Two‐dimensional morphogen gradient in <i>Xenopus</i>: Boundary formation and real‐time transduction response

Kinoshita, Tsutomu; Jullien, Jérôme; Gurdon, J. B.

doi:10.1002/dvdy.20963

Cited by 13 publications

(16 citation statements)

References 39 publications

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“…w t ¼ w xx − ðu þ vÞw ðx;tÞ ∈ ð0;∞Þ × ð0;∞Þ w x ð0;tÞ ¼ 0 t ∈ ð0;∞Þ wðx;0Þ ¼ v x∈ ½0;∞Þ: [27] and decreases monotonically to zero for each x as t → 0. We now explicitly construct super-and subsolutions for this problem.…”

Section: Resultsmentioning

confidence: 99%

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Local kinetics of morphogen gradients

Gordon

Sample

Berezhkovskii

et al. 2011

Proc. Natl. Acad. Sci. U.S.A.

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Some aspects of pattern formation in developing embryos can be described by nonlinear reaction-diffusion equations. An important class of these models accounts for diffusion and degradation of a locally produced single chemical species. At long times, solutions of such models approach a steady state in which the concentration decays with distance from the source of production. We present analytical results that characterize the dynamics of this process and are in quantitative agreement with numerical solutions of the underlying nonlinear equations. The derived results provide an explicit connection between the parameters of the problem and the time needed to reach a steady state value at a given position. Our approach can be used for the quantitative analysis of tissue patterning by morphogen gradients, a subject of active research in biophysics and developmental biology.robustness | tissue regulation | concentration gradient

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Section: Resultsmentioning

confidence: 99%

“…In particular, the dynamics of morphogen gradients has been studied only in a handful of experimental systems and mathematical models (13,(20)(21)(22)(23)(24)(25)(26)(27)(28)(29)(30)(31). This motivates our work, in which we present analytical results for the dynamics in reaction-diffusion equations based on the source-sink mechanism.…”

mentioning

confidence: 99%

Local kinetics of morphogen gradients

Gordon

Sample

Berezhkovskii

et al. 2011

Proc. Natl. Acad. Sci. U.S.A.

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“…Smad2/4 bimolecular fluorescence complementation provides a direct read-out of long-range signalling by TGF-β family members In an effort to visualise a direct response to long-range TGF-β signalling, we have turned to Smad2-Smad4 bimolecular fluorescence complementation (Smad2/4-BiFC). This approach has already been used to visualise Smad signalling in cells of the Xenopus embryo , and it provides a direct, quantitative and rapid read-out of activin-like signalling, with a better signal-to-noise ratio than obtained by monitoring the nuclear translocation of GFP-Smad2 (Bourillot et al, 2002;Grimm and Gurdon, 2002;Kinoshita et al, 2006). Animal pole explants were therefore derived from embryos co-injected with mRNAs encoding (1) Smad2/4-BiFC constructs ; (2) activin or Xnr1;…”

Section: Resultsmentioning

confidence: 99%

Rab5-mediated endocytosis of activin is not required for gene activation or long-range signalling inXenopus

Hagemann

Nentwich

et al. 2009

Development

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Morphogen gradients provide positional cues for cell fate specification and tissue patterning during embryonic development. One important aspect of morphogen function, the mechanism by which long-range signalling occurs, is still poorly understood. In Xenopus, members of the TGF-β family such as the nodal-related proteins and activin act as morphogens to induce mesoderm and endoderm. In an effort to understand the mechanisms and dynamics of morphogen gradient formation, we have used fluorescently labelled activin to study ligand distribution and Smad2/Smad4 bimolecular fluorescence complementation (BiFC) to analyse, in a quantitative manner, the cellular response to induction. Our results indicate that labelled activin travels exclusively through the extracellular space and that its range is influenced by numbers of type II activin receptors on responding cells. Inhibition of endocytosis, by means of a dominant-negative form of Rab5, blocks internalisation of labelled activin, but does not affect the ability of cells to respond to activin and does not significantly influence signalling range. Together, our data indicate that longrange signalling in the early Xenopus embryo, in contrast to some other developmental systems, occurs through extracellular movement of ligand. Signalling range is not regulated by endocytosis, but is influenced by numbers of cognate receptors on the surfaces of responding cells.

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“…In addition to the concentration-dependent mesoderm induction, the refinement mechanism of Xbra expression has been reported, which requires protein synthesis (Papin and Smith, 2000). Animal cap assay demonstrates that the boundary formation of activininduced Xbra expression requires protein synthesis (Kinoshita et al, 2006). However, the type of proteins that control the boundary formation of Xbra expression remains to be determined.…”

Section: Boundary Formation Of Xbra Expressionmentioning

confidence: 99%

Antagonistic role of XESR1 and XESR5 in mesoderm formation in Xenopus laevis

Kinoshita¹,

Haruta²,

Sakamoto³

et al. 2011

Int. J. Dev. Biol.

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The notch signaling pathway is widely conserved from vertebrates to invertebrates and mediates the specification of numerous cell fates during developmental processes. In the Xenopus gastrula embryo, Xdelta1, one of the Notch ligands, is expressed in the prospective mesoderm prior to Xbra expression. Here, we examined the role of Notch signaling in mesoderm formation. Embryos injected with Xdelta1 morpholino oligo DNA showed a severe gastrulation defect and suppression of Xbra expression, which were completely rescued by co-injection with the active form of Notch. In order to fully understand the role of Notch signaling, we examined the expression of the Notch target genes XESR1 and XESR5. RT-PCR and whole-mount in situ hybridization analyses showed that XESR5 was highly expressed in the marginal zone of the early gastrula embryo, whereas expression of XESR1 was not detected. Animal cap assays indicated that expression of XESR5 was not induced by Notch signaling but by nodal signaling. To clarify the role of XESR5 in the gastrula embryo, a dominant negative form of XESR5 was injected into the prospective mesoderm. The truncated form of XESR5 induced the ectopic expression of XESR1, which caused a decrease in Xbra expression and defective gastrulation. In contrast, the truncated form of XESR1 caused an upregulation of XESR5 resulting in an increase in Xbra expression. The antagonistic effect of XESR1 and XESR5 suggests a dual regulation in which XESR5 produces a competent area for mesoderm formation by suppressing the gene expression of XESR1, while XESR1 sharpens the boundary of Xbra expression.

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Two‐dimensional morphogen gradient in Xenopus: Boundary formation and real‐time transduction response

Cited by 13 publications

References 39 publications

Local kinetics of morphogen gradients

Local kinetics of morphogen gradients

Rab5-mediated endocytosis of activin is not required for gene activation or long-range signalling inXenopus

Antagonistic role of XESR1 and XESR5 in mesoderm formation in Xenopus laevis

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