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

拟议研究的目标是了解粘附如何 调节细胞增殖。 重点将放在Abl酪氨酸 激酶作为生长调节信号的转换器。 无处不在的 c-Abl定位于细胞质和细胞核中。 核c-abl 结合DNA并调节转录。 胞质c-abl相互作用 G肌动蛋白和F肌动蛋白 最近，两个单位之间的合作 该项目的研究表明，激酶活性和 c-Abl的亚细胞定位受粘附状态的调节， 一间牢房此外，激酶缺陷型c-Abl的过表达可 干扰粘附介导MAP激酶活化。 c-Abl 激酶通过与Bcr序列融合而被组成性激活， Bcr-Abl蛋白产生于费城染色体慢性 骨髓性白血病（CML）。 慢性粒细胞白血病的转化靶点 是附着在骨髓上的多能干细胞 基质。 慢性粒细胞白血病干细胞表现出减少的粘附和这种缺陷 与疾病状态有关。 在成纤维细胞模型中， Bcr-Abl也被发现影响粘附功能。 此外，Bcr-Abl可以消除粘附要求，以促进 锚定非依赖性生长，但不作为有丝分裂原发挥作用。 综上所述，这些观察结果表明，在一个模型中， c-Abl酪氨酸激酶的活化将粘附信号转导至 促进正常生长和Bcr-Abl信号失调 不依赖于粘附而引起转化。 为了验证这一 假设，我们建议追求四个具体目标。 在目标1中， c-Abl响应粘附所需的功能结构域将是 确定并比较abl+/+和abl-/-细胞的 对粘连的反应。 在目的2中，Bcr-Abl 将研究影响粘附性的因素。 在目标3中，下游目标 粘附调节通路中的c-Abl和Bcr-Abl将被 确定，特别是由Rho调节的途径， MAP激酶的激活。 我们已经证明p130 cas是一种潜在的 Bcr-Abl的底物，并将确定其他。 我们还将隔离 这些基因通常由粘附和Bcr-Abl调节。 目标是获得核目标，以便更好地了解 粘附调节途径。在目标4中，我们将检查函数 Abl靶点在细胞增殖调节中的作用。 结果和 从用成纤维细胞进行的实验中获得的试剂 模型将扩展到造血细胞和长期使用， 长期骨髓培养，研究Abl酪氨酸激酶在 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.