TYROSINE KINASE C-ABL AND BCR-ABL IN INTEGRIN DEPENDENT SIGNALING

这项拟议的研究的目标是了解粘附性如何 调节细胞增殖。重点将放在Abl酪氨酸上 作为生长调节信号的传导者。无处不在的 C-Abl定位于胞浆和胞核。核c-abl 结合DNA并调节转录。细胞质中的c-abl相互作用 G-肌动蛋白和F-肌动蛋白。最近，两个单位之间的一次合作 已经证明了这一过程中的激酶活性和 C-Abl的亚细胞定位受黏附状态的调节 一个牢房。此外，过表达一种有缺陷的激酶c-Abl可以 干扰黏附介导的MAP激酶的激活。C-Abl 激酶通过与BCR序列融合在一起而被结构性激活 慢性阻塞性肺疾病患者费城染色体产生的bcr-Abl蛋白 髓系白血病(CML)。慢性粒细胞白血病的转型目标 是附着在骨髓上的多能干细胞 斯特尔玛。慢性粒细胞白血病干细胞表现出粘附性降低，这一缺陷 与疾病状态相关。在成纤维细胞模型中，我们有 发展起来的BCR-Abl也被发现影响黏附功能。 此外，BCR-Abl可以取消粘附性要求以促进 不依赖于锚定生长，但不起有丝分裂原的作用。 综上所述，这些观察结果提出了一个模型，在该模型中， 激活c-Abl酪氨酸激酶转导黏附信号 促进正常生长，并解除对BCR-Abl信号的调控 不依赖于粘连而引起变形。为了测试这一点 假设，我们提出追求四个具体目标。在目标1中， C-Abl应答黏附所需的功能结构域为 将比较已鉴定的ABL+/+和ABL-/-细胞 对粘连的反应。在目标2中，bcr-abl 将对粘附性的影响进行调查。在目标3中，下游目标为 C-Abl和bcr-Abl在黏附调节通路中将被 确定，特别是受Rho和 MAP激酶的激活。我们已经证明了p130Cas是一种潜在的 BCR-Abl的底物，并将识别其他底物。我们还将隔离 通常受黏附和bcr-Abl调控的基因。这个 目标是获得核目标，以便更好地了解 黏附调节通路。在目标4中，我们将研究该函数 Abl靶点在调节细胞增殖中的作用。结果和 从用成纤维细胞进行的实验中获得的试剂 该模型将扩展到造血细胞，并最终在 足月骨髓培养法研究急性髓系白血病患者血清酪氨酸激酶活性 控制干细胞增殖。

The goal of the proposed research is to understand how adhesion regulates cell proliferation. The focus will be on the Abl tyrosine kinase as a transducer of the growth regulatory signal. The ubiquitous c-Abl is localized in the cytoplasm and the nucleus. The nuclear c-abl binds DNA and regulates transcription. The cytoplasmic c-abl interacts with both G and F-actin. Recently, a collaboration between two units of this program has demonstrated that the kinase activity and the subcellular localization of c-Abl is regulated by the adherent status of a cell. In addition, overexpression of a kinase-defective c-Abl can interfere with adhesion-mediated activation of MAP kinase. The c-Abl kinase is constitutively activated by fusion with Bcr sequences in the Bcr-Abl protein produced from the Philadelphia chromosome in chronic myelogenous leukemia (CML). The targets of transformation in CML are the pluripotent stem cells which are adherent to the bone marrow stroma. The CML stem cells show reduced adhesion and this defect is correlated with the diseased state. In a fibroblast model we have developed, Bcr-Abl is also found to affect the adhesive function. Moreover, Bcr-Abl can abrogate the adhesion requirement to promote anchorage-independent growth, but does not function as a mitogen. Taken together, these observations suggest a model in which regulated activation of c-Abl tyrosine kinase transduces adhesion signal to promote normal growth, and a deregulated Bcr-Abl signals independently of adhesion to cause transformation. To test this hypothesis, we propose to pursue four specific aims. In Aim 1, the functional domains required for c-Abl to respond to adhesion will be identified and the abl+/+ and abl-/- cells will be compared for their response to adhesion. In Aim 2, the mechanism by which Bcr-Abl affects adhesion will be investigated. In Aim 3, downstream targets of c-Abl and Bcr-Abl in the adhesion-regulated pathways will be identified, in particular the pathways regulated by Rho and the activation of MAP kinase. We have shown p130cas to be a potential substrate of Bcr-Abl, and will identify others. We will also isolate genes that are commonly regulated by adhesion and by Bcr-Abl. The goal is to obtain nuclear targets with which to better understand the adhesion-regulated pathways. In Aim 4, we will examine the function of Abl targets in the regulation of cell proliferation. Results and reagents obtained from the experiments conducted with the fibroblast model will be extended to hematopoietic cells and utimately in long- term bone marrow culture to study the Abl tryosine kinase in the control of stem cell proliferation.