fgf8 mRNA decay establishes a gradient that couples axial elongation to patterning in the vertebrate embryo.
Formation and patterning of the vertebrate embryo occur in a head-to-tail sequence. This progressive mode of body formation from the posterior end of the embryo requires a strict temporal coordination of tissue differentiation--a process involving fibroblast growth factor (FGF) signalling. Here we show that transcription of fgf8 messenger RNA is restricted to the growing posterior tip of the embryo. fgf8 mRNA is progressively degraded in the newly formed tissues, resulting in the formation of an mRNA gradient in the posterior part of the embryo. This fgf8 mRNA gradient is translated into a gradient of FGF8 protein, which correlates with graded phosphorylation of the kinase Akt, a downstream effector of FGF signalling. Such a mechanism provides an efficient means to monitor the timing of FGF signalling, coupling the differentiation of embryonic tissues to the posterior elongation of the embryo. In addition, this mechanism provides a novel model for morphogen gradient formation.
Dubrulle
Julien
J
Stowers Institute for Medical Research, 1000 East 50th Street, 64110 Kansas City, Missouri, USA.
Pourquié
Olivier
O
D000818:Animals; D019521:Body Patterning / Q000235:genetics*; D002642:Chick Embryo / Q000196:embryology* / Q000378:metabolism; D051524:Fibroblast Growth Factor 8; D005346:Fibroblast Growth Factors / Q000235:genetics* / Q000378:metabolism*; D017403:In Situ Hybridization; D051379:Mice; D020871:RNA Stability; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014158:Transcription, Genetic
C496457:Fgf8 protein, mouse; D012333:RNA, Messenger; D051524:Fibroblast Growth Factor 8; D005346:Fibroblast Growth Factors