Siamois cooperates with TGFbeta signals to induce the complete function of the Spemann-Mangold organizer.

In Xenopus, the Spemann-Mangold organizer induces and patterns the body axis. Siamois, a Wnt-responsive transcriptional activator, functions to establish and maintain the Spemann-Mangold organizer by regulating organizer gene transcription. While expression of Siamois in marginal blastomeres induces an axis consisting of both head and trunk structures, we show that expression of Siamois in animal blastomeres induces an axis that lacks head structures. Consistent with the absence of head organizer activity in Siamois-expressing animal pole tissue, Siamois did not induce animal expression of Cerberus, Frzb1 and Xlim1, genes implicated in anterior development. A dominant negative form of Siamois inhibited endogenous expression of Cerberus, Frzb1 and Xlim1, indicating that Siamois is necessary for organizer-specific expression of these head organizer genes, but is not sufficient in animal tissue. Siamois induces Cerberus, Frzb1 and Xlim1 in vegetal blastomeres and vegetal induction by Siamois is dependent on endogenous TGFbeta signals. The results provide evidence that Siamois cooperates with TGFbeta signals to activate the expression of organizer genes and to generate an organizer with both head- and trunk-inducing activity.

• Publication year

  2001

• Venue

  International Journal of Developmental Biology

• Publication date

  Unknown publication date

• Fields of study

  Biology, Medicine

• Identifiers
  DOI 10.1387/IJDB.11291853PMID 11291853
• External record

  Open on Semantic Scholar

• Source metadata

  Semantic Scholar, PubMed

• Siamois cooperates with TGFbeta signals to activate organizer gene transcription and produce Spemann-Mangold organizer activity with both head- and trunk-inducing capacity.

  Confidence 0.89

  박진우 (dztg5apj7m) extractionB (s683577b42) reviewAnonymous (6atugeptpk) review
• Siamois induces head organizer genes in vegetal blastomeres only when endogenous TGFbeta signals are present.

  Confidence 0.91

  박진우 (dztg5apj7m) extractionB (s683577b42) reviewAnonymous (6atugeptpk) review
• In animal blastomeres, Siamois is insufficient to induce head organizer genes such as Cerberus, Frzb1, and Xlim1.

  Confidence 0.93

  박진우 (dztg5apj7m) extractionB (s683577b42) reviewAnonymous (6atugeptpk) review
• Siamois expression in marginal blastomeres yields a complete axis with head and trunk structures, whereas expression in animal blastomeres yields an axis lacking head structures.

  Confidence 0.96

  박진우 (dztg5apj7m) extractionB (s683577b42) reviewAnonymous (6atugeptpk) review

• animal blastomeres

  cell population

  Blastomeres from the animal pole region used to test Siamois-driven axis induction.

  박진우 (dztg5apj7m) extractionB (s683577b42) reviewAnonymous (6atugeptpk) review
• head organizer genes

  gene set

  Organizer-associated genes in Xenopus embryos linked to anterior development, including Cerberus, Frzb1, and Xlim1.

  Aliases: Cerberus, Frzb1, Xlim1

  박진우 (dztg5apj7m) extractionB (s683577b42) reviewAnonymous (6atugeptpk) review
• marginal blastomeres

  cell population

  Blastomeres from the marginal region used as a context for Siamois-driven axis induction.

  박진우 (dztg5apj7m) extractionB (s683577b42) reviewAnonymous (6atugeptpk) review
• siamois

  transcription factor

  A Wnt-responsive transcriptional activator in Xenopus embryos that regulates organizer gene expression.

  박진우 (dztg5apj7m) extractionB (s683577b42) reviewAnonymous (6atugeptpk) review
• spemann-mangold organizer

  embryonic organizer

  The embryonic organizer in Xenopus that patterns the body axis and contributes head- and trunk-inducing activity.

  Aliases: organizer

  박진우 (dztg5apj7m) extractionB (s683577b42) reviewAnonymous (6atugeptpk) review
• tgfbeta signals

  signaling pathway

  Endogenous TGFbeta-dependent signaling inputs that interact with Siamois in vegetal blastomeres.

  Aliases: TGF-β signals

  박진우 (dztg5apj7m) extractionB (s683577b42) reviewAnonymous (6atugeptpk) review
• vegetal blastomeres

  cell population

  Blastomeres from the vegetal pole region used to test Siamois-dependent organizer gene induction.

  박진우 (dztg5apj7m) extractionB (s683577b42) reviewAnonymous (6atugeptpk) review

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