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节近造血的分子机制。为此，我使用小鼠CD34基因作为模型系统。CD34是可用于分离用于人类干细胞移植的造血重建细胞的最佳特征性抗原。它的表达与造血分化中的谱系定型协调调节，使得CD34在造血干细胞和祖细胞上表达，并且随着成熟的进行，表达降低并且所有成熟血细胞都是CD34阴性的。CD34的强制过表达抑制终末分化，表明分化过程需要CD34下调。在迄今为止的工作中，我已经确定了CD 34基因的关键区域，这些区域以组织特异性方式增强CD 34启动子的表达。本提案中提出的目标从几个方向探讨早期造血分化的研究：1.分离和鉴定一个潜在的新的干细胞特异性转录因子，2。建立了一个基因家族，该基因家族共享CD 34的阶段特异性表达模式，因此可能受到协同调控。分离和鉴定了CD34在体内的位置非依赖性、拷贝数依赖性、细胞类型特异性表达所需的DNA序列，以及4.）这些基因是骨髓分化所需的，但当CD34下调被阻止时被抑制。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节的。这增加了对干细胞如何“知道”保持干细胞或分裂和分化成外周血中的任何成熟细胞的理解，对白血病和其他造血系统疾病如骨髓增生异常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.