Gene expression data from E14.5 Pogz-WT and Pogz-KO fetal livers.

Fetal and adult beta-globin gene expression is tightly regulated during human development. Fetal globin genes are transcriptionally silenced during embryogenesis through the process of hemoglobin switching. Efforts to understand the transcriptional mechanism(s) behind fetal globin silencing have led to novel strategies to derepress fetal globin expression in the adult, which could alleviate symptoms in hereditary b-globin disorders including sickle cell disease (SCD) and beta-thalassemia. We identified a novel zinc finger protein, pogo transposable element with zinc finger domain (Pogz), expressed in mouse and human hematopoietic stem and progenitor cells, which represses embryonic b-like globin gene expression in mice. Ablation of Pogz expression in adult hematopoietic cells in vivo results in persistence of embryonic b-like globin expression without significantly affecting erythroid development or mouse survival. Elevated embryonic β-like globin expression correlates with reduced expression of Bcl11a, a known repressor of embryonic beta-like globin expression, in Pogz-/- fetal liver cells. Pogz binds to the Bcl11a promoter, and, to erythroid specific intragenic regulatory regions. Importantly, Pogz+/- mice develop normally, but show elevated embryonic b-like globin expression in peripheral blood cells, demonstrating that reducing Pogz levels results in persistence of embryonic b-like globin expression. Finally, knockdown of POGZ in primary human CD34+ hematopoietic stem and progenitor cell derived erythroblasts, reduces BCL11A expression and increases fetal hemoglobin expression. These findings are significant since new therapeutic targets and strategies are needed to treat the increasing global burden of b-globin disorders. Total RNA was isolated from E14.5 Pogz-WT and Pogz-KO fetal livers (N=3 each genotype) and analyzed for differential gene expression using Affymetrix GeneChip Mouse Genome 430 2.0 arrays.人类发育过程中，胎儿与成人β-珠蛋白（beta-globin）基因的表达受到严格调控。胎儿珠蛋白基因在胚胎发生阶段通过血红蛋白转换（hemoglobin switching）过程发生转录沉默。解析胎儿珠蛋白沉默背后的转录机制相关研究，催生了在成人体内重新激活胎儿珠蛋白表达的全新策略，有望缓解镰状细胞病（SCD, sickle cell disease）与β-地中海贫血等遗传性β-珠蛋白病的临床症状。我们在小鼠与人类造血干祖细胞中鉴定出一种新型锌指蛋白——含锌指结构域的pogo转座因子（Pogz, pogo transposable element with zinc finger domain），该蛋白可在小鼠体内抑制胚胎型β样珠蛋白基因的表达。在成体造血细胞中敲除Pogz的体内实验显示，胚胎型β样珠蛋白的表达持续存在，但并未显著影响红细胞系发育或小鼠存活率。在Pogz敲除（Pogz-/-）胎肝细胞中，升高的胚胎型β样珠蛋白表达与已知的胚胎型β样珠蛋白沉默因子Bcl11a的表达降低相关。Pogz可结合至Bcl11a启动子区域，以及红细胞特异性基因内调控区域。值得注意的是，Pogz杂合（Pogz+/-）小鼠发育正常，但外周血细胞中的胚胎型β样珠蛋白表达升高，这表明降低Pogz的表达水平即可使胚胎型β样珠蛋白的表达持续存在。最后，在原代人CD34+造血干祖细胞来源的成红细胞中敲低POGZ，可降低BCL11A的表达并提升胎儿血红蛋白的表达水平。上述研究结果具有重要意义，因为目前亟需全新的治疗靶点与策略，以应对日益加重的全球遗传性β-珠蛋白病负担。本研究的数据集来源于胚胎发育第14.5天（E14.5）的Pogz野生型（Pogz-WT）与Pogz敲除型（Pogz-KO）胎肝（每组基因型n=3），通过Affymetrix小鼠基因组430 2.0基因芯片（Affymetrix GeneChip Mouse Genome 430 2.0 arrays）分析差异基因表达情况。