Quantifying Changes in Neural Stem Cell Lineages in the Aging Niche

描述（由申请人提供）：本研究的目的是量化衰老对成体神经干细胞（NSCs）的动力学和谱系的影响。虽然已知NSC活性随着衰老而降低，并且这种下降可能在衰老和与年龄相关的疾病中发挥作用，但仍然存在一些基本问题。干细胞活性的哪些方面会随着衰老而改变？祖细胞群、它们在小生境中的运动和它们的增殖动力学是否有变化？祖细胞是否会随着年龄的增长而改变命运，产生更多的神经胶质细胞而不是神经元，或者它们是否会衰老？另一个重要的未解决的问题是NSC活性的下降是细胞自主变化的结果还是由于干细胞龛的老化。 拟议的研究旨在解决这些重要的悬而未决的问题。我们将确定年轻成年和老年小鼠脑中神经干细胞的谱系和动态特性。这项涉及干细胞生物学家和计算机工程师的合作努力将专注于直接观察-捕获延时图像序列，显示NSC在利基内的动态及其识别后代的生产。活细胞成像结果将通过最先进的自动化软件工具进行量化和分析，用于跟踪干细胞和生成谱系树，使我们能够准确识别不同年龄段NSC行为的差异。将为胚胎中的NSC谱系分析开发的技术应用于成人系统将允许更完整地理解干细胞特性和祖细胞关系，成人谱系树的构建以及这些元素如何随年龄变化。 具体而言，拟议的研究将通过长期延时显微镜确定和比较年轻和老年小鼠脑室下区（SVZ）神经干细胞的谱系和动态特性。它将提供洞察的重要问题，是否减少神经发生与老化是细胞自主的，或由于在小生境的变化，通过移植干细胞从年轻到老年和从老年到年轻的SVZ，并测量的整合，谱系和移植细胞的动态特性的变化。此外，它将通过探索趋化因子SDF 1和相应的CXCR 4受体在衰老过程中发挥的作用来研究与年龄相关的NSC活性下降的分子事件。SDF/CXCR 4信号转导在大脑中随着年龄的增长而下降; CXCR 4表达减少被认为有助于其他组织中干细胞活性的下降。在这里，我们将测量年轻人和老年人大脑中SDF 1和CXCR 4的水平。将使用特异性拮抗剂或条件性敲除幼年和老年小鼠NSC谱系中的CXCR 4来阻断SDF 1/CXCR 4信号传导，并将分析谱系进展的变化。这项工作将提供对祖细胞行为变化如何可能导致癌症和记忆丧失等衰老疾病的理解，并开始确定分子靶点，以减轻成人干细胞生态位中与衰老相关的神经退行性变化。 公共卫生相关性：随着衰老和与年龄相关的疾病，神经系统中的干细胞会下降，这可能导致学习和记忆的缺陷。我们将研究神经干细胞及其环境中与年龄相关的变化，使用最先进的实时成像和自动细胞跟踪软件来测量干细胞增殖，运动和分化为神经系统细胞的关键特征。这项工作将提供对干细胞行为变化如何导致癌症和记忆丧失等衰老疾病的理解，并有可能确定分子靶点以减轻与衰老相关的神经退行性变化。

DESCRIPTION (provided by applicant): The goal of this research is to quantify the effect of aging on the dynamics and lineage of adult neural stem cells (NSCs). While it is known that there is reduced NSC activity with aging and that this decline may play a role in aging and age-related diseases, a number of fundamental questions remain. Which aspects of stem cell activity change with aging? Are there changes in the progenitor cell population, their movements within the niche and their proliferation kinetics? Do progenitor cells switch fate with aging, making more glial cells rather than neurons or do they undergo senescence? Another important unresolved issue is whether the declines in NSC activity are the result of cell autonomous changes or due to aging of the stem cell niche. The proposed research is designed to address these important unanswered questions. We will determine the lineage and dynamic properties of NSCs in young adult and aged mouse brains. This collaborative effort involving stem cell biologists and computer engineers will focus on direct observation - capturing time-lapse image sequences showing the dynamics of NSCs within the niche and their production of identified progeny. The live cell imaging results will be quantified and analyzed with state-of-the-art automated software tools for tracking stem cells and generating lineage trees, enabling us to accurately identify differences in NSC behavior at different ages. Applying techniques developed for NSC lineage analysis in embryos to the adult system will allow a much more complete understanding of stem cell properties and progenitor relationships, of the construction of adult lineage trees and how these elements change with age. Specifically, the proposed research will determine and compare the lineage and dynamic properties of NSCs in the subventricular zone (SVZ) in young and aged mice by long-term time lapse microscopy. It will provide insight into the important question of whether decreased neurogenesis with aging is cell autonomous or is due to changes in the niche by transplanting stem cells from young to aged and from aged to young SVZ, and measuring changes in the integration, lineage and dynamic properties of the transplanted cells. Furthermore, it will investigate molecular events underlying age-related declines in NSC activity by exploring the role that the chemokine SDF1 and the corresponding CXCR4 receptor play in the aging process.SDF/CXCR4 signaling declines with age in the brain; reduced CXCR4 expression has been suggested to contribute to a decline in stem cell activity in other tissues. Here we will measure SDF1 andCXCR4 levels in young and aged brains. SDF1 /CXCR4 signaling will be blocked using a specific antagonist or conditional knockout of CXCR4 in the NSC lineage in young and aged mice and changes in lineage progression will be analyzed. This work will provide an understanding of how changes in progenitor behavior might contribute to diseases of aging such as cancer and memory loss and begin to identify molecular targets to alleviate aging- related neurodegenerative changes in the adult stem cell niche. PUBLIC HEALTH RELEVANCE: With aging and age-related diseases, stem cells in the nervous system decline, which can contribute to deficits in learning and memory. We will study age-related changes in neural stem cells and their environment using state of the art live imaging and automated cell tracking software to measure critical features of stem cell proliferation, movement and differentiation into nervous system cells. This work will provide an understanding of how changes in stem cell behavior might contribute to diseases of aging such as cancer and memory loss and has the potential to identify molecular targets to alleviate aging-related neurodegenerative changes.