Genomic dissection of platelet production

血小板产生的基因组解剖

• 批准号: 7141819
• 负责人: WARREN S ALEXANDER
• 金额: $ 24.3万
• 依托单位: WALTER AND ELIZA HALL INST MEDICAL RES
• 依托单位国家: 美国
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-08-17 至 2010-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7141819
• 关键词: cytotoxicity; gene mutation; genetic screening; growth factor receptors; hematopoietic stem cells; laboratory mouse; megakaryocytes; platelets; protein localization; protooncogene; thrombocytopenia; thrombopoiesis; thrombopoietic factor; transcription factor

DESCRIPTION (provided by applicant): Thrombocytopenia, or low platelet count, is a life threatening condition associated with cytotoxic cancer treatments and other disorders. Platelet transfusion is the only current effective treatment for severe thrombocytopenia. Although effective, transfusion is associated with immunohematological side effects and infections. The aim of this project is to better understand the molecular regulation of platelet production with the ultimate goal of discovering novel targets for the development of new therapeutics for thrombocytopenia. We propose that forward genetic screens using random mutagenesis provide an unbiased, genome-wide discovery tool for regulators of circulating platelet numbers that do not rely on pre-existing knowledge of potential gene function and thus have the capacity to discover hitherto unanticipated modulators of platelet numbers. Moreover, mutagenesis screens using a murine model of thrombocytopenia will uncover genes in which loss-of function mutations lead to amelioration of disease. Since drugs overwhelmingly inhibit their targets, the proteins normally encoded by these suppressors of thrombocytopenia should provide biologically validated targets for therapeutic discovery. In preliminary studies, we have isolated several suppressors of thrombocytopenia (PIt mutants) including three that have mutations in the c-Myb transcription factor (Plt3 and Plt4) or the p300 transcriptional co-regulator/c-Myb partner protein (Plt6). Mice heterozygous for these mutations display amelioration of the thrombocytopenia inherent in mice lacking c-MpI, the receptor for thrombopoietin (TPO) and homozygotes exhibit supra-physiological platelet counts characterized by excessive megakaryocytopoiesis. We hypothesize that c-Myb/p300 activity is normally required to keep megakaryocytopoiesis in appropriate check and that pharmacological disruption of c-Myb/p300 may provide a novel therapeutic strategy to treat thrombocytopenia. The aims of this application are to fully define the biological consequences of c-Myb/p300 mutation in Plt3, Plt4 and Plt6 mice, to determine the effects of these mutations on the transcriptional regulatory functions of c-Myb/p300, to define the key target genes of this complex that control megakaryocyte and platelet production and to begin to test the potential of inhibiting c- Myb/p300 clinically by studying the responses of mice bearing c-Myb/p300 mutations in animal models of chemotherapy or bone marrow transplant-induced thrombocytopenia.

描述（由申请方提供）：血小板减少症或血小板计数低是一种与细胞毒性癌症治疗和其他疾病相关的危及生命的疾病。血小板输注是目前治疗严重血小板减少症的唯一有效方法。输血虽然有效，但与免疫血液学副作用和感染有关。该项目的目的是更好地了解血小板生成的分子调控，最终目标是发现新的靶点，用于开发血小板减少症的新疗法。我们建议，使用随机诱变的正向遗传筛选提供了一个公正的，全基因组的发现工具，不依赖于潜在的基因功能的预先存在的知识，从而有能力发现迄今未预料到的血小板数量的调节剂的循环血小板数量的调节。此外，使用血小板减少症的鼠模型的诱变筛选将揭示其中功能丧失突变导致疾病改善的基因。由于药物压倒性地抑制其靶点，通常由这些血小板减少症抑制因子编码的蛋白质应该为治疗发现提供生物学验证的靶点。在初步研究中，我们已经分离出几种血小板减少症抑制因子（PIT突变体），包括三种在c-Myb转录因子（Plt 3和Plt 4）或p300转录辅助调节因子/c-Myb伴侣蛋白（Plt 6）中具有突变的抑制因子。这些突变的杂合子小鼠表现出缺乏c-MpI、血小板生成素受体（TPO）的小鼠固有的血小板减少症的改善，纯合子表现出以过度巨核细胞生成为特征的超生理血小板计数。我们推测，c-Myb/p300活性通常需要保持巨核细胞生成在适当的检查和药理学中断c-Myb/p300可能提供一种新的治疗策略来治疗血小板减少症。本申请的目的是完全确定Plt 3、Plt 4和Plt 6小鼠中c-Myb/p300突变的生物学后果，以确定这些突变对c-Myb/p300的转录调节功能的影响，确定控制巨核细胞和血小板生成的复合物的关键靶基因，并开始测试抑制c-Myb/通过研究携带c-Myb/p300突变的小鼠在化疗或骨髓移植诱导的血小板减少症的动物模型中的反应，在临床上观察p300。