Division of Molecular Medicine and Gene Therapy, Lund Stem Cell Center, Lund University, 221 84 Lund, Sweden.
Division of Molecular Hematology, Lund Stem Cell Center, Lund University, 221 84 Lund, Sweden.
Cell Rep. 2016 Mar 29;14(12):2988-3000. doi: 10.1016/j.celrep.2016.02.082. Epub 2016 Mar 17.
To gain insights into the regulatory mechanisms of hematopoietic stem cells (HSCs), we employed a genome-wide RNAi screen in human cord-blood derived cells and identified candidate genes whose knockdown maintained the HSC phenotype during culture. A striking finding was the identification of members of the cohesin complex (STAG2, RAD21, STAG1, and SMC3) among the top 20 genes from the screen. Upon individual validation of these cohesin genes, we found that their knockdown led to an immediate expansion of cells with an HSC phenotype in vitro. A similar expansion was observed in vivo following transplantation to immunodeficient mice. Transcriptome analysis of cohesin-deficient CD34(+) cells showed an upregulation of HSC-specific genes, demonstrating an immediate shift toward a more stem-cell-like gene expression signature upon cohesin deficiency. Our findings implicate cohesin as a major regulator of HSCs and illustrate the power of global RNAi screens to identify modifiers of cell fate.
为了深入了解造血干细胞（HSCs）的调控机制，我们在人类脐血来源的细胞中进行了全基因组 RNAi 筛选，鉴定出了一些候选基因，其敲低可在培养过程中维持 HSC 表型。一个显著的发现是，在筛选出的前 20 个基因中，有成员属于黏合蛋白复合物（STAG2、RAD21、STAG1 和 SMC3）。对这些黏合蛋白基因进行单独验证后，我们发现它们的敲低导致体外具有 HSC 表型的细胞立即扩增。在免疫缺陷小鼠体内移植后也观察到类似的扩增。黏合蛋白缺陷的 CD34(+)细胞的转录组分析显示，HSC 特异性基因上调，表明黏合蛋白缺陷后，HSC 特异性基因表达特征立即向更类似于干细胞的方向转变。我们的研究结果表明黏合蛋白是 HSCs 的主要调节因子，并说明了全基因组 RNAi 筛选在鉴定细胞命运修饰因子方面的强大功能。
