Role of the Lin28b/let-7 axis in the maturation of hematopoietic progenitor cells

项目总结 在正常的哺乳动物发育过程中，造血系统经历受控成熟。驾驶 在这个过程中，造血干细胞和祖细胞(HSPC)在其定义中执行戏剧性的转变 特点。这些变化包括自我更新、谱系偏见、分化细胞的谱系 产生，甚至有可能产生效力。这一过程在特定年龄的生物学中具有重要意义。 血液疾病，造血干细胞移植，正常衰老，以及努力改造患者- 用于治疗的特定造血细胞。我们和其他人的工作都高度牵涉到 保守的异时性Lin28b/let-7 microRNA调控轴的研究进展 HSPC。我们已经证明，Lin28b对let-7 microRNAs生物发生的抑制定义了红系- 偏向胎儿髓系祖细胞输出，同时下调Lin28b在发育过程中的表达 成年期允许成熟骨髓具有强大的骨髓生成能力。初步数据 在这一建议中，支持了新兴的范式，即单个中医被赋予单一的血统命运 在它们的起源(即，单能性)，这是由它们的转录状态决定的。这项提案考验着 假设在造血系统成熟期间，HSPC群体在其 异质单细胞组合物为了在自我更新中实现发育必需的变化， 效力和谱系限制分支点；并且Lin28b/let-7轴在调节中起中心作用 这一过程。这项提案的具体目的是：1)调查LIN28b/LET-7在调节 随着体内发育时间的推移而发生的谱系潜力的变化；2)直接联系 LIN28b/LET-7轴向谱系结局；以及3)评估LIN28b/LET-7调节 指定HSPC发育状态的基因调控网络。 我目前是波士顿儿童医院儿科血液学-肿瘤学的临床研究员。我有过 提出了一项为期五年的职业发展计划，该计划将建立在我在 儿童血液学以及我以前在发育造血方面的研究经验，以建立一个 在一个重要的学术中心担任独立调查员/内科科学家。在合并后的 乔治·Q·戴利博士、医学博士和本杰明·L·埃伯特博士的指导在 在正常血液学和疾病血液学的研究中，我建议严格调查基本情况 造血祖细胞正常发育成熟的机制。K08大奖 将为我提供必要的保护时间，以执行拟议的学习和职业发展 在五年的时间框架内进行规划。

PROJECT SUMMARY During normal mammalian development, the hematopoietic system undergoes controlled maturation. Driving this process, hematopoietic stem and progenitor cells (HSPCs) execute dramatic transitions in their defining characteristics. These include changes in self-renewal, lineage biases, repertoires of differentiated cells produced, and possibly even potency. This process is of critical significance in the biology of age-specific blood disorders, hematopoietic stem cell transplantation, normal aging, and efforts to engineer of patient- specific hematopoietic cells for use in therapy. Our work and that of others has implicated the highly conserved heterochronic Lin28b/let-7 microRNA regulatory axis in specification of the developmental state of HSPCs. We have shown that repression of the biogenesis of let-7 microRNAs by Lin28b defines erythroid- biased fetal myeloerythroid progenitor output, while downregulation of Lin28b expression during development to adulthood permits the robust myelopoiesis characteristic of the mature bone marrow. The Preliminary Data in this proposal supports the emerging paradigm that individual CMPs are imbued with a single lineage destiny at their genesis (i.e., unipotency) that is dictated by their transcriptional state. This proposal tests the hypothesis that during maturation of the hematopoietic system, populations of HSPCs evolve in their heterogeneous single cell composition in order to effect developmentally necessary changes in self-renewal, potency, and lineage restricting branch points; and that the Lin28b/let-7 axis plays a central role in regulating this process. The Specific Aims of this proposal are to: 1) investigate the role of Lin28b/let-7 in regulating the changes in lineage potency that occur over developmental time in vivo; 2) directly connect the activity of the Lin28b/let-7 axis to lineage outcomes; and 3) evaluate the mechanisms by which Lin28b/let-7 modulates the gene regulatory networks that specify developmental state in HSPCs. I am currently a clinical fellow in Pediatric Hematology-Oncology at Boston Children's Hospital. I have proposed a five-year career development plan that will build upon the foundation of my clinical background in Pediatric Hematology as well as my prior research experience in developmental hematopoiesis to establish a career as an independent investigator/physician-scientist at a major academic center. Under the combined mentorship of Dr. George Q. Daley, M.D., Ph.D. and Dr. Benjamin L. Ebert, M.D., Ph.D., established leaders in research in normal and diseased hematology, I propose rigorous investigation into the fundamental mechanisms underlying normal developmental maturation of hematopoietic progenitor cells. The K08 award will provide me with the necessary protected time to execute the proposed studies and career development plan within the five-year time frame.