Dorsal downregulation of GSK3beta by a non-Wnt-like mechanism is an early molecular consequence of cortical rotation in early Xenopus embryos

Development ◽  
2000 ◽  
Vol 127 (4) ◽  
pp. 861-868 ◽  
Author(s):  
I. Dominguez ◽  
J.B. Green
Keyword(s):  
Mammalian Cells ◽  
Specific Activity ◽  
Glycogen Synthase ◽  
Dorsal Side ◽  
Dominant Negative ◽  
Axis Formation ◽  
Beta Catenin ◽  
Dorsoventral Patterning ◽  
Xenopus Embryos ◽  
Mode Of Regulation

Cortical rotation and concomitant dorsal translocation of cytoplasmic determinants are the earliest events known to be necessary for dorsoventral patterning in Xenopus embryos. The earliest known molecular target is beta-catenin, which is essential for dorsal development and becomes dorsally enriched shortly after cortical rotation. In mammalian cells cytoplasmic accumulation of beta-catenin follows reduction of the specific activity of glycogen synthase kinase 3-beta (GSK3beta). In Xenopus embryos, exogenous GSK3beta) suppresses dorsal development as predicted and GSK3beta dominant negative (kinase dead) mutants cause ectopic axis formation. However, endogenous GSK3beta regulation is poorly characterized. Here we demonstrate two modes of GSK3beta regulation in Xenopus. Endogenous mechanisms cause depletion of GSK3beta protein on the dorsal side of the embryo. The timing, location and magnitude of the depletion correspond to those of endogenous beta-catenin accumulation. UV and D(2)O treatments that abolish and enhance dorsal character of the embryo, respectively, correspondingly abolish and enhance GSK3beta depletion. A candidate regulator of GSK3beta, GSK3-binding protein (GBP), known to be essential for axis formation, also induces depletion of GSK3beta. Depletion of GSK3beta is a previously undescribed mode of regulation of this signal transducer. The other mode of regulation is observed in response to Wnt and dishevelled expression. Neither Wnt nor dishevelled causes depletion but instead they reduce GSK3beta-specific activity. Thus, Wnt/Dsh and GBP appear to effect two biochemically distinct modes of GSK3beta regulation.

Maternal beta-catenin establishes a ‘dorsal signal’ in early Xenopus embryos

Development ◽  
1996 ◽  
Vol 122 (10) ◽  
pp. 2987-2996 ◽  
Author(s):  
C. Wylie ◽  
M. Kofron ◽  
C. Payne ◽  
R. Anderson ◽  
M. Hosobuchi ◽  
...  
Keyword(s):  
Glycogen Synthase ◽  
Axis Formation ◽  
Beta Catenin ◽  
Cell Stage ◽  
Midblastula Transition ◽  
Xenopus Embryos ◽  
Ability To Act ◽  
Zygotic Transcription ◽  
Spatial Terms ◽  
Marginal Zones

In previous work, we demonstrated that maternally encoded beta-catenin, the vertebrate homolog of armadillo, is required for formation of dorsal axial structures in early Xenopus embryos (Heasman, J., Crawford, A., Goldstone, K., Garner-Hamrick, P., Gumbiner, B., Kintner, C., Yoshida-Noro, C. and Wylie, C. (1994). Cell 79, 791–803). Here we investigated, firstly, the role(s) of beta-catenin in spatial terms, in different regions of the embryo, by injecting beta-catenin mRNA into individual blastomeres of beta-catenin-depleted embryos at the 32 cell stage. The results indicate that beta-catenin can rescue the dorsal axial structures in a non-cell-autonomous way and without changing the fates of the injected cells. This suggests that cells overexpressing beta-catenin send a ‘dorsal signal’ to other cells. This was confirmed by showing that beta-catenin overexpressing animal caps did not cause wild-type caps to form mesoderm, but did cause isolated beta-catenin-deficient marginal zones to form dorsal mesoderm. Furthermore beta-catenin-deficient vegetal masses treated with overexpressing caps regained their ability to act as Nieuwkoop Centers. Secondly, we studied the temporal activity of beta-catenin. We showed that zygotic transcription of beta-catenin starts after the midblastula transition (MBT), but does not rescue dorsal axial structures. We further demonstrated that the vegetal mass does not release a dorsal signal until after the onset of transcription, at the midblastula stage, suggesting that maternal beta-catenin protein is required at or before this time. Thirdly we investigated where, in relationship to other gene products known to be active in axis formation, beta-catenin is placed. We find that BVg1, bFGF, tBR (the truncated form of BMP2/4R), siamois and noggin activities are all downstream of beta-catenin, as shown by the fact that injection of their mRNAs rescues the effect of depleting maternally encoded beta-catenin. Interference with the action of glycogen synthase kinase (GSK), a vertebrate homolog of the Drosophila gene product, zeste white 3 kinase, does not rescue the effect, suggesting that it is upstream.

scholarly journals Interaction among Gsk-3, Gbp, Axin, and APC in Xenopus Axis Specification

2000 ◽  
Vol 148 (4) ◽  
pp. 691-702 ◽  
Author(s):  
Gist H. Farr ◽  
Denise M. Ferkey ◽  
Cynthia Yost ◽  
Sarah B. Pierce ◽  
Carole Weaver ◽  
...  
Keyword(s):  
Mammalian Cells ◽  
Glycogen Synthase ◽  
Wnt Signaling Pathway ◽  
Early Embryo ◽  
Dominant Negative ◽  
Axis Formation ◽  
Downstream Effector ◽  
Axis Specification ◽  
Subsequent Degradation ◽  
Canonical Wnt

Glycogen synthase kinase 3 (GSK-3) is a constitutively active kinase that negatively regulates its substrates, one of which is β-catenin, a downstream effector of the Wnt signaling pathway that is required for dorsal–ventral axis specification in the Xenopus embryo. GSK-3 activity is regulated through the opposing activities of multiple proteins. Axin, GSK-3, and β-catenin form a complex that promotes the GSK-3–mediated phosphorylation and subsequent degradation of β-catenin. Adenomatous polyposis coli (APC) joins the complex and downregulates β-catenin in mammalian cells, but its role in Xenopus is less clear. In contrast, GBP, which is required for axis formation in Xenopus, binds and inhibits GSK-3. We show here that GSK-3 binding protein (GBP) inhibits GSK-3, in part, by preventing Axin from binding GSK-3. Similarly, we present evidence that a dominant-negative GSK-3 mutant, which causes the same effects as GBP, keeps endogenous GSK-3 from binding to Axin. We show that GBP also functions by preventing the GSK-3–mediated phosphorylation of a protein substrate without eliminating its catalytic activity. Finally, we show that the previously demonstrated axis-inducing property of overexpressed APC is attributable to its ability to stabilize cytoplasmic β-catenin levels, demonstrating that APC is impinging upon the canonical Wnt pathway in this model system. These results contribute to our growing understanding of how GSK-3 regulation in the early embryo leads to regional differences in β-catenin levels and establishment of the dorsal axis.

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.

A novel role for glycogen synthase kinase-3 in Xenopus development: maintenance of oocyte cell cycle arrest by a beta-catenin-independent mechanism

Development ◽  
1999 ◽  
Vol 126 (3) ◽  
pp. 567-576 ◽  
Author(s):  
D.L. Fisher ◽  
N. Morin ◽  
M. Doree
Keyword(s):  
Cell Cycle ◽  
Cell Cycle Arrest ◽  
Glycogen Synthase ◽  
Cyclin B1 ◽  
Dominant Negative ◽  
Glycogen Synthase Kinase ◽  
Beta Catenin ◽  
Xenopus Development ◽  
Cycle Arrest ◽  
Cell Cycle Inhibition

We have examined the expression of glycogen synthase kinase-3beta in oocytes and early embryos of Xenopus and found that the protein is developmentally regulated. In resting oocytes, GSK-3beta is active and it is inactivated on maturation in response to progesterone. GSK-3beta inactivation is necessary and rate limiting for the cell cycle response to this hormone and the subsequent accumulation of beta-catenin. Overexpression of a dominant negative form of the kinase accelerates maturation, as does inactivation by expression of Xenopus Dishevelled or microinjection of an inactivating antibody. Cell cycle inhibition by GSK-3beta is not mediated by the level of beta-catenin or by a direct effect on either the MAP kinase pathway or translation of mos and cyclin B1. These data indicate a novel role for GSK-3beta in Xenopus development: in addition to controlling specification of the dorsoventral axis in embryos, it mediates cell cycle arrest in oocytes.

scholarly journals Erratum: Glycogen synthase kinase-3 and dorsoventral patterning in Xenopus embryos

Nature ◽  
1995 ◽  
Vol 375 (6528) ◽  
pp. 253-253 ◽  
Author(s):  
Xi He ◽  
Jean-Pierre Saint-Jeannet ◽  
James R. Woodgett ◽  
Harold E. Varmus ◽  
Igor B. Dawid
Keyword(s):  
Glycogen Synthase ◽  
Glycogen Synthase Kinase ◽  
Glycogen Synthase Kinase 3 ◽  
Dorsoventral Patterning ◽  
Xenopus Embryos

scholarly journals Jun NH2-terminal kinase (JNK) prevents nuclear beta-catenin accumulation and regulates axis formation in Xenopus embryos

2006 ◽  
Vol 103 (44) ◽  
pp. 16313-16318 ◽  
Author(s):  
G. Liao ◽  
Q. Tao ◽  
M. Kofron ◽  
J.-S. Chen ◽  
A. Schloemer ◽  
...  
Keyword(s):  
Axis Formation ◽  
Beta Catenin ◽  
Xenopus Embryos

Glycogen synthase kinase-3 and dorsoventral patterning in Xenopus embryos

Nature ◽  
1995 ◽  
Vol 374 (6523) ◽  
pp. 617-622 ◽  
Author(s):  
Xi He ◽  
Jean-Pierre Saint-Jeannet ◽  
James R. Woodgett ◽  
Harold E. Varmus ◽  
Igor B. Dawid
Keyword(s):  
Glycogen Synthase ◽  
Glycogen Synthase Kinase ◽  
Glycogen Synthase Kinase 3 ◽  
Dorsoventral Patterning ◽  
Xenopus Embryos
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