GATA2 functions at multiple steps in hemangioblast development and differentiation

Abstract

*Molecular mechanisms that regulate the generation of hematopoietic and endothelial cells from mesoderm are poorly understood. To define the underlying mechanisms, we compared gene expression profiles between embryonic stem (ES) cell-derived hemangioblasts (Blast-Colony-Forming Cells, BL-CFCs) and their differentiated progeny, Blast cells. Bioinformatic analysis indicated that BL-CFCs resembled other stem cell populations. A role for Gata2, one of the BL-CFC-enriched transcripts, was further characterized by utilizing the in vitro model of ES cell differentiation. Our studies revealed that Gata2 was a direct target of BMP4 and that enforced GATA2 expression upregulated Bmp4, Flk1 and Scl. Conditional GATA2 induction resulted in a temporal-sensitive increase in hemangioblast generation, precocious commitment to erythroid fate, and increased endothelial cell generation. GATA2 additionally conferred a proliferative signal to primitive erythroid progenitors. Collectively, we provide compelling evidence that GATA2 plays specific, contextual roles in the generation of Flk-1 + mesoderm, the Flk-1 + Scl + hemangioblast, primitive erythroid and endothelial cells.

GATA Switches as Developmental Drivers

“…A change in factor concentration therefore may be insufficient to instigate a bona fide switch at a target gene. GATA switches occur in primary cells and in vivo (55,86). Three aspects of this proposed mechanism are of considerable interest.…”

Human induced pluripotent stem cells derived endothelial cells mimicking vascular inflammatory response under flow

“…20,33,34 The transcription of GATA2 and RUNX1 increased on the second day, indicating early stage vasculogenesis (Figs. 2(c) and 2(d)).…”

Molecular and developmental biology of the hemangioblast

“…Endoglin, an ancillary receptor for TGF␤ and BMPs, is expressed in hemangioblasts and required for the formation of hemangioblasts using blast colony assays (Perlingeiro, 2007). Gata2, a direct target of BMP4, is enriched in the BL-CFCs and is required for the generation of Flk1 ϩ mesoderm and hemangioblasts (Lugus et al, 2007). Smad1 is enriched in the Bry ϩ Flk1 ϩ hemangioblasts and sufficient to increase the formation of hemangioblasts (Zafonte et al, 2007), while overexpression of the inhibitory Smad6 reduces the generation of Flk1 ϩ mesodermal cells in EBs (Park et al, 2004).…”

“…The blast colony assay will be aided by genetic manipulation of mouse and human ESCs such as knockin and knockout by homologous recombination (Thomas and Capecchi, 1987;Chung et al, 2002;D'Souza et al, 2005;Davis et al, 2007;Irion et al, 2007). Isolating hemangioblasts and other progenitor cell populations by fluorescence-activated cell sorting (FACS) will help to identify additional players in hemangioblast development with the aid of microarray (Lugus et al, 2007) and proteomics approaches. The blast colony assay in a serum-free system will be useful for isolating growth factors and cytokines to promote hemangioblast development (Adelman et al, 2002;Park et al, 2004;Lu et al, 2006).…”

“…Inactivation of a single VEGF allele, of VEGFR-2 (flk1) or of phospholipase C-gamma 1 (Plcg1) in mice has reduced angioblasts and hematopoietic stem cells (HSCs; Shalaby et al, 1995Shalaby et al, , 1997Carmeliet et al, 1996;Ferrara et al, 1996;Damert et al, 2002;Liao et al, 2002). Genetically engineered ESCs are assessed for their ability to differentiate into BL-CFCs in vitro, by which Flk1, Scl, Runx1, Hhex, Mixl1, Bmp4, Smad1, Gata2, and lysocardiolipin acyltransferase (Lycat) are shown to be essential for the generation of BL-CFCs (Hidaka et al, 1999;Schuh et al, 1999;Faloon et al, 2000;Robertson et al, 2000;Chung et al, 2002;Lacaud et al, 2002Lacaud et al, , 2004Lugus et al, 2007;Wang et al, 2007;Zafonte et al, 2007). Zebrafish cloche mutant affects both endothelial and hematopoietic lineages (Stainier et al, 1995).…”