Human Tyr-tRNA Synthetase as a Potent Effector of Megakaryocytopoiesis

人 Tyr-tRNA 合成酶作为巨核细胞生成的有效效应子

• 批准号: 9053286
• 负责人: Taisuke Kanaji
• 金额: $ 48.13万
• 依托单位: SCRIPPS RESEARCH INSTITUTE, THE
• 依托单位国家: 美国
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-05-15 至 2020-01-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9053286
• 关键词: Acute; Adverse effects; Affect; Amino Acyl-tRNA Synthetases; Animal Model; Antibodies; Biological; Biology; Blood Cells; Blood Platelets; Blood Vessels; Bone Marrow; Bone Marrow Cells; C-terminal; Cell Culture Techniques; Cells; Chronic; Cleaved cell; Cytotoxic Chemotherapy; Development; Disease; Dose; Engineering; Enzymes; Eukaryota; Exhibits; Extracellular Space; Generations; Goals; Hematological Disease; Hematopoietic; Hemorrhage; Human; Human Activities; Human Pathology; ITGAM gene; Immune; In Vitro; Individual; Injury; Interleukin-8; Knockout Mice; Leukocyte Elastase; Leukocytes; Life; MPL gene; Mediating; Megakaryocytes; Methods; Modeling; Molecular; Mus; Mutation; N-terminal; Outcome; Pathway interactions; Patients; Pharmaceutical Preparations; Pharmacologic Substance; Pharmacotherapy; Platelet Activation; Platelet Count measurement; Play; Population; Process; Production; Property; Protein Biosynthesis; Protein Engineering; Proteins; Recombinant Proteins; Regulation; Risk; Role; Side; Signal Pathway; Signal Transduction; Smooth Muscle Myocytes; Stem cells; Supporting Cell; TLR2 gene; Tars; Testing; Therapeutic; Thrombocytopenia; Thrombopoiesis; Thrombopoietin; Thrombosis; Time; Tyrosine-tRNA Ligase; Variant; Vascular Diseases; Vascular Smooth Muscle; Work; base; chemotherapy; cytokine; efficacy testing; endothelial monocyte-activating polypeptide II; improved; in vivo; innovation; intravenous administration; irradiation; migration; mimetics; mouse model; novel; novel therapeutic intervention; novel therapeutics; progenitor; public health relevance; receptor; response; stem; treatment strategy

 DESCRIPTION (provided by applicant): Goal of this project is to understand the mechanisms through which tyrosyl-tRNA synthetase (YRS) exerts its newly recognized role in regulating platelet production and, on the bases of this information, develop a novel therapeutic strategy for the treatment of thrombocytopenia. In preliminary studies we have determined that YRS exhibits the previously unrecognized property of accelerating megakaryocyte development and platelet generation. This effect appears to be independent of thrombopoietin (TPO) signaling because YRS can support the proliferation and maturation of c-Mpl-/- (TPO receptor knock-out) mouse megakaryocytes in vitro. The studies proposed in this application will establish the mechanisms underlying the novel function of YRS in the regulation of platelet production. We will also develop a pharmaceutical approach to a new class of drugs with the potential of enhancing platelet production in various diseases in which TPO mimetics alone are not effective. In aim 1, we will elucidate the molecular mechanisms by which YRS stimulates megakaryocytopoiesis. Based on preliminary studies, the effect of YRS on megakaryocytopoiesis is mediated by at least two mechanisms: (1) activation of monocytic cells and cytokine production, and (2) expansion of Sca1+CD11b+ progenitors that give rise to hematopoietic cells and vascular cells. We will identify the cells responsible to mediate the effect of YRS and the receptor(s) targeted in the process. Involvement of TLR-MyD88 pathway has been shown by preliminary testing of TLR2-/- and MyD88-/- mice. We will also focus on a unique population of Sca1+CD11b+ progenitor cells that are greatly expanded by YRS stimulation in bone marrow cell cultures. Our preliminary result suggested the differentiation potential of YRS-induced Sca1+CD11b+ progenitor cells into hematopoietic cells and vascular smooth muscle cells. We hypothesize that expansion of these progenitor cells also contributes to thrombocytopoiesis either by differentiating into hematopoietic progenitors or vascular cells that support proplatelet formation in the vascular niche. In aim 2, we will define the functional domains of YRS required to exert the effects on megakaryocytopoiesis, and use protein engineering to de- sign YRS variants with an optimal therapeutic window. In Aim 3, we will test the efficacy of engineered YRS as a potential drug for the treatment of thrombocytopenia using in vivo animal models. In addition to the acute immune-mediated thrombocytopenia model employed in preliminary studies, we are generating models of chronic thrombocytopenia induced by low-dose antibody administration, irradiation or chemotherapy to evaluate the effects of YRS in various conditions as may occur in human pathology. Finally, to test the possibility of thrombotic side effects, we will determine whether YRS affects platelet activation, platelet-leukocyte inter- actions and models of thrombosis. The studies proposed in this application will delineate a novel cellular pathway in which YRS contributes to the regulation of platelet production; and support the development of innovative approaches with translational potential for improving the treatment of thrombocytopenia.

 描述（由申请人提供）：本项目的目的是了解酪氨酰-tRNA合成酶（YRS）在调节血小板生成中发挥其新认识的作用的机制，并在此信息的基础上开发治疗血小板减少症的新治疗策略。在初步的研究中，我们已经确定，YRS表现出以前未被认识到的加速巨核细胞发育和血小板生成的特性。这种作用似乎不依赖于血小板生成素（TPO）信号传导，因为YRS可以在体外支持c-Mpl-/-（TPO受体敲除）小鼠巨核细胞的增殖和成熟。本申请中提出的研究将建立YRS在血小板产生调节中的新功能的机制。我们还将开发一种新的药物，这种药物有可能在各种疾病中增强血小板的生成，而TPO模拟物单独使用是无效的。在目的1中，我们将阐明YRS刺激巨核细胞生成的分子机制。基于初步研究，YRS对巨核细胞生成的作用至少通过两种机制介导：（1）单核细胞活化和细胞因子产生，以及（2）Sca 1 + CD 11b+祖细胞扩增，产生造血细胞和血管细胞。我们将鉴定负责介导YRS效应的细胞和该过程中靶向的受体。TLR-MyD 88通路的参与已通过TLR 2-/-和MyD 88-/-小鼠的初步测试显示。我们还将重点关注一个独特的Sca 1 + CD 11b+祖细胞的群体，在骨髓细胞培养物中通过YRS刺激大大扩增。我们的初步结果表明YRS诱导Sca 1 + CD 11b+祖细胞分化为造血细胞和血管平滑肌细胞的潜力。我们假设这些祖细胞的扩增也有助于血小板生成，通过分化成造血祖细胞或支持血管龛中前血小板形成的血管细胞。在目标2中，我们将确定对巨核细胞生成发挥作用所需的YRS功能结构域，并使用蛋白质工程设计具有最佳治疗窗的YRS变体。在目标3中，我们将使用体内动物模型测试工程化YRS作为治疗血小板减少症的潜在药物的功效。除了在初步研究中采用的急性免疫介导的血小板减少症模型外，我们还生成了由低剂量抗体给药、放疗或化疗诱导的慢性血小板减少症模型，以评价YRS在人类病理学中可能发生的各种情况下的作用。最后，为了测试血栓形成副作用的可能性，我们将确定YRS是否影响血小板活化、血小板-白细胞相互作用和血栓形成模型。本申请中提出的研究将描述一种新的细胞途径，其中YRS有助于调节血小板生成;并支持开发具有转化潜力的创新方法，以改善血小板减少症的治疗。