Elucidating the cytoskeletal mechanics in stem cell niche morphogenesis

项目摘要： 干细胞功能缺陷通过诱导肿瘤形成或组织变性严重影响人类健康。 为了保持自我更新和分化的适当平衡，干细胞依赖于来自其细胞的信号线索。 生态位，也就是它们所处的微环境。我们必须了解 作为生态位生物学的基础，揭示促进正常干细胞功能的机制， 人体健康在许多组织中，小生境具有精确和可再现的形态。然而， 了解生态位形态如何控制或如何影响生态位功能。This project will use the 果蝇性腺研究生态位形成的机制，结合遗传的易驾驭性和强大的生命力， 成像技术在迪纳多实验室开创。在该系统中，生态位具有定义的独特形态 通过小生境和相邻干细胞之间平滑的边界。这一界限进一步提到 as the niche利基peripheral周边.在功能上，小生境在调节干细胞行为中起着关键作用：1）它是干细胞的主要功能。 2）它限制了这些线索只接近邻近的细胞，3）它调节干细胞 细胞分裂方向初步证据表明，平滑的生态位外围对于确保 生殖系干细胞（GSC）的适当分裂角度，表明生态位结构和功能之间的联系。 此外，F-肌动蛋白和肌球蛋白II（MyoII）在生态位周边富集，伴随着张力， 提示肌动球蛋白收缩性。该项目的一个关键目标是揭示肌动球蛋白收缩性的作用 生态位形态发生和功能（目标1）。由于生态位形态发生是高度可重复的，该项目 还将解决上游机制，有力地将BNF-肌动蛋白和MyoII的生态位周边（目标2）。 一个有趣的可能性是，粘附的GSC施加在小生境上的机械力诱导了细胞骨架 极化沿着生态位外围。初步证据表明，需要GSC部门进行适当的 它是生态位形态，并且已知多种力协同作用以驱动纺锤体在分裂中伸长。 cell.这个项目将解决的假设，F-肌动蛋白和肌II富集沿着生态位周边是 GSC纺锤体的伸长诱导的，是必要的生态位的形成和功能。的组合 转基因技术将用于操纵肌动球蛋白收缩性并抑制微管马达 参与纺锤体的伸长。这个项目可能会揭示一种反馈机制， 塑造引导他们行为的利基，并将成为第一个描述塑造机制的人。 一个功能性的利基市场这个项目的培训计划包括实验室工作，会议出席，期刊俱乐部， 实验室会议，研究生小组研讨会，以及接触教学和指导角色。这项工作将 在果蝇生物学和形态发生专家Stephen DiNardo博士的指导下完成， 由Erfei Bi博士共同指导，他是肌球蛋白，肌动球蛋白环形成和细胞极性的专家。

Project Abstract: Defects in stem cell function severely impact human health by inducing tumor formation or tissue degeneration. To maintain a proper balance of self-renewal and differentiation, stem cells rely on signaling cues from their niche, which is the microenvironment in which they reside. It is imperative to understand the intricacies that underlie niche biology to reveal mechanisms that promote normal stem cell function and minimize defects in human health. In many tissues, the niche has a precise and reproducible morphology. However, not much is known about how niche morphology is controlled or how it impacts niche function. This project will use the Drosophila gonad to study the mechanics of niche formation, combining genetic tractability with powerful live- imaging techniques pioneered in the DiNardo lab. In this system, the niche has a distinct morphology defined by a smoothened boundary between the niche and the adjacent stem cells. This boundary is further referred to as the niche periphery. Functionally, the niche plays key roles in regulating stem cell behavior: 1) it is the source for self-renewal cues, 2) it restricts access of these cues to only adjacent cells, and 3) it regulates stem cell division orientation. Preliminary evidence suggests that the smooth niche periphery is crucial to ensure proper division angles for germline stem cells (GSCs), suggesting a link between niche structure and function. Furthermore, F-actin and Myosin II (MyoII) are enriched at the niche periphery, accompanied by tensile forces, suggestive of actomyosin contractility. A key goal for this project is to unveil the role of actomyosin contractility in niche morphogenesis and function (Aim 1). Since niche morphogenesis is highly reproducible, this project will also address upstream mechanisms that robustly polarize F-actin and MyoII to the niche periphery (Aim 2). An intriguing possibility is that mechanical forces exerted on the niche by adherent GSCs induce cytoskeletal polarization along the niche periphery. Preliminary evidence suggests GSC divisions are required for proper niche morphology, and it is known that multiple forces act in concert to drive spindle elongation in a dividing cell. This project will address the Hypothesis that F-actin and MyoII enrichment along the niche periphery is induced by GSC spindle elongation, and is necessary for niche formation and function. A combination of transgenic techniques will be used to manipulate actomyosin contractility, as well as inhibit microtubule motors involved in spindle elongation. This project will potentially unveil a feedback mechanism where stem cells shape the niche that guides their behavior, and will be among the first to describe the mechanisms of shaping a functional niche. The training plan for this project consists of lab work, conference attendance, journal clubs, lab meetings, graduate group seminars, and exposure to teaching and mentoring roles. This work will be completed under the mentorship of Dr. Stephen DiNardo, an expert in Drosophila biology and morphogenesis, with co-mentorship by Dr. Erfei Bi, an expert on Myosin, actomyosin ring formation, and cell polarity.