Regulated proteolysis of Xom mediates dorsoventral pattern formation during early Xenopus development.
To identify a regulatory role for proteolysis during early Xenopus development, we developed a biochemical screen for proteins that are degraded in an embryonic stage-specific manner. We found that Xom, a homeobox transcriptional repressor of dorsal-specific genes, was degraded precipitously during early gastrulation. Xom degradation is regulated by phosphorylation at a GSK3-like consensus site and is most likely mediated by the SCF-beta-TRCP complex. Expression of nondegradable Xom represses transcription of dorsal genes much more effectively than wild-type Xom and results in a more strongly ventralized phenotype. We propose that regulated Xom proteolysis plays an essential role in the establishment of the dorsoventral axis, by converting a gradient in BMP abundance into a sharp dorsoventral pattern.
Zhu
Zhenglun
Z
Department of Cell Biology, Harvard Medical School, Boston, MA 02115, USA.
Kirschner
Marc
M
D000818:Animals; D019521:Body Patterning / Q000502:physiology*; D004625:Embryo, Nonmammalian / Q000196:embryology; D038362:Glycogen Synthase Kinase 3 / Q000502:physiology; D018398:Homeodomain Proteins / Q000502:physiology*; D015398:Signal Transduction; D014157:Transcription Factors / Q000502:physiology*; D014981:Xenopus / Q000196:embryology* / Q000502:physiology; D029867:Xenopus Proteins
D018398:Homeodomain Proteins; D014157:Transcription Factors; D029867:Xenopus Proteins; C099992:ventx2.1 protein, Xenopus; D038362:Glycogen Synthase Kinase 3