The Cdx‐Hox Pathway in Hematopoietic Stem Cell Formation from Embryonic Stem Cells

Abstract

Embryonic stem cells (ESCs) differentiated in vitro will yield a multitude of hematopoietic derivatives, yet progenitors displaying true stem cell activity remain difficult to obtain. Possible causes are a biased differentiation to primitive yolk sac-type hematopoiesis, and a variety of developmental or functional deficiencies. Recent studies in the zebrafish have identified the caudal homeobox transcription factors (cdx1/4) and posterior hox genes (hoxa9a, hoxb7a) as key regulators for blood formation during embryonic development. Activation of Cdx and Hox genes during the in vitro differentiation of mouse ESCs followed by co-culture on supportive stromal cells generates ESC-derived hematopoietic stem cells (HSCs) capable of multilineage repopulation of lethally irradiated adult mice. We show here that brief pulses of ectopic Cdx4 or HoxB4 expression are sufficient to enhance hematopoiesis during ESC differentiation, presumably by acting as developmental switches to activate posterior Hox genes. Insights into the role of the Cdx-Hox gene pathway during embryonic hematopoietic development in the zebrafish have allowed us to improve the derivation of repopulating HSCs from murine ESCs.

DifferentialHoxExpression in Murine Embryonic Stem Cell Models of Normal and Malignant Hematopoiesis

“…This phenotype was validated by reduction in alkaline phosphatase expression and upregulation of Hoxb4 and Cdx4. Increased Hoxb4 and Cdx4 expression levels are known to enhance the clonogenic potential of EB-derived cells during hematopoietic differentiation [49,50]. Recent evidence suggests that Cdx4 is upregulated in 23% of AML patients, with preferential expression shown in primitive stem and progenitor cells.…”

Modeling murine yolk sac hematopoiesis with embryonic stem cell culture systems

“…The most notable platform for this type of study is the AinV cell line developed by Kyba and Daley (Kyba et al, 2002) to induce expression of the homeobox family gene HoxB4 . Along with several other homeobox factors, HoxB4 is a potent stimulator of stem/progenitor cell output (Sauvageau et al, 1995; Helgason et al, 1996; Pineault et al, 2002; Lengerke et al, 2007). This cell line employs engineered loci on the X chromosome and chromosome 6 to allow single-site targeted insertion of a transgenic construct, with tetracycline-mediated (“tet-on”) transactivation via expression of the reverse tet-transactivator protein from the constitutive ROSA26 promoter.…”

Temporal specification of blood progenitors from mouse embryonic stem cells and induced pluripotent stem cells

“…For this purpose, we focused on the nodal/TGFb, BMP4 and VEGF pathways as they are known to play a role at different stages of mesoderm induction and hematopoietic specification in vivo (Conlon et al, 1994;Liu et al, 1999;Winnier et al, 1995) and have been shown to function in a similar capacity in vitro (Lengerke et al, 2007;Ng et al, 2005;Nostro et al, 2008). Using an ESC line carrying the enhanced green fluorescent protein cDNA targeted to the brachyury (T) gene [T-EGFP (Fehling et al, 2003)], we evaluated both T-EGFP and Flk1 expression over time to monitor mesoderm induction and specification.…”