MECHANISM OF HOXA9 & MEIS1 PROTEIN INDUCED LEUKEMIA

HOXA9的机制

• 批准号: 6951241
• 负责人: COREY LARGMAN
• 金额: $ 33.41万
• 依托单位: NORTHERN CALIFORNIA INSTITUTE/RES/EDU
• 依托单位国家: 美国
• 财政年份: 1999
• 资助国家: 美国
• 起止时间: 1999-07-01 至 2009-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6951241
• 关键词: DNA binding protein; RNA interference; Retroviridae; acute myelogenous leukemia; cell transformation; gene deletion mutation; gene expression; genetic regulation; genetic regulatory element; genetic transcription; hematopoietic tissue; homeobox genes; laboratory mouse; leukemia; molecular oncology; mutant; neoplastic cell; neoplastic transformation; phosphorylation; protein localization; protein protein interaction; tissue /cell culture

DESCRIPTION (provided by applicant): HOXA9 expression is a common feature of human acute myelocytic leukemia (AML) and high level expression is correlated with poor prognosis. Moreover, HOXA9 overexpression immortalizes murine marrow progenitors which are arrested at a promyelocytic stage of differentiation when cultured, and causes leukemia in recipient mice following transplantation of HOXA9 expressing bone marrow. Our laboratory is now focused on developing treatment strategies based on blocking HOXA9 activity. Our recent data showed that protein kinase C (PKC) mediates phosphorylation of HOXA9 on S 204 and T205 at the N-terminus of the homeodomain. PKC phosphorylation of HOXA9 on S 204 abrogated the protein's DNA binding in vitro and the ability of endogenous HOXA9 to form cooperative DNA binding complexes with PBX. This HOXA9 phosphorylation was correlated with differentiation of myeloid cell lines and HOXA9-immortalized bone marrow cells. We hypothesize that this myeloid differentiation was in part due to PKC-mediated phosphorylation of HOXA9, which decreases the DNA binding of the homeoprotein. We have also recently determined the first set of downstream gene targets for HOXA9. We propose three aims: 1) to show a causal relationship between HOXA9 phosphorylation and myeloid differentiation, by elucidating the relationship between phosphorylation and HOXA9 pathological activity; 2) part I - determine which PKC isoform acts on HOXA9; part 2 - develop strategies to block HOXA9 transforming activity by: A) using RNAi to directly block HOXA9; B) using PKC stimulators or ser/thr phosphatase inhibitors to block HOXA9 activity in immortalized cell and leukemia models; and C) determine the X-ray crystal structure of HOXA9, to understand how phosphorylation blocks activity. This information will form the basis for future rationale drug design of HOXA9 inhibitors; and 3) to elucidate the direct molecular targets of the HOXA9 transcription factor with and without the MEIS1 and PBX cofactor proteins. The long range goal of this aim is to develop methods to block the biological activity of these downstream effector pathways. Taken together these studies should move us closer to achieving drug-based therapies for the treatment of acute myelogenous leukemias.

描述（由申请人提供）：HOXA 9表达是人急性髓细胞白血病（AML）的共同特征，高水平表达与不良预后相关。 此外，H0XA 9过表达使培养时在分化的早幼粒细胞阶段停滞的鼠骨髓祖细胞永生化，并在移植表达H0XA 9的骨髓后在受体小鼠中引起白血病。 我们的实验室现在专注于开发基于阻断HOXA 9活性的治疗策略。 我们最近的数据表明，蛋白激酶C（PKC）介导的HOXA 9的磷酸化的S 204和T205在N-末端的同源结构域。S204上HOXA 9的PKC磷酸化在体外废除了蛋白质的DNA结合和内源性HOXA 9与PBX形成协同DNA结合复合物的能力。 这种HOXA 9磷酸化与骨髓细胞系和HOXA 9永生化骨髓细胞的分化相关。 我们推测，这种髓样分化部分是由于PKC介导的HOXA 9磷酸化，这降低了同源异型蛋白的DNA结合。 我们最近还确定了HOXA 9的第一组下游基因靶点。我们提出三个目标：1）通过阐明磷酸化和HOXA 9病理活性之间的关系来显示HOXA 9磷酸化和骨髓分化之间的因果关系; 2）第I部分-确定哪种PKC同种型作用于HOXA 9; B）使用PKC刺激剂或ser/thr磷酸酶抑制剂阻断永生化细胞和白血病模型中的HOXA 9活性;和C）确定HOXA 9的X射线晶体结构，以了解磷酸化如何阻断活性。 这些信息将成为HOXA 9抑制剂未来合理药物设计的基础; 3）阐明HOXA 9转录因子在有和没有MEIS 1和PBX辅因子蛋白的情况下的直接分子靶点。 该目标的长期目标是开发阻断这些下游效应物途径的生物活性的方法。 这些研究加在一起，应该使我们更接近于实现以药物为基础的治疗急性髓性白血病的疗法。