Mechanisms of human pre-B cell differentiation

 描述（由申请人提供）：通过早期B细胞分化的受调节的转变对于成熟B细胞库的产生和选择非常重要。我们最近描述了小鼠B细胞分化早期的过渡阶段，除了前BCR和IL 7 R信号传导外，还显示整合素依赖性基质粘附、强增殖能力和自我更新。转录调节因子Ikaros的丢失导致在该基质粘附前B细胞阶段的停滞，其中整合素信号传导、基质粘附和自我更新显著增加，并且前BCR分化信号传导丢失。虽然早期B细胞分化的这一阶段对于人类血液系统疾病的发展也很重要，包括免疫缺陷和白血病，但对人类造血系统中的这一过程知之甚少，这是我们目前研究的重点。在第一个目标中，我们将评估在骨髓基质依赖系统中出现的人B细胞前体的层次结构。我们将研究早期人类B细胞前体增殖扩增和分化的体外基质依赖性，并确定与这些事件相关的信号通路和转录因子。将以类似的方式评价免疫缺陷NSG小鼠体内产生的人B细胞前体的分化特性。在第二个目标中，我们将研究IKAROS在人前B细胞分化中的作用。IKZF 1基因座将通过人类B细胞前体中的基因组编辑来破坏，以模拟人类疾病中的突变。将在体外基质培养物中和在NSG小鼠体内移植后测试IKAROS突变体B细胞前体的分化、增殖和粘附特性。从IKAROS缺陷型人前B细胞前体及其正常对应物产生的细胞和分子数据可以作为血液学疾病可以比较的基线。这些研究将共同产生关于驱动人类发育过程及其异常表现的分子途径的重要新知识。这项工作将使我们能够在小鼠和人类之间无缝移动，以发现治疗血液疾病的更好方法。

 DESCRIPTION (provided by applicant): Regulated transitions through early B cell differentiation are of great importance for the generation and selection of the mature B cell repertoire. We have recently described a transitional phase in early mouse B cell differentiation that in addition to pre-BCR and IL7R signaling also displays integrin-dependent stromal adhesion, strong proliferative capacity and self-renewal. Loss in the transcriptional regulator Ikaros causes arrest at this stromal- adherent pre-B cell stage with a profound increase in integrin signaling, stromal adhesion and self-renewal and loss in pre-BCR differentiation signaling. Although this stage of early B cell differentiation is also important for the developmen of human hematological disorders, including immunodeficiencies and leukemias, little is known of this process in the human hematopoietic system and is the focus of our current investigation. In the first aim, we will evaluate the hierarchy of human B cell precursors that arise in a bone marrow stromal-dependent system. We will examine the in vitro stromal dependence of early human B cell precursors for proliferative expansion and differentiation and identify the signaling pathways and transcriptional factors associated with these events. The differentiation properties of human B cell precursors generated in vivo in immune-deficient NSG mice will be evaluated in a similar fashion. In the second aim, we will examine the role of IKAROS in human pre-B cell differentiation. The IKZF1 locus will be disrupted by genome editing in human B cell precursors to model mutations in human disease. IKAROS mutant B cell precursors will be tested for differentiation, proliferation and adhesion properties in in vitro stromal cultures and in vivo aftr transplantation in NSG mice. Cellular and molecular data generated from IKAROS deficient human pre-B cell precursors and its normal counterparts can serve as baselines to which hematological disorders can be compared. Together these studies will generate critical new knowledge on the molecular pathways that drive the human developmental process and its aberrant manifestations. This work will enable us to move seamlessly between the mouse and human to discover better approaches for treating hematological disorders.