KLF2 is essential for primitive erythropoiesis and regulates the human and murine embryonic β-like globin genes in vivo

Abstract

The Krü ppel-like factors (KLFs) are a family of C2/H2 zinc finger DNA-binding proteins that are important in controlling developmental programs. Erythroid Krü ppel-like factor (EKLF or KLF1) positively regulates the ␤-globin gene in definitive erythroid cells. KLF2 (LKLF) is closely related to EKLF and is expressed in erythroid cells. KLF2 ؊/؊ mice die between embryonic day 12.5 (E12.5) and E14.5, because of severe intraembryonic hemorrhaging. They also display growth retardation and anemia. We investigated the expression of the ␤-like globin genes in KLF2 knockout mice. Our results show that KLF2 ؊/؊ mice have a significant reduction of murine embryonic Ey-and ␤h1-globin but not -globin gene expression in the E10.5 yolk sac, compared with wild-type mice. The expression of the adult ␤ maj -and ␤ min -globin genes is unaffected in the fetal livers of E12.5 embryos. In mice carrying the entire human globin locus, KLF2 also regulates the expression of the human embryonic ⑀-globin gene but not the adult ␤-globin gene, suggesting that this developmentalstage-specific role is evolutionarily conserved. KLF2 also plays a role in the maturation and/or stability of erythroid cells in the yolk sac. KLF2 ؊ IntroductionHematopoiesis represents a complex differentiation pathway involving many transcription factors and growth factors that interact in a concerted fashion during mammalian development. 1 Transcription factors often exist as multigene families of structurally and functionally related members that are involved in the different stages of development of a particular cell lineage. For example, members of the GATA family of transcription factors are involved in both primitive and definitive erythropoiesis. 2-4 Different phenotypic features seen after ablation of either the GATA1 or the GATA2 gene in mice clearly demonstrate that these factors have different but overlapping functions. The Krüppel-like factors (KLFs) are a family of DNA-binding proteins named after the Drosophila Krüppel protein. KLFs have 3 C2/H2 zinc finger domains and share conserved residues located primarily within these zinc fingers. 5,6 Several of the KLFs are expressed in erythroid cells starting early in development. Erythroid Krüppel-like factor (EKLF or KLF1) was the first of 16 KLFs to be identified. EKLF Ϫ/Ϫ mice develop fatal anemia during fetal liver erythropoiesis. 7,8 EKLF is responsible for positively regulating the adult ␤-globin gene, but it is not required for embryonic/fetal globin gene expression. [9][10][11] Other KLF family members may be involved in the developmental control of the embryonic and fetal globin genes. A few of the KLFs, namely KLF2 and KLF5, 12 and KLF11 and KLF13,13,14 have been shown to activate the fetal ␥-globin gene in transient transfection assays in human erythroleukemia cell lines. So far none of these studies have been replicated in vivo. In a recent study, KLF11 (fetal Krüppel like factor, FKLF1)-null mice were found to be fertile, with normal hematopoiesis at all stages of development. There was no effe...

Kruppel-like transcription factors KLF1 and KLF2 have unique and coordinate roles in regulating embryonic erythroid precursor maturation

“…KLF2 is necessary for primitive erythropoiesis, and positively regulates embryonic globin gene expression, as shown in KLF2 knockout and erythroid-conditional knockout mouse embryos. 11,19,20 Global gene expression assays indicate that many genes that are important in the processes of development, differentiation and cell migration are dysregulated in KLF2-/-compared to wild-type primitive erythroid cells. 21 Ablation of KLF2 causes lethality between E11.5 and E14.…”

“…cDNA synthesis and quantitative reverse-transcriptase PCR (qRT-PCR) were performed as previously described. 11,12,19,20 Primer sequences for qRT-PCR are listed in Online Supplementary Table S1.…”

Kruppel-like factor 2 (KLF2) regulates proinflammatory activation of monocytes

“…Forced overexpression of KLF2 induced a quiescent T cell phenotype whereas KLF2-null T cells exhibited a spontaneously activated phenotype (9). More recently, KLF2 has also been implicated in the regulation of embryonic globin gene synthesis (10).…”

Identification, characterization, and expression pattern of the chicken EKLF gene

“…We have determined the chromosomal location of the chicken KLFs, and they are presented in Table 1. Although the EKLF and KLF2 genes are located in close proximity on the same chromosome in mouse and human (Basu et al, 2005), this finding is not the case in chicken. Chicken EKLF has three exons, as do its mammalian homologues.…”

“…Recently, we reported that KLF2/LKLF is essential for primitive erythropoiesis and regulates the embryonic globin genes in vivo (Basu et al, 2005). These mice also have a defect in blood vessel formation and die between E12 and E14 (Kuo et al, 1997;Wani et al, 1998).…”