AbI-Abi signaling in neoplastic hematopoiesis

描述(由申请人提供)：本提案的总体目标是描述与bcr-Abl诱导的白血病发生相关的机制。以前的研究已经确定了两种Abl相互作用蛋白，Abi-1和Abi-2，它们与细胞Abl(c-Abl)结合，是Abl酪氨酸酶的底物。在bcr-abl转化的造血细胞中，ABI-1被酪氨酸磷酸化。最近的研究表明，Abi-1是Rac信号的关键调节者，Rac信号是调节造血细胞迁移和归巢的重要途径。另一方面，ABI-2在表达bcr-abl的造血细胞中被降解。在侵袭性bcr-abl阳性白血病患者分离的细胞系和骨髓细胞中，Abi-2的表达缺失。这一假设是基于从bcr-Abl到Abi-1和Abi-2的信号转导可能在BCR-Abl诱导的白血病发生中起重要作用的假设。我们推测，Abi-1的酪氨酸磷酸化和随后激活的Rac通路可能是BCR-Abl导致白血病细胞骨架功能异常和转移表型异常的重要机制。我们认为Abi-2的缺失可能是bcr-Abl阳性白血病进展的一个组成部分。因此，本研究的目的是检测在Abi-1和Abi-2信号通路缺陷的突变型bcr-Abl的致白血病潜能；确定Abi-1和Abi-2在bcr-Abl诱导的白血病发生中的作用；以及确定bcr-Abl调节Abi信号转导的机制。为了实现这些目标，生物化学和遗传学方法被设计用来干扰或失活造血系统中Abi-1和Abi-2的信号转导。骨髓移植小鼠模型将被用来评估Abi信号的干扰在bcr-abl诱导的白血病发生中的作用。Abi-1和Abi-2中对信号转导调控至关重要的序列将被定义，并将进行突变以进行功能分析。总而言之，这些研究可能对细胞迁移、归巢和转移的调节机制提供洞察力。了解Abi信号在肿瘤造血中的作用将有助于开发更有效的治疗人类白血病的方法。

DESCRIPTION (provided by applicant): The overall objective of this proposal is to delineate the mechanisms associated with Bcr-Abl-induced leukemogenesis. Previous studies have identified two Abl interactor (Abi) proteins, Abi-1 and Abi-2, that bind to cellular Abl (c-Abl) and are substrates of Abl tyrosine kinase. Abi-1 is tyrosine-phosphorylated in hematopoietic cells transformed by Bcr-Abl. Recent studies indicate that Abi-1 is a key regulator of Rac signaling, a pathway important for regulation of hematopoietic cell migration and homing. Abi-2, on the other hand, is degraded in Bcr-Abl-expressing hematopoietic cells. The expression of Abi-2 is lost in cell lines and bone marrow cells isolated from patients with aggressive Bcr-Abl-positive leukemia. This proposal is based on the hypothesis that the signal transduction from Bcr-Abl to Abi-1 and Abi-2 may play an important role in Bcr-Abl-induced leukernogenesis. We postulate that the tyrosine phosphorylation of Abi-1 and subsequent activation of Rac pathway may represent an important mechanism by which Bcr-Abl induces abnormalities of cytoskeletal function and metastatic phenotype in leukemic cells. We believe that loss of Abi-2 may be a component in the progression of Bcr-Abl-positive leukemia. The goals of this proposal, therefore, are to examine the leukemogenic potential of a mutant Bcr-Abl that is defective in signaling to Abi-1 and Abi-2; to determine the role of Abi-1 and Abi-2 in Bcr-Abl-induced leukemogenesis; and to define the mechanisms by which Bcr-Abl regulates Abi signal transduction. To achieve these goals, biochemical and genetic approaches are designed to disrupt or inactivate signal transduction of Abi-1 and Abi-2 in hematopoietic system. Bone marrow transplant mouse models will be employed to evaluate the effect of disruption of Abi signaling on Bcr-Abl-induced leukemogenesis. Sequences in Abi-1 and Abi-2 that are critical for regulation of signal transduction will be defined and mutations wilt be made for functional analysis. Collectively, these studies may provide insight into the regulatory mechanisms of cell migration, homing, and metastasis. Understanding the role of Abi signaling in neoplastic hematopoiesis should shed light on development of more effective therapies for the treatment of human leukemia.