Rac1 and Rac2 Guanosine Triphosphatases in Erythroid Function and Differentiation

Rac1 和 Rac2 鸟苷三磷酸酶在红细胞功能和分化中的作用

• 批准号: 7565917
• 负责人: Theodosia Anastasios Kalfa
• 金额: $ 12.87万
• 依托单位: CINCINNATI CHILDRENS HOSP MED CTR
• 依托单位国家: 美国
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-02-11 至 2012-11-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7565917
• 关键词: Actins; Adhesions; Affect; Anemia; Apoptosis; Biological Assay; Bone Marrow; Cell Cycle; Cell Lineage; Cell Nucleus; Cell Polarity; Cell Survival; Cells; Classification; Cytoskeletal Proteins; Cytoskeleton; Data; Defect; Development; Erythroblasts; Erythrocyte Deformability; Erythrocyte Membrane; Erythrocytes; Erythroid; Erythroid Cells; Erythropoiesis; Evaluation; F-Actin; Flow Cytometry; Gene Targeting; Genetic Transcription; Goals; Growth Factor Receptors; Guanosine; Guanosine Triphosphate Phosphohydrolases; Hematopoietic; Hematopoietic stem cells; Hemolytic Anemia; Homing; In Vitro; Label; Mammals; Mechanics; Mediating; Membrane Biology; Microtubules; Molecular; Morphogenesis; Movement; Mus; Nature; Pathogenesis; Pathway interactions; Phenotype; Phosphorylation; Play; Poikilocytosis; Population; Process; Protein Kinase C; Proteins; Proto-Oncogene Protein c-kit; Regulation; Relative (related person); Research; Reticulocytes; Reticulocytosis; Rho-associated kinase; Role; Signal Pathway; Signal Transduction; Signaling Molecule; Spectrin; Spleen; Staging; Stem Cell Factor; Stress; Structure; Testing; Tropomyosin; abstracting; adducin; cell type; cofilin; cytokine; erythroid differentiation; extracellular; granulocyte; human disease; in vitro Assay; in vivo; microcytic anemia; polymerization; rac GTP-Binding Proteins; response; rho; rho GTP-Binding Proteins; therapeutic target; tropomodulin

DESCRIPTION (provided by applicant): The Rho guanosine triphosphatases (GTPases) Rac1 and Rac2 regulate actin cytoskeleton, microtubule dynamics, gene transcription, proliferation, and survival in multiple cell types. They have been shown to have overlapping as well as distinct roles in actin organization, cell survival, and proliferation in various hematopoietic cell lineages. However their role in erythroid precursors and erythrocytes has not been evaluated. Using gene-targeted mice we have found that deficiency of Rac1 and Rac2 GTPases causes a significant phenotype in erythroid lineage: mild anemia with relative reticulocytosis, both hemolytic (abnormal structure of the erythrocyte cytoskeleton with decreased mechanical stability) and dyserythropoietic in nature. Erythropoiesis is affected mainly at the early stages, when stem cell factor (SCF) plays a critical role. We therefore hypothesize that Rac GTPases (1) dynamically regulate the structure and function of the erythrocyte cytoskeleton, and (2) play a critical role in homing, proliferation, survival, and differentiation of erythroid precursors, likely intersecting signaling pathways activated via the SCF receptor, c-Kit. To test our hypotheses, we propose a systematic characterization of the effects of Rac GTPase deficiency on the actin polymerization mechanics in the RBC cytoskeleton, with analysis of the actin-associated proteins and evaluation of possible cross-talk of Rac with other Rho GTPases and signaling molecules. In parallel, we will investigate the perturbations of erythropoiesis in Rac1"/";Rac2"/" mice, seeking the mechanism/s by which Rac GTPases, integrating multiple signals from one or more of the erythropoietic cytokines, affect erythropoiesis. These two proposed aims intent to explore and test how Rac GTPases regulate erythroid development, morphogenesis, and structure-function relation of the RBC cytoskeleton and its components. The central goal is to define critical molecular signaling pathways that participate in normal erythroid development and RBC structural membrane biology. In the long-term, this research is expected to offer new perspectives on the pathogenesis of hemolytic anemia and provide potential therapeutic targets in human disease characterized by abnormal erythropoiesis and decreased RBC survival. (End of Abstract)

描述（由申请人提供）： Rho鸟苷三磷酸酶（GTPases）RAC1和RAC2调节肌动蛋白细胞骨架，微管动力学，基因转录，增殖和多种细胞类型的存活。已显示它们在肌动蛋白组织，细胞存活和各种造血细胞谱系中具有重叠以及不同的作用。但是，尚未评估它们在红细胞前体和红细胞中的作用。使用靶向基因的小鼠，我们发现Rac1和Rac2 GTPases的缺乏会导致红细胞谱系的显着表型：轻度贫血患有相对网状细胞增多症（溶血性异常（红细胞骨骼的异常结构），机械稳定性降低，机械稳定性下降）和育种性含量为中性。当干细胞因子（SCF）起关键作用时，红细胞生成主要在早期阶段受到影响。因此，我们假设RAC GTPase（1）动态调节红细胞细胞骨架的结构和功能，（2）在归因，增殖，存活和红细胞前体的分化中起关键作用，可能与SCF受体C-KTKIT激活的信号通路可能相互作用。为了检验我们的假设，我们提出了RAC GTPase缺乏症对RBC细胞骨架中肌动蛋白聚合力学的影响的系统表征，并分析了与肌动蛋白相关的蛋白质的分析，并评估RAC可能与其他Rho GTPase和其他Rho GTPase和信号分子的RAC可能的交叉Talk。同时，我们将研究Rac1“/”; Rac2“/”小鼠中红细胞生成的扰动，寻求RAC GTPases的机制，从而整合了来自一种或多种红细胞生成细胞因子的多个信号，影响erythropoiesis。这两个拟议的目的是探索和测试RAC GTPases如何调节RBC细胞骨架及其成分的红细胞发育，形态发生和结构功能关系。中心目标是定义参与正常红细胞发育和RBC结构膜生物学的关键分子信号通路。从长远来看，预计这项研究将提供有关溶血性贫血发病机理的新观点，并为人类疾病提供了潜在的治疗靶标，其特征是异常的红细胞生成和RBC存活率降低。 （抽象的结尾）