Identification and characterization of new factors involved in feedback regulation of stem cell proliferation

干细胞增殖反馈调节涉及的新因子的鉴定和表征

• 批准号: RGPIN-2019-06863
• 负责人: Narbonne, Patrick
• 金额: $ 2.99万
• 依托单位: Université du Québec à Trois-Rivières
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2022
• 资助国家: 加拿大
• 起止时间: 2022-01-01 至 2023-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=745048
• 关键词: Identification; characterization; new; factors; involved

Stem cells are amongst the most important cells in the human body. They are relatively undifferentiated cells that have the capacity to proliferate and expand in numbers, while they can also differentiate into more specialized cell types. From the embryonic stem cells to the plethora of adult (tissue-specific) stem cells, they are essential to the generation and regeneration of our tissues and organs. How these critical cells function and how they are regulated has therefore been the focus of intensive investigation. Particularly key was the discovery of the stem cell niche, which provides a spatially restricted environment in which stem cells are maintained in their proliferative, undifferentiated state. Niche-resident stem cells thus uniquely have the capacity to proliferate and expand in numbers, although they can also exist there in an inactive or quiescent state. Whether stem cells remain quiescent or proliferate is the result of the integration of the growth factors that they receive from various sources. One important such growth factor is an insulin/IGF-1 signal that is systemically distributed to stimulate the proliferation of most (if not all) stem cells following nutrient uptake. Yet, not all stem cell populations across and within an animal's tissues equally respond to this signal, such that at any one time: some stem cell populations may proliferate, but others may not. We, and others, found evidence that stem cell proliferation is adjusted locally by homeostatic signals originating from the stem cells' differentiated progeny. This feedback signal is generated by the need for newly differentiated cells in a tissue, to replace old or damaged cells. As such, when no new differentiated cells are needed in a given tissue, such feedback signals locally antagonize insulin/IGF-1 and block proliferation of the parental stem cell population. How a tissue's needs for new differentiated cells overrides the systemic insulin/IGF-1 signal to locally adjust adult SC proliferation rates is a major unsolved problem in biology. Through a new screening method that we have developed in a convenient, well-characterized invertebrate model (C. elegans), we have isolated 5 new alleles that specifically prevent homeostatic regulation of germline stem cell proliferation. We found that one of these mutations affects an extracellular matrix protein called Papilin. We aim to resolve how Papilin, the extracellular matrix and four new factors participate in feedback stem cell regulation through the following three specific objectives: 1) Establish the role of Papilin in homeostatic regulation of GSC proliferation. 2) Define Papilin's PLAC domain-mediated interaction network in homeostatic GSC regulation. 3) Clone and characterize four new mutations implicated in homeostatic GSC regulation. In line with NSERC's mandate, the broad goal of the proposed research is thus to expand our fundamental knowledge about the in vivo mechanisms that regulate stem cell activity.

干细胞是人体内最重要的细胞之一。它们是相对未分化的细胞，具有在数量上增殖和扩张的能力，同时它们也可以分化为更专业的细胞类型。从胚胎干细胞到过多的成人(组织特异性)干细胞，它们对我们组织和器官的生成和再生是必不可少的。因此，这些关键细胞如何发挥作用以及它们是如何被调控的一直是深入研究的重点。尤其关键的是干细胞生态位的发现，它提供了一个空间受限的环境，在这个环境中干细胞保持在其增殖的、未分化的状态。因此，居住在利基环境中的干细胞具有独特的增殖和数量扩张的能力，尽管它们也可以以不活跃或静止的状态存在。干细胞是否保持静止或增殖是它们从各种来源获得的生长因子整合的结果。一种重要的此类生长因子是胰岛素/IGF-1信号，该信号在营养吸收后系统地分布以刺激大多数(如果不是全部)干细胞的增殖。然而，并不是动物组织内外的所有干细胞群体都对这一信号做出同样的反应，以至于在任何时候：一些干细胞群体可能会增殖，但另一些可能不会。我们和其他人发现了干细胞增殖受到来自干细胞分化后代的动态平衡信号的局部调节的证据。这种反馈信号是由于组织中需要新分化的细胞来取代陈旧或受损的细胞而产生的。因此，当给定的组织中不需要新的分化细胞时，这种反馈信号会在局部对抗胰岛素/IGF-1，并阻止父母干细胞群体的增殖。组织对新分化细胞的需求如何超过系统的胰岛素/IGF-1信号来局部调节成人SC的增殖率，这是生物学中一个尚未解决的主要问题。通过我们在一个方便、特征良好的无脊椎动物模型(秀丽线虫)中开发的一种新的筛选方法，我们分离出了5个新的等位基因，这些等位基因专门阻止生殖系干细胞增殖的动态平衡调节。我们发现，其中一个突变会影响一种名为Paplin的细胞外基质蛋白。我们的目标是通过以下三个具体目标来了解Paplin、细胞外基质和四个新的因子如何参与干细胞的反馈调节：1)建立Paplin在GSC增殖的动态平衡调节中的作用。2)确定Paplin的Plac结构域介导的内稳态GSC调节的相互作用网络。3)克隆并鉴定了四个与动态平衡GSC调控有关的新突变。因此，根据NSERC的授权，这项拟议研究的广泛目标是扩大我们对调节干细胞活动的体内机制的基础知识。