MEIS2在人胚胎干细胞造血分化中的功能和作用机制研究

Human embryonic stem cells (hESCs) can differentiate into hematopoietic progenitor cells (HPCs). However, the low efficiency of differentiation and the functional defect of HPCs have been the major obstacles for realizing it potential for research and clinical applications. Dissection of the mechanism underlying hESCs differentiating into HPCs would facilitate the derivation of high-quality HPCs with high efficiency. Our preliminary data suggested MEIS2 dramatically up-regulated during the process of hESCs differentiating into HPCs. Interfering the expression of MEIS2 by shRNAs attenuated the expression of hematopoiesis related markers HOXB4 and CD34. Consistently, forced expression of MEIS2 increased the percentage of HPCs as well as the upregulation of HOXB4 and CD34. These results indicated that MEIS2 might play important roles in regulating the process of hESCs differentiating into HPCs. In further study, we will systematically dissect the function of MEIS2 in different stages of hESCs hematopoiesis through gain of function and loss of function assay. Furthermore, the potential downstream targets of MEIS2 and its function will be explored by using ChIP-SEQ and other genomic approaches. Our results will clarify the function and molecular mechanisms of MEIS2 regulating hESCs hematopoietic differentiating and facilitate the derivation of HPCs for regenerative medicine.

人胚胎干细胞可以分化成造血前体细胞。然而，分化效率低和分化产生的造血前体细胞功能不成熟严重制约了基础和临床应用。因此，阐明人胚胎干细胞造血分化内在机制，将有利于提高胚胎干细胞源造血前体细胞的分化效率和质量。我们前期研究表明：MEIS2在人胚胎干细胞早期造血分化过程中显著上升。在人胚胎干细胞造血分化过程中，干扰MEIS2表达导致造血分化相关标志分子HOXB4和CD34显著下降。外源表达MEIS2促进造血前体细胞增多，HOXB4和CD34表达显著上升，提示其可能在人胚胎干细胞造血分化中具有重要作用。因此，本研究将通过功能获得性和缺失性实验，揭示MEIS2在人胚胎干细胞造血分化中的功能，并利用TALEN和ChIP-SEQ等新技术，阐明MEIS2在此过程中的作用机制，为高效获得用于再生医学的人胚胎干细胞源造血前体细胞提供理论依据。

人胚胎干细胞可以分化成造血干/祖细胞，然而分化效率低和分化出的造血干/祖细胞功能不成熟严重制约了其基础和临床应用。本研究利用CRISPR/Cas9编辑技术成功建立了MEIS2敲除的人胚胎干细胞株，并发现敲除MEIS2后可显著抑制CD43+造血干/祖细胞的产生，而对后续血细胞的各系分化并不产生影响。同时荧光素酶报告实验发现MEIS2可以激活在造血发生中起重要作用的Wnt信号通路。后续我们将确定MEIS2的最佳作用窗口进而进行RNA-seq分析，将筛选出的MEIS2的靶基因与MEIS2参与的信号通路整合，阐明MEIS2的作用机制。最终能更好地优化现有的造血分化模型，提高分化效率和造血干/祖细胞的质量，为早日获得人胚胎干细胞源的可移植造血干/祖细胞奠定理论基础。