ROLE OF THE PNH PHENOTYPE IN LEUKEMIC TRANSFORMATION

描述(改编自申请人的摘要)：阵发性夜间发作 血红蛋白尿(PNH)是一种由克隆性贫血引起的血液疾病。 携带体细胞突变的造血祖细胞的扩增 X连锁的PIGA基因。它的典型表现是血红蛋白尿，原因是 血管内溶血、血栓并发症和全血细胞减少。《野猪》 该基因编码一种糖基转移酶的蛋白质亚单位，在 糖基磷脂酰肌醇(GPI)锚定分子的合成病人 因此，在所有与GPI相关的血细胞中，有一定比例的PNH患者的血细胞缺乏 表面分子。PNH常见于再生障碍性贫血患者。 (AA)和骨髓发育不良(MDS)患者。虽然不是肿瘤 疾病本身，PNH患者发生疾病的风险增加 急性髓系白血病(AML)。 在PNH与AA、MDS和AML的临床协会的推动下，我们提出了 PIGA基因突变本身不会导致克隆性扩张的假设 或白血病转化。但由于它们不能喜欢某些蛋白质 通过GPI锚定的PNH细胞逃脱免疫监视 和细胞死亡，导致再生障碍性贫血和控制肿瘤 白血病发生早期的细胞生长。 在这项拟议的研究中，我们将使用一种非常接近于 并研究PNH与MDS和AML的关系。我们会 通过干扰GPI连接蛋白获得血细胞缺乏的小鼠 小鼠PIGA基因在骨髓早期造血祖细胞中的表达 使用Cre-loxP系统。通过这种方法，我们将产生两种类型的小鼠， 一种是所有血细胞都缺乏GPI连接蛋白，而另一种是 将同时拥有PIGA(+)和PIGA(-)循环血细胞。到时候我们会的 这些小鼠体内和体外PIGA(+)和PIGA(-)造血功能的比较 在各种情况下，包括给予刺激 引发细胞死亡以及已知的导致白血病转化的药物。 表达野生型PIGA的细胞与表达PIGA的细胞之间的竞争 重组的PIGA等位基因将使我们能够发现 在造血分化的任何阶段，细胞死亡和增殖。 这些实验将证明PIGA(-)血细胞是否比 抵抗激活凋亡细胞死亡的特定刺激，以及是否 拥有PIGA(-)血细胞的小鼠患白血病的时间更早、频率更高 与血细胞表型正常的小鼠相比。通过这种方式，我们希望 找出对PNH和PNH死亡有不同影响的因素 正常造血祖细胞和阐明可能导致 对PNH患者白血病转化的影响。鼠标的可用性 PNH模型将为我们测试新的治疗方法提供一个强大的工具 治疗PNH、PNH/MDS、PNH、AML和可能的其他克隆性疾病的药物 血液紊乱。

DESCRIPTION (adapted from the applicant's abstract): Paroxysmal nocturnal hemoglobinuria (PNH) is a blood disorder, which is caused by the clonal expansion of a hematopoietic progenitor cell that carries a somatic mutation in the X-linked PIGA gene. It presented classically with hemoglobinuria due to intravascular hemolysis, thrombotic complications, and pancytopenia. The PIGA gene encodes a protein subunit of a glycosyltransferase essential in the synthesis of glycosyl phosphatidylinositol (GPI) anchor molecules. Patients with PNH therefore have a proportion of blood cells deficient in all GPI-linked surface molecules. PNH is frequently found in patients with aplastic anemia (AA) and in patients with myelodysplasia (MDS). Although not a neoplastic disease on its own, patients with PNH have an increased risk of developing acute myeloid leukemia (AML). Promoted by the clinical association of PNH with AA, MDS, and AML, we raised the hypothesis that a PIGA gene mutation alone does not cause clonal expansion or leukemic transformation. But due to their inability to like certain proteins to the cell surface through a GPI-anchor PNH cells escape immuno surveillance and cell death that causes bone marrow aplasia in AA and controls neoplastic cell growth in early leukemogenesis. In the proposed research we will use a mouse model that closely mimics the human disease and investigate the association of PNH with MDS and AML. We will obtain mice with blood cells lacking GPI-linked proteins by disrupting the murine Piga gene in early hematopoietic progenitor cells in the bone marrow using the Cre-loxP system. By this approach we will generate two types of mice, one with all blood cells deficient in GPI-linked proteins whereas the other will have both PIGA (+) and PIGA(-) circulating blood cells. We will then compare PIGA(+) and PIGA(-) hematopoiesis in these mice in vitro and in vivo under a variety of circumstances, including the administration of stimuli that trigger cell death along with agents known to cause leukemia transformation. Competition between cells expressing wild type Piga and those expressing the recombined Piga allele will enable us to uncover even subtle differences in cell death and proliferation in any stages of hematopoietic differentiation. These experiments will demonstrate whether PIGA(-) blood cells are more resistant to specific stimuli that activate apoptotic cell death and whether mice with PIGA(-) blood cells develop leukemia earlier and more frequent compared to mice with phenotypically normal blood cells. In this way we hope to identify the factors that differentially influence growth and death of PNH and normal hematopoietic progenitor cells and to elucidate mechanisms that may lead to leukemia transformation in patients with PNH. The availability of a mouse model for PNH will provide us with a powerful tool to test new therapeutic agents for the treatment of PNH, PNH/MDS, PNH,AML and possibly other clonal blood disorders.