Transcriptional Regulator BPTF/FAC1 Is Essential for Trophoblast Differentiation during Early Mouse Development

ABSTRACT The putative transcriptional regulator BPTF/FAC1 is expressed in embryonic and extraembryonic tissues of the early mouse conceptus. The extraembryonic trophoblast lineage in mammals is essential to form the fetal part of the placenta and hence for the growth and viability of the embryo in utero. Here, we describe a loss-of-function allele of the BPTF/FAC1 gene that causes embryonic lethality in the mouse. BPTF/FAC1-deficient embryos form apparently normal blastocysts that implant and develop epiblast, visceral endoderm, and extraembryonic ectoderm including trophoblast stem cells. Subsequent development of mutants, however, is arrested at the early gastrula stage (embryonic day 6.5), and virtually all null embryos die before midgestation. Most notably, the ectoplacental cone is drastically reduced or absent in mutants, which may cause the embryonic lethality. Development of the mutant epiblast is also affected, as the anterior visceral endoderm and the primitive streak do not form correctly, while brachyury-expressing mesodermal cells arise but are delayed. The mutant phenotype suggests that gastrulation is initiated, but no complete anteroposterior axis of the epiblast appears. We conclude that BPTF/FAC1 is essential in the extraembryonic lineage for correct development of the ectoplacental cone and fetomaternal interactions. In addition, BPTF/FAC1 may also play a role either directly or indirectly in anterior-posterior patterning of the epiblast.

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Ontogeny of hyaluronan secretion during early mouse development

Development ◽

10.1242/dev.117.2.483 ◽

1993 ◽

Vol 117 (2) ◽

pp. 483-492 ◽

Cited By ~ 1

Author(s):

J.J. Brown ◽

V.E. Papaioannou

Keyword(s):

Primitive Streak ◽

Synthetic Activity ◽

Visceral Endoderm ◽

Mouse Development ◽

Cell Lineages ◽

Early Mouse ◽

Serum Substitute ◽

Embryonic Ectoderm

The ontogeny of hyaluronan (HA) secretion during early mouse embryogenesis has been investigated using a biotin-labelled HA-binding complex from cartilage proteoglycan. HA is first secreted by visceral endoderm cells of the early egg cylinder on day 5.5 post coitum (p.c.), predominantly into the expanding yolk cavity. On day 6.5 p.c., HA is present in both the yolk and proamniotic cavities, but pericellular staining is restricted to the visceral endoderm and a population of embryonic ectoderm cells at the antimesometrial end of the proamniotic cavity. By the primitive streak stage, HA is secreted into the ectoplacental, exocoelomic, amniotic and yolk cavities, whilst the only cells exhibiting pericellular staining are those of the embryonic and extraembryonic mesoderm, including the allantois. Comparisons of HA-staining patterns of cultured whole blastocysts, microdissected trophectoderm fragments and immunosurgically isolated inner cell masses, revealed no trophoblast-associated HA secretion during outgrowth in vitro but significant synthetic activity by the endodermal derivatives of differentiating inner cell masses. To identify the cell lineages responsible for secretion of HA into the embryonic cavities and to investigate the origin of the HA observed around migrating mesoderm cells, day 7.5 p.c. primitive streak stage conceptuses were dissected into their various embryonic and extraembryonic cell lineages. HA secretion was observed after short-term suspension culture of mesoderm, embryonic ectoderm and embryonic endoderm, but was undetectable in fragments of ectoplacental cone, parietal yolk sac (primary giant trophoblast and parietal endoderm), extraembryonic ectoderm or extraembryonic endoderm. The level of synthesis by the HA-positive tissues was markedly enhanced by culture in medium containing serum, compared with that obtained following culture in medium supplemented with a defined serum substitute containing insulin, transferrin, selenous acid and linoleic acid. This suggests that additional growth factors, present in serum but absent from the serum substitute, are required for optimal HA synthesis by the HA-secreting tissues in vitro, and probably also in vivo. The implications of these events for implantation and the development of peri- and early post-implantation mouse embryos are discussed, and a new role for HA in the initial formation and expansion of the embryonic cavities is proposed.

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The Foxh1-dependent autoregulatory enhancer controls the level of Nodal signals in the mouse embryo

Development ◽

10.1242/dev.129.14.3455 ◽

2002 ◽

Vol 129 (14) ◽

pp. 3455-3468 ◽

Cited By ~ 14

Author(s):

Dominic P. Norris ◽

Jane Brennan ◽

Elizabeth K. Bikoff ◽

Elizabeth J. Robertson

Keyword(s):

Mouse Embryo ◽

Late Onset ◽

Axis Formation ◽

Visceral Endoderm ◽

Mouse Development ◽

Developmental Abnormalities ◽

Intronic Enhancer ◽

Vertebrate Embryo ◽

Early Mouse ◽

Pitx2 Expression

The TGFβ-related growth factor Nodal governs anteroposterior (AP) and left-right (LR) axis formation in the vertebrate embryo. A conserved intronic enhancer (ASE), containing binding sites for the fork head transcription factor Foxh1, modulates dynamic patterns of Nodal expression during early mouse development. This enhancer is responsible for early activation of Nodal expression in the epiblast and visceral endoderm, and at later stages governs asymmetric expression during LR axis formation. We demonstrate ASE activity is strictly Foxh1 dependent. Loss of this autoregulatory enhancer eliminates transcription in the visceral endoderm and decreases Nodal expression in the epiblast, but causes surprisingly discrete developmental abnormalities. Thus lowering the level of Nodal signaling in the epiblast disrupts both orientation of the AP axis and specification of the definitive endoderm. Targeted removal of the ASE also dramatically reduces left-sided Nodal expression, but the early events controlling LR axis specification are correctly initiated. However loss of the ASE disrupts Lefty2 (Leftb) expression and causes delayed Pitx2 expression leading to late onset, relatively minor LR patterning defects. The feedback loop is thus essential for maintenance of Nodal signals that selectively regulate target gene expression in a temporally and spatially controlled fashion in the mouse embryo.

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Functional evaluation of transposable elements as enhancers in mouse embryonic and trophoblast stem cells

eLife ◽

10.7554/elife.44344 ◽

2019 ◽

Vol 8 ◽

Cited By ~ 24

Author(s):

Christopher D Todd ◽

Özgen Deniz ◽

Darren Taylor ◽

Miguel R Branco

Keyword(s):

Stem Cells ◽

Gene Regulation ◽

Transposable Elements ◽

Specific Gene ◽

Functional Evaluation ◽

Mouse Development ◽

Trophoblast Stem Cells ◽

Trophoblast Stem ◽

Gene Regulatory ◽

Early Mouse

Transposable elements (TEs) are thought to have helped establish gene regulatory networks. Both the embryonic and extraembryonic lineages of the early mouse embryo have seemingly co-opted TEs as enhancers, but there is little evidence that they play significant roles in gene regulation. Here we tested a set of long terminal repeat TE families for roles as enhancers in mouse embryonic and trophoblast stem cells. Epigenomic and transcriptomic data suggested that a large number of TEs helped to establish tissue-specific gene expression programmes. Genetic editing of individual TEs confirmed a subset of these regulatory relationships. However, a wider survey via CRISPR interference of RLTR13D6 elements in embryonic stem cells revealed that only a minority play significant roles in gene regulation. Our results suggest that a subset of TEs are important for gene regulation in early mouse development, and highlight the importance of functional experiments when evaluating gene regulatory roles of TEs.

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A primary requirement for nodal in the formation and maintenance of the primitive streak in the mouse

Development ◽

10.1242/dev.120.7.1919 ◽

1994 ◽

Vol 120 (7) ◽

pp. 1919-1928 ◽

Cited By ~ 88

Author(s):

F.L. Conlon ◽

K.M. Lyons ◽

N. Takaesu ◽

K.S. Barth ◽

A. Kispert ◽

...

Keyword(s):

Direct Evidence ◽

Primitive Streak ◽

Morphological Evidence ◽

Axis Formation ◽

Tgf Beta ◽

Loss Of Function ◽

Primitive Endoderm ◽

Mouse Development ◽

Mature Node ◽

Embryonic Ectoderm

The 413.d insertional mutation arrests mouse development shortly after gastrulation. nodal, a novel TGF beta-related gene, is closely associated with the locus. The present study provides direct evidence that the proviral insertion causes a loss of function mutation. nodal RNA is initially detected at day 5.5 in the primitive ectoderm. Concomitant with gastrulation, expression becomes restricted to the proximal posterior regions of the embryonic ectoderm. nodal RNA is also expressed in the primitive endoderm overlying the primitive streak. A few hours later, expression is strictly confined to the periphery of the mature node. Interestingly 413.d mutant embryos show no morphological evidence for the formation of a primitive streak. Nonetheless, about 25% of mutant embryos do form randomly positioned patches of cells of a posterior mesodermal character. Data presented in this report demonstrate the involvement of a TGF beta-related molecule in axis formation in mammals.

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HNF3beta and Lim1 interact in the visceral endoderm to regulate primitive streak formation and anterior-posterior polarity in the mouse embryo

Development ◽

10.1242/dev.126.20.4499 ◽

1999 ◽

Vol 126 (20) ◽

pp. 4499-4511 ◽

Cited By ~ 9

Author(s):

A. Perea-Gomez ◽

W. Shawlot ◽

H. Sasaki ◽

R.R. Behringer ◽

S. Ang

Keyword(s):

Mouse Embryo ◽

Primitive Streak ◽

Axis Formation ◽

Visceral Endoderm ◽

Primary Defect ◽

Homozygous Mutant ◽

Early Mouse ◽

Mesoderm Patterning ◽

Anterior Posterior ◽

Anterior Visceral Endoderm

Recent embryological and genetic experiments have suggested that the anterior visceral endoderm and the anterior primitive streak of the early mouse gastrula function as head- and trunk-organising centers, respectively. Here, we report that HNF3beta and Lim1 are coexpressed in both organising centers suggesting synergistic roles of these genes in regulating organiser functions and hence axis development in the mouse embryo. To investigate this possibility, we generated compound HNF3beta and Lim1 mutant embryos. An enlarged primitive streak and a lack of axis formation were observed in HNF3beta (−)(/)(−);Lim1(−)(/)(−), but not in single homozygous mutant embryos. Chimera experiments indicate that the primary defect in these double homozygous mutants is due to loss of activity of HNF3beta and Lim1 in the visceral endoderm. Altogether, these data provide evidence that these genes function synergistically to regulate organiser activity of the anterior visceral endoderm. Moreover, HNF3beta (−)(/)(−);Lim1(−)(/)(−) mutant embryos also exhibit defects in mesoderm patterning that are likely due to lack of specification of anterior primitive streak cells.

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An extra maternally derived X chromosome is deleterious to early mouse development

Development ◽

10.1242/dev.110.3.969 ◽

1990 ◽

Vol 110 (3) ◽

pp. 969-975 ◽

Cited By ~ 2

Author(s):

C. Shao ◽

N. Takagi

Keyword(s):

X Chromosome ◽

Early Death ◽

X Inactivation ◽

Mouse Development ◽

Extra Copy ◽

X Chromosomes ◽

Extraembryonic Membranes ◽

Early Mouse ◽

Ectoplacental Cone ◽

Embryonic Death

An extra copy of the X chromosome, unlike autosomes, exerts only minor effects on development in mammals including man and mice, because all X chromosomes except one are genetically inactivated. Contrary to this contention, we found that an additional maternally derived X (XM) chromosome, but probably not a paternally derived one (XP), consistently contributes to early death of 41,XXY and 41,XXX embryos in mice. Because of imprinted resistance to inactivation, two doses of XM remain active in the trophectoderm, and seem to be responsible for the failure in the development of the ectoplacental cone and extraembryonic ectoderm, and hence, from early embryonic death. Discordant observations in man indicating viability of XMXMXP and XMXMY individuals suggest that imprinting on the human X chromosome is either weak, unstable or erased before the initiation of X-inactivation in progenitors of extraembryonic membranes.

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Expression of inhibin subunits and follistatin during postimplantation mouse development: decidual expression of activin and expression of follistatin in primitive streak, somites and hindbrain

Development ◽

10.1242/dev.120.4.803 ◽

1994 ◽

Vol 120 (4) ◽

pp. 803-813 ◽

Cited By ~ 14

Author(s):

R.M. Albano ◽

R. Arkell ◽

R.S. Beddington ◽

J.C. Smith

Keyword(s):

Primitive Streak ◽

Beta Subunits ◽

Single Chain ◽

Mouse Development ◽

Mammalian Embryo ◽

Mesoderm Formation ◽

B Subunits ◽

Inducing Factors ◽

Early Mouse ◽

Mesoderm Inducing Factors

Members of the activin family are believed to act as mesoderm-inducing factors during early amphibian development. Little is known, however, about mesoderm formation in the mammalian embryo, and as one approach to investigating this we have studied activin and follistatin expression during early mouse development. Activins are homo- or heterodimers of the beta A or beta B subunits of inhibin, itself a heterodimer consisting of one of the beta subunits together with an alpha subunit. Follistatin is a single-chain polypeptide which inhibits activin function. Expression of the inhibin alpha chain could not be detected in embryonic or extraembryonic tissues at any of the stages studied (5.5 to 8.5 days) and expression of the beta A and beta B subunits could only be observed in the deciduum in cells surrounding the embryo. Expression of follistatin could also be detected in the deciduum, but in a pattern complementary to that of the beta subunits. Embryonic expression of follistatin first occurred in the primitive streak, and at later stages transcripts were detectable in the somites and in rhombomeres 2, 4 and 6 of the hindbrain. These results are consistent with a role for activin in mesoderm formation in the mouse embryo, and suggest functions for follistatin in addition to its role as an inhibitor of activin.

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Brachyury cooperates with Wnt/β-Catenin signalling to elicit Primitive Streak like behaviour in differentiating mouse ES cells.

10.1101/003871 ◽

2014 ◽

Cited By ~ 1

Author(s):

David Andrew Turner ◽

Pau Rué ◽

Jonathan P Mackenzie ◽

Eleanor Davies ◽

Alfonso Martinez Arias

Keyword(s):

Epithelial To Mesenchymal Transition ◽

Es Cells ◽

Single Cells ◽

Embryonic Stem ◽

Primitive Streak ◽

Mouse Development ◽

Mesenchymal Transition ◽

Mouse Es Cells ◽

Cellular Events ◽

Early Mouse

The formation of the Primitive Streak is the first visible sign of gastrulation, the process by which the three germ layers are formed from a single epithelium during early development. Embryonic Stem Cells (ESCs) provide a good system to understand the molecular and cellular events associated with these processes. Previous work, both in embryos and in culture, has shown how converging signals from both Nodal/TGFβR and Wnt/β-Catenin signalling pathways specify cells to adopt a Primitive Streak like fate and direct them to undertake an epithelial to mesenchymal transition (EMT). However, many of these approaches have relied on genetic analyses without taking into account the temporal progression of events within single cells. In addition, it is still unclear as to what extent events in the embryo are able to be reproduced in culture. Here, we combine flow-cytometry and a quantitative live single-cell imaging approach to demonstrate how the controlled differentiation of mouse ESCs (mESCs) towards a Primitive Streak fate in culture results in cells displaying many of the characteristics observed during early mouse development including transient Brachyury expression, EMT and increased motility. We also find that the EMT initiates the process, and this is both fuelled and terminated by the action of Bra, whose expression is dependent on the EMT and β-Catenin activity. As a consequence of our analysis, we propose that a major output of Brachyury expression is in controlling the velocity of the cells that are transiting out of the Primitive Streak.

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