REGULATION OF HEMATOPOIESIS BY THROMBOPOIETIN

产品说明：（改编自申请人摘要）该项目旨在了解巨核细胞和血小板产生的细胞因子控制，长期目标是设计更好的临床策略，用于管理与癌症治疗和其他疾病相关的血小板减少症。TPO是一种具有刺激巨核细胞和血小板生成能力的分子。缺乏TPO或其受体c-Mpl的小鼠中的血小板减少症证明TPO是巨核细胞生成的主要生理调节剂，但产生足够的TPO非依赖性产物以维持止血。确定TPO非依赖性过程的细胞因子控制和TPO与其他调节剂相互作用的机制是确定TPO和其他巨核细胞生成剂最有效临床应用的关键步骤。目前的建议旨在确定巨核细胞生成的已知调节剂的作用：IL-3，IL-6，IL-11，GM-CSF，LIF，SCF，在残余的稳态以及紧急巨核细胞和血小板生产的Mpl缺陷小鼠，虽然分析的复合突变小鼠缺乏这些调节剂或其受体除了c-Mpl。初步结果表明，TPO信号也发挥了重要作用，在调节造血干细胞室。如果TPO被用于患者，特别是白血病患者，必须充分了解其对干细胞的作用。在长期造血重建测定中，通过细胞分选策略分离的特定干细胞群的分析将用于精确地确定Mpl缺陷小鼠和缺乏c-Mpl和其他干细胞调节剂（IL-6、LIF、IL-11、SCF、G-CSF）的复合突变体中的干细胞缺陷。还将分离来自表达c-Mpl受体的正常小鼠的干细胞，并通过产生在c-mpl基因座控制下表达绿色荧光蛋白的敲入小鼠来功能性表征。对来自c-Mpl受体不同区域的信号刺激的特定生物反应的了解最终可能有助于识别用于治疗性操纵TPO反应的细胞内靶点。将c-Mpl胞质结构域突变掺入小鼠生殖系中将用于确定在体外参与增殖和分化的TPO受体的不同胞质区域是否也介导巨核细胞生成和干细胞的生理调节中的这些应答。

DESCRIPTION: (Adapted from Applicant's Abstract) This project aims to understand the cytokine control of megakaryocytes and platelet production, with the long-term goal of devising better clinical strategies for the management of thrombocytopenias associated with cancer treatment and other disorders. The recent cloning of TPO has provided a molecule with potent capacity to stimulate megakaryocyte and platelet generation. The thrombocytopenia in mice lacking TPO or its receptor c-Mpl is evidence that TPO is the dominant physiologic regulator of megakaryocytopoiesis, but that sufficient TPO-independent production occurs to maintain hemostasis. Defining the cytokine control of the TPO-independent processes and the mechanisms by which TPO interacts with other regulators is a key step in determining the most effective clinical application of TPO and other megakaryocytopoietic agents. The current proposal aims to define the roles of known regulators of megakaryocytopoiesis: IL-3, IL-6, IL-11, GM-CSF, LIF, and SCF, in residual steady-state as well as emergency megakaryocyte and platelet production in Mpl-deficient mice, although analysis of compound mutant mice lacking these regulators or their receptors in addition of c-Mpl. Preliminary results suggest that TPO signaling also plays a critical role in regulation of the hemopoietic stem cell compartment. If TPO is to be administered to patients, particularly those with leukemia, its actions on stem cells must be fully understood. Analysis of specific stem cell populations, isolated by cell sorting strategies, in long term hemopoietic reconstitution assays will be used to precisely define the stem cell deficiency in Mpl-deficient mice and in compound mutants lacking c-Mpl and other stem cell regulators (IL-6, LIF, Il-11, SCF, G-CSF). Stem cells from normal mice that express the c-Mpl receptor will also be isolated and functionally characterized by generating knock-in mice expressing green fluorescent protein under the control of the c-mpl locus. An understanding of the specific biological responses stimulated by signals from different regions of the c-Mpl receptor may ultimately allow identification of intracellular targets for therapeutic manipulations of the TPO responses. Incorporation of c-Mpl cytoplasmic domain mutations into the mouse germline will be used to determine if the distinct cytoplasmic regions of the TPO receptor implicated in proliferation and differentiation in vitro, also mediate these responses in the physiological regulation of megakaryocytopoiesis and stem cells.