Novel Pathways for Bcr-Abl transformation

Bcr-Abl 转化的新途径

• 批准号: 6616480
• 负责人: IAN P WHITEHEAD
• 金额: $ 27.68万
• 依托单位: UNIV OF MED/DENT OF NJ-NJ MEDICAL SCHOOL
• 依托单位国家: 美国
• 财政年份: 2003
• 资助国家: 美国
• 起止时间: 2003-04-03 至 2007-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6616480
• 关键词: SDS polyacrylamide gel electrophoresis; binding sites; biological signal transduction; bone marrow transplantation; carcinogenesis; chronic myelogenous leukemia; gene expression; gene mutation; immunoprecipitation; laboratory mouse; mitogen activated protein kinase; neoplasm /cancer genetics; neoplastic transformation; northern blottings; phosphorylation; polymerase chain reaction; protein protein interaction; protein tyrosine kinase; protooncogene; site directed mutagenesis; tissue /cell culture; transcription factor; transfection; western blottings; yeast two hybrid system

Chromosomal rearrangements that fuse amino terminal sequences of the Bcr protein to carboxyl terminal sequences of the Abl tyrosine kinase (p210 Bcr-Abl) are associated with virtually all cases of chronic myelogenous leukemia (CML). Whereas the contribution of Abl encoded sequences to Bcr-Abl-mediated leukemogenesis are relatively well understood, the contribution from the Bcr encoded sequences is unclear. For example, several in vitro studies have identified catalytic activities within the amino terminus of Bcr, yet the relationship of these activities to the in vivo functions of Bcr, and Bcr-Abl, are not known. We have recently completed two studies which suggest that Bcr may contribute to the transforming activity of Bcr-Abl in ways that were not previously realized. First, we have identified a functional interaction between Bcr and the oncogenic transcription factor c-Myc. The disruption of this interaction may account for the elevated levels of c-Myc expression that are observed in Bcr-Abl transformed cells. Consistent with this, we have observed that c-Myc protein levels are sensitive to the dosage of Bcr in a CML-derived leukemic cell line. Second, we have demonstrated that the central RhoGEF domain of Bcr (which is retained in Bcr-Abl) contains in vivo catalytic, signaling and transforming activity. Importantly, a similar catalytic activity is observed within the context of p210 Bcr-Abl. The objective of this proposal is to characterize these new activities, and determine their fates within the context of Bcr-Abl. Specifically, we propose to (1) determine if the association of Bcr with the c-Myc transcription factor has functional consequences that contribute to Bcr-Abl-mediated transformation, and (2) determine whether the transforming and catalytic activities that we have mapped to the RhoGEF domain of Bcr contribute to Bcr-Abl-mediated transformation. The results from these studies should contribute substantially to our knowledge of the molecular basis of Philadelphia chromosome positive leukemias.

将 Bcr 蛋白的氨基末端序列融合到羧基的染色体重排 Abl 酪氨酸激酶 (p210 Bcr-Abl) 的末端序列几乎与所有慢性粒细胞白血病 (CML) 病例相关。虽然 Abl 编码序列对 Bcr-Abl 介导的白血病发生的贡献相对较好地了解，但 Bcr 编码序列的贡献尚不清楚。例如，一些体外研究已经鉴定了 Bcr 氨基末端的催化活性，但这些活性与 Bcr 和 Bcr-Abl 体内功能的关系尚不清楚。我们最近完成了两项研究，表明 Bcr 可能以以前未意识到的方式促进 Bcr-Abl 的转化活性。首先，我们确定了 Bcr 和 致癌转录因子c-Myc。这种相互作用的破坏可能是 Bcr-Abl 转化细胞中观察到的 c-Myc 表达水平升高的原因。与此一致的是，我们观察到在 CML 衍生的白血病细胞系中，c-Myc 蛋白水平对 Bcr 的剂量敏感。其次，我们证明了 Bcr 的中央 RhoGEF 结构域（保留在 Bcr-Abl 中）包含体内催化、信号传导和转化活性。重要的是，在 p210 Bcr-Abl 的背景下观察到类似的催化活性。该提案的目的是描述这些新活动的特征，并在 Bcr-Abl 的背景下确定它们的命运。具体来说，我们建议（1）确定Bcr与c-Myc转录因子的关联是否具有有助于Bcr-Abl介导的转化的功能后果，以及（2）确定我们映射到Bcr的RhoGEF结构域的转化和催化活性是否有助于Bcr-Abl介导的转化。这些研究的结果应该大大有助于我们了解费城染色体阳性白血病的分子基础。