Molecular Genetic Basic of Cyclic Hematopiesis

描述(由申请人提供)：这是第一次从一个新的研究人员的PI竞争续期，这是通过总统科学家和工程师早期职业奖(PECASE)延长的，并成功地发现了导致遗传性中性粒细胞减少症的基因、分子特征和动物模型。中性粒细胞是白血球中含量最丰富的一种，是抵御细菌和真菌败血症的天然防御物。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：常染色体显性遗传性循环造血(又称循环中性粒细胞减少症)和遗传异质性重度先天性中性粒细胞减少症(SCN，又称科斯特曼综合征)。周期性造血者的中性粒细胞计数以三周为周期振荡，在接近正常值和零之间交替，使他们在周期的最低点容易受到感染。SCN包括持续性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查显示，编码中性粒细胞丝氨酸蛋白酶(NE)的ELA2杂合突变可导致周期性造血，候选基因分析发现它也是SCN最常见的原因。由于其严重性和随之而来的遗传适应性降低，许多病例零星地出现于新的显性突变。候选基因调查发现了罕见的SCN病例，可归因于转录抑制癌基因Gfi1的突变。对犬类循环造血的遗传分析发现，这是由于AP3B1基因突变导致的，AP3B1编码参与亚细胞运输的APS复合体的一个亚单位。GFI1抑制去甲肾上腺素的表达，去甲肾上腺素被AP从反式高尔基体网络输送到中性粒细胞颗粒，并与其他通过酵母双杂交和人类突变筛选确定的因子一起，作为造血的负反馈调节因子发挥作用，其干扰解释了循环现象。在反馈假说的检验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.评估编码建议的反馈电路的节点的基因作为不明原因的中性粒细胞减少症的候选。

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.