Studies of morphogens: keep calm and carry on

Abstract

Morphogens are signaling factors that direct cell fate and tissue development at a distance from their source, and various modes of transport and interpretation have been suggested for morphogens. The recent EMBO Workshop on 'Morphogen gradients', which took place in Oxford, UK in June 2013, centered on the formation and interpretation of such morphogen gradients during development. This meeting allowed an exchange of views in light of recent results. Here, we provide a brief overview of the talks, organized in relation to several major themes of discussion at the meeting: (1) morphogen gradient formation; (2) morphogen gradient interpretation; (3) signaling networks and feedback in morphogenesis; (4) emergence of patterns; (5) scaling of patterns; (6) the control of growth; and (7) new techniques in the field.

Keywords: Cell fate; Morphogens; Tissue development.

Fig. 1.

Examples of morphogens in development. (A) Morphogens in the Drosophila wing disc. The morphogen Hedgehog (Hh) is expressed in the posterior compartment of the wing disc. At the boundary with anterior cells, Hh activates the expression of Decapentaplegic (Dpp), which disperses into both compartments. Wingless (Wg) is expressed at the dorsal-ventral boundary. Adapted, with permission, from Wolpert (Wolpert, 2003). (B) The Bicoid gradient in the syncytial Drosophila embryo. The transcription factor Bicoid, which accumulates within nuclei, is present in a gradient that decreases in concentration with distance from the anterior pole. mRNA encoding Bicoid is initially tightly localized to the anterior pole. The extent to which the mRNA encoding Bicoid, which is initially tightly localized to the anterior pole, becomes delocalized is a matter of controversy. Expression of the Bicoid target gene hunchback is also shown. Adapted, with permission, from Grimm et al. (Grimm et al., 2010). (C) Morphogens in the neural tube. A transverse section of an amniote embryo is shown, highlighting the morphogens Shh (red), which is secreted by the notochord and floor plate, and BMP and Wnt (blue), which are produced dorsally. Adapted, with permission, from Dessaud et al. (Dessaud et al., 2008).