Author

Jan Christian

Published on SDB CoRe: Mar 8 2012

Organisms: Model Organisms; Vertebrates
Early Embryogenesis: Cleavage; Blastula
Embryonic Patterning: Axis Formation
Signaling: Morphogens and Gradients; Secreted Signals
Gene Regulation: Transcriptional Control
Organism: Xenopus
Stage of Development: Embryo

Object Description

Morphogens are substances that form concentration gradients and elicit distinct cellular responses in a dose-dependent manner. The Xenopus VegT-nodal axis provides one example of how a morphogen gradient can form and function in a multicellular embryo. RNA encoding the transcription factor VegT (green shading) is anchored to the vegetal cortex in the oocyte (a) but is released and becomes distributed throughout the vegetal half of the early cleavage stage embryo (b).The RNA is then translated to generate a graded distribution of nuclear VegT protein (orange shading) that is restricted to prospective endodermal cells near the bottom half of the embryo (b,c). A few hours later, VegT activates transcription of target genes such as nodal and other transforming growth factor-β family members, which encode secreted morphogens (c, small white circles). Nodal binds to cell surface receptors and activates a signaling cascade that ultimately leads to dose-dependent changes in gene transcription that specify distinct cell fates. WIREs Dev Biol 2012. DOI: 10.1002/wdev.2

References

Christian, J.L. Morphogen gradients in development: from form to function. WIREs Dev Biol, 2012, 1:3-15.

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