Beta-catenin signaling activity dissected in the early Xenopus embryo: a novel antisense approach.
Xenopus embryos develop dorsal/ventral and anterior/posterior axes as a result of the activity of a maternal Xwnt pathway, in which beta-catenin is an essential component, acting as a transactivator of transcription of zygotic genes. However, the questions of where and when beta-catenin is required in early embryogenesis have not been addressed directly, because no loss-of-function method has been available. Here we report the use of a novel antisense approach that allows us to target depletion of protein to individual blastomeres. When a "morpholino" oligo complementary to beta-catenin mRNA is injected into early embryos, it depletes beta-catenin protein effectively through the neurula stage. By targeting the oligo to different cleavage blastomeres, we block beta-catenin activity in different areas and at different times. Dorsal vegetal injection at the 2- and 4-cell stages blocks dorsal axis formation and at the 8-cell stage blocks head formation, while A-tier injection at the 32-cell stage causes abnormal cement gland formation. This approach shows the complex involvement of Xwnt pathways in embryonic patterning and offers a rapid method for the functional analysis of both maternal and early zygotic gene products in Xenopus.
Heasman
J
J
Department of Genetics, Cell and Developmental Biology, University of Minnesota, Minneapolis 55455, USA. heasman@lenti.med.umn.edu
Kofron
M
M
Wylie
C
C
D000818:Animals; D001483:Base Sequence; D003598:Cytoskeletal Proteins / Q000235:genetics / Q000378:metabolism*; D017931:DNA Primers; D004625:Embryo, Nonmammalian / Q000378:metabolism; D016376:Oligonucleotides, Antisense / Q000235:genetics*; D015398:Signal Transduction; D015534:Trans-Activators; D014981:Xenopus / Q000196:embryology; D029867:Xenopus Proteins; D051176:beta Catenin
C495266:CTNNB1 protein, Xenopus; D003598:Cytoskeletal Proteins; D017931:DNA Primers; D016376:Oligonucleotides, Antisense; D015534:Trans-Activators; D029867:Xenopus Proteins; D051176:beta Catenin