Negative Regulation of Signal Transduction by G-CSF

G-CSF 对信号转导的负调控

• 批准号: 6686316
• 负责人: FAN DONG
• 金额: $ 19.46万
• 依托单位: UNIVERSITY OF TOLEDO
• 依托单位国家: 美国
• 财政年份: 2002
• 资助国家: 美国
• 起止时间: 2002-09-02 至 2007-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6686316
• 关键词: SDS polyacrylamide gel electrophoresis; antibody; biological signal transduction; carcinogenesis; cell differentiation; cell proliferation; colony stimulating factor; cytokine receptors; enzyme activity; flow cytometry; gel mobility shift assay; granulocyte; immunoprecipitation; leukemia; leukopoiesis; mutant; phosphorylation; protein structure function; protein tyrosine phosphatase; receptor binding; receptor expression; thin layer chromatography; western blottings

Binding of granulocyte colony-stimulating factor (G-CSF) to its cognate receptor results in activation of multiple signal transduction pathways that are critical for the regulation of granulopoiesis. How G-CSF-activated signaling events are downmodulated is largely unknown. Mutations in the G-CSF receptor gene leading to its C-terminal truncation have been reported in patients with acute myeloid leukemia (AML), providing the first clinical evidence for the involvement of abnormal cytokine receptors in human leukemia. Expression of the truncated receptors in hematopoietic cells results in enhanced cell proliferation and survival but impaired myeloid differentiation in response to G-CSF. The truncated receptors also mediate dramatically augmented and/or prolonged activation of Stats and Akt, which play crucial roles in regulating cell proliferation and survival. Interestingly, substitution of the three C-terminal tyrosine residues with phenylalanine leads to prolonged but not enhanced activation of Stats and Akt whereas deficiency of tyrosine phosphatase SHP-1 is associated with enhanced but not prolonged Stat activation by G-CSF. We hypothesize that the magnitude and duration of Stat and Akt activation by G-CSF are downregulated by distinct negative regulatory mechanisms and that the C-terminal region of the G-CSF receptor may contain critical subdomains implicated in interactions with the negative regulatory mechanisms. Two specific aims are proposed to test this hypothesis: (1) to define the C-terminal subdomain required for the downregulation of the magnitude of Stat activation and examine the mechanism by which SHP-1 exerts its negative effect on Stat activation; and (2) to identify the C-terminal tyrosine residues involved in the negative regulation of the duration of Stat and Akt activation by G-CSF and investigate the roles of negative regulatory molecules such as SHP-2 and SHIP in G-CSF receptor signaling. The proposed research will improve our understanding of the regulatory network of G-CSF signaling and the molecular mechanisms by which C- terminal truncation of the G-CSF receptor contribute to leukemogenesis.

粒细胞集落刺激因子 (G-CSF) 与其同源受体的结合导致多个信号转导途径的激活，这对于粒细胞生成的调节至关重要。 G-CSF 激活的信号事件如何下调尚不清楚。 据报道，急性髓系白血病 (AML) 患者的 G-CSF 受体基因突变导致其 C 末端截短，这为人类白血病中异常细胞因子受体的参与提供了首个临床证据。 造血细胞中截短受体的表达导致细胞增殖和存活增强，但响应 G-CSF 损害骨髓分化。 截短的受体还介导 Stats 和 Akt 的激活显着增强和/或延长，这在调节细胞增殖和存活中发挥着至关重要的作用。 有趣的是，用苯丙氨酸取代三个 C 端酪氨酸残基会导致 Stats 和 Akt 的激活延长但不增强，而酪氨酸磷酸酶 SHP-1 的缺乏与 G-CSF 的 Stat 激活增强但不延长有关。 我们假设 G-CSF 激活 Stat 和 Akt 的幅度和持续时间受到不同的负调节机制的下调，并且 G-CSF 受体的 C 末端区域可能包含与负调节机制相互作用有关的关键子结构域。 提出了两个具体目标来检验这一假设：（1）定义下调 Stat 激活幅度所需的 C 端子结构域，并研究 SHP-1 对 Stat 激活发挥负面影响的机制； (2) 鉴定参与 G-CSF 对 Stat 和 Akt 激活持续时间负调节的 C 端酪氨酸残基，并研究 SHP-2 和 SHIP 等负调节分子在 G-CSF 受体信号传导中的作用。 拟议的研究将提高我们对 G-CSF 信号传导调节网络以及 G-CSF 受体 C 端截短导致白血病发生的分子机制的理解。