MOLECULAR CHARACTERIZATION OF GM-CSF ACTION

粒细胞巨噬细胞集落刺激因子(GM-CSF)是一种 促进细胞增殖和增殖的造血生长因子 促进髓系祖细胞的成熟，增强其功能。GM-CSF 能有效改善化疗引起的骨髓抑制和 促进骨髓移植后的血液学恢复。这个 GM-CSF的生物学活性是由高亲和力受体介导的， 它由α和β亚基组成(也与IL-3共享 和IL-5受体)。精确的生化和分子事件 GM-CSF的作用机制目前尚不清楚。 我们的实验室已经证明了快速和瞬时的诱导 即刻早期基因Egr-1在增殖期和终末期的表达 分化的造血细胞。通过使用Egr-1诱导作为一种 终点，我们已经开始鉴定介导GM-CSF诱导的序列 基因表达。这将允许我们向后工作以确定密钥 GM-CSF信号转导通路中的各个步骤。重组构建物 含有人Egr-1启动子和氯霉素的区域 乙酰转移酶(CAT)报告基因瞬时导入 依赖GM-CSF或IL-3的细胞系TF-1。初步结果 已经证明GM-CSF和IL-3通过重叠和 不同的序列，表明它们的信号通路存在分歧。 这项提议的目的是：1)准确地识别核苷酸 调节GM-CSF诱导基因的人Egr-1启动子序列 表达；2)分离和表征核因子 与GM-CSF反应序列相互作用；以及3)确定其作用 这些因素在正常和肿瘤靶细胞中。总的来说，这些 调查将提供关于准确的 控制髓系细胞增殖的机制和将屈服 对髓系白血病的病理生理学和治疗的洞察。 作为一名儿科血液学家/肿瘤学家，我的最终目标是了解 浅谈生物学与患者临床管理的关系 患有这种潜在致命疾病的人。这个项目将允许我 追求我对儿科血液学/肿瘤学的兴趣，并 弥合基础科学研究和临床医学之间的鸿沟。

Granulocyte-macrophage colony-stimulating factor (GM-CSF) is a hematopoietic growth factor which promotes the proliferation and maturation of myeloid progenitors and enhances their function. GM-CSF is effective in ameliorating chemotherapy-induced myelosuppression and enhances hematologic recovery following bone marrow transplantation. The biological activity of GM-CSF is mediated by a high-affinity receptor, which consists of an alpha and beta subunit (also shared with the IL-3 and IL-5 receptors). The precise biochemical and molecular events mediating the effects of GM-CSF are presently unknown. Our laboratory has demonstrated the rapid and transient induction of the immediate early gene, Egr-1, in both proliferating and terminally differentiated hematopoietic cells. By using Egr-1 induction as an endpoint, we have begun to identify sequences mediating GM-CSF-induced gene expression. This will allow us to work backwards to identify key steps in the GM-CSF signal transduction pathway. Recombinant constructs containing regions of the human Egr-1 promoter and chloramphenicol acetyltransferase (CAT) reporter gene were transiently transfected into the GM-CSF- or IL-3-dependent cell line, TF-1 . Preliminary results have demonstrated that GM-CSF and IL-3 work through both overlapping and distinct sequences, suggesting that their signaling pathways diverge. The aims of this proposal are to: 1) precisely identify the nucleotide sequences of the human Egr-1 promoter regulating GM-CSF-induced gene expression; 2) fractionate and characterize the nuclear factors interacting with GM-CSF-responsive sequences; and 3) determine the role of these factors in normal and neoplastic target cells. Overall, these investigations will provide new and important information on the precise mechanisms controlling proliferation of myeloid cells and will yield insights into the pathophysiology and treatment of myeloid leukemias. As a Pediatric Hematologist/Oncologist, my ultimate goal is to understand the relationship between the biology and clinical management of patients who have this potentially fatal condition. This project will allow me to pursue my interests in academic pediatric hematology/oncology and to bridge the gap between basic science research and clinical medicine.