PI 3-KINASE AND KIT RECEPTOR SIGNALING

这项建议的总体目标是调查PI 3的作用- C-kit受体介导的体内和体外过程中的激酶。 原癌基因c-kit编码受体酪氨酸激酶(Rtk)。 它属于包括血小板在内的受体家族- 衍生生长因子(PDGF)。C-kit受体的配体， KL编码一种细胞表面分子，该分子可能是 加工以产生一种可溶产品。而c-kit基因是 小鼠白斑基因W等位基因Kit-Ligand(KL) 等位基因与小鼠的钢基因座(Sl)。W和S1突变 影响造血的各个方面，包括干细胞 胚胎发育过程中的配子发生 成年动物，导致大细胞性贫血，肥大细胞缺乏 贫血，肥大细胞缺乏，斑点，男性和女性不孕不育 大冒号。 基于突变表型，c-受体介导的细胞反应 KIT受体种类繁多，包括：细胞增殖、细胞 生存，细胞黏附，细胞迁移，介质的分泌，细胞 分化和其他有丝分裂后的功能。对这一问题的解释 这些不同反应的机制是至关重要的。 类似于其他RTK的Kit通过各种不同的 KIT介导的包括PI 3-K在内的细胞质信号转导系统 骨髓基质细胞与纤维连接蛋白基质的黏附及对IgE的增强作用 BMMC介导性分泌。Kit/PI-3-K介导的研究 在其他细胞系统中，我们将修改c-kit基因 突变Kit受体中PI3-激酶结合位点的胚系 使用基于cre-lox的策略并获得纯合子的小鼠 突变。然后我们将研究突变对不同物种的影响 W和SI突变的靶点，造血细胞的动力学 在需要细胞黏附的情况下的种群及其行为 和迁移，即归巢到骨髓室和 动员干细胞进入外周。我们还将修改 Kit受体膜旁区域的酪氨酸残基 影响KL介导的细胞增殖但不影响的ES细胞 抑制细胞凋亡并研究其后果 体内突变。最后，我们将对Kit的作用机制进行研究 介导的辐射抑制和因子剥夺诱导 肥大细胞的凋亡。

The overall objectives of this proposal is to investigate the role of PI 3- kinase in c-kit receptor mediated processes in vivo and in vitro. The proto-oncogene c-kit, encodes a receptor tyrosine kinase (RTK) which belongs to a family of receptors that includes the platelet- derived growth factor (PDGF). The ligand of the c-kit receptor, designated KL, encodes a cell surface molecule which may be processed to produce a soluble product. Whereas the c-kit gene is allelic with the white spotting locus (W) in the mouse, kit-ligand (KL) is allelic with the steel locus (Sl) in the mouse. W and Sl mutations affect various aspects of hematopoiesis, including the stem cell compartment, gametogenesis during embryonic development and in the adult animal, causing macrocytic anemia, mast cell deficiency anemia, mast cell deficiency, spotting, male and female sterility and megacolon. Based on mutant phenotypes the cellular responses mediated by the c- kit receptor are quite diverse and include: cell proliferation, cell survival, cell adhesion, cell migration, secretion of mediators, cell differentiation and other post mitotic functions. The elucidation of the mechanisms of these different responses is of fundamental importance. Similar to other RTK's Kit mediates its action through a variety of cytoplasmic signal transducers including PI 3-kinase in KIT mediated adhesion of BMMC to a fibronectin matrix and potentiation of IgE mediated secretion in BMMC. To study Kit/PI 3-kinase mediated processes in other cell systems we will modify the c-kit gene in the germ line to mutate the PI 3-kinase binding site in the Kit receptor by using a cre-lox based strategy and derive mice homozygous for this mutation. We then will study the effect of the mutation on various targets of W and SI mutations, the dynamics of hematopoietic cell populations and their behavior in situations that require cell adhesion and migration, i.e. homing to the marrow compartment and mobilization of stem cells into the periphery. We will also modify tyrosine residues in the juxtamembrane region of the Kit receptor in ES cells which affect KL mediated cell proliferation but not suppression of apoptosis and investigate the consequences of this mutation in vivo. Finally, we will investigate the mechanism of Kit mediated suppression of radiation and factor deprivation induced apoptosis in mast cells.