β-Catenin is essential for patterning the maternally specified animal-vegetal axis in the sea urchin embryo

Athula H. Wikramanayake, Ling Huang, William H. Klein

Research output: Contribution to journalArticle

202 Scopus citations

Abstract

In sea urchin embryos, the animal-vegetal axis is specified during oogenesis. After fertilization, this axis is patterned to produce five distinct territories by the 60-cell stage. Territorial specification is thought to occur by a signal transduction cascade that is initiated by the large micromeres located at the vegetal pole. The molecular mechanisms that mediate the specification events along the animal-vegetal axis in sea urchin embryos are largely unknown. Nuclear β-catenin is seen in vegetal cells of the early embryo, suggesting that this protein plays a role in specifying vegetal cell fates. Here, we test this hypothesis and show that β-catenin is necessary for vegetal plate specification and is also sufficient for endoderm formation. In addition, we show that β-catenin has pronounced effects on animal blastomeres and is critical for specification of aboral ectoderm and for ectoderm patterning, presumably via a noncell-autonomous mechanism. These results support a model in which a Wnt-like signal released by vegetal cells patterns the early embryo along the animal-vegetal axis. Our results also reveal similarities between the sea urchin animal-vegetal axis and the vertebrate dorsal-ventral axis, suggesting that these axes share a common evolutionary origin.

Original languageEnglish (US)
Pages (from-to)9343-9348
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Volume95
Issue number16
DOIs
StatePublished - Aug 4 1998
Externally publishedYes

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