Galloway Jenna L, Wingert Rebecca A, Thisse Christine, Thisse Bernard, Zon Leonard I
Stem Cell Program and Division of Hematology/Oncology, Children's Hospital Boston and Dana-Farber Cancer Institute, Boston, Mass., USA.
Exp Hematol. 2008 Apr;36(4):424-32. doi: 10.1016/j.exphem.2007.11.015. Epub 2008 Feb 4.
The specification and differentiation of hematopoietic stem cells into red blood cells requires precise coordination by multiple transcription factors. Most genes important for erythroid maturation are regulated by the Gata family of DNA-binding proteins. Previously, we identified three novel genes kelch-repeat containing protein (krcp), kiaa0650, and testhymin/glucocorticoid inducible transcript 1 (glcci1) to be expressed in erythroid cells in a Gata-independent manner, and we sought to further understand how these transcripts are regulated during zebrafish hematopoiesis.
We employed a loss-of-function approach, using combinations of antisense morpholinos to hematopoietic transcription factors and assayed for changes in gene expression in zebrafish embryos.
Upon examination of embryos deficient for Gata1, Gata2, Biklf, and/or Scl, we found distinct gene combinations were required for expression of the novel genes. While krcp expression was dependent upon Gata1 and Biklf, kiaa0650 expression was greatly reduced and glcci1 was maintained in Gata1/Gata2/Biklf-deficient embryos. As with the gata1 gene, kiaa0650 and krcp required Scl for blood expression. Although reduced, glcci1 was expressed in posterior blood precursors in the absence of Scl and Gata2.
This work identifies glcci1 as having Scl-independent expression in the posterior hematopoietic mesoderm, suggesting that its posterior expression is activated by factors upstream or parallel to Scl and Gata2. Additionally, these studies establish that blood gene expression programs are regulated by transcription factors acting in combination during erythroid maturation.
造血干细胞向红细胞的特异性分化需要多种转录因子的精确协调。大多数对红细胞成熟重要的基因受DNA结合蛋白的Gata家族调控。此前,我们鉴定出三个新基因,即含kelch重复序列蛋白(krcp)、kiaa0650和胸腺素/糖皮质激素诱导转录物1(glcci1),它们以不依赖Gata的方式在红细胞中表达,我们试图进一步了解这些转录物在斑马鱼造血过程中是如何被调控的。
我们采用功能丧失方法,使用针对造血转录因子的反义吗啉代组合,并检测斑马鱼胚胎中基因表达的变化。
在检查缺乏Gata1、Gata2、Biklf和/或Scl的胚胎时,我们发现新基因的表达需要不同的基因组合。虽然krcp的表达依赖于Gata1和Biklf,但kiaa0650的表达大幅降低,而glcci1在缺乏Gata1/Gata2/Biklf的胚胎中仍能维持表达。与gata1基因一样,kiaa0650和krcp在血液中的表达需要Scl。虽然glcci1的表达有所降低,但在没有Scl和Gata2的情况下,它仍在后侧血液前体细胞中表达。
这项研究确定glcci1在后侧造血中胚层中具有不依赖Scl的表达,这表明它的后侧表达是由Scl和Gata2上游或与之平行的因子激活的。此外,这些研究表明,在红细胞成熟过程中,血液基因表达程序是由多种转录因子组合作用调控的。