Negative Regulation of Signal Transduction by G-CSF

G-CSF 对信号转导的负调控

• 批准号: 6469391
• 负责人: FAN DONG
• 金额: $ 2.83万
• 依托单位: CLEVELAND CLINIC FOUNDATION
• 依托单位国家: 美国
• 财政年份: 2002
• 资助国家: 美国
• 起止时间: 2002-07-01 至 2002-09-01
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6469391
• 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种信号转导途径的激活，这些信号转导途径对于调节粒细胞生成至关重要。 G-CSF激活的信号事件如何下调在很大程度上是未知的。 在急性髓性白血病（AML）患者中，G-CSF受体基因突变导致其C-末端截短，这为异常细胞因子受体参与人类白血病提供了第一个临床证据。 造血细胞中截短受体的表达导致细胞增殖和存活增强，但响应于G-CSF的髓样分化受损。 截短的受体还介导Stats和Akt的显著增强和/或延长的激活，其在调节细胞增殖和存活中起关键作用。 有趣的是，用苯丙氨酸取代三个C-末端酪氨酸残基导致Stats和Akt的活化延长但不增强，而酪氨酸磷酸酶SHP-1的缺乏与G-CSF的Stats活化增强但不延长相关。 我们推测，由G-CSF激活的Stat和Akt的幅度和持续时间被不同的负调控机制下调，并且G-CSF受体的C-末端区域可能包含与负调控机制相互作用的关键亚结构域。 本论文的主要目的是：（1）确定SHP-1抑制Stat激活的C端亚结构域，并探讨SHP-1抑制Stat激活的机制;和（2）鉴定参与G-受体对Stat和Akt激活持续时间负调控的C-末端酪氨酸残基。研究了SHP-2和SHIP等负调控分子在G-CSF受体信号转导中的作用。 这项研究将有助于我们更好地理解G-CSF信号转导的调控网络和G-CSF受体C端截短导致白血病发生的分子机制。