Genetic and Transcriptional Control of Spleen Development

脾脏发育的遗传和转录控制

• 批准号: 8466346
• 负责人: Licia Selleri
• 金额: $ 31.95万
• 依托单位: WEILL MEDICAL COLL OF CORNELL UNIV
• 依托单位国家: 美国
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-09-15 至 2015-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8466346
• 关键词: Architecture; Autopsy; Bacterial Infections; Biological Assay; Cell Culture Techniques; Cell Cycle Regulation; Cell Proliferation; Cell Therapy; Cells; Child; Complex; Comprehension; Defect; Development; Diagnosis; Disease; Embryo; Endothelial Cells; Endothelium; Gene Targeting; Generations; Genetic; Genetically Engineered Mouse; Growth; Hematopoiesis; Hematopoietic; Homeobox Genes; Human; Immune response; Immunity; Intervention; Invaded; Knowledge; Lateral; Life; Light; Liver; Mammals; Mesenchymal; Mesenchymal Stem Cells; Mesenchyme; Mesoderm; Modeling; Molecular; Molecular Diagnosis; Molecular Genetics; Morphogenesis; Mouse Strains; Mus; Newborn Infant; Organ; Organogenesis; Pancreas; Pathogenesis; Pathway interactions; Population; Positioning Attribute; Primordium; Process; Proteins; Relative (related person); Reporting; Research; Role; Sepsis; Spleen; Spleen Development; Staging; Stem cells; System; Testing; Tissues; Transcriptional Regulation; Transgenic Mice; Transgenic Organisms; Work; base; blood filter; cell type; established cell line; high risk; immortalized cell; mouse model; neglect; novel; prenatal; programs; public health relevance; reconstitution; repaired; research study

DESCRIPTION (provided by applicant): Organogenesis begins with the specification, positioning and assembly of the cell types specific to an organ into the organ primordium (anlage). Active cell proliferation also takes place to build a critical mass for organ morphogenesis and expansion to occur. In this proposal, we will use the vertebrate spleen as a model to investigate these fundamental steps. The complex architecture and functions of the spleen result from intimate interactions among different cell types: mesenchymal cells ("basic parenchyma"), invading endothelial cells and colonizing hematopoietic cells. In humans, the spleen has critical roles in early hematopoiesis, immunity and blood filtering and its absence (as in congenital asplenia, an under-diagnosed disorder often recognized only at autopsy) results in a high risk for life-threatening bacterial infections in newborns and children. Our long-term objective is to identify genetic pathways that control the successive stages of spleen development: i.e. morphogenesis, expansion, and influx of hematopoietic and endothelial cells, since these interrelated organogenetic processes are of utmost importance to spleen function and yet mostly unknown. Using genetic approaches and asplenic mouse strains, we defined key steps in the genetic pathways that govern early spleen development. We reported that the homeobox gene Pbx1 is required for spleen cell fates and is a hierarchical co-regulator of Nkx2.5 and Hox11 (which are also essential for spleen formation). We also found that Pbx1 expression commences earlier than that of both Nkx2.5 and Hox11 in the Lateral Plate Mesoderm (LPM). Additionally, we uncovered that Pbx1 is expressed in the endothelium of the developing spleen anlage. In view of these findings, our hypothesis is that a distinct sub-population of Pbx1-positive progenitor cells within the LPM is required for spleen parenchyma specification, morphogenesis, and expansion and that Pbx expression in the endothelium also contributes to its function in spleen morphogenesis and expansion. In addition, we hypothesize that both an intact mesenchymal anlage and endothelium are essential for normal spleen hematopoietic colonization and function. Using available lines of gene-targeted and transgenic mice, we will test our hypothesis through embryologic, genetic, and molecular approaches. First, we will establish genetic and molecular pathways that control spleen morphogenesis and expansion. To this end, we will characterize the spleen morphogenesis and cellular proliferation defects in a mouse line with conditional inactivation of Pbx1 in the spleen mesenchymal parenchyma, but not in the endothelium. We will further utilize immortalized cell cultures generated from these embryonic spleens to determine the roles of Pbx in cell cycle regulation. Second, we will assess whether an intact endothelium is essential for spleen morphogenesis and expansion by characterizing a mouse line in which only the endothelium is altered by genetic inactivation of Pbx1. Also, by Pbx1 inducible inactivation, we will establish Pbx temporal requirements in the spleen endothelium. Third, we will genetically dissect the role of the mesenchyme and endothelium, respectively, in spleen hematopoietic colonization, development, and function. Our studies will shed light on novel genetic and molecular networks that underlie the development of the spleen, a neglected organ in regard to its ontogeny. In light of the intimate interactions among the mesenchymal spleen anlage, invading endothelial cells and hematopoietic cells, the new knowledge generated from this work will have a deep impact on the understanding of spleen function. Lastly, our studies aspire to provide a better comprehension of the pathogenesis of congenital asplenia, as we put forth the prerequisite basic genetic background towards prenatal molecular diagnosis of this condition.

描述（由申请人提供）：器官发生开始于器官特异性细胞类型的特化、定位和组装成器官原基（原基）。活跃的细胞增殖也发生，以建立器官形态发生和扩张发生的临界质量。在这个建议中，我们将使用脊椎动物脾脏作为模型来研究这些基本步骤。脾的复杂结构和功能是由不同细胞类型之间的密切相互作用引起的：间充质细胞（“基本实质”），侵入的内皮细胞和定植的造血细胞。在人类中，脾脏在早期造血、免疫和血液过滤中起着关键作用，其缺失（如先天性无脾，一种诊断不足的疾病，通常仅在尸检中才能发现）导致新生儿和儿童发生危及生命的细菌感染的高风险。我们的长期目标是确定控制脾脏发育的连续阶段的遗传途径：即造血和内皮细胞的形态发生，扩增和流入，因为这些相互关联的器官发生过程对脾脏功能至关重要，但大多数是未知的。利用遗传学方法和无脾小鼠品系，我们确定了控制早期脾脏发育的遗传途径中的关键步骤。我们报道了同源异型盒基因Pbx1是脾细胞命运所必需的，并且是Nkx2.5和Hox11（这也是脾形成所必需的）的分级共调节因子。我们还发现，Pbx1的表达开始早于Nkx2.5和Hox11在侧板中胚层（LPM）。此外，我们发现Pbx 1在发育中的脾原基的内皮中表达。鉴于这些发现，我们的假设是，一个独特的亚群的Pbx 1阳性祖细胞内的LPM是必需的脾实质的规范，形态发生，和扩张，以及Pbx在内皮细胞的表达也有助于其功能在脾形态发生和扩张。此外，我们推测，一个完整的间充质原基和内皮细胞是必不可少的正常脾脏造血定植和功能。利用现有的基因靶向和转基因小鼠品系，我们将通过胚胎学、遗传学和分子方法来检验我们的假设。首先，我们将建立控制脾脏形态发生和扩张的遗传和分子途径。为此，我们将在脾间充质实质中Pbx 1条件性失活的小鼠系中表征脾形态发生和细胞增殖缺陷，但在内皮中不。我们将进一步利用这些胚胎脾脏产生的永生化细胞培养物，以确定Pbx在细胞周期调控中的作用。其次，我们将评估是否一个完整的内皮是必不可少的脾脏形态发生和扩张的特点，只有内皮细胞被改变基因失活的Pbx1的小鼠品系。此外，通过Pbx 1诱导失活，我们将建立脾内皮中的Pbx时间要求。第三，我们将分别从遗传学角度剖析间充质和内皮在脾造血定植、发育和功能中的作用。我们的研究将揭示新的遗传和分子网络的基础上的发展，脾脏，一个被忽视的器官在其个体发育。鉴于间充质脾原基、入侵内皮细胞和造血细胞之间的密切相互作用，这项工作产生的新知识将对脾功能的理解产生深刻的影响。最后，我们的研究希望提供一个更好的理解先天性无脾的发病机制，因为我们提出了必要的基本遗传背景，产前分子诊断这种情况。