Runx1 is sufficient for blood cell formation from non-hemogenic endothelial cells <i>in vivo</i> only during early embryogenesis

Yzaguirre, Amanda D.; Howell, Elizabeth D.; Li, Yán; Liu, Zijing; Speck, Nancy A.

doi:10.1242/dev.158162

Cited by 35 publications

(33 citation statements)

References 29 publications

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“…Thus, perturbation of blood development at hemogenic sites can be caused by the selective effect of transcription factors on HE specification, EHT per se, or alternatively by their effect on amplification, survival, and specification of blood progenitors at the post-EHT stage. Among transcription factors involved in hematopoietic development, Runx1 has been shown to specify endothelial cells as hemogenic during a very short developmental window ( Yzaguirre et al., 2018 ). In addition, Runx1 affects post-EHT stages of blood development, including transition of VEC + CD45 − CD41 + type I HSCs to the CD45 + type II HSCs ( Liakhovitskaia et al., 2014 ).…”

Section: Discussionmentioning

confidence: 99%

GATA2 Is Dispensable for Specification of Hemogenic Endothelium but Promotes Endothelial-to-Hematopoietic Transition

et al. 2018

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SummaryThe transcriptional factor GATA2 is required for blood and hematopoietic stem cell formation during the hemogenic endothelium (HE) stage of development in the embryo. However, it is unclear if GATA2 controls HE lineage specification or if it solely regulates endothelial-to-hematopoietic transition (EHT). To address this problem, we innovated a unique system, which involved generating GATA2 knockout human embryonic stem cell (hESC) lines with conditional GATA2 expression (iG2−/− hESCs). We demonstrated that GATA2 activity is not required for VE-cadherin+CD43−CD73+ non-HE or VE-cadherin+CD43−CD73– HE generation and subsequent HE diversification into DLL4+ arterial and DLL4– non-arterial lineages. However, GATA2 is primarily needed for HE to undergo EHT. Forced expression of GATA2 in non-HE failed to induce blood formation. The lack of GATA2 requirement for generation of HE and non-HE indicates the critical role of GATA2-independent pathways in specification of these two distinct endothelial lineages.

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Section: Discussionmentioning

confidence: 99%

GATA2 Is Dispensable for Specification of Hemogenic Endothelium but Promotes Endothelial-to-Hematopoietic Transition

et al. 2018

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“…Initial hematopoietic specification associated with upregulation of CD41 does not require Runx1 ( Liakhovitskaia et al., 2014 ). Runx1 sensitivity of the embryonic endothelium is limited to the period around E7.5–E8.5 ( Tanaka et al., 2012 , Yzaguirre et al., 2018 ). Induced stage-specific inactivation using explant cultures followed by long-term transplantations showed that, up to E11.5, Runx1 is absolutely required for HSC development but becomes dispensable after that ( Tober et al., 2013 ).…”

Section: Discussionmentioning

confidence: 99%

Analysis of Runx1 Using Induced Gene Ablation Reveals Its Essential Role in Pre-liver HSC Development and Limitations of an In Vivo Approach

et al. 2018

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SummaryHematopoietic stem cells (HSCs) develop in the embryonic aorta-gonad-mesonephros (AGM) region and subsequently relocate to fetal liver. Runx1 transcription factor is essential for HSC development, but is largely dispensable for adult HSCs. Here, we studied tamoxifen-inducible Runx1 inactivation in vivo. Induction at pre-liver stages (up to embryonic day 10.5) reduced erythromyeloid progenitor numbers, but surprisingly did not block the appearance of Runx1-null HSCs in liver. By contrast, ex vivo analysis showed an absolute Runx1 dependency of HSC development in the AGM region. We found that, contrary to current beliefs, significant Cre-inducing tamoxifen activity persists in mouse blood for at least 72 hr after injection. This deferred recombination can hit healthy HSCs, which escaped early Runx1 ablation and result in appearance of Runx1-null HSCs in liver. Such extended recombination activity in vivo is a potential source of misinterpretation, particularly in analysis of dynamic developmental processes during embryogenesis.

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“…Whereas vasculogenesis in mouse ES cells occurs within the first 9 days following removal of LIF from the cell culture medium, the differentiation of leukocytes occurs between Day 12 and Day 14 of cell culture, which implies that inhibition of vasculogenesis should abolish differentiation of leukocytic cells (Hannig et al, ). During embryogenesis, hematopoietic stem cells differentiate from a population of endothelial cells called hemogenic endothelium (HE) in a process called the endothelial‐to‐hematopoietic transition (EHT) and is regulated by the transcription factor Runx1 (Yzaguirre, Howell, Li, Liu, & Speck, ). Recently transcriptional overlap between hemogenic endothelial cells and hematopoietic progenitor cells was reported (Angelos, Abrahante, Blum, & Kaufman, ).…”

Section: Discussionmentioning

confidence: 99%

The milk thistle (Silybum marianum) compound Silibinin stimulates leukopoiesis from mouse embryonic stem cells

Sharifpanah

Ali

Wartenberg

et al. 2018

Phytotherapy Research

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The milk thistle compound Silibinin (i.e., a 1:1 mixture of Silybin A and Silybin B) stimulates vasculogenesis of mouse embryonic stem (ES) cells. Because vasculogenesis and leukopoiesis are interrelated, the effect of Silibinin on leukopoiesis of ES cells was investigated. Treatment of differentiating ES cells with hydrosolubleSilibinin-C-2′,3-dihydrogen succinate dose-dependent increased the number of CD18 + , CD45 + , and CD68 + cells, indicating leukocyte/macrophage differentiation.Silibinin treatment activated phosphoinositide 3-kinase (PI3K), AKT (protein kinase B), signal transducer and activator of transcription 3 (STAT3), stimulated hypoxiainduced factor-1α (HIF-1α), and vascular endothelial growth factor receptor 2 (VEGFR2) expression and raised intracellular nitric oxide (NO). Western blot experiments showed that upon coincubation with either the PI3K inhibitor LY294002, the STAT3 inhibitor Stattic, the AKT antagonist AKT inhibitor VIII, or the NO inhibitor L-NAME, the Silibinin-induced expression of CD18, CD45, and CD68 was abolished.Moreover, the stimulation of HIF-1α and VEGFR2 expression was blunted upon STAT3 and PI3K/AKT inhibition. Treatment of differentiating ES cells with L-NAME abolished the stimulation of VEGFR2 and VE-cadherin expression achieved with Silibinin, indicating that NO is involved in vasculogenesis and leukocyte differentiation pathways. In summary, the data of the present study demonstrate that Silibinin stimulates leukocyte differentiation of ES cells, which is associated to vasculogenesis and regulated by PI3K/AKT-, STAT3-, and NO-mediated signaling.

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Runx1 is sufficient for blood cell formation from non-hemogenic endothelial cells in vivo only during early embryogenesis

Cited by 35 publications

References 29 publications

GATA2 Is Dispensable for Specification of Hemogenic Endothelium but Promotes Endothelial-to-Hematopoietic Transition

GATA2 Is Dispensable for Specification of Hemogenic Endothelium but Promotes Endothelial-to-Hematopoietic Transition

Analysis of Runx1 Using Induced Gene Ablation Reveals Its Essential Role in Pre-liver HSC Development and Limitations of an In Vivo Approach

The milk thistle (Silybum marianum) compound Silibinin stimulates leukopoiesis from mouse embryonic stem cells

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