The Mouse GATA-2 Gene is Expressed in the Para-Aortic Splanchnopleura and Aorta-Gonads and Mesonephros Region

Abstract

We previously reported that the mouse GATA-2 gene is regulated by two alternative promoters (Minegishi et al, J Biol Chem, 273:3625, 1998). Although the more proximal IG (general) promoter is active in almost all GATA-2–expressing cells, the distal IS (specific) promoter activity was selectively detected in hematopoietic tissues but not in other mesodermal tissues. We report here in vivo analysis of the GATA-2 locus and its regulatory characteristics in hematopoietic tissues of transgenic mice. Transgenes containing 6 or 7 kbp of sequence flanking the 5′ end of the IS first exon direct expression of β-galactosidase or green fluorescent protein (GFP) reporter genes specifically to the para-aortic splanchnopleura, aorta-gonads, and mesonephros (AGM) region, and in the neural tissues. In situ hybridization analysis showed that reporter gene expression specifically recapitulates the endogenous expression profile of GATA-2 in these tissues. The flk-1, CD34, c-kit, and CD45 antigens were identified in the GFP-positive cells from the AGM region and fetal liver, indicating that GATA-2 is expressed in immature hematopoietic cells. Deletion of 3.5 kbp from the 5′ end of the 6.0 kbp IS promoter construct, including one of the DNase I hypersensitive sites, completely abolished hematopoietic expression. These experiments describe an early developmental GATA-2 hematopoietic enhancer located between 6.0 and 2.5 kbp 5′ to the IS exon.

Ontogeny of the Hematopoietic System

“…Whereas all the genes necessary for hematopoietic cell generation (and differentiation) in the YS are also required for HSC production in the P-Sp/AGM, the reverse is not true; the latter depends on a set of genes whose disruption does not interfere with YSderived hematopoiesis. Among these genes, some (Runx-1 and GATA-2) are first expressed in the extraembryonic mesoderm, then by YS endothelial and hematopoietic precursors (96,141), as well as in the AGM (81, 96,147). The invalidation of these genes leads to embryonic lethality between 9.5 and 11.5 dpc (at the stage extending from the starting hemogenic activity in the P-Sp/AGM and the onset of HSC expansion and differentiation activity in the FL) (101,(148)(149)(150).…”

GATA-2 functions downstream of BMPs and CaM KIV in ectodermal cells during primitive hematopoiesis

“…Intriguingly, BMPs are required to signal to the VE to generate a non-cell autonomous signal that enables adjacent mesoderm in the posterior epiblast to form primordial germ cells (de Sousa Lopes et al, 2004;Gu et al, 1999). Expression of Gata-2 has been reported as early as E7.5 in the lateral mesoderm and extraembryonic ectoderm (Minegishi et al, 1999), but it is not known if it is expressed in the VE at earlier stages, or whether its expression is dependent on BMPs. Gata-2 is required for both primitive and definitive hematopoiesis, and chimeric analysis, as well as in vitro differentiation assays reveal a cell autonomous role for this transcription factor in definitive blood progenitors (Tsai et al, 1994).…”

Polarized expression of bone morphogenetic protein-4 in the human aorta-gonad-mesonephros region

“…The factors that regulate expression of BMP-4, and downstream signaling events that determine this process are at present unclear, but may involve tightly regulated expression (spatial and temporal) of transcription factors such as Tal-1/SCL, Lmo2, GATA-2, and AML1/Cbfa2, a member of the family of core-binding transcription factors. [16][17][18][19][20] For example, in a parallel system, the induction of core-binding factor AML3 by BMP family members has been shown to be tightly linked to the process of osteoblastic differentiation. 21,22 AML1 is now known to be required for definitive hematopoiesis 23,24 and is transiently expressed in cells in the ventral wall of the dorsal aorta in the murine AGM coincident with the appearance of hematopoietic clusters.…”