Extreme cell growth in support of stem cell proliferation and niche exit

K·戈登，北卡罗来纳大学R35摘要 生殖系干细胞及其分化后代的规范和稳健维护 形式配子对于生物谱系的成功是必不可少的。干细胞的利基是主要的调节因子 干细胞的命运，其特点是具有不断自我更新和分化的能力。因此 干细胞壁龛的结构--通常与其支持的干细胞有广泛的细胞接触 必须被继续分化的子代细胞破坏的种群-似乎对调控至关重要 关于细胞命运的决定。这样的接触在各种干细胞的利基中都是共享的，但与利基相关的研究 从结构到功能的研究落后于干细胞调控的遗传分析。干细胞的利基位于组织的深处， 这使得它们很难被观察到，而且干细胞分裂是随机的。这项提议避免了这些挑战 通过研究线虫的生殖系干细胞生态位，线虫是一种适合在体内进行多路成像的动物。 该研究计划的总体目标是发现未分化的生殖细胞是如何接受提示的 从它们的微环境刺激增殖和细胞命运切换到配子分化，以及 支持生殖细胞的动态细胞结构是如何形成的。保守的增殖和细胞生长 通路与人类健康密切相关。追寻这些问题将导致洞察，就像其他发现一样 在这种典型的干细胞生态位模型中制作的，可能广泛适用于其他干细胞系统。 未来五年的研究和目标概述：戈登实验室在北卡罗来纳大学开幕之前 大流行开始了。它追问的关键问题包括：干细胞巢和性腺鞘细胞是如何生长和 在分化的不同阶段，在内部进行自我分割以适当地与生殖细胞相互作用 程序？在发育过程中，壁龛细胞和鞘都经历了大量的生长和转化。 将对这两个体细胞进行基因操作，以确定是否介导了对生殖细胞增殖的影响 通过这些调控细胞的生长和分割。细胞特异性RNAi菌株将用于筛选基因 导致SH1生长减弱和生殖细胞增殖。定向的分子机制是什么 细胞在生态位边界的分裂和不对称的细胞命运获得？主轴方向一直是 对线虫早期胚胎进行了非常详细的研究，但尚不清楚增殖中的胚胎是否有分裂 细胞是定向的。壁龛和生殖细胞之间的黏附一直是一个被忽视的研究领域，直到最近 研究结果表明，钙粘素复合体--它在胚胎中定位纺锤体--与戏剧性的包裹有关。 干细胞周围的小生境的行为。干细胞的生态位是如何从幼虫成熟到成虫的？RNA- 跨越幼虫/成虫过渡的生态位细胞的SEQ将识别与 从性腺生长过程中的迁徙生态位过渡到稳定的、成熟的成体生态位。这些都是已知的 在这种转变的实时成像研究中，将通过标记和功能丧失分析来研究基因。 这项工作将共同解决出现的和长期存在的关于经典干细胞模型系统的问题。

K. Gordon, UNC R35 Abstract The specification and robust maintenance of the germ line stem cells and their differentiated descendants that form gametes are essential to the success of an organismal lineage. Stem cell niches are primary regulators of stem cell fate, which is characterized by continuous self-renewal with the capability of differentiation. Therefore the structure of stem cell niches—which often have extensive cellular contacts with their supported stem cell populations that must be broken by daughter cells that go on to differentiate—appear crucial for the regulation of the cell fate decision. Such contacts are shared in a variety of stem cell niches, but studies relating niche structure to function lag behind genetic analysis of stem cell regulation. Stem cell niches lie deep in tissues, making them difficult to observe, and stem cell divisions are stochastic. This proposal avoids these challenges by studying the germ line stem cell niche of C. elegans, an animal that is suited to multiplex in vivo imaging. The overall goal for the research program is to discover how undifferentiated germ stem cells receive cues from their micro-environment to stimulate proliferation and the cell fate switch to gamete differentiation, and how the dynamic cell structures supporting germ stem cells form. Conserved proliferation and cell growth pathways are relevant to human health. Pursuit of these questions will lead to insights that, like other findings made in this canonical stem cell niche model, may be broadly applicable to other stem cell systems. Overview of research and goals for the next five years: The Gordon Lab opened at UNC just before the pandemic began. It pursues key questions like: How do the stem cell niche and gonad sheath cells grow and internally partition themselves to interact appropriately with germ cells at different steps of the differentiation program? Both the niche cell and sheath undergo substantial growth and transformation during development. Both somatic cells will be genetically manipulated to determine if effects on germ cell proliferation are mediated by growth and partitioning of these regulatory cells. Cell-specific RNAi strains will be used to screen for genes resulting in diminished Sh1 growth and germ cell proliferation. What molecular mechanisms underlie oriented cell divisions at the niche boundary and asymmetrical cell fate acquisition? Spindle orientation has been studied in great detail in early C. elegans embryos, but it was not known that divisions in proliferating germ cells were oriented. Adhesion between the niche and germ cells was a neglected area of inquiry until recent findings implicated cadherin complexes—which orient spindles in the embryo—in the dramatic wrapping behavior of the niche around the stem cells. How does the stem cell niche mature from larvae to adults? RNA- seq of niche cells across the larva/adult transition will identify candidate genes that are correlated with the transition from a migratory niche during gonad growth to a stationary, mature adult niche. These and known genes will be investigated by tagging and loss of function analysis in live-imaging studies of the transition. Together this work will address arising and long-standing questions about a classical stem cell model system.