Molecular Genetic Basic of Cyclic Hematopiesis

描述（由申请人提供）：这是第一次竞争性更新PI的资助，PI是一名新的研究者，并通过总统科学家和工程师早期职业奖（PECASE）扩展，并成功发现，分子表征和遗传性中性粒细胞减少症基因的动物建模。中性粒细胞是最丰富的白色血细胞，并作为一种先天防御细菌和真菌败血症。中性粒细胞减少症是指中性粒细胞数量不足，主要有两种遗传形式：常染色体显性周期性造血（也称为“周期性中性粒细胞减少症”）和遗传异质性重度先天性中性粒细胞减少症（SCN，也称为“Kostmann综合征”）。具有周期性造血的个体患有以三周周期振荡的中性粒细胞计数，在接近正常值和零之间交替，并使他们在周期的最低点期间容易受到感染。SCN包括持续的中性粒细胞减少和白血病的易感性。全基因组定位克隆连锁筛选显示，ELA 2（编码中性粒细胞颗粒丝氨酸蛋白酶、中性粒细胞弹性蛋白酶（NE））的杂合突变导致循环造血，候选基因分析发现它也是SCN最常见的原因。由于它们的严重性，以及随之而来的遗传适应性降低，许多病例都是由新的显性突变引起的。候选基因的研究确定了罕见的SCN病例可归因于转录抑制癌基因Gfi1的突变。对犬周期性造血的遗传分析发现，这是由AP3B1突变引起的，AP3B1编码参与亚细胞运输的APS复合物的亚基。Gfi 1抑制NE的表达，反过来，NE被APS从高尔基体网络运输到嗜中性粒细胞颗粒，并被假设与通过酵母双杂交和人突变筛选鉴定的其他因子一起沿着起作用，作为造血的负反馈调节剂，其中断导致循环现象.三个具体的目标，提出了一个框架内的反馈假设的测试：1。开发遗传性中性粒细胞减少症的ELA2细胞和小鼠模型。2.测试所提出的反馈电路的节点（PFAAP5、SOCS3和Notch家族蛋白）之间的分子相互作用。3.评估作为中性粒细胞减少症不明病例候选者的建议反馈电路的节点编码基因。

DESCRIPTION (provided by applicant): This is the first competing renewal for a grant from a PI who had been a new investigator and that was extended through the Presidential Early Career Award for Scientists and Engineers (PECASE) and was successful for the discovery, molecular characterization, and animal modeling of genes responsible for hereditary neutropenia. Neutrophils are the most abundant of the white blood cells and act as an innate defense against bacterial and fungal sepsis. Neutropenia refers to a deficiency in the number of neutrophils, and there are two main hereditary forms: autosomal dominant cyclic hematopoiesis (also known as "cyclic neutropenia") and the genetically heterogeneous severe congenital neutropenia (SCN, also known as "Kostmann syndrome"). Individuals with cyclic hematopoiesis suffer from neutrophil counts that oscillate with three week periodicity, alternating between near normal values and zero and leaving them vulnerable to infection during the nadir of the cycle. SCN consists of continuous neutropenia and a predisposition to leukemia. A genome wide screen for linkage with positional cloning showed that heterozygous mutation of ELA2, encoding the neutrophil granule serine protease, neutrophil elastase (NE), causes cyclic hematopoiesis, and candidate gene analysis found it also to be the most common cause of SCN. Because of their severity, and attendantly reduced genetic fitness, many cases arise sporadically from new dominant mutations. Candidate gene investigation identified rare cases of SCN attributable to mutations in the transcriptional represser oncogene Gfi1. Genetic analysis of canine cyclic hematopoiesis found it to result from mutations in AP3B1, encoding a subunit of the APS complex involved in subcellular trafficking. Gfi1 represses the expression of NE, which, in turn, is trafficked by APS from the trans-Golgi network to neutrophil granules, and is hypothesized to function, along with other factors identified through yeast two- hybrid and human mutational screens, as a negative feedback regulator of hematopoiesis whose interruption accounts for the cyclic phenomenon. Three Specific Aims are proposed within the framework of a test of the feedback hypothesis: 1. Develop ELA2 cellular and mouse models of hereditary neutropenia. 2. Test molecular interactions between nodal points (PFAAP5, SOCS3, and Notch family proteins) of the proposed feedback circuit. 3. Evaluate the genes encoding nodal points of the proposed feedback circuit as candidates for unaccounted cases of neutropenia.