Fujiwara Y, Browne C P, Cunniff K, Goff S C, Orkin S H
Children's Hospital, Department of Pediatrics, Harvard Medical School, Howard Hughes Medical Institute, Boston, MA 02115, USA.
Proc Natl Acad Sci U S A. 1996 Oct 29;93(22):12355-8. doi: 10.1073/pnas.93.22.12355.
The X chromosome-linked transcription factor GATA-1 is expressed specifically in erythroid, mast, megakaryocyte, and eosinophil lineages, as well as in hematopoietic progenitors. Prior studies revealed that gene-disrupted GATA-1- embryonic stem cells give rise to adult (or definitive) erythroid precursors arrested at the proerythroblast stage in vitro and fail to contribute to adult red blood cells in chimeric mice but did not clarify a role in embryonic (or yolk sac derived) erythroid cells. To examine the consequences of GATA-1 loss on embryonic erythropoiesis in vivo, we inactivated the GATA-1 locus in embryonic stem cells by gene targeting and transmitted the mutated allele through the mouse germ line. Male GATA-1- embryos die between embryonic day 10.5 and 11.5 (E10.5-E11.5) of gestation. At E9.5, GATA-1- embryos exhibit extreme pallor yet contain embryonic erythroid cells arrested at an early proerythroblast-like stage of their development. Embryos stain weakly with benzidine reagent, and yolk sac cells express globin RNAs, indicating globin gene activation in the absence of GATA-1. Female heterozygotes (GATA-1+/-) are born pale due to random inactivation of the X chromosome bearing the normal allele. However, these mice recover during the neonatal period, presumably as a result of in vivo selection for progenitors able to express GATA-1. Our findings conclusively establish the essential role for GATA-1 in erythropoiesis within the context of the intact developing mouse and further demonstrate that the block to cellular maturation is similar in GATA-1- embryonic and definitive erythroid precursors. Moreover, the recovery of GATA-1+/- mice from anemia seen at birth provides evidence indicating a role for GATA-1 at the hematopoietic progenitor cell level.
X染色体连锁转录因子GATA-1特异性表达于红细胞、肥大细胞、巨核细胞和嗜酸性粒细胞谱系以及造血祖细胞中。先前的研究表明，基因敲除GATA-1的胚胎干细胞在体外可产生停滞于早幼红细胞阶段的成年（或定型）红细胞前体，且在嵌合小鼠中无法生成成年红细胞，但并未阐明其在胚胎（或卵黄囊来源）红细胞中的作用。为了研究体内GATA-1缺失对胚胎红细胞生成的影响，我们通过基因打靶使胚胎干细胞中的GATA-1基因座失活，并将突变等位基因通过小鼠生殖系传递下去。雄性GATA-1基因敲除胚胎在妊娠第10.5至11.5天（E10.5-E11.5）死亡。在E9.5时，GATA-1基因敲除胚胎呈现极度苍白，但含有停滞于早期早幼红细胞样发育阶段的胚胎红细胞。胚胎用联苯胺试剂染色较弱，卵黄囊细胞表达珠蛋白RNA，表明在没有GATA-1的情况下珠蛋白基因被激活。雌性杂合子（GATA-1+/-）由于携带正常等位基因的X染色体随机失活而出生时面色苍白。然而，这些小鼠在新生儿期恢复，推测是由于体内对能够表达GATA-1的祖细胞进行了选择。我们的研究结果确凿地证实了GATA-1在完整发育小鼠体内红细胞生成中的关键作用，并进一步证明GATA-1基因敲除的胚胎和定型红细胞前体中细胞成熟的阻滞是相似的。此外，GATA-1+/-小鼠从出生时出现的贫血中恢复，提供了证据表明GATA-1在造血祖细胞水平上发挥作用。
