Identification in Xenopus of a structural homologue of the Drosophila gene snail

We have cloned a Xenopus cDNA that is related to snail, a gene that is required for mesoderm formation in Drosophila. The cDNA encodes a protein that contains five zinc-fingers that closely resemble those of snail. In the non-canonical parts of the DNA-binding loop, there is almost 90% homology between snail and xsna. The corresponding mRNA (xsna) is expressed strongly at the start of zygotic transcription simultaneously with the transcription factor EF1 alpha. In early gastrulae, xsna is equally distributed between the dorsal and ventral halves of the equatorial zone. The possibility that the capacity to synthesise xsna is more localised before the start of zygotic transcription has been investigated by culturing fragments of stage 8 embryos until xsna is synthesised. The capacity to synthesise xsna at stage 8 is located principally in the dorsal half of the equatorial zone. A small amount of maternal xsna is localised in the vegetal hemisphere before zygotic transcription starts. xsna is not present in isolated animal caps but can be induced by the mesoderm-inducing factors XTC-MIF and bFGF. Synthesis of xsna does not occur autonomously in dispersed cells but is restored when cells reaggregate in the presence of calcium and magnesium.

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Mesoderm induction in Xenopus is a zygotic event regulated by maternal VegT via TGFbeta growth factors

Development ◽

10.1242/dev.126.24.5759 ◽

1999 ◽

Vol 126 (24) ◽

pp. 5759-5770 ◽

Cited By ~ 15

Author(s):

M. Kofron ◽

T. Demel ◽

J. Xanthos ◽

J. Lohr ◽

B. Sun ◽

...

Keyword(s):

Transcription Factor ◽

Growth Factors ◽

Body Axis ◽

Mesoderm Induction ◽

Equatorial Zone ◽

Wild Type ◽

Germ Layers ◽

Endogenous Factors ◽

Mesoderm Formation ◽

Mesodermal Tissue

The maternal transcription factor VegT is important for establishing the primary germ layers in Xenopus. In previous work, we showed that the vegetal masses of embryos lacking maternal VegT do not produce mesoderm-inducing signals and that mesoderm formation in these embryos occurred ectopically, from the vegetal area rather than the equatorial zone of the blastula. Here we have increased the efficiency of the depletion of maternal VegT mRNA and have studied the effects on mesoderm formation. We find that maternal VegT is required for the formation of 90% of mesodermal tissue, as measured by the expression of mesodermal markers MyoD, cardiac actin, Xbra, Xwnt8 and alphaT4 globin. Furthermore, the transcription of FGFs and TGFbetas, Xnr1, Xnr2, Xnr4 and derriere does not occur in VegT-depleted embryos. We test whether these growth factors may be endogenous factors in mesoderm induction, by studying their ability to rescue the phenotype of VegT-depleted embryos, when their expression is restricted to the vegetal mass. We find that Xnr1, Xnr2, Xnr4 and derriere mRNA all rescue mesoderm formation, as well as the formation of blastopores and the wild-type body axis. Derriere rescues trunk and tail while nr1, nr2 and nr4 rescue head, trunk and tail. We conclude that mesoderm induction in Xenopus depends on a maternal transcription factor regulating these zygotic growth factors.

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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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Quantitative comparison of mesoderm inducing factors in xenopus

Cell Differentiation and Development ◽

10.1016/0922-3371(89)90191-3 ◽

1989 ◽

Vol 27 ◽

pp. 53

Author(s):

J.B.A. Green ◽

G. Howes ◽

M. Yaqoob ◽

J. Cooke ◽

J.C. Smith

Keyword(s):

Quantitative Comparison ◽

Inducing Factors ◽

Mesoderm Inducing Factors

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13-P135 Xenopus Tbx2, T-box transcription factor, specify ventral ectoderm by the inhibition of neural ectoderm and mesoderm formation

Mechanisms of Development ◽

10.1016/j.mod.2009.06.608 ◽

2009 ◽

Vol 126 ◽

pp. S235

Author(s):

Gun-Sik Cho ◽

Jin-Kwan Han

Keyword(s):

Transcription Factor ◽

T Box ◽

Mesoderm Formation ◽

Neural Ectoderm

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Mutations in DNA-Binding Loop of NFAT5 Transcription Factor Produce Unique Outcomes on Protein–DNA Binding and Dynamics

The Journal of Physical Chemistry B ◽

10.1021/jp403310a ◽

2013 ◽

Vol 117 (42) ◽

pp. 13226-13234 ◽

Cited By ~ 13

Author(s):

Minghui Li ◽

Benjamin A. Shoemaker ◽

Ratna R. Thangudu ◽

Joan D. Ferraris ◽

Maurice B. Burg ◽

...

Keyword(s):

Transcription Factor ◽

Dna Binding ◽

Binding Loop

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Mesoderm-inducing factors and Spemann's organiser phenomenon in amphibian development

Development ◽

10.1242/dev.107.2.229 ◽

1989 ◽

Vol 107 (2) ◽

pp. 229-241 ◽

Cited By ~ 1

Author(s):

J. Cooke

Keyword(s):

Growth Factor ◽

Pattern Formation ◽

Marginal Zone ◽

Natural Control ◽

Graft Size ◽

Two Factors ◽

Inducing Factors ◽

Mesoderm Inducing Factors ◽

Host Embryo ◽

Factor Concentration

Certain proteins from ‘growth factor’ families can initiate mesodermal development in animal cap cells of the amphibian blastula. Cells that are in early stages of their response to one such factor, XTC-MIF (Smith et al. 1988), initiate the formation of a new axial body plan when grafted to the ventral marginal zone of a similarly aged host embryo (Cooke et al. 1987). This replicates the natural control of this phase of development by the dorsal blastoporal lip when similarly grafted; the classical ‘organiser’ phenomenon. I have explored systematically the effect, upon the outcome of this pattern formation using defined inducing factors, of varying graft size, XTC-MIF concentration to which graft cells were exposed, length of exposure before grafting, and host age. The ‘mesodermal organiser’ status, evoked by the factor, appears to be stable, and the variables most influencing the degree of completeness and orderliness of second patterns are graft size and factor concentration. Inappropriately large grafts are not effective. A Xenopus basic fibroblast growth factor homologue, present in the embryo and known to be a strong inducer but of mesoderm with a different character from that induced by XTC-MIF, produced no episode of pattern formation at all when tested in the procedure described in this paper. Organiser status of grafts that have been exposed to mixtures of the two factors is set entirely by the supplied XTC-MIF concentration. Lineage labelling of these grafts, and of classical dorsal lip grafts, reveals closely similar though not identical patterns of contribution to the new structure within the host. Implications of the results for the normal mechanism of body pattern formation are discussed.

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Transcriptional activity of the zinc finger protein NGFI-A is influenced by its interaction with a cellular factor

Molecular and Cellular Biology ◽

10.1128/mcb.13.11.6858-6865.1993 ◽

1993 ◽

Vol 13 (11) ◽

pp. 6858-6865

Author(s):

M W Russo ◽

C Matheny ◽

J Milbrandt

Keyword(s):

Transcription Factor ◽

Dna Binding ◽

Transcriptional Activity ◽

Zinc Fingers ◽

Fold Increase ◽

Binding Domain ◽

Dna Binding Domain ◽

Activation Domains ◽

Cellular Factor ◽

Inhibitory Domain

NGFI-A is an immediate-early gene that encodes a transcription factor whose DNA-binding domain is composed of three zinc fingers. To define the domains responsible for its transcriptional activity, a mutational analysis was conducted with an NGFI-A molecule in which the zinc fingers were replaced by the GAL4 DNA-binding domain. In a cotransfection assay, four activation domains were found within NGFI-A. Three of the activation domains are similar to those characterized previously: one contains a large number of acidic residues, another is enriched in proline and glutamine residues, and another has some sequence homology to a domain found in Krox-20. The fourth bears no resemblance to previously described activation domains. NGFI-A also contains an inhibitory domain whose removal resulted in a 15-fold increase in NGFI-A activity. This increase in activity occurred in all mammalian cell types tested but not in Drosophila S2 cells. Competition experiments in which increasing amounts of the inhibitory domain were cotransfected along with NGFI-A demonstrated a dose-dependent increase in NGFI-A activity. A point mutation within the inhibitory domain of the competitor (I293F) abolished this property. When the analogous mutation was introduced into native NGFI-A, a 17-fold increase in activity was observed. The inhibitory effect therefore appears to be the result of an interaction between this domain and a titratable cellular factor which is weakened by this mutation. Downmodulation of transcription factor activity through interaction with a cellular factor has been observed in several other systems, including the regulation of transcription factor E2F by retinoblastoma protein, and in studies of c-Jun.

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