造血干细胞的蛋白翻译调控及其与低氧应激关联的研究

Hematopoietic stem cells (HSCs) are capable of self-renewal and multi-potent differentiation, and thereby forming the basis on which the entire hematopoietic system is established. Genetic mutations accumulated in HSCs result in many hematopoietic diseases. Recent studies revealed that mutations of some genes responsible for protein translation are highly associated with hematopoietic diseases, suggesting that protein translation plays an important role in HSC development and function, although the underlying mechanism is poorly understood. Through a mutagenetic screening, we obtained a mutant zebrafish line with defective HSC development, and identified the mutated gene encodes an aminoacyl tRNA synthetase. This family of enzymes control the first step of protein translation, and play an important role in regulation of the entire process. Out preliminary study also revealed that this phenotype of the zebrafish is affected by the hypoxic regulatory genes. Based on these findings, we plan to study the role of protein translational regulation in HSC development and malignant transformation, as well as its connection with hypoxic environment, with approaches at the levels of model organism, cell biology and biochemistry. Furthermore, we will also use our system of in vivo cell tracing and in vitro culturing mouse HSCs, to apply the hereby identified mechanism to the purpose of HSC expansion and reprogramming. Thus, these studies should provide new insights into the mechanism of HSC development and malignant transformation, as well as a new angle for realizing HSC expansion and reprogramming.

造血干细胞（HSC）具有自我更新和多潜能分化能力，是建立整个造血系统的基础。HSC积累的遗传变异可导致多种血液疾病。最近的研究发现，一些负责蛋白翻译的基因突变与血液疾病密切相关，提示蛋白翻译对HSC发育和功能有重要作用，但这方面的机制研究较少。我们通诱变筛选获得一个HSC发育缺陷的斑马鱼系，其致病基因编码一个氨酰-tRNA合成酶。这类酶控制蛋白翻译的第一步，对整个蛋白翻译过程具有重要调控作用。我们的初步研究还发现该斑马鱼的表型受到低氧调控基因的影响。基于这些发现，本项目将从模式生物、细胞生物学和生物化学水平，解析蛋白翻译在HSC发育和恶性转化中的作用，并研究蛋白翻译和低氧环境之间的内在联系。另外，我们还将利用我们建立的小鼠HSC体内示踪和体外培养模型，研究这些分子机制在HSC扩增和重编程方面的应用。这些研究可望揭示HSC发育和恶性转化的新的分子机制，并为实现HSC扩增和重编程提供新的视角。

氨酰-tRNA合成酶控制蛋白翻译的第一步，对整个蛋白翻译过程具有重要调控作用。本项目基于我们诱变筛选得到的苏氨酰-tRNA合成酶（tars）突变的斑马鱼株，对其表型和调控机制进行深入研究，并聚焦于解析蛋白翻译调控与多种应激信号通路的关系。值得注意的是，生命体能够对多种刺激产生反应，是因为细胞内存在感受这些刺激的多种应激信号通路；然而，很多信号通路是互相交叉甚至重叠的，这种情况对研究造成了很大的困难，使人们很难厘清不同信号通路对某一生物学现象的贡献，也不能充分理解细胞/个体如何区分如此多种刺激类型。在本项目中，我们对多种基因型的斑马鱼胚胎进行了系统的RNA-seq分析以及表型挽救实验，表明氨基酸反应（AAR）信号通路的激活在tars突变导致的斑马鱼表型中起关键作用，这一工作也使我们建立了一种系统分析多种应激信号通路的思路和方法。作为进一步的延伸，我们还发现了基础的表观遗传调控机制与这些应激调控之间的关联。通过跨物种比较，我们解析了组蛋白甲基转移酶Setd2介导的表观遗传调控机制在发育应激和生物进化中的作用，从而回答了表观遗传学领域的关键科学问题。综上所述，这些研究结果揭示了蛋白翻译调控相关的多种应激信号通路虽然密切偶联，但可以通过系统的比较分析方法对它们的关系进行解析，这一策略对于理解发育和疾病中的应激调控机制以及疾病的诊疗策略等都具有一定的应用价值。