Molecular Genetic Basic of Cyclic Hematopiesis

描述（由申请人提供）：这是第一次从一名新研究员获得资助的PI竞争更新，并通过总统科学家和工程师早期职业奖（PECASE）延长，并成功地发现，分子表征和动物建模负责遗传性中性粒细胞减少症的基因。中性粒细胞是白细胞中最丰富的，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的缺乏，主要有两种遗传形式：常染色体显性循环造血（也称为“循环中性粒细胞减少症”）和遗传异质性严重先天性中性粒细胞减少症（SCN，也称为“Kostmann综合征”）。具有循环造血的个体遭受中性粒细胞计数振荡，以三周为周期，在接近正常值和零之间交替，使他们在周期的最低点易受感染。SCN包括持续中性粒细胞减少和白血病易感性。基因组宽筛选与定位克隆的联系显示，编码中性粒细胞颗粒丝氨酸蛋白酶，中性粒细胞弹性酶（NE）的ELA2杂合突变导致循环造血，候选基因分析发现它也是SCN的最常见原因。由于其严重程度和随之而来的遗传适应度降低，许多病例零星地出现在新的显性突变中。候选基因调查发现罕见的SCN病例可归因于转录抑制癌基因Gfi1的突变。犬循环造血的遗传分析发现，它是由AP3B1突变引起的，AP3B1编码APS复合物的一个亚基，参与亚细胞运输。Gfi1抑制NE的表达，而NE反过来又被APS从反式高尔基网络转运到中性粒细胞颗粒，并被假设与通过酵母双杂交和人类突变筛选确定的其他因素一起，作为造血的负反馈调节器，其中断解释了循环现象。在反馈假设检验的框架内提出了三个具体目标：1。建立遗传性中性粒细胞减少症的ELA2细胞和小鼠模型。2. 测试反馈电路中节点（PFAAP5、SOCS3和Notch家族蛋白）之间的分子相互作用。3. 评估所提出的反馈回路的节点编码基因作为未解释的中性粒细胞减少病例的候选。

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.