Physiologic Regulation of Hematopoiesis by Notch

描述（由申请人提供）：关于 在细胞水平上调节造血细胞自我更新的过程 和分化，特别是在对应激的生理反应期间， 炎症和感染。该项目的总体目标是 研究Notch受体在维持骨髓中的生理作用 体内平衡，特别是在炎症应激期间。主要假设 在我们的研究中测试的是：I）Notch激活是否有利于决定 在干细胞和祖细胞水平上自我更新超过分化，以及2） 这是否代表了骨髓中重要的调节功能， 对炎症和感染的生理反应。我们假设Notch 激活可能平衡炎症因子的促分化作用， 细胞因子，允许祖细胞增殖池的扩增 需要对生理压力作出反应，并防止干细胞库 因为精疲力竭具体目标：为了验证这些假设，我们计划：（1） 确定陷波增益函数和（2）陷波损失函数的影响， 对干细胞和祖细胞自我更新和扩增潜力的影响;（3） 评估炎症过程中BM细胞中Notch途径活化的水平 应力;（4）确定骨过程中Notchi功能丧失的后果 骨髓对炎症应激的反应。研究设计和方法：我们将 使用不同和互补的体内模型：a）异种移植 工程化以表达Notch 1组成型的人细胞的实验 或配体J2的转基因小鼠; B）转基因小鼠 将使用经工程改造以表达Notch反义的细胞来评估 c）“小鼠全皮肤厚度烧伤模型” （脓毒症模型）将用作炎症模型，以评价BM反应 Notch函数重要性：这些研究旨在产生洞察力 调节成人造血的生理机制我们认为 更好地理解这些事件对于理解 造血系统疾病的生物学， 新的治疗策略，特别是靶向离体扩增的那些 人类造血干细胞

DESCRIPTION (provided by applicant): Little is known about the mechanisms that regulate, at the cellular level, the process of hematopoietic cell self-renewal and differentiation, in particular during physiologic responses to stress, such as inflammation and infection. The overall objective of this project is to study the physiologic role of Notch receptors in maintaining bone marrow homeostasis, in particular during inflammatory stress. The main hypotheses to be tested in our study are: I) whether Notch activation favors the decision of self-renewal over differentiation at the stem and progenitor cell level, and 2) whether this represents an important regulatory function during bone marrow physiologic response to inflammation and infection. We hypothesize that Notch activation may balance the prodifferentiative effects of inflammatory cytokines, permitting expansion of the proliferating pool of progenitor cells required to respond to physiologic stress and preventing the stem cell pool from exhaustion. Specific Aims: to test these hypotheses we plan to: (1) determine the impact of Notch gain-of function and (2) Notch loss-of function, on self-renewal and expansion potential of stem and progenitor cells; (3) evaluate the level of Notch pathway activation in BM cells during inflammatory stress; (4) determine the consequences of Notchi loss-of function during bone marrow response to inflammatory stress. Research Design and Methods: We will use different and complementary in vivo models: a) xenotransplantation experiments of human cells, engineered to express constitutive forms of Notch 1 or the ligand J2, will be carried out into NOD/S CID mice; b) transgenic mice engineered to express the Notch antisense will be used to evaluate the effects of Notch loss-of function; c) the "mouse full skin thickness burn model" (sepsis model) will be used as a model of inflammation to evaluate BM response and Notch function. Significance: These studies are intended to yield insight into the physiologic mechanisms that regulate adult hematopoiesis. We believe that a better comprehension of these events is crucial for the understanding of the biology of hematopoietic disorders and essential for the development of novel therapeutic strategies, in particular those targeted to ex-vivo expansion of human hematopoietic stem cells.