Comparison of human and mouse stem cells: differences in microRNA regulation

项目总结/摘要 干细胞，包括多能干细胞（PSC）和组织特异性干细胞，可以分化为 功能性组织，并因此用作基于细胞的疗法的有希望的供体来源。的小鼠模型具有 在理解干细胞的基本生物学特性和潜在应用方面发挥了不可或缺的作用。 然而，由于人类和啮齿动物从一个共同的祖先物种分化了8500万年， 因此，人类干细胞也具有小鼠细胞中不保守的特征也就不足为奇了。 因此，提高对人类和小鼠干细胞之间的相似性和差异性的理解， 对于使用小鼠模拟人类疾病和测试干细胞疗法至关重要。microRNAs（miRNAs）在 在细胞增殖、分化和存活中起重要作用。小鼠PSC和神经干细胞（NSC）缺陷 因为Dicer或Dgcr 8编码miRNA生物发生所必需的因子，可以自我更新但不能分化， 这表明miRNAs对于这些小鼠细胞的自我更新不是必需的。因为miRNAs 调节人类干细胞尚未进行系统研究，是否类似的miRNA调控是 物种间的保守性尚不清楚。在初步研究中，我们产生了DGCR 8 flox/flox人PSC （hPSC），其能够在PSC和分化的后代中使DGCR 8失活。我们的初步数据显示 与小鼠细胞不同，人类PSC和NSC的自我更新需要miRNA。此外，委员会认为， 自我更新在仅具有一个功能性DGCR 8等位基因的hPSC中受损。重要的是，我们发现miR-302 或miR-92，当单独表达时，足以拯救DGCR 8-/-人PSC或NSC的自我更新， 分别基于这些数据，我们假设人类PSC和NSCs的自我更新需要miRNAs的参与。 例如miR-302或miR-92，它们与小鼠干细胞有根本的不同。基本原理是 关于miRNAs如何调节人类干细胞的知识将提高我们对miRNAs与干细胞之间差异的理解。 人类和小鼠干细胞，这将允许在小鼠模型中重现人类疾病， 精确度，使小鼠模型更可预测，可用，适用于生物医学研究。要求1 Aim 2将比较miR-302如何调节人类和小鼠PSC，Aim 2将比较miR-92如何调节人类PSC。 Aim 3将比较DGCR 8的杂合缺失如何影响人和小鼠PSC 和NSC。预期的结果是：1）发现关于miRNA的根本差异 人和小鼠干细胞之间的调节，这对于使用小鼠干细胞模型至关重要。 研究和再生医学应用; 2）获得有关miRNAs如何调节人类干细胞的知识 细胞，这将作为未来与其他动物模型干细胞比较的基础。

Project Summary/Abstract Stem cells, including pluripotent stem cells (PSCs) and tissue-specific stem cells, can differentiate into functional tissues and therefore serve as promising donor sources for cell-based therapies. Mouse models have played indispensable roles in understanding the basic biological features and potential applications of stem cells. However, because human and rodent have diverged from a common ancestral species over 85 million years ago, it is not surprising that human stem cells also possess features that are not conserved in mouse cells. Therefore, an improved understanding to the similarities and differences between human and mouse stem cells is critical for using mice to model human diseases and test stem cell therapies. MicroRNAs (miRNAs) play a central role in cell proliferation, differentiation, and survival. Mouse PSCs and neural stem cells (NSCs) deficient for Dicer or Dgcr8, which encode factors essential for miRNA biogenesis, can self-renew but cannot differentiate, demonstrating that miRNAs are not essential for self-renewal of these mouse cells. Because how miRNAs regulate human stem cells have not been systematically investigated, whether similar miRNA regulation is conserved across species remains unclear. In the preliminary studies, we generated DGCR8flox/flox human PSCs (hPSCs), which enable DGCR8 inactivation in PSCs and the differentiated progeny. Our preliminary data showed that, different from mouse cells, miRNAs are required for self-renewal of human PSCs and NSCs. Furthermore, self-renewal is impaired in hPSCs with only one functional DGCR8 allele. Importantly, we identified that miR-302 or miR-92, when expressed alone, is sufficient to rescue self-renewal of DGCR8-/- human PSCs or NSCs, respectively. Based on these data, we hypothesize that self-renewal of human PSCs and NSCs require miRNAs such as miR-302 or miR-92, which differ fundamentally from the mouse stem cells. The rationale is that knowledge on how miRNAs regulate human stem cells will improve our understanding to the differences between human and mouse stem cells, which will allow recapitulation of human diseases in mouse models with greater precision and make the mouse models more predictable, usable, and applicable for biomedical research. Aim 1 will compare how miR-302 regualtes human and mouse PSCs, Aim 2 will compare how miR-92 regulates human and mouse NSCs, and Aim 3 will compare how heterozygous loss of DGCR8 affects human and mouse PSCs and NSCs. The expected outcomes are to 1) discover the fundamental differences regarding to miRNA regulation between human and mouse stem cells, which will be critical for the use of mouse models for stem cell research and regenerative medicine applications; and 2) gain knowledge on how miRNAs regulate human stem cells, which will serve as the basis for future comparison with stem cells from other animal models.