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XB-ART-11186
Development May 1, 2000; 127 (10): 2053-62.

The Xenopus homologue of Bicaudal-C is a localized maternal mRNA that can induce endoderm formation.



Abstract
In Xenopus, zygotic transcription starts 6 hours after fertilization at the midblastula transition and therefore the first steps in embryonic development are regulated by maternally inherited proteins and mRNAs. While animal-vegetal polarity is already present in the oocyte, the dorsoventral axis is only established upon fertilization by the entry of the sperm and the subsequent rotation of the egg cortex. In a screen for maternal mRNAs whose stability is regulated by this cortical rotation, we isolated the Xenopus homologue of the Drosophila gene Bicaudal-C (xBic-C). It encodes a putative RNA-binding molecule expressed maternally and localized predominantly to the vegetal half of the egg. Upon fertilization and cortical rotation, xBic-C mRNA is displaced together with the heavy yolk towards the future dorsal side of the embryo. In UV-ventralized embryos, xBic-C is polyadenylated less than in untreated embryos that undergo cortical rotation. Overexpression of xBic-C by injection of synthetic mRNA in whole embryos or in ectodermal explants leads to ectopic endoderm formation. This endoderm-inducing activity is dependent on the presence of the RNA-binding domain of the protein. In contrast to the two other known maternally encoded endoderm inducers, Vg1 and VegT, xBic-C ectopic expression leads specifically to endoderm formation in the absence of mesoderm induction.

PubMed ID: 10769230
PMC ID: PMC2292106
Article link: Development
Grant support: [+]
Genes referenced: a2m actl6a bicc1 cat2 fabp2 gdf1 krt12.4 nanos1 ncam1 odc1 tbx2 vegt


Article Images: [+] show captions
References [+] :
Adinolfi, Novel RNA-binding motif: the KH module. 1999, Pubmed


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