Click here to close
Hello! We notice that you are using Internet Explorer, which is not supported by Xenbase and may cause the site to display incorrectly.
We suggest using a current version of Chrome,
FireFox, or Safari.
???displayArticle.abstract???
Activin and the Nodal-related proteins induce mesendodermal tissues during Xenopus development. These signals act through specific receptors to cause the phosphorylation, at their carboxyl termini, of Smad2 and Smad3. The phosphorylated Smad proteins form heteromeric complexes with Smad4 and translocate into the nucleus to activate the transcription, after the midblastula transition, of target genes such as Xbra and goosecoid (gsc). In this paper we use bimolecular fluorescence complementation (BiFC) to study complex formation between Smad proteins both in vivo and in response to exogenous proteins. The technique has allowed us to detect Smad2-Smad4 heteromeric interactions during normal Xenopus development and Smad2 and Smad4 homo- and heteromers in isolated Xenopus blastomeres. Smad2-Smad2 and Smad2-Smad4 complexes accumulate rapidly in the nuclei of responding cells following Activin treatment, whereas Smad4 homomeric complexes remain cytoplasmic. When cells divide, Smad2-Smad4 complexes associate with chromatin, even in the absence of ligand. Our observation that Smad2-Smad4 complexes accumulate in the nucleus only after the midblastula transition, irrespective of the stage at which cells were treated with Activin, may shed light on the mechanisms of developmental timing.
Armes,
The ALK-2 and ALK-4 activin receptors transduce distinct mesoderm-inducing signals during early Xenopus development but do not co-operate to establish thresholds.
1997, Pubmed,
Xenbase
Armes,
The ALK-2 and ALK-4 activin receptors transduce distinct mesoderm-inducing signals during early Xenopus development but do not co-operate to establish thresholds.
1997,
Pubmed
,
Xenbase
Batut,
Kinesin-mediated transport of Smad2 is required for signaling in response to TGF-beta ligands.
2007,
Pubmed
,
Xenbase
Bengtsson,
What MAN1 does to the Smads. TGFbeta/BMP signaling and the nuclear envelope.
2007,
Pubmed
,
Xenbase
Bourillot,
A changing morphogen gradient is interpreted by continuous transduction flow.
2002,
Pubmed
,
Xenbase
Campbell,
A monomeric red fluorescent protein.
2002,
Pubmed
Cho,
Molecular nature of Spemann's organizer: the role of the Xenopus homeobox gene goosecoid.
1991,
Pubmed
,
Xenbase
Cooke,
Measurement of developmental time by cells of early embryos.
1990,
Pubmed
Cooke,
The organization of mesodermal pattern in Xenopus laevis: experiments using a Xenopus mesoderm-inducing factor.
1987,
Pubmed
,
Xenbase
Dong,
Microtubule binding to Smads may regulate TGF beta activity.
2000,
Pubmed
Dreyer,
Differential accumulation of oocyte nuclear proteins by embryonic nuclei of Xenopus.
1987,
Pubmed
,
Xenbase
Faure,
Endogenous patterns of TGFbeta superfamily signaling during early Xenopus development.
2000,
Pubmed
,
Xenbase
Green,
Responses of embryonic Xenopus cells to activin and FGF are separated by multiple dose thresholds and correspond to distinct axes of the mesoderm.
1992,
Pubmed
,
Xenbase
Grimm,
Nuclear exclusion of Smad2 is a mechanism leading to loss of competence.
2002,
Pubmed
,
Xenbase
Gruenbaum,
The nuclear lamina comes of age.
2005,
Pubmed
Hata,
Mutations increasing autoinhibition inactivate tumour suppressors Smad2 and Smad4.
1997,
Pubmed
,
Xenbase
Heasman,
Patterning the early Xenopus embryo.
2006,
Pubmed
,
Xenbase
Howell,
Xenopus Smad3 is specifically expressed in the chordoneural hinge, notochord and in the endocardium of the developing heart.
2001,
Pubmed
,
Xenbase
Hu,
Visualization of interactions among bZIP and Rel family proteins in living cells using bimolecular fluorescence complementation.
2002,
Pubmed
Hu,
Simultaneous visualization of multiple protein interactions in living cells using multicolor fluorescence complementation analysis.
2003,
Pubmed
Inman,
Stoichiometry of active smad-transcription factor complexes on DNA.
2002,
Pubmed
,
Xenbase
Jayaraman,
Distinct oligomeric states of SMAD proteins in the transforming growth factor-beta pathway.
2000,
Pubmed
Kerppola,
Design and implementation of bimolecular fluorescence complementation (BiFC) assays for the visualization of protein interactions in living cells.
2006,
Pubmed
Kurisaki,
Transforming growth factor-beta induces nuclear import of Smad3 in an importin-beta1 and Ran-dependent manner.
2001,
Pubmed
Lee,
Timing of endogenous activin-like signals and regional specification of the Xenopus embryo.
2001,
Pubmed
,
Xenbase
Nagai,
A variant of yellow fluorescent protein with fast and efficient maturation for cell-biological applications.
2002,
Pubmed
Nagai,
Circularly permuted green fluorescent proteins engineered to sense Ca2+.
2001,
Pubmed
Newport,
A major developmental transition in early Xenopus embryos: II. Control of the onset of transcription.
1982,
Pubmed
,
Xenbase
Newport,
A major developmental transition in early Xenopus embryos: I. characterization and timing of cellular changes at the midblastula stage.
1982,
Pubmed
,
Xenbase
Nicolás,
Analysis of Smad nucleocytoplasmic shuttling in living cells.
2004,
Pubmed
Piepenburg,
Activin redux: specification of mesodermal pattern in Xenopus by graded concentrations of endogenous activin B.
2004,
Pubmed
,
Xenbase
Qin,
Crystal structure of a transcriptionally active Smad4 fragment.
1999,
Pubmed
Rekas,
Crystal structure of venus, a yellow fluorescent protein with improved maturation and reduced environmental sensitivity.
2002,
Pubmed
Saka,
A Xenopus tribbles orthologue is required for the progression of mitosis and for development of the nervous system.
2004,
Pubmed
,
Xenbase
Sawano,
Directed evolution of green fluorescent protein by a new versatile PCR strategy for site-directed and semi-random mutagenesis.
2000,
Pubmed
Schohl,
Beta-catenin, MAPK and Smad signaling during early Xenopus development.
2002,
Pubmed
,
Xenbase
Shen,
Nodal signaling: developmental roles and regulation.
2007,
Pubmed
Shyu,
Identification of new fluorescent protein fragments for bimolecular fluorescence complementation analysis under physiological conditions.
2006,
Pubmed
Smith,
Mesoderm induction and the control of gastrulation in Xenopus laevis: the roles of fibronectin and integrins.
1990,
Pubmed
,
Xenbase
Smith,
Expression of a Xenopus homolog of Brachyury (T) is an immediate-early response to mesoderm induction.
1991,
Pubmed
,
Xenbase
Tada,
Analysis of competence and of Brachyury autoinduction by use of hormone-inducible Xbra.
1997,
Pubmed
,
Xenbase
