Metabolic regulation of stem cell niche development and function

项目摘要 造血干细胞(HSCs)和造血祖细胞受细胞内在机制和 由专门的骨髓(BM)基质细胞创造的微环境(也称为生态位)。然而， 干细胞或祖细胞壁龛是如何发展、维持和重塑以应对压力的，目前尚不清楚。 特色化的。缺乏这样的基础知识阻碍了我们理解某些血液学的能力 直接或间接影响骨髓微环境的疾病。HSCs，是导致ALL的前体细胞 血统，在胚胎发育期间保持在离散的解剖微环境中，以及 它们最终在围产期从胎肝迁移到骨髓(“归巢”)。但我们对此的理解 管理这一进程的机制仍然有限。我们之前展示了一个关键的细胞内在作用 PTPMT1，一种以线粒体为基础的类似Pten的磷脂酰肌醇磷酸磷酸酶 发展的−基因敲除PTPMT1来自造血系统导致造血衰竭，原因是 生物能量/代谢应激、细胞周期停滞和肝星状细胞分化受阻。使用PTPMT1基因敲除 模型中，我们最近研究了协调细胞代谢在干细胞微环境中的作用 骨髓基质细胞PTPMT1缺失的PTPMT1fl/fl/Prx1-Cre+小鼠的建立及鉴定 (和肢芽祖细胞衍生的其他间充质细胞)。令人惊讶的是，骨髓基质中PTPMT1的缺失 细胞导致严重的造血缺陷：1)。近80%的PTPMT1fl/fl/Prx1-Cre+小鼠死亡 出生后3周内出生。HSCs(野生型)从胎肝到骨髓的迁移/归巢受到损害 这些动物--基因敲除小鼠骨髓中的HSCs比对照小鼠减少了~5倍 出生后7周，基因敲除小鼠肝脏中的造血灶(CD45+)数约为对照组的13倍。2)。 PTPMT1fl/fl/Prx1-Cre+小鼠B淋巴细胞发育受阻于PRO-B期。这些引人注目的东西 观察结果使我们假设PTPMT1介导的新陈代谢在建立或 维持骨髓中支持性干细胞的位置。目前提案的目标是进一步确定 潜在的细胞和分子机制。通过研究这种特殊的线粒体蛋白质，我们的目标是 破译HSC生态位发育/维持/重塑的代谢调控。我们计划测试我们的 通过追求以下三个目标来实现假设。1)。为了确定PTPMT1缺失的利基细胞- 诱导的生物能量/代谢应激导致围产期HSC归巢缺陷。2)。至 确定PTPMT1介导的HSC巢细胞代谢与稳态和 应激成人的造血功能。3)。为了确定解释PTPMT1效应的生物活性分子- 造血干细胞上的生态位耗竭以及PTPMT1缺乏对细胞重新编程的机制 新陈代谢。

Project Summary Hematopoietic stem cells (HSCs) and progenitors are tightly regulated by both cell intrinsic mechanisms and the microenvironment (also known as niches) created by specialized bone marrow (BM) stromal cells. However, how stem cell or progenitor niches are developed, maintained, and remodeled in response to stress is poorly characterized. Lack of such fundamental knowledge hinders our ability to understand certain hematological diseases directly or indirectly involving the BM microenvironment. HSCs, the precursor cells that give rise to all blood lineages, are maintained in discrete anatomical microenvironments during embryonic development, and they ultimately migrate from the fetal liver to the BM (“homing”) at the perinatal stage. Yet our understanding of the mechanisms regulating this process remains limited. We previously demonstrated a crucial cell-intrinsic role of PTPMT1, a mitochondria-based Pten-like phosphatidylinositol phosphate phosphatase, in hematopoietic cell development − Knockout of PTPMT1 from the hematopoietic system resulted in hematopoietic failure due to the bioenergetic/metabolic stress, cell cycle arrest, and differentiation block of HSCs. Using the PTPMT1 knockout model, we recently examined the role of coordinated cellular metabolism in the stem cell microenvironment by generating and characterizing PTPMT1fl/fl/Prx1-Cre+ mice, in which PTPMT1 was deleted from BM stromal cells (and limb bud progenitor-derived other mesenchymal cells). Surprisingly, deletion of PTPMT1 from BM stromal cells resulted in profound hematopoietic defects: 1). Nearly eighty percent of PTPMT1fl/fl/Prx1-Cre+ mice died within 3 weeks of birth. The migration/homing of HSCs (wild-type) from the fetal liver to the BM was impaired in these animals – HSCs in the BM of knockout mice decreased by ~5-fold compared to those in control mice 2 weeks after birth, while there were ~13 times more hematopoietic foci (CD45+) in the liver of knockout mice. 2). B lymphocyte development was blocked in the pro-B stage in PTPMT1fl/fl/Prx1-Cre+ mice. These striking observations led us to hypothesize that PTPMT1-mediated metabolism plays an important role in establishing or maintaining supportive stem cell niches in the BM. The objective of the current proposal is to further determine the underlying cellular and molecular mechanisms. By studying this particular mitochondrial protein, we aim to decipher the metabolic regulation of HSC niche development/maintenance/remodeling. We plan to test our hypothesis by pursuing the following three aims. 1). To identify the niche cells in which PTPMT1 depletion- induced bioenergetic/metabolic stress causes HSC homing defects during perinatal development. 2). To determine the functional relevance of PTPMT1-mediated metabolism in HSC niche cells to steady-state and stress hematopoiesis in adults. 3). To identify the bioactive molecules that account for the effects of PTPMT1- depletion from the niche on HSCs, and the mechanisms by which PTPMT1 deficiency reprograms cellular metabolism.