The regulation of protein synthesis in stem cells

干细胞中蛋白质合成的调控

• 批准号: 8997792
• 负责人: SEAN J MORRISON
• 金额: $ 6.77万
• 依托单位: UT SOUTHWESTERN MEDICAL CENTER
• 依托单位国家: 美国
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-02-25 至 2016-01-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8997792
• 关键词: 1-Phosphatidylinositol 3-Kinase; Address; Adult; Area; Attenuated; Biological Assay; Biology; Cell Count; Cell Cycle; Cell Maintenance; Cell Size; Cell physiology; Cells; Data; Defect; Dependence; Disease; Health; Hematopoiesis; Hematopoietic; Hematopoietic System; Hematopoietic stem cells; Hemorrhage; Housing; Individual; Learning; Left; Life; Maintenance; Measures; Mus; Natural regeneration; PTEN gene; Paper; Population; Protein Biosynthesis; Regulation; Relative (related person); Ribosomal Proteins; Role; Signal Pathway; Signal Transduction; Sirolimus; Stem cells; Techniques; Testing; Translations; Tumor Suppressor Proteins; Work; human FRAP1 protein; in vivo; leukemogenesis; polypeptide; progenitor; response; self-renewal; stem cell population

DESCRIPTION (provided by applicant): To sustain hematopoiesis, hematopoietic stem cells (HSCs) must persist throughout life, constantly regenerating hematopoietic cells lost to normal turnover, bleeding, and disease. Much has been learned over the past ten years regarding the mechanisms that regulate HSC maintenance. This work has demonstrated that several aspects of cellular physiology are regulated differently in HSCs as compared to other hematopoietic cells. This raises the fundamental question of whether all aspects of cellular physiology are regulated differently in stem cells as compared to restricted progenitors, or whether certain aspects of cellular physiology are "house-keeping" functions that are regulated similarly in stem cells and restricted progenitors. Unfortunately, many aspects of cellular physiology are technically difficult to study with existing techniques in small numbers of stem cells and therefore have not yet been addressed, leaving large areas of biology unexplored. One such aspect of cellular physiology is the regulation of protein synthesis. There are almost no data on the regulation of translation in any somatic stem cell population, partly because assays have not yet been developed to study translation in small numbers of cells in vivo. We have recently developed an assay that makes it possible to study the rate at which polypeptides are synthesized by individual cells in vivo. Using this assay we have determined that HSCs have significantly lower rates of protein synthesis than other hematopoietic cells even when we control for differences in cell cycle distribution. Our preliminary functional data suggest that HS maintenance depends upon highly regulated rates of protein synthesis. This discovery may explain previously observed defects in HSC self-renewal that were not understood at a mechanistic level. For example, we have demonstrated previously that deletion of the PTEN tumor suppressor in adult hematopoietic cells increases PI3-kinase pathway signaling in HSCs, leading to leukemogenesis and HSC depletion. Although the depletion of PTEN deficient HSCs is known to depend upon a tumor suppressor response induced by mTORC1 and mTORC2 signaling, it is unknown how elevated mTOR signaling increases tumor suppressor expression. In this application, we propose to extend our preliminary data to test whether PTEN is required in adult HSCs to maintain an unusually low level of protein synthesis and whether increased protein synthesis after PTEN deletion induces the tumor suppressor response that depletes HSCs. This work has the potential to yield new techniques to study protein synthesis in rare cell populations in vivo and to open new areas of inquiry related to the role of regulated protein synthesis in hematopoiesis and stem cell function. Defects in the regulation of protein synthesis could potentially contribute to diverse and poorly understood diseases of the hematopoietic system.

描述（由申请人提供）：为了维持造血性，造血干细胞（HSC）必须持续一生，不断再生造血细胞因正常的周转，出血和疾病而失去的造血细胞。在过去的十年中，关于调节HSC维护的机制，已经学到了很多东西。这项工作表明，与其他造血细胞相比，在HSC中，细胞生理的几个方面的调节不同。这就提出了一个基本问题，即与受限祖细胞相比，干细胞中细胞生理的各个方面是否受到不同的调节，或者细胞生理的某些方面是否是在干细胞和受限祖细胞中受到类似调节的“家政保管”功能。不幸的是，在技术上很难通过少量干细胞的现有技术研究细胞生理学的许多方面，因此尚未解决，因此没有探索大量的生物学。细胞生理的这样一个方面是蛋白质合成的调节。几乎没有关于任何体细胞干细胞群体翻译调节的数据，部分原因是尚未开发用于研究体内少量细胞的翻译。我们最近开发了一种测定法，该测定法可以研究由体内单个细胞合成多肽的速率。使用此测定，我们已经确定，即使我们控制细胞周期分布的差异，HSC的蛋白质合成速率也明显低于其他造血细胞。我们的初步功能数据表明，HS维护取决于高度调节的蛋白质合成速率。这一发现可以解释先前观察到的HSC自我更新中的缺陷，这些缺陷在机械级别尚未理解。例如，我们先前已经证明，成年造血细胞中PTEN肿瘤抑制剂的缺失增加了HSC中的PI3-激酶途径信号传导，从而导致白血病和HSC耗竭。尽管已知PTEN缺乏HSC的耗竭取决于MTORC1和MTORC2信号诱导的肿瘤抑制反应，但尚不清楚MTOR信号升高如何增加肿瘤抑制器的表达。在此应用中，我们建议扩展我们的初步数据，以测试成人HSC中是否需要PTEN，以维持异常低的蛋白质合成水平，以及PTEN缺失后蛋白质合成的增加是否会诱导抑制HSC的肿瘤抑制反应。这项工作有可能产生新技术，以研究体内稀有细胞群体中蛋白质合成，并打开与调节蛋白质合成在造血和干细胞功能中的作用相关的新调查领域。蛋白质合成调节的缺陷可能导致造血系统的多样化和了解不足的疾病。