Mechanism of niche formation, and impact of niche position on tissue function

生态位形成机制及生态位位置对组织功能的影响

• 批准号: 10710395
• 负责人: Kara Nelson
• 金额: $ 4.77万
• 依托单位: UNIVERSITY OF PENNSYLVANIA
• 依托单位国家: 美国
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-09-26 至 2025-09-25
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10710395
• 关键词: Ablation; Address; Adhesions; Affect; Apoptosis; Atrophic; Behavior; Biological Assay; Cancerous; Cell Adhesion; Cell Communication; Cells; Communication; Companions; Competence; Creativeness; Cues; Data; Defect; Development; Dorsal; Drosophila genus; Ectopic Expression; Embryonic Development; Environment; Equilibrium; Faculty; Feedback; Fellowship; Functional disorder; Gland; Glean; Health; Hematopoietic; Hematopoietic stem cells; Hemocytes; Homeostasis; Human; Hyperactivity; Image; Immune; Immune response; Infection; Larva; Lateral; Maintenance; Measures; Mentorship; Mesoderm; Modeling; Morphogenesis; Natural Immunity; Nutrient; Organism; Pennsylvania; Population; Positioning Attribute; Postdoctoral Fellow; Primordium; RNA Interference; Regulation; Reproducibility; Research; Research Training; Role; Signal Transduction; Specific qualifier value; Structure; Surface; Testing; Testis; Tissues; Training; Transducers; Universities; Visceral; Wasps; Writing; career; cell motility; cell type; comparison control; experience; improved; knock-down; lymph nodes; migration; mutant; overexpression; progenitor; prospective; self-renewal; single-cell RNA sequencing; stem cell differentiation; stem cells; symposium; tumor; verbal; wound healing

Project Summary/Abstract Understanding how niches regulate stem cells is critical to human health because aberrant regulation by the niche can cause tumor formation or tissue atrophy. Well-studied niches form in predictable structures following reproducible morphogenetic changes, suggesting niche structure is regulated and functionally important. This has not been directly studied. Additionally, the mechanisms that determine the initial positioning of niches during development remain understudied. To address these deficits, we study the Drosophila posterior signaling center (PSC)—the niche of the larval lymph gland. The PSC maintains hematopoietic progenitors, and it induces differentiation of a special immune cell upon immune challenge. The PSC forms during embryogenesis: its cells migrate dorsally, where they ultimately reside, coalesced at the lymph gland posterior. Preliminary data indicates that mutants without visceral mesoderm (vm) have dispersed PSCs and fewer PSC cells. As such, the overall hypothesis is that the vm guides PSC positioning to the lymph gland posterior. We further hypothesize that a coalesced PSC is required for its optimal function as a niche. Aim 1 will identify the role of vm and its mechanism of action in instructing PSC formation via live-imaging of vm mutants to identify the timing and type of the PSC defect, and then testing vm candidate cues with vm-specific RNAi knockdown of the cue followed by analysis of PSC positioning. The PSC signal transducer will be identified by PSC-specific RNAi knockdown of candidate transducers. Ectopic expression of the vm cue in a nearby tissue will reveal if the cue is a true guidance cue sufficient to guide PSC positioning, or whether it confers competency to respond to other positional cues. Aim 2 will investigate how PSC coalescence contributes to niche function by causing PSC dispersion and then assessing PSC functions. Ability of the dispersed PSC to maintain progenitors will be tested by quantitating PSC- dependent progenitors, and ability to generate an immune response by challenging larvae with parasitoid wasp infection, and then quantitating a specialized immune cell type. The PSC can sense the organism’s nutrient and immune environment, but it is unknown if it senses feedback from the cells it regulates. This will be tested with lineage-specific ablation of progenitors or mature hemocytes in the lymph gland with Gal4/UAS-driven apoptosis. Then the level of PSC maintenance and differentiation signals will be measured for comparison to controls. Accomplishing these aims will reveal principles of niche formation, how niche structure impacts its function, and whether a niche receives feedback from the tissue it supports. Research training will take place at the University of Pennsylvania under the advisement of the Sponsor, the PI’s thesis committee, and Penn faculty as needed. The training plan consists of an integrated and creatively unique sequence of mentorship experiences to prepare the PI for their career. Training includes several opportunities to improve written and verbal communication, and professional development activities (course, conferences, seminars) for the PI to transition to a new research topic for an academic postdoctoral fellowship.

项目摘要/摘要 了解壁细分如何调节干细胞对人类健康至关重要，因为 利基可以引起肿瘤形成或组织萎缩。可预测的结构以后的壁nighes形成 可再现的形态发生变化，表明利基结构受到调节，在功能上很重要。这 尚未直接研究。此外，确定壁ches初始定位的机制 发展仍然是被理解的。为了解决这些缺陷，我们研究果蝇后信号传导中心 （PSC） - 幼虫淋巴腺体的细分市场。 PSC保持造血祖细胞，并诱导 在免疫挑战时区分特殊免疫力。胚胎发生过程中的PSC形成：其细胞 向后迁移，最终居住在淋巴腺后方。初步数据指示 没有内脏中胚层（VM）的突变体具有分散的PSC和较少的PSC细胞。因此，总体 假设是，VM将PSC定位在淋巴腺后部。我们进一步假设 合并为PSC是其作为利基市场的最佳功能所必需的。 AIM 1将确定VM及其机制的作用 通过VM突变体的现场成像来指导PSC形成的作用，以识别PSC的时间和类型 缺陷，然后用VM特异性的RNAi敲低测试VM候选线索，然后分析 PSC定位。 PSC信号传感器将通过PSC特异性RNAi击倒候选者识别 传感器。 VM提示在近组织中的异位表达将揭示是否提示是真正的指导提示 足以指导PSC定位，或者是否承认响应其他位置提示的能力。目标2 将研究PSC结合如何通过引起PSC分散并随后导致利基功能的贡献 评估PSC功能。分散PSC维持祖细胞的能力将通过定量PSC-进行测试 依赖的祖细胞，以及通过用寄生虫黄蜂挑战幼虫产生免疫反应的能力 感染，然后定量专门的免疫细胞类型。 PSC可以感觉到有机体的营养和 免疫环境，但未知是否从其调节的细胞中感受到反馈。这将通过 与GAL4/UAS驱动的细胞凋亡中祖细胞或成熟血细胞的谱系特异性消融。 然后，将测量PSC维护和分化信号的水平，以与对照组进行比较。 实现这些目标将揭示利基形成原则，利基结构如何影响其功能以及 利基市场是否从其支持的组织中收到反馈。研究培训将在大学进行 在赞助商，PI论文委员会和宾夕法尼亚州的建议下，宾夕法尼亚州的院长。 培训计划包括一系列综合而创造性的独特经验，以准备 他们职业生涯的PI。培训包括一些改善书面和口头交流的机会，以及 专业开发活动（课程，会议，半段），供PI过渡到一项新研究 学术博士后奖学金的主题。