Department of Cell and Developmental Biology, School of Medicine, Oregon Health and Science University, Portland, Oregon, United States of America.
PLoS One. 2012;7(1):e29882. doi: 10.1371/journal.pone.0029882. Epub 2012 Jan 3.
Friend of GATA (FOG) plays many diverse roles in adult and embryonic hematopoiesis, however the mechanisms by which it functions and the roles of potential interaction partners are not completely understood. Previous work has shown that overexpression of FOG in Xenopus laevis causes loss of blood suggesting that in contrast to its role in mammals, FOG might normally function to repress erythropoiesis in this species. Using loss-of-function analysis, we demonstrate that FOG is essential to support primitive red blood cell (RBC) development in Xenopus. Moreover, we show that it is specifically required to prevent excess apoptosis of circulating primitive RBCs and that in the absence of FOG, the pro-apoptotic gene Bim-1 is strongly upregulated. To identify domains of FOG that are essential for blood development and, conversely, to begin to understand the mechanism by which overexpressed FOG represses primitive erythropoiesis, we asked whether FOG mutants that are unable to interact with known co-factors retain their ability to rescue blood formation in FOG morphants and whether they repress erythropoiesis when overexpressed in wild type embryos. We find that interaction of FOG with the Nucleosome Remodeling and Deacetylase complex (NuRD), but not with C-terminal Binding Protein, is essential for normal primitive RBC development. In contrast, overexpression of all mutant and wild type constructs causes a comparable repression of primitive erythropoiesis. Together, our data suggest that a requirement for FOG and its interaction with NuRD during primitive erythropoiesis are conserved in Xenopus and that loss of blood upon FOG overexpression is due to a dominant-interfering effect.
GATA 朋友（FOG）在成人和胚胎造血中发挥着许多不同的作用，但其作用机制和潜在相互作用伙伴的角色尚不完全清楚。以前的工作表明，FOG 在非洲爪蟾中的过表达会导致血液丧失，这表明与在哺乳动物中的作用相反，FOG 可能正常情况下在该物种中发挥抑制红细胞生成的作用。通过功能丧失分析，我们证明 FOG 对于支持非洲爪蟾原始红细胞（RBC）的发育是必不可少的。此外，我们表明它是专门需要防止循环原始 RBC 过度凋亡的，并且在没有 FOG 的情况下，促凋亡基因 Bim-1 被强烈上调。为了确定 FOG 的哪些结构域对于血液发育是必不可少的，并且相反，开始理解过表达 FOG 如何抑制原始红细胞生成，我们询问了是否无法与已知共因子相互作用的 FOG 突变体是否保留其在 FOG 形态发生体中拯救血液形成的能力，以及它们在野生型胚胎中过表达时是否抑制红细胞生成。我们发现 FOG 与核小体重塑和去乙酰化酶复合物（NuRD）的相互作用，但不是与 C 末端结合蛋白的相互作用，对于正常的原始 RBC 发育是必不可少的。相比之下，所有突变体和野生型构建体的过表达都会导致原始红细胞生成的类似抑制。总之，我们的数据表明，在非洲爪蟾中，原始红细胞生成过程中需要 FOG 及其与 NuRD 的相互作用是保守的，并且过表达 FOG 导致血液丧失是由于显性干扰效应。
