假设麻木信号的重要调节因子在进化上是保守的，但在小鼠和果蝇中的使用有所不同，以满足它们神经发生的特定需求。我们打算阐明哺乳动物麻木蛋白如何被神经祖细胞不对称分离，首先检查不同的 Numbl 蛋白变体在小鼠神经发生过程中介导不对称细胞分裂的能力，然后识别和表征与不对称分离的 Numbl 变体特异性结合的蛋白质。当哺乳动物麻木和 ACBD3 蛋白被引入果蝇时，可以以剂量依赖的方式协同作用来指定细胞命运。因此，我们试图通过在果蝇中进行遗传筛选来寻找 Numb-ACBD3 活性的增强子和抑制子，从而鉴定 numb 信号通路的新成分。我们还试图确定果蝇 ACBD3 同源物的功能。通过拟议的研究，我们希望更好地了解麻木蛋白如何指定神经祖细胞的命运，并利用这些知识作为切入点来阐明调节哺乳动物神经干细胞行为的基本机制。更好地了解干细胞的调控方式将为干细胞修复因疾病、损伤或衰老而受损的组织的治疗用途提供新的见解。 公共健康相关性：我们寻求识别麻木蛋白的新型调节剂，这些蛋白是进化上保守的信号分子，它们不对称分离，使两个子细胞在不对称细胞分裂后采取不同的命运。我们一直在使用哺乳动物麻木蛋白 Numb 和 Numbl 来探讨干细胞在小鼠神经发生过程中两种细胞分裂模式（对称与不对称）的贡献。我们的研究揭示了麻木介导的不对称细胞分裂对于神经干/祖细胞平衡自我更新和分化的基本要求，以及以前未被认识的在神经发生过程中严格控制干细胞数量的稳态机制。不对称分裂允许干细胞在器官发生和组织维持过程中平衡自我更新和分化，而干细胞可以使用对称分裂来扩大其种群，例如，响应组织损伤。癌症干细胞也可能通过自我更新的对称分裂来维持。因此，更好地了解麻木功能可能会为实现干细胞研究的一个关键目标提供新的见解，即通过引入外部来源的干细胞或扩大内源细胞群来修复因疾病、损伤或衰老而受损的组织。