Role of Spi-C in eosinophil development and functional responses

描述（由申请人提供）：嗜酸性粒细胞增多症发生在各种临床疾病中，包括寄生虫感染、嗜酸性粒细胞增多综合征、癌症和特应性疾病。嗜酸性粒细胞来源于谱系造血祖细胞，表达转录因子GATA-1和白细胞介素-5受体α (IL-5Ra)。尽管GATA-1在嗜酸性粒细胞发育中的重要性已得到证实，但指导嗜酸性粒细胞谱系的祖细胞向成熟嗜酸性粒细胞分化的调控途径尚不清楚，特别是与其他造血谱系比较时。Fulkerson博士的长期目标是确定新的治疗靶点，以阻断嗜酸性粒细胞的产生和募集，用于治疗嗜酸性粒细胞哮喘和其他炎症性疾病患者。Fulkerson博士致力于学术医学事业，并成为一名独立的研究调查员。本提案中概述的培训计划将为Fulkerson博士提供一个建立科学利基的机会，并在提案的第三年提交R01拨款，促进Fulkerson博士成熟为一名独立的内科科学家。本提案的目的是描述转录因子Spi-C在嗜酸性粒细胞成熟中的调节活性。Spi-C在成熟嗜酸性粒细胞或嗜酸性粒细胞分化中的作用是完全未知的。这些研究有望通过调节IL-5Ra的表达和嗜酸性粒细胞颗粒蛋白的表达，详细了解嗜酸性粒细胞分化、存活和效应功能的重要途径。确定嗜酸性粒细胞功能和IL-5反应性的分子调节因子无疑将为临床应用提供关键信息，特别是考虑到目前正在蓬勃发展的IL-5Ra和IL-5定向治疗。本研究的核心假设是，转录因子Spi-C与转录因子PU.1和GATA-1协同作用，通过调控嗜酸性粒细胞存活、增殖和效应因子功能相关基因的表达，调控嗜酸性粒细胞的分化。我们将用三个具体目标来检验这一假设。首先，我们将使用Fulkerson博士开发的一种新型体外培养系统确定Spi-C在嗜酸性粒细胞成熟中的作用，该系统可导致嗜酸性粒细胞表型成熟。其次，我们将描述Spi-C和pu对IL-5Ra的调控。最后，我们将确定Spi-C和PU.1在调节嗜酸性粒细胞颗粒蛋白表达中的作用。总之，这些研究将阐明Spi-C在嗜酸性粒细胞分化中的作用。具体来说，这些研究将描述Spi-C和pu对颗粒蛋白表达和IL-5反应性的调节。由于颗粒蛋白的释放是嗜酸性粒细胞的重要效应功能，而IL-5信号传导对与疾病相关的嗜酸性粒细胞至关重要，因此进一步确定它们的调控可能会导致嗜酸性粒细胞相关疾病的新治疗靶点。

DESCRIPTION (provided by applicant): Eosinophilia occurs in a variety of clinical disorders including parasitic infections, hypereosinophilic syndrome, cancer, and atopic diseases. Eosinophils are derived from lineage-committed hematopoietic progenitor cells expressing the transcription factor GATA-1 and interleukin-5 receptor alpha (IL-5Ra). Although the significance of GATA-1 in eosinophil development is well established, the regulatory pathways that direct the differentiation of the eosinophil lineage-committed progenitor to mature eosinophils are not well understood, especially when compared with other hematopoietic lineages. The long term goals of the candidate, Dr. Fulkerson, are to identify novel therapeutic targets to block eosinophil production and recruitment for the treatment of patients with eosinophilic asthma and other inflammatory disorders. Dr. Fulkerson is dedicated to a career in academic medicine and to becoming an independent research investigator. The training plan outlined in this proposal will provide Dr. Fulkerson an opportunity to establish a scientific niche and facilitate the maturation of Dr. Fulkerson into an independent physician scientist with submission of a R01 grant in year three of the proposal. The objective of this proposal is to delineate the regulatory activity of the transcription factor Spi-C in eosinophil maturation. The role of Spi-C in mature eosinophils or eosinophil differentiation is completely unknown. The proposed studies are expected to provide a detailed understanding of the pathways important for eosinophil differentiation, survival and effector function via regulation of IL-5Ra expression and expression of eosinophil granule proteins. Defining the molecular regulators of eosinophil function and IL-5 responsiveness will undoubtedly provide key information with clinical applications, especially given the IL-5Ra- and IL-5-directed therapies that are currently under avid development. The central hypothesis of this proposal is that the transcription factor Spi-C coordinates with the transcription factors PU.1 and GATA-1 to regulate eosinophil differentiation via regulation of expression of genes important for eosinophil survival, proliferation and effector function. We will test this hypothesis with three specific aims. First, we will identify the role of Spi-C in eosinophil maturation using a novel in vitro culture system developed by Dr. Fulkerson that results in phenotypically mature eosinophils. Second, we will characterize the regulation of IL-5Ra by Spi-C and PU.1. Finally, we will determine the role of Spi-C and PU.1 in regulating expression of eosinophil granule proteins. Together, the proposed studies will elucidate the role of Spi-C in eosinophil differentiation. Specifically, the studies will delineate the regulation of granule protein expression and IL-5 responsiveness by Spi-C and PU.1. As release of granule proteins is an important effector function of eosinophils and IL-5 signaling is critical to eosinophilia associated with disease, further defining their regulation could lead to new therapeutic targets in eosinophil-associated disorders.