Notch1 regulates progenitor cell proliferation and differentiation during mouse yolk sac hematopoiesis

Abstract

Loss-of-function studies have demonstrated the essential role of Notch in definitive embryonic mouse hematopoiesis. We report here the consequences of Notch gain-of-function in mouse embryo hematopoiesis, achieved by constitutive expression of Notch1 intracellular domain (N1ICD) in angiopoietin receptor tyrosine kinase receptor-2 (Tie2)-derived enhanced green fluorescence protein (EGFP þ ) hematovascular progenitors. At E9.5, N1ICD expression led to the absence of the dorsal aorta hematopoietic clusters and of definitive hematopoiesis. The EGFP þ transient multipotent progenitors, purified from E9.5 to 10.5 Tie2-Cre;N1ICD yolk sac (YS) cells, had strongly reduced hematopoietic potential, whereas they had increased numbers of hemogenic endothelial cells. Late erythroid cell differentiation stages and mature myeloid cells (Gr1 þ , MPO þ ) were also strongly decreased. In contrast, EGFP þ erythro-myeloid progenitors, immature and intermediate differentiation stages of YS erythroid and myeloid cell lineages, were expanded. Tie2-Cre;N1ICD YS had reduced numbers of CD41 þ þ megakaryocytes, and these produced reduced below-normal numbers of immature colonies in vitro and their terminal differentiation was blocked. Cells from Tie2-Cre;N1ICD YS had a higher proliferation rate and lower apoptosis than wild-type (WT) YS cells. Quantitative gene expression analysis of FACS-purified EGFP þ YS progenitors revealed upregulation of Notch1-related genes and alterations in genes involved in hematopoietic differentiation. These results represent the first in vivo evidence of a role for Notch signaling in YS transient definitive hematopoiesis. Our results show that constitutive Notch1 activation in Tie2 þ cells hampers YS hematopoiesis of E9.5 embryos and demonstrate that Notch signaling regulates this process by balancing the proliferation and differentiation dynamics of lineage-restricted intermediate progenitors.

Constitutive notch signaling in adult transgenic mice inhibits bFGF‐induced angiogenesis and blocks ovarian follicle development

“…1h,i). These vascular remodeling defects are similar to the observations from other mouse models with conditional activation of the IC-Notch1 in ECs (Cortegano et al, 2014;Krebs et al, 2010;Venkatesh et al, 2008).…”

Loss of Apela Peptide in Mice Causes Low Penetrance Embryonic Lethality and Defects in Early Mesodermal Derivatives

“…Distribution of EMPs from the YS is facilitated by circulation (Kasaai et al, 2017), yet there is also evidence for active cell mobilization (Tanaka et al, 2014). Overrepresentation of YS-derived myeloid cells has been linked to remodeling of the venous plexus of the YS (Kasaai et al, 2017), leading to embryonic lethal phenotypes resembling Apela mutants (Cortegano et al, 2014, Venkatesh et al, 2008). Whether erythromyeloid defects in late gastrulation stage Apela null embryos can be directly linked to lethal cardiovascular defects observed after circulation remains an open question.…”

Evaluation of velvet antler total protein effect on bone marrow-derived endothelial progenitor cells

“…Notch1 combines with the ligands, and then NICD is releaseed into the cytoplasm and gets into nucleus, it binds to CSL (C-promoter binding protein-1, CBF-1) and a complex is formed to activate the genes of transcription inhibitory factor family, such as Hes, Hey or Herp ( 27 ). To be expected, it is related to EPCs proliferation, differentiation ( 4 ) and tube formation ( 5 ). EPCs activity reduces when Notch mRNA is inhibited ( 28 ).…”

“…Notch signaling pathway is highly conserved, and plays a key role in neovascularization and angiogenesis process. It participates in progenitor cells differentiation, proliferation ( 4 ) and tube formation ( 5 ). We assumed that the two signaling pathways were involved in the effect of velvet antler (VA) on EPCs.…”