Increased hemangioblast commitment, not vascular disorganization, is the primary defect in flt-1 knock-out mice

Development ◽  
1999 ◽  
Vol 126 (13) ◽  
pp. 3015-3025 ◽  
Author(s):  
G.H. Fong ◽  
L. Zhang ◽  
D.M. Bryce ◽  
J. Peng
Keyword(s):  
Endothelial Cells ◽  
Population Density ◽  
Cell Fate ◽  
Vascular System ◽  
Primitive Streak ◽  
Cellular Level ◽  
Wild Type ◽  
Primary Defect ◽  
Knock Out ◽  
Vascular Channels

We previously demonstrated the essential role of the flt-1 gene in regulating the development of the cardiovascular system. While the inactivation of the flt-1 gene leads to a very severe disorganization of the vascular system, the primary defect at the cellular level was unknown. Here we report a surprising finding that it is an increase in the number of endothelial progenitors that leads to the vascular disorganization in flt-1(−/−) mice. At the early primitive streak stage (prior to the formation of blood islands), hemangioblasts are formed much more abundantly in flt-1(−/−) embryos. This increase is primarily due to an alteration in cell fate determination among mesenchymal cells, rather than to increased proliferation, migration or reduced apoptosis of flt-1(−/−) hemangioblasts. We further show that the increased population density of hemangioblasts is responsible for the observed vascular disorganization, based on the following observations: (1) both flt-1(−/−) and flt-1(+/+) endothelial cells formed normal vascular channels in chimaeric embryos; (2) wild-type endothelial cells formed abnormal vascular channels when their population density was significantly increased; and (3) in the absence of wild-type endothelial cells, flt-1(−/−) endothelial cells alone could form normal vascular channels when sufficiently diluted in a developing embryo. These results define the primary defect in flt-1(−/−) embryos at the cellular level and demonstrate the importance of population density of progenitor cells in pattern formation.

Disturbed Endothelial Blood-Bone Marrow-Barrier In Nox4 Deficient Mice

Blood ◽  
2013 ◽  
Vol 122 (21) ◽  
pp. 1169-1169
Author(s):  
Maren Weisser ◽  
Kerstin B. Kaufmann ◽  
Tomer Itkin ◽  
Linping Chen-Wichmann ◽  
Tsvee Lapidot ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Endothelial Cells ◽  
Stem Cell ◽  
Steady State ◽  
Wild Type ◽  
Hematopoietic Stem ◽  
Knock Out ◽  
Deficient Mice ◽  
Permeability State

Abstract Reactive oxygen species (ROS) have been implicated in the regulation of stemness of hematopoietic stem cells (HSC). HSC with long-term repopulating capabilities are characterized by low ROS levels, whereas increased ROS levels correlate with lineage specification and differentiation. Several tightly regulated sources of ROS production are well known among which are the NADPH oxidases (Nox). HSC are known to express Nox1, Nox2 and Nox4, however, their role in maintenance of stem cell potential or in the activation of differentiation programs are poorly understood. While Nox2 is activated in response to various extrinsic and intrinsic stimuli, mainly during infection and inflammation, Nox4 is constitutively active and is considered to be responsible for steady-state ROS production. Consequently, Nox4 deficiency might lower ROS levels at steady-state hematopoiesis and thereby could have an impact on HSC physiology. In this work we studied HSC homeostasis in Nox4 knock-out mice. Analysis of the hematopoietic stem and progenitor cell (HSPC) pool in the bone marrow (BM) revealed no significant differences in the levels of Lineage marker negative (Lin-) Sca-1+ ckit+ (LSK) and LSK-SLAM (LSK CD150+ CD48-) cells in Nox4 deficient mice compared to wild type (WT) C57BL/6J mice. HSPC frequency upon primary and secondary BM transplantation was comparable between Nox4 deficient and WT mice. In addition, the frequency of colony forming cells in the BM under steady-state conditions did not differ between both mouse groups. However, Nox4 deficient mice possess more functional HSCs as observed in in vivo competitive repopulating unit (CRU) assays. Lin- cells derived from Nox4 knock out (KO) mice showed an increased CRU frequency and superior multilineage engraftment upon secondary transplantation. Surprisingly, ROS levels in different HSPC subsets of NOX4 KO mice were comparable to WT cells, implying that the absence of Nox4 in HSCs does not have a major intrinsic impact on HSC physiology via ROS. Therefore, the increased levels of functional HSCs observed in our studies may suggest a contribution of the BM microenvironment to steady-state hematopoiesis in the BM of Nox4 KO animals. Recent observations suggest a regulation of the BM stem cell pool by BM endothelial cells, in particular by the permeability state of the blood-bone marrow-barrier (Itkin T et al., ASH Annual Meeting Abstracts, 2012). Endothelial cells interact with HSCs predominantly via paracrine effects and control stem cell retention, egress and homing as well as stem cell activation. As Nox4 is highly expressed in endothelial cells and is involved in angiogenesis, we reasoned that the absence of NOX4 could affect HSC homeostasis through altered BM endothelium properties and barrier permeability state. Indeed, in preliminary assays we found reduced short-term homing of BM mononuclear cells into the BM of Nox4 deficient mice as compared to wild type hosts. Furthermore, in vivo administration of Evans Blue dye revealed reduced dye penetration into Nox4-/- BM compared to wild type mice upon intravenous injection. Taken together, these data indicate a reduced endothelial permeability in Nox4 KO mice. Ongoing experiments aim at further characterization of the Nox4-/- phenotype in BM sinusoidal and arteriolar endothelial cells, the impact of Nox4 deletion on BM hematopoietic and mesenchymal stem cells, and in deciphering the role of Nox4 in the bone marrow microenvironment. Disclosures: No relevant conflicts of interest to declare.

Indian hedgehog activates hematopoiesis and vasculogenesis and can respecify prospective neurectodermal cell fate in the mouse embryo

Development ◽  
2001 ◽  
Vol 128 (10) ◽  
pp. 1717-1730 ◽  
Author(s):  
M.A. Dyer ◽  
S.M. Farrington ◽  
D. Mohn ◽  
J.R. Munday ◽  
M.H. Baron
Keyword(s):  
Endothelial Cells ◽  
Cell Fate ◽  
Mouse Embryo ◽  
Hedgehog Signaling ◽  
Vascular System ◽  
Vascular Endothelial Cells ◽  
Indian Hedgehog ◽  
Vascular Endothelial ◽  
Primitive Endoderm ◽  
Genes Encoding

During gastrulation in the mouse, mesoderm is induced and patterned by secreted signaling molecules, giving rise first to primitive erythroblasts and vascular endothelial cells. We have demonstrated previously that development of these lineages requires a signal(s) secreted from the adjacent primitive endoderm. We now show that Indian hedgehog (Ihh) is a primitive endoderm-secreted signal that alone is sufficient to induce formation of hematopoietic and endothelial cells. Strikingly, as seen with primitive endoderm, Ihh can respecify prospective neural ectoderm (anterior epiblast) along hematopoietic and endothelial (posterior) lineages. Downstream targets of the hedgehog signaling pathway (the genes encoding patched, smoothened and Gli1) are upregulated in anterior epiblasts cultured in the presence of Ihh protein, as is Bmp4, which may mediate the effects of Ihh. Blocking Ihh function in primitive endoderm inhibits activation of hematopoiesis and vasculogenesis in the adjacent epiblast, suggesting that Ihh is an endogenous signal that plays a key role in the development of the earliest hemato-vascular system. To our knowledge, these are the earliest functions for a hedgehog protein in post-implantation development in the mouse embryo.

Identification and analysis of a gene that is essential for morphogenesis and prespore cell differentiation in Dictyostelium

Development ◽  
1998 ◽  
Vol 125 (14) ◽  
pp. 2565-2576 ◽  
Author(s):  
H. Yasukawa ◽  
S. Mohanty ◽  
R.A. Firtel
Keyword(s):  
Gene Expression ◽  
Cell Differentiation ◽  
Cell Fate ◽  
Stalk Cell ◽  
Specific Gene ◽  
Wild Type ◽  
Cell Type ◽  
Primary Defect ◽  
Experimental Conditions ◽  
Prespore Cell

We have identified a gene (PslA) that is expressed throughout Dictyostelium development and encodes a novel protein that is required for proper aggregation and subsequent cell-type differentiation and morphogenesis. pslA null (pslA-) cells produce large aggregation streams under conditions in which wild-type cells form discrete aggregates. Tips form along the stream, elongate to produce a finger, and eventually form a terminal structure that lacks a true sorus (spore head). More than half of the cells remain as a mass at the base of the developing fingers. The primary defect in the pslA- strain is the inability to induce prespore cell differentiation. Analyses of gene expression show a complete lack of prespore-specific gene expression and no mature spores are produced. In chimeras with wild-type cells, pslA- cells form the prestalk domain and normal, properly proportioned fruiting bodies can be produced. This indicates that pslA- cells are able to interact with wild-type cells and regulate patterning, even though pslA- cells are unable to express prespore cell-type-specific genes, do not participate in prespore cell differentiation and do not produce pslA- spores in the chimeras. While pslA- cells produce mature, vacuolated stalk cells during multicellular development, pslA- cells are unable to do so in vitro in response to exogenous DIF (a morphogen required for prestalk and stalk cell differentiation). These results indicate that pslA- cells exhibit a defect in the prestalk/stalk cell pathways under these experimental conditions. Our results suggest that PslA's primary function is to regulate prespore cell determination very early in the prespore pathway via a cell-autonomous mechanism, possibly at the time of the initial prestalk/prespore cell-fate decision. Indirect immunofluorescence of myc-tagged PslA localizes the protein to the nucleus, suggesting that PslA may function to control the prespore pathway at the level of transcription.

Oncogenic Transcription Factor Evi1 Regulates Hematopoietic Stem Cell Proliferation through GATA-2 Expression.

Blood ◽  
2004 ◽  
Vol 104 (11) ◽  
pp. 228-228 ◽  
Author(s):  
Hiromi Yuasa ◽  
Yuichi Oike ◽  
Atsushi Iwama ◽  
Daisuke Sugiyama ◽  
Ichiro Nishikata ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Transcription Factor ◽  
Network Formation ◽  
Vascular System ◽  
Upstream Region ◽  
Wild Type ◽  
Hematopoietic Stem ◽  
Adult Bone

Abstract Chromosomal abnormalities, such as translocation, mutation or deletion, are central to the pathogenesis of human cancers. Recently, several transcription factors have been isolated as genes responsible for leukemia from the region surrounding chromosomal breakpoints, which are implicated in the regulation of normal hematopoiesis. Among on them, ecotropic viral integration site-1 (Evi1) is a transcription factor activated by retroviral integration in murine leukemias and chromosomal rearrangements in human leukemias. Evi1 is a zinc finger transcription factor and contains two separated DNA-binding domains. It was reported that Evi1−/− embryos die at approximately E10.5, exhibiting widespread hypocellularity and hemorrhaging. However, the role in normal hematopoiesis or authentic target genes of Evi1 has not been elucidated. Here, we show that Evi1 is predominantly expressed in hematopoietic stem cells (HSCs) in embryos and adult bone marrows, and Evi1−/− embryos are markedly decreased in numbers of HSC. One embryo-equivalent cells from E9.5 P-Sp of Evi1+/+, Evi1+/− and Evi1−/− embryos (Ly5.2) were transplanted into a busulfan-conditioned newborn recipient (Ly5.1). At 2 months posttransplant, donor-derived Ly5.2(+) cells could be detected in the peripheral blood of the recipients that received P-Sp cells from the Evi1+/+ and Evi1+/− but not from the Evi1−/− embryos. Thus, Evi1 is critical for the generation of HSCs in the P-Sp. Both Evi1−/− embryos and yolk sac showed marked retardation in the organization of the vascular system, particularly in vascular remodeling, compared with controls. Using an in vitro P-Sp culture analysis, we found normal in vitro differentiation of endothelial cells in Evi1−/− P-Sp cultures but defects in their in vitro network formation, which is normally promoted by Ang-1 secreted from developing HSCs in P-Sp cultures. HSCs from adult bone marrow or HSCs from E9.5 wild type embryos rescued defective angiogenesis in Evi1−/− embryos. The fine vascular network coincided with the region where HSCs formed a colony. Their round morphology confirmed that exogenous adult HSCs did not differentiate into elongated endothelial cells. We showed that recombinant Ang-1 alone restored the defective angiogenesis in Evi1−/− embryos to a wild type level. It is suggested that the defect in hematopoietic cells induced defective angiogenesis in Evi1−/− embryos mediated by Ang-1. Notably, mRNA expression of GATA-2, which is essential for proliferation of definitive HSCs, was profoundly reduced in Evi1−/− embryos. Analysis of the GATA-2 promotor revealed that Evi1 directly binds to the 5′ upstream region of the GATA−2 exon and positively regulates its promoter activity in vitro and in vivo. Restoration of GATA-2 expression dramatically rescued the defective expansion of Evi1−/− embryos HSCs in vitro. Our results reveal that GATA-2 is a critical in vivo target for Evi1 and indicate hierarchical regulation of the HSC pool by transcriptional regulators.

scholarly journals Cell Fate Determination of Lymphatic Endothelial Cells

2020 ◽  
Vol 21 (13) ◽  
pp. 4790
Author(s):  
Young Jae Lee
Keyword(s):  
Endothelial Cells ◽  
Immune Responses ◽  
Cell Fate ◽  
Dietary Fat ◽  
Vascular System ◽  
Lymphatic Endothelial Cells ◽  
Lymphatic Vasculature ◽  
Fat Uptake ◽  
Mammalian System

The lymphatic vasculature, along with the blood vasculature, is a vascular system in our body that plays important functions in fluid homeostasis, dietary fat uptake, and immune responses. Defects in the lymphatic system are associated with various diseases such as lymphedema, atherosclerosis, fibrosis, obesity, and inflammation. The first step in lymphangiogenesis is determining the cell fate of lymphatic endothelial cells. Several genes involved in this commitment step have been identified using animal models, including genetically modified mice. This review provides an overview of these genes in the mammalian system and related human diseases.

Formation of the definitive endoderm in mouse is a Smad2-dependent process

Development ◽  
2000 ◽  
Vol 127 (14) ◽  
pp. 3079-3090 ◽  
Author(s):  
K.D. Tremblay ◽  
P.A. Hoodless ◽  
E.K. Bikoff ◽  
E.J. Robertson
Keyword(s):  
Cell Fate ◽  
Es Cells ◽  
Primitive Streak ◽  
Definitive Endoderm ◽  
Effector Proteins ◽  
The Body ◽  
Cell Surface Receptor ◽  
Specific Cell ◽  
Primary Defect ◽  
Surface Receptor

TGFbeta growth factors specify cell fate and establish the body plan during early vertebrate development. Diverse cellular responses are elicited via interactions with specific cell surface receptor kinases that in turn activate Smad effector proteins. Smad2-dependent signals arising in the extraembryonic tissues of early mouse embryos serve to restrict the site of primitive streak formation and establish anteroposterior identity in the epiblast. Here we have generated chimeric embryos using lacZ-marked Smad2-deficient ES cells. Smad2 mutant cells extensively colonize ectodermal and mesodermal populations without disturbing normal development, but are not recruited into the definitive endoderm lineage during gastrulation. These experiments provide the first evidence that TGFbeta signaling pathways are required for specification of the definitive endoderm lineage in mammals and identify Smad2 as a key mediator that directs epiblast derivatives towards an endodermal as opposed to a mesodermal fate. In largely Smad2-deficient chimeras, asymmetric nodal gene expression is maintained and expression of pitx2, a nodal target, is also unaffected. These results strongly suggest that other Smad(s) act downstream of Nodal signals in mesodermal populations. We found Smad2 and Smad3 transcripts both broadly expressed in derivatives of the epiblast. However, Smad2 and not Smad3 mRNA is expressed in the visceral endoderm, potentially explaining why the primary defect in Smad2 mutant embryos originates in this cell population.

Lasertechniques treatment of vascular malformations

Phlebologie ◽  
2010 ◽  
Vol 39 (03) ◽  
pp. 167-175
Author(s):  
M. Poetke ◽  
P. Urban ◽  
H.-P. Berlien
Keyword(s):  
Endothelial Cells ◽  
Spontaneous Regression ◽  
Vascular System ◽  
Vascular Malformations ◽  
Clinical Importance ◽  
Vascular Structure ◽  
Laser Application ◽  
Vascular Morphogenesis ◽  
Structural Abnormalities

SummaryVascular malformations are structural abnormalities, errors of vascular morphogenesis, which can be localized in all parts of the vascular system. All vascular malformations by definition, are present at birth and grow proportionately with the child; their volume can change. In contrast to the haemangiomas, which only proliferate from the endothelial cells the division in stages is of clinical importance. Vascular malformations are divided from the part of vascular system, which is affected.In principle the techniques of laser application in congenital vascular tumours like haemangiomas and in vascular malformations are similar, but the aim is different. In tumours the aim is to induce regression, in vascular malformations the aim is to destroy the pathologic vascular structure because there is no spontaneous regression. This means that the parameters for treatment of vascular malformations must be more aggressive than for vascular tumours.

Functional characterization of the H+/K+ ATPase in wild type and gastrin knock-out mice

2007 ◽  
Vol 45 (05) ◽  
Author(s):  
A Schnur ◽  
P Hegyi ◽  
V Venglovecz ◽  
Z Rakonczay ◽  
I Ignáth ◽  
...  
Keyword(s):  
Functional Characterization ◽  
Wild Type ◽  
Knock Out ◽  
Knock Out Mice

Instructions from the Vascular System - Directing Neural Stem Cell Fate in Health and Disease

2014 ◽  
Vol 21 (19) ◽  
pp. 2190-2207 ◽  
Author(s):  
S. Schildge ◽  
C. Bohrer ◽  
S. Pfurr ◽  
K. Mammadzada ◽  
K. Schachtrup ◽  
...  
Keyword(s):  
Stem Cell ◽  
Cell Fate ◽  
Neural Stem Cell ◽  
Vascular System ◽  
Stem Cell Fate ◽  
Health And Disease

Metabolic Regulation of Hippocampal Neuronal Development and Its Inhibition After Irradiation

2021 ◽  
Vol 80 (5) ◽  
pp. 467-475
Author(s):  
Yu-Qing Li ◽  
C Shun Wong
Keyword(s):  
Cell Fate ◽  
Metabolic Regulation ◽  
Energy Homeostasis ◽  
Neuronal Development ◽  
Adenosine Monophosphate ◽  
Hippocampal Neurogenesis ◽  
Adult Hippocampal Neurogenesis ◽  
Wild Type ◽  
Newborn Neuron ◽  
Negative Effect

Abstract 5′-Adenosine monophosphate-activated protein kinase (AMPK), a key regulator of cellular energy homeostasis, plays a role in cell fate determination. Whether AMPK regulates hippocampal neuronal development remains unclear. Hippocampal neurogenesis is abrogated after DNA damage. Here, we asked whether AMPK regulates adult hippocampal neurogenesis and its inhibition following irradiation. Adult Cre-lox mice deficient in AMPK in brain, and wild-type mice were used in a birth-dating study using bromodeoxyuridine to evaluate hippocampal neurogenesis. There was no evidence of AMPK or phospho-AMPK immunoreactivity in hippocampus. Increase in p-AMPK but not AMPK expression was observed in granule neurons and subgranular neuroprogenitor cells (NPCs) in the dentate gyrus within 24 hours and persisted up to 9 weeks after irradiation. AMPK deficiency in Cre-lox mice did not alter neuroblast and newborn neuron numbers but resulted in decreased newborn and proliferating NPCs. Inhibition of neurogenesis was observed after irradiation regardless of genotypes. In Cre-lox mice, there was further loss of newborn early NPCs and neuroblasts but not newborn neurons after irradiation compared with wild-type mice. These results are consistent with differential negative effect of AMPK on hippocampal neuronal development and its inhibition after irradiation.

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