TRANSCRIPTION FACTORS/ GENETIC SEQUENCES REQUIRED FOR CD34 IN EARLY HEMATOPOIESIS

我的研究计划的长期目标是确定调控近乎造血的分子机制。为了做到这一点，我正在使用小鼠CD34基因作为模型系统。CD34是目前鉴定最好的抗原，可用于分离人干细胞移植中的造血重建细胞。它的表达与造血分化过程中的谱系承诺相协调，CD34在造血干、祖细胞上表达，随着成熟度的增加，CD34表达减弱，所有成熟血细胞CD34阴性。强迫过表达CD34抑制终末分化，提示CD34下调在分化过程中是必需的。到目前为止，我已经确定了CD34基因的关键区域，这些区域以组织特异性的方式增强CD34启动子的表达。本提案提出的目标是从几个方向探讨早期造血分化的研究。一个潜在的干细胞特异性转录因子的分离和鉴定，2。建立一个共享CD34阶段特异性表达模式的基因家族，因此可能受到协调调控，3)分离和鉴定CD34在体内的位置非依赖性、拷贝数依赖性、细胞型特异性表达所需的DNA序列；确定这些基因是髓系分化所必需的，但当CD34下调被阻止时，这些基因被抑制。这些目标中的每一个都有助于更好地理解造血干细胞是如何调控的。干细胞如何“知道”保持干细胞，或在外周血中分裂和分化为任何成熟细胞，这一理解的加深对白血病和其他造血系统疾病(如骨髓发育不良和再生障碍性贫血)的发病机制有直接影响。

The long-term goal of my research program is to define the molecular mechanisms that regulate nearly hematopoiesis. To do this I am using the murine CD34 gene as a model system. CD34 is the best characterized antigen that can be used to isolate hematopoietic reconstituting cells for human stem cell transplantation. It's expression is coordinately regulated with lineage commitment in hematopoietic differentiation such that CD34 is expressed on hematopoietic stem and progenitor cells, and as maturation progresses, expression decreases and all mature blood cells are CD34 negative. Forced over-expression of CD34 inhibits terminal differentiation suggesting that CD34 down-regulation is required for the differentiation process. In work to date, I have identified critical regions of the CD34 gene that enhance expression from the CD34 promoter in a tissue-specific manner. The aims presented in this proposal approach the study of early hematopoietic differentiation from several directions-1.) The isolation and identification of a potentially novel stem cell-specific transcription factor, 2.) The establishment of a family of genes that share the stage specific expression pattern of CD34, and therefore may be coordinately regulated, 3.) The isolation and identification of the DNA sequences required for position-independent, copy-number dependent, ell typed specific expression of CD34 in vivo, and 4.) Identification of these genes that are required for myeloid differentiation, but are inhibited when CD34 down-regulation is prevented. Each of this goals contributes to a better understanding of how hematopoietic stem cells are regulated. This increased understanding of how a stem cell "knows" to remain a stem cell, or to divide and differentiate into any of the mature cells in the peripheral blood has direct implications for the pathogenesis of leukemia and other hematopoietic disorders such as myelodysplasia and aplastic anemia.