EMBRYONIC HEMATOPOIESIS

胚胎造血

• 批准号: 2224881
• 负责人: LEONARD Ira ZON
• 金额: $ 21.95万
• 依托单位: BOSTON CHILDREN'S HOSPITAL
• 依托单位国家: 美国
• 财政年份: 1992
• 资助国家: 美国
• 起止时间: 1992-08-01 至 1996-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/2224881
• 关键词: DNA binding protein; RNA biosynthesis; RNase protection assay; Xenopus; alternatives to animals in research; complementary DNA; developmental genetics; embryogenesis; embryonic stem cell; fibroblast growth factor; genetic promoter element; globin; growth factor receptors; hematopoiesis; in situ hybridization; inhibin; laboratory rabbit; lithium; mesoderm; molecular cloning; monoclonal antibody; northern blottings; polymerase chain reaction; protein structure function; receptor expression; reporter genes; retinoate; tissue /cell culture; transcription factor; ultraviolet radiation

Embryonic hematopoietic stem cells are derived from totipotent stem cells through activation of a coordinated cascade of spatially-expressed inductive, proliferative and differentiating signals. Although growth factors involved in hematopoietic progenitor maturation have been extensively studied, the mechanisms responsible for the commitment of stem cells to hematopoiesis are poorly understood. The proposed studies are aimed at (1) characterization of the expression and function of hematopoietic transcription factors in defining the embryonic hematopoietic axis; (2) isolation and characterization of the signals involved in hematopoietic stem cell determination. The process of hematopoiesis is well conserved throughout vertebrate evolution. Xenopus is an ideal organism to study hematopoiesis since development has been extensively studied, cell fate maps have been constructed from the 32 cell embryo, multipotential embryonic stem cells can be easily obtained from staged embryos before blood island formation, and hematopoietic maturation occurs rapidly within 36 hours after fertilization. cDNA clones have been isolated which encode the Xenopus homologs of transcription factors expressed early in the hematopoietic program including GATA-1, 2, and 3, and SCL. In situ analysis of whole embryos has demonstrated that GATA-1 and 2 are expressed in the ventral region before blood is histologically evident, indicating that the GATA-binding proteins are involved in the determination of the embryonic hematopoietic axis. By studying the expression of these DNA-binding proteins in multipotential stem cells incubated with factors which affect mesoderm induction, we hope to define the environmental conditions necessary for hematopoiesis. Our results to date indicate that a signal derived from the ventral region of the embryo functions to induce hematopoietic development and maintain GATA-1 expression. This signal does not appear to be a known mesoderm inducing factor such as activin or fibroblast growth factor. This early hematopoietic signal will be isolated and characterized. The proposed study will provide new insights into the developmental biology of hematopoiesis in both normal and pathologic states such as anemia and hemoglobinopathies.

胚胎造血干细胞来源于全能干细胞 通过激活空间表达的协调级联 感应、增殖和分化信号。 虽然成长 与造血祖细胞成熟有关的因素 广泛研究了负责承诺的机制 人们对干细胞造血作用知之甚少。 拟议的研究 旨在 (1) 表达和功能的表征 造血转录因子定义胚胎 造血轴； (2) 信号的隔离和表征 参与造血干细胞测定。 的过程 在脊椎动物的进化过程中，造血功能得到了很好的保存。 爪蟾属 自从发育以来，它是研究造血的理想生物体 经过广泛研究，细胞命运图谱已从 32 细胞胚胎，多能胚胎干细胞轻松获得 来自血岛形成之前的分期胚胎和造血 受精后36小时内迅速成熟。 cDNA 已分离出编码非洲爪蟾同源物的克隆 在造血程序早期表达的转录因子 包括 GATA-1、2、3 和 SCL。 整个胚胎的原位分析 已证明 GATA-1 和 2 在腹侧区域表达 在血液之前，组织学上是明显的，表明 GATA 结合 蛋白质参与胚胎造血的决定 轴。 通过研究这些 DNA 结合蛋白的表达 与影响中胚层的因子一起孵育的多能干细胞 归纳，我们希望定义必要的环境条件 造血作用。 我们迄今为止的结果表明，信号源自 胚胎的腹侧区域具有诱导造血功能 发育并维持 GATA-1 表达。 该信号不出现 是已知的中胚层诱导因子，例如激活素或成纤维细胞 生长因子。 这种早期造血信号将被分离并 特点。 拟议的研究将为这一问题提供新的见解 正常和病理状态下造血的发育生物学 贫血和血红蛋白病等状态。