scholarly journals The homeobox gene Hex is required in definitive endodermal tissues for normal forebrain, liver and thyroid formation

Development ◽  
2000 ◽  
Vol 127 (11) ◽  
pp. 2433-2445 ◽  
Author(s):  
J.P. Martinez Barbera ◽  
M. Clements ◽  
P. Thomas ◽  
T. Rodriguez ◽  
D. Meloy ◽  
...  
Keyword(s):  
Normal Development ◽  
Embryonic Stem ◽  
Homeobox Gene ◽  
Definitive Endoderm ◽  
Visceral Endoderm ◽  
Wild Type ◽  
Zona Limitans Intrathalamica ◽  
Ventral Thalamus ◽  
Septum Transversum ◽  
Early Mouse

The homeobox gene Hex is expressed in the anterior visceral endoderm (AVE) and rostral definitive endoderm of early mouse embryos. Later, Hex transcripts are detected in liver, thyroid and endothelial precursor cells. A null mutation was introduced into the Hex locus by homologous recombination in embryonic stem cells. Hex mutant embryos exhibit varying degrees of anterior truncation as well as liver and thyroid dysplasia. The liver diverticulum is formed but migration of hepatocytes into the septum transversum fails to occur. Development of the thyroid is arrested at the thyroid bud stage at 9.5 dpc. Brain defects are restricted to the rostral forebrain and have a caudal limit at the zona limitans intrathalamica, the boundary between dorsal and ventral thalamus. Analysis of Hex(−/−) mutants at early stages shows that the prospective forebrain ectoderm is correctly induced and patterned at 7.5 days post coitum (dpc), but subsequently fails to develop. AVE markers are expressed and correctly positioned but development of rostral definitive endoderm is greatly disturbed in Hex(−/−) embryos. Chimeric embryos composed of Hex(−/−) cells developing within a wild-type visceral endoderm show forebrain defects indicating that Hex is required in the definitive endoderm. All together, these results demonstrate that Hex function is essential in definitive endoderm for normal development of the forebrain, liver and thyroid gland.

Tissue-specific requirements for the proprotein convertase furin/SPC1 during embryonic turning and heart looping

Development ◽  
2000 ◽  
Vol 127 (2) ◽  
pp. 245-254 ◽  
Author(s):  
D.B. Constam ◽  
E.J. Robertson
Keyword(s):  
Serine Proteases ◽  
Es Cells ◽  
Embryonic Stem ◽  
Axial Rotation ◽  
Yolk Sac ◽  
Definitive Endoderm ◽  
Visceral Endoderm ◽  
Wild Type ◽  
Extraembryonic Mesoderm ◽  
Tissue Abnormalities

Furin, the mammalian prototype of a family of serine proteases, is required for ventral closure and axial rotation, and formation of the yolk sac vasculature. Here we show additionally that left-sided expression of pitx2 and lefty-2 are also perturbed in Furin-deficient embryos. These tissue abnormalities are preceded by a marked delay in the expansion of the definitive endoderm during gastrulation. Using a chimera approach, we show that Furin activity is required in epiblast derivatives, including the primitive heart, gut and extraembryonic mesoderm, whereas it is nonessential in the visceral endoderm. Thus, chimeric embryos, derived by injecting wild-type embryonic stem (ES) cells into fur(−/−) blastocysts, develop normally until at least 9.5 d.p.c. In contrast, Furin-deficient chimeras developing in the context of wild-type visceral endoderm fail to undergo ventral closure, axial rotation and yolk sac vascularization. Fur(−/−) cells are recruited into all tissues examined, including the yolk sac vasculature and the midgut, even though these structures fail to form in fur mutants. The presence of wild-type cells in the gut strikingly correlates with the ability of chimeric embryos to undergo turning. Overall, we conclude that Furin activity is essential in both extraembryonic and precardiac mesoderm, and in definitive endoderm derivatives.

Lim1 is required in both primitive streak-derived tissues and visceral endoderm for head formation in the mouse

Development ◽  
1999 ◽  
Vol 126 (22) ◽  
pp. 4925-4932 ◽  
Author(s):  
W. Shawlot ◽  
M. Wakamiya ◽  
K.M. Kwan ◽  
A. Kania ◽  
T.M. Jessell ◽  
...  
Keyword(s):  
Marker Gene ◽  
Embryonic Stem ◽  
Homeobox Gene ◽  
Primitive Streak ◽  
Mouse Embryos ◽  
Chimeric Mouse ◽  
Visceral Endoderm ◽  
Wild Type ◽  
Targeted Mutation ◽  
Head Formation

Lim1 is a homeobox gene expressed in the extraembryonic anterior visceral endoderm and in primitive streak-derived tissues of early mouse embryos. Mice homozygous for a targeted mutation of Lim1 lack head structures anterior to rhombomere 3 in the hindbrain. To determine in which tissues Lim1 is required for head formation and its mode of action, we have generated chimeric mouse embryos and performed tissue layer recombination explant assays. In chimeric embryos in which the visceral endoderm was composed of predominantly wild-type cells, we found that Lim1(−)(/)(−) cells were able to contribute to the anterior mesendoderm of embryonic day 7.5 chimeric embryos but that embryonic day 9.5 chimeric embryos displayed a range of head defects. In addition, early somite stage chimeras generated by injecting Lim1(−)(/)(−) embryonic stem cells into wild-type tetraploid blastocysts lacked forebrain and midbrain neural tissue. Furthermore, in explant recombination assays, anterior mesendoderm from Lim1(−)(/)(−) embryos was unable to maintain the expression of the anterior neural marker gene Otx2 in wild-type ectoderm. In complementary experiments, embryonic day 9.5 chimeric embryos in which the visceral endoderm was composed of predominantly Lim1(−)(/)(−) cells and the embryo proper of largely wild-type cells, also phenocopied the Lim1(−)(/)(−) headless phenotype. These results indicate that Lim1 is required in both primitive streak-derived tissues and visceral endoderm for head formation and that its inactivation in these tissues produces cell non-autonomous defects. We discuss a double assurance model in which Lim1 regulates sequential signaling events required for head formation in the mouse.

Cell autonomous and non-cell autonomous functions of Otx2 in patterning the rostral brain

Development ◽  
1999 ◽  
Vol 126 (19) ◽  
pp. 4295-4304 ◽  
Author(s):  
M. Rhinn ◽  
A. Dierich ◽  
M. Le Meur ◽  
S. Ang
Keyword(s):  
Cell Adhesion ◽  
Target Genes ◽  
Homeobox Gene ◽  
Visceral Endoderm ◽  
Wild Type ◽  
Candidate Target ◽  
Important Regulator ◽  
Mutant Cells ◽  
The Brain ◽  
Brain Patterning

Previous studies have shown that the homeobox gene Otx2 is required first in the visceral endoderm for induction of forebrain and midbrain, and subsequently in the neurectoderm for its regional specification. Here, we demonstrate that Otx2 functions both cell autonomously and non-cell autonomously in neurectoderm cells of the forebrain and midbrain to regulate expression of region-specific homeobox and cell adhesion genes. Using chimeras containing both Otx2 mutant and wild-type cells in the brain, we observe a reduction or loss of expression of Rpx/Hesx1, Wnt1, R-cadherin and ephrin-A2 in mutant cells, whereas expression of En2 and Six3 is rescued by surrounding wild-type cells. Forebrain Otx2 mutant cells subsequently undergo apoptosis. Altogether, this study demonstrates that Otx2 is an important regulator of brain patterning and morphogenesis, through its regulation of candidate target genes such as Rpx/Hesx1, Wnt1, R-cadherin and ephrin-A2.

Hex: a homeobox gene revealing peri-implantation asymmetry in the mouse embryo and an early transient marker of endothelial cell precursors

Development ◽  
1998 ◽  
Vol 125 (1) ◽  
pp. 85-94 ◽  
Author(s):  
P.Q. Thomas ◽  
A. Brown ◽  
R.S. Beddington
Keyword(s):  
Endothelial Cell ◽  
Mouse Embryo ◽  
Expression Patterns ◽  
Homeobox Gene ◽  
Definitive Endoderm ◽  
Visceral Endoderm ◽  
Primitive Endoderm ◽  
Mouse Development ◽  
Expression Domain ◽  
Early Marker

The divergent homeobox gene Hex exhibits three notable expression patterns during early mouse development. Initially Hex is expressed in the primitive endoderm of the implanting blastocyst but by 5.5 dpc its transcripts are present only in a small patch of visceral endoderm at the distal tip of the egg cylinder. Lineage analysis shows that these cells move unilaterally to assume an anterior position while continuing to express Hex. The primitive streak forms on the opposite side of the egg cylinder from this anterior Hex expression domain approximately 24 hours after the initial anterior movement of the distal visceral endoderm. Thus, Hex expression marks the earliest unequivocal molecular anteroposterior asymmetry in the mouse embryo and indicates that the anteroposterior axis of the embryo develops from conversion of a proximodistal asymmetry established in the primitive endoderm lineage. Subsequently, Hex is expressed in the earliest definitive endoderm to emerge from the streak and its expression within the gut strongly suggests that the ventral foregut is derived from the most anterior definitive endoderm and that the liver is probably the most anterior gut derivative. Hex is also an early marker of the thyroid primordium. Within the mesoderm, Hex is transiently expressed in the nascent blood islands of the visceral yolk sac and later in embryonic angioblasts and endocardium. Comparison with flk-1 (T. P. Yamaguchi et al., Development 118, 489–498, 1993) expression indicates that Hex is also an early marker of endothelial precursors but its expression in this progenitor population is much more transient than that of flk-1, being downregulated once endothelial cell differentiation commences.

scholarly journals The homeobox gene HEX regulates proliferation and differentiation of hemangioblasts and endothelial cells during ES cell differentiation

Blood ◽  
2005 ◽  
Vol 105 (12) ◽  
pp. 4590-4597 ◽  
Author(s):  
Atsushi Kubo ◽  
Vincent Chen ◽  
Marion Kennedy ◽  
Elizabeth Zahradka ◽  
George Q. Daley ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Cell Differentiation ◽  
Fetal Liver ◽  
Embryonic Stem ◽  
Homeobox Gene ◽  
Embryoid Bodies ◽  
Negative Regulator ◽  
Proliferative Potential ◽  
Es Cell ◽  
Wild Type

Abstract In this report we have investigated the role of the homeobox gene Hex in the development and differentiation of the blast colony-forming cell (BL-CFC), a progenitor with hemangioblast characteristics generated in embryonic stem (ES) cell-derived embryoid bodies (EBs). Molecular analysis showed that Hex is expressed in mesoderm, in populations that contain BL-CFCs, and in blast cell colonies, the progeny of the BL-CFCs. Hex-/- EBs displayed a defect in macrophage development but generated higher numbers of BL-CFCs than did wild-type EBs. In addition to differences in these progenitor populations, we also found that endothelial cells from the Hex-/- EBs showed enhanced proliferative potential compared with those from wild-type EBs. Forced expression of Hex at the onset of ES cell differentiation resulted in reduced EB cellularity, fetal liver kinase-1 (Flk-1) expression, and BL-CFC development. Taken together, these findings demonstrate that Hex functions at multiple stages of development within the differentiating EBs and uncover a novel role for this transcription factor as a negative regulator of the hemangioblast and the endothelial lineage. (Blood. 2005;105: 4590-4597)

Deficiency in GATA-4 or GATA-6 Diminishes Definitive Hematopoiesis in Murine Embryonic Stem Cell Derived Embryoid Bodies.

Blood ◽  
2007 ◽  
Vol 110 (11) ◽  
pp. 2230-2230
Author(s):  
Monique S. Pierre ◽  
Mervin Yoder
Keyword(s):  
Es Cells ◽  
Embryonic Stem ◽  
Embryoid Bodies ◽  
Vegf Receptor ◽  
Visceral Endoderm ◽  
Wild Type ◽  
Hematopoietic Progenitor ◽  
Erythroid Progenitor ◽  
Blood Island

Abstract Formation of mesoderm derived blood islands in the mouse embryonic yolk sac requires the presence of visceral endoderm (VE) and VE derived factors. Murine embryonic stem (ES) cells can be differentiated into embryoid bodies (EBs) which serve as an in vitro model recapitulating many embryonic developmental processes, including formation of early hematopoietic cells. Previous investigators have reported that differentiation of ES cells deficient in either GATA-4 or GATA-6 results in EBs with disrupted differentiation of visceral endoderm and defective blood island formation. In the current study, we have compared GATA-4 and GATA-6 null ES cell derived EBs to wild-type EBs in their ability to commit to early hematopoietic lineages using hematopoietic progenitor colony assays, and used RT-PCR to assess the expression of endoderm genes. As expected, we observed differences in expression of endoderm genes in wild-type and GATA-4 or GATA-6 null EBs. Blast colony forming cell assays and primitive erythroid progenitor assays revealed no difference in the ability of wild-type and GATA-4 or GATA-6 null EBs to form hemangioblast or primitive erythroid progenitor colonies. In contrast, comparisons of definitive hematopoietic progenitor colonies from day 8, 9 and 10 GATA-4 and GATA-6 null EBs revealed a significant reduction in colony numbers at day 8 (p-values < 0.05) compared to wild-type. Strikingly, definitive progenitor colony numbers are rescued nearly to wild-type levels after the addition of the visceral endoderm derived factor vascular endothelial growth factor (VEGF) during EB differentiation. Furthermore, this rescue response can be blocked by the addition of soluble Flk-1 (VEGF receptor) to EB cultures. These results suggest that GATA-4 and GATA-6 transcription factors and/or visceral endoderm are not necessary for hemangioblast, primitive erythroid, or definitive progenitor emergence from EBs but play a role in definitive progenitor expansion in EBs.

scholarly journals The chromosomal protein SMCHD1 regulates DNA methylation and the 2c-like state of embryonic stem cells by antagonizing TET proteins

2021 ◽  
Vol 7 (4) ◽  
pp. eabb9149
Author(s):  
Zhijun Huang ◽  
Jiyoung Yu ◽  
Wei Cui ◽  
Benjamin K. Johnson ◽  
Kyunggon Kim ◽  
...  
Keyword(s):  
Es Cells ◽  
Embryonic Stem ◽  
Homeobox Gene ◽  
Dna Demethylation ◽  
Chromosomal Protein ◽  
Dna Hypomethylation ◽  
Tet Proteins ◽  
Target Sites ◽  
Structural Maintenance Of Chromosomes ◽  
Hinge Domain

5-Methylcytosine (5mC) oxidases, the ten-eleven translocation (TET) proteins, initiate DNA demethylation, but it is unclear how 5mC oxidation is regulated. We show that the protein SMCHD1 (structural maintenance of chromosomes flexible hinge domain containing 1) is found in complexes with TET proteins and negatively regulates TET activities. Removal of SMCHD1 from mouse embryonic stem (ES) cells induces DNA hypomethylation, preferentially at SMCHD1 target sites and accumulation of 5-hydroxymethylcytosine (5hmC), along with promoter demethylation and activation of the Dux double-homeobox gene. In the absence of SMCHD1, ES cells acquire a two-cell (2c) embryo–like state characterized by activation of an early embryonic transcriptome that is substantially imposed by Dux. Using Smchd1/Tet1/Tet2/Tet3 quadruple-knockout cells, we show that DNA demethylation, activation of Dux, and other genes upon SMCHD1 loss depend on TET proteins. These data identify SMCHD1 as an antagonist of the 2c-like state of ES cells and of TET-mediated DNA demethylation.

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