XB-ART-47999Curr Biol. August 5, 2013; 23 (15): R652-4.
Development: scaling to size by protease inhibition.
The dorsal half of bisected Xenopus laevis embryos can regenerate a well-proportioned organism on a smaller scale. A new study indicates that the removal of ventral tissue generates a steeper Chordin gradient by reducing Sizzled, a secreted inhibitor of Tolloid chordinases.
PubMed ID: 23928082
Article link: Curr Biol.
Grant support: Howard Hughes Medical Institute
Genes referenced: bmp1 chrd.1 frzb2 szl
Morpholinos referenced: chrd MO1 chrd MO2 szl MO1
Article Images: [+] show captions
|Figure 1. Extracellular protein interactions in Xenopus dorsal-ventral patterning. (A) Chordin inhibits BMPs, which activate expression of Sizzled, an inhibitor of Tolloid proteases that degrades Chordin. (B) The dorsal-ventral network consists of many components under opposite transcriptional control by BMPs . Crescent is a Sizzled homolog expressed in the Spemann Organizer . (C) A simplified pathway in which Chordin and Sizzled regulate each other . The in situ hybridization in the background illustrates that chd and szl mRNAs are expressed at opposite poles of the mid-gastrula . The arrows indicate direct protein�protein interactions in black, transcriptional regulation by BMP signaling in blue, and diffusion (flux) of Chordin/BMP in red.|
|Figure 2. Chordin and Sizzled are key regulators of dorsal-ventral patterning. Depletion of Chordin or Sizzled with morpholinos (MOs) results in identical high-BMP phenotypes marked by an expanded ventral domain of sizzled mRNA expression.|