Goosecoid promotes head organizer activity by direct repression of Xwnt8 in Spemann’s organizer

Development ◽  
2001 ◽  
Vol 128 (15) ◽  
pp. 2975-2987 ◽  
Author(s):  
Jie Yao ◽  
Daniel S. Kessler
Keyword(s):  
Marginal Zone ◽  
The Body ◽  
Treated Animal ◽  
Homeodomain Protein ◽  
Regulatory Domains ◽  
Spemann's Organizer ◽  
Transcriptional Regulatory ◽  
Head Formation ◽  
Wnt Inhibitor ◽  
Organizer Activity

Formation of the vertebrate body plan is controlled by discrete head and trunk organizers that establish the anteroposterior pattern of the body axis. The Goosecoid (Gsc) homeodomain protein is expressed in all vertebrate organizers and has been implicated in the activity of Spemann’s organizer in Xenopus. The role of Gsc in organizer function was examined by fusing defined transcriptional regulatory domains to the Gsc homeodomain. Like native Gsc, ventral injection of an Engrailed repressor fusion (Eng-Gsc) induced a partial axis, while a VP16 activator fusion (VP16-Gsc) did not, indicating that Gsc functions as a transcriptional repressor in axis induction. Dorsal injection of VP16-Gsc resulted in loss of head structures anterior to the hindbrain, while axial structures were unaffected, suggesting a requirement for Gsc function in head formation. The anterior truncation caused by VP16-Gsc was fully rescued by Frzb, a secreted Wnt inhibitor, indicating that activation of ectopic Wnt signaling was responsible, at least in part, for the anterior defects. Supporting this idea, Xwnt8 expression was activated by VP16-Gsc in animal explants and the dorsal marginal zone, and repressed by Gsc in Activin-treated animal explants and the ventral marginal zone. Furthermore, expression of Gsc throughout the marginal zone inhibited trunk formation, identical to the effects of Frzb and other Xwnt8 inhibitors. A region of the Xwnt8 promoter containing four consensus homeodomain-binding sites was identified and this region mediated repression by Gsc and activation by VP16-Gsc, consistent with direct transcriptional regulation of Xwnt8 by Gsc. Therefore, Gsc promotes head organizer activity by direct repression of Xwnt8 in Spemann’s organizer and this activity is essential for anterior development.

Axis-inducing activities and cell fates of the zebrafish organizer

Development ◽  
2000 ◽  
Vol 127 (16) ◽  
pp. 3407-3417 ◽  
Author(s):  
L. Saude ◽  
K. Woolley ◽  
P. Martin ◽  
W. Driever ◽  
D.L. Stemple
Keyword(s):  
Organizer Region ◽  
Complete Removal ◽  
Floor Plate ◽  
Significant Loss ◽  
Cell Fates ◽  
Deep Tissue ◽  
Head Formation ◽  
Prechordal Plate ◽  
Embryonic Shield ◽  
Organizer Activity

We have investigated axis-inducing activities and cellular fates of the zebrafish organizer using a new method of transplantation that allows the transfer of both deep and superficial organizer tissues. Previous studies have demonstrated that the zebrafish embryonic shield possesses classically defined dorsal organizer activity. When we remove the morphologically defined embryonic shield, embryos recover and are completely normal by 24 hours post-fertilization. We find that removal of the morphological shield does not remove all goosecoid- and floating head-expressing cells, suggesting that the morphological shield does not comprise the entire organizer region. Complete removal of the embryonic shield and adjacent marginal tissue, however, leads to a loss of both prechordal plate and notochord. In addition, these embryos are cyclopean, show a significant loss of floor plate and primary motorneurons and display disrupted somite patterning. Motivated by apparent discrepancies in the literature we sought to test the axis-inducing activity of the embryonic shield. A previous study suggested that the shield is capable of only partial axis induction, specifically being unable to induce the most anterior neural tissues. Contrary to this study, we find shields can induce complete secondary axes when transplanted into host ventral germ-ring. In induced secondary axes donor tissue contributes to notochord, prechordal plate and floor plate. When explanted shields are divided into deep and superficial fragments and separately transplanted we find that deep tissue is able to induce the formation of ectopic axes with heads but lacking posterior tissues. We conclude that the deep tissue included in our transplants is important for proper head formation.

XIPOU 2 is a potential regulator of Spemann's Organizer

Development ◽  
1997 ◽  
Vol 124 (6) ◽  
pp. 1179-1189 ◽  
Author(s):  
S.E. Witta ◽  
S.M. Sato
Keyword(s):  
Gene Expression ◽  
Wnt Pathway ◽  
Marginal Zone ◽  
Branchial Arch ◽  
Class Iii ◽  
Domain Family ◽  
Potent Inducer ◽  
Pou Domain ◽  
Spemann's Organizer ◽  
Dorsal Mesoderm

XIPOU 2, a member of the class III POU-domain family, is expressed initially at mid-blastula transition (MBT) and during gastrulation in the entire marginal zone mesoderm, including Spemann's Organizer (the Organizer). To identify potential targets of XIPOU 2, the interaction of XIPOU 2 with other genes co-expressed in the Organizer was examined by microinjecting XIPOU 2's mRNA into the lineage of cells that contributes to the Organizer, head mesenchyme and prechordal plate. XIPOU 2 suppresses the expression of a number of dorsal mesoderm-specific genes, including gsc, Xlim-1, Xotx2, noggin and chordin, but not Xnot. As a consequence of the suppression of dorsal mesoderm gene expression, bone morphogenetic factor-4 (Bmp-4), a potent inducer of ventral mesoderm, is activated in the Organizer. Gsc is a potential target of XIPOU 2. XIPOU 2 is capable of binding a class III POU protein binding site (CATTAAT) that is located within the gsc promoter, in the activin-inducible (distal) element. Furthermore, XIPOU 2 suppresses the activation of the gsc promoter by activin signaling. At the neurula and tailbud stages, dorsoanterior structures are affected: embryos displayed micropthalmia and the loss of the first branchial arch, as detected by the expression of pax-6, Xotx2 and en-2. By examining events downstream from the Wnt and chordin pathways, we determined that XIPOU 2, when overexpressed, acts specifically in the Organizer, downstream from GSK-3beta of the Wnt pathway and upstream from chordin. The interference in dorsalizing events caused by XIPOU 2 was rescued by chordin. Thus, in addition to its direct neuralizing ability, in a different context, XIPOU 2 has the potential to antagonize dorsalizing events in the Organizer.

The origins of primitive blood in Xenopus: implications for axial patterning

Development ◽  
1999 ◽  
Vol 126 (3) ◽  
pp. 423-434 ◽  
Author(s):  
M.C. Lane ◽  
W.C. Smith
Keyword(s):  
Xenopus Laevis ◽  
Marginal Zone ◽  
Cell Stage ◽  
Axial Patterning ◽  
Xenopus Embryos ◽  
Spemann's Organizer ◽  
Dorsal Mesoderm

The marginal zone in Xenopus laevis is proposed to be patterned with dorsal mesoderm situated near the upper blastoporal lip and ventral mesoderm near the lower blastoporal lip. We determined the origins of the ventralmost mesoderm, primitive blood, and show it arises from all vegetal blastomeres at the 32-cell stage, including blastomere C1, a progenitor of Spemann's organizer. This demonstrates that cells located at the upper blastoporal lip become ventral mesoderm, not solely dorsal mesoderm as previously believed. Reassessment of extant fate maps shows dorsal mesoderm and dorsal endoderm descend from the animal region of the marginal zone, whereas ventral mesoderm descends from the vegetal region of the marginal zone, and ventral endoderm descends from cells located vegetal of the bottle cells. Thus, the orientation of the dorsal-ventral axis of the mesoderm and endoderm is rotated 90(degrees) from its current portrayal in fate maps. This reassessment leads us to propose revisions in the nomenclature of the marginal zone and the orientation of the axes in pre-gastrula Xenopus embryos.

A role for the vegetally expressed Xenopus gene Mix.1 in endoderm formation and in the restriction of mesoderm to the marginal zone

Development ◽  
1998 ◽  
Vol 125 (13) ◽  
pp. 2371-2380 ◽  
Author(s):  
P. Lemaire ◽  
S. Darras ◽  
D. Caillol ◽  
L. Kodjabachian
Keyword(s):  
Marginal Zone ◽  
Ectopic Expression ◽  
Homeobox Gene ◽  
Early Response ◽  
Endoderm Differentiation ◽  
Head Formation ◽  
Mutual Repression ◽  
Regulatory Loop ◽  
Strong Activator

We have studied the role of the activin immediate-early response gene Mix.1 in mesoderm and endoderm formation. In early gastrulae, Mix.1 is expressed throughout the vegetal hemisphere, including marginal-zone cells expressing the trunk mesodermal marker Xbra. During gastrulation, the expression domains of Xbra and Mix.1 become progressively exclusive as a result of the establishment of a negative regulatory loop between these two genes. This mutual repression is important for the specification of the embryonic body plan as ectopic expression of Mix.1 in the Xbra domain suppresses mesoderm differentiation. The same effect was obtained by overexpressing VP16Mix.1, a fusion protein comprising the strong activator domain of viral VP16 and the homeodomain of Mix.1, suggesting that Mix.1 acts as a transcriptional activator. Mix.1 also has a role in endoderm formation. It cooperates with the dorsal vegetal homeobox gene Siamois to activate the endodermal markers edd, Xlhbox8 and cerberus in animal caps. Conversely, vegetal overexpression of enRMix.1, an antimorphic Mix.1 mutant, leads to a loss of endoderm differentiation. Finally, by targeting enRMix.1 expression to the anterior endoderm, we could test the role of this tissue during embryogenesis and show that it is required for head formation.

Xenopus axis formation: induction of goosecoid by injected Xwnt-8 and activin mRNAs

Development ◽  
1993 ◽  
Vol 118 (2) ◽  
pp. 499-507 ◽  
Author(s):  
H. Steinbeisser ◽  
E.M. De Robertis ◽  
M. Ku ◽  
D.S. Kessler ◽  
D.A. Melton
Keyword(s):  
Uv Irradiation ◽  
High Frequency ◽  
Marginal Zone ◽  
Homeobox Gene ◽  
Dorsal Side ◽  
Axis Formation ◽  
Gene Products ◽  
Turn On ◽  
Xenopus Embryos ◽  
Spemann's Organizer

In this study, we compare the effects of three mRNAs-goosecoid, activin and Xwnt-8- that are able to induce partial or complete secondary axes when injected into Xenopus embryos. Xwnt-8 injection produces complete secondary axes including head structures whereas activin and goosecoid injection produce partial secondary axes at high frequency that lack head structures anterior to the auditory vesicle and often lack notochord. Xwnt-8 can activate goosecoid only in the deep marginal zone, i.e., in the region in which this organizer-specific homeobox gene is normally expressed on the dorsal side. Activin B mRNA, however, can turn on goosecoid in all regions of the embryo. We also tested the capacity of these gene products to restore axis formation in embryos in which the cortical rotation was blocked by UV irradiation. Whereas Xwnt-8 gives complete rescue of anterior structures, both goosecoid and activin give partial rescue. Rescued axes including hindbrain structures up to level of the auditory vesicle can be obtained at high frequency even in the absence of notochord structures. The possible functions of Wnt-like and activin-like signals and of the goosecoid homeobox gene, and their order of action in the formation of Spemann's organizer are discussed.

Properties of the primary organization field in the embryo of Xenopus laevis

Development ◽  
1972 ◽  
Vol 28 (1) ◽  
pp. 13-26
Author(s):  
J. Cooke
Keyword(s):  
Marginal Zone ◽  
Organizer Region ◽  
Angular Distance ◽  
Cell Polarization ◽  
Subsequent Paper ◽  
Basic Operation ◽  
Primary Organization ◽  
Organizer Activity ◽  
Set Up ◽  
Cell Immigration

The work presented, in this and the subsequent papers of a series, was begun in order to re-examine the properties of the amphibian primary embryonic field, in the light of current theories concerning the nature of individuation fields in developing animal systems. A detailed description is given of the basic operation whose results are described in this and the subsequent paper. This involves the transplantation, into a late blastula or stage-10 gastrula host, of a supernumerary stage-10 organizer region. The consequences of such operations during the following 4–6 h, up to the late gastrula stage, are also described. Evidence is presented that, from a time some 2·5 h before the organizer site first becomes externally visible, its presumptive region is immune from interference by the proximity of another, implanted organizer, even one which is itself 2·5 h older. That is to say, the final site of development of host organizer activity is not altered by the presence of such an implant. Pairs of early organizers at comparable stages of activity appear to set up competing fields of cellular orientation and immigration, which show a fairly sharp boundary at their interface. This is most obvious for pairs of organizers fairly close together, since the cell polarization and stretching is most pronounced in the region near to the apex of the field, i.e. the initial site of cell immigration. Independent initial fields of immigration due to two organizers can reliably be distinguished in cases where they are as little as 30° of angular distance apart in the marginal zone of the host. These results are to be considered in relation to those of Paper II, for the same series of operations, where the final patterns of cell differentiation are studied, and to those of Paper III, where evidence is given for the development of autonomous polarity in the region of the organizer.

scholarly journals DNA-dependent homodimerization, sub-cellular partitioning, and protein destabilization control WUSCHEL levels and spatial patterning

2016 ◽  
Vol 113 (41) ◽  
pp. E6307-E6315 ◽  
Author(s):  
Kevin Rodriguez ◽  
Mariano Perales ◽  
Stephen Snipes ◽  
Ram Kishor Yadav ◽  
Mercedes Diaz-Mendoza ◽  
...  
Keyword(s):  
Dna Binding ◽  
Nuclear Export ◽  
Spatial Patterning ◽  
Nuclear Retention ◽  
Regulatory Domains ◽  
Stem Cell Maintenance ◽  
Protein Levels ◽  
Transcriptional Regulatory ◽  
Responsive Element ◽  
Nuclear Levels

The homeodomain transcription factor WUSCHEL (WUS) promotes stem cell maintenance in inflorescence meristems of Arabidopsis thaliana. WUS, which is synthesized in the rib meristem, migrates and accumulates at lower levels in adjacent cells. Maintenance of WUS protein levels and spatial patterning distribution is not well-understood. Here, we show that the last 63-aa stretch of WUS is necessary for maintaining different levels of WUS protein in the rib meristem and adjacent cells. The 63-aa region contains the following transcriptional regulatory domains: the acidic region, the WUS-box, which is conserved in WUS-related HOMEOBOX family members, and the ethylene-responsive element binding factor-associated amphiphilic repression (EAR-like) domain. Our analysis reveals that the opposing functions of WUS-box, which is required for nuclear retention, and EAR-like domain, which participates in nuclear export, are necessary to maintain higher nuclear levels of WUS in cells of the rib meristem and lower nuclear levels in adjacent cells. We also show that the N-terminal DNA binding domain, which is required for both DNA binding and homodimerization, along with the homodimerization sequence located in the central part of the protein, restricts WUS from spreading excessively and show that the homodimerization is critical for WUS function. Our analysis also reveals that a higher level of WUS outside the rib meristem leads to protein destabilization, suggesting a new tier of regulation in WUS protein regulation. Taken together our data show that processes that influence WUS protein levels and spatial distribution are highly coupled to its transcriptional activity.

scholarly journals A CONTRIBUTION TO THE CHEMOTHERAPY OF TUBERCULOSIS

1916 ◽  
Vol 24 (2) ◽  
pp. 107-147 ◽  
Author(s):  
Gensaburo Koga
Keyword(s):  
Microscopic Examination ◽  
Guinea Pigs ◽  
Single Injection ◽  
Abdominal Cavity ◽  
The Body ◽  
Treated Animal ◽  
Leukocytic Infiltration ◽  
Absolute Test ◽  
Tubercular Lesion

Judging from the macroscopic and microscopic study of the animals treated with the liquid, its action upon the tubercular lesions seems to be about as follows: The effect of a single injection upon the lesions is either negative or inconspicuous. But after repeated injections of the preparation the congestion and leukocytic infiltration about the lesions are markedly decreased, the cheesy material resulting from degeneration of the lesions and other degeneration products are in process of absorption, and young connective tissue is being actively produced in the periphery. While these changes are taking place the number of the bacilli is also being reduced until finally they can no longer be detected on microscopic examination. Hence it appears that while the preparation may lack bactericidal action in vivo powerful enough to destroy all the bacilli at one injection, yet repeated infusions may nevertheless bring about the destruction of all the bacilli and the modification of the tubercular lesion into that of the suspended stage or even into the healed condition. Whether, therefore, the preparation brings about these results directly by killing the bacilli or indirectly by favoring the healing processes of the body, nevertheless it has power to inhibit the growth of or annihilate entirely the bacilli in vivo. The experiments reported leave no doubt that Liquid D is capable of bringing about the healing of experimental tubercular lesions; but thus far that most important problem in chemotherapeutics, namely, the extent of the cure produced, has not been solved. The experiments indicate that sterility of the tissues as far as microscopic examinations go has been secured; but microscopic examination is not after all an absolute test of sterility. In order to test this point, emulsions were made of the lungs, liver, spleen, and other organs of Treated Animals 134 and 135 (Table VII), and they were inoculated into the abdominal cavity of guinea pigs. Some of the animals receiving the emulsion developed tuberculosis, and therefore absolute sterility of the treated animals had not been obtained in these instances. The problem of the destination and distribution of the preparation in the body of the treated animal, as well as its action against the tubercle bacilli, lesions, and the tubercular organs of the infected guinea pigs, is now being studied further with results to be reported at some future time.

scholarly journals TopBP1 contains transcriptional regulatory domains and regulates gene pathways involved in breast cancer

2008 ◽  
Vol 10 (S2) ◽  
Author(s):  
RHG Wright ◽  
ES Dornan ◽  
MM Donaldson ◽  
M MacFarlane ◽  
P Herzyk ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Regulatory Domains ◽  
Transcriptional Regulatory
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