Cortical rotation and messenger RNA localization in Xenopus axis formation

Author: Houston, Douglas W.

Description: In Xenopus eggs, fertilization initiates a rotational movement of the cortex relative to the cytoplasm, resulting in the transport of critical determinants to the future dorsal side of the embryo. Cortical rotation is mediated by microtubules, resulting in activation of the Wnt/B-catenin signaling pathway and expression of organizer genes on the dorsal side of the blastula. Similar cytoplasmic localizations resulting in B-catenin activation occur in many chordate embryos, suggesting a deeply conserved mechanism for patterning early embryos. This review summarizes the experimental evidence for the molecular basis of this model, focusing on recent maternal loss-of-function studies that shed light on two main unanswered questions: (1) what regulates microtubule assembly during cortical rotation and (2) how is Wnt/B-catenin signaling activated dorsally? In addition, as these processes depend on vegetally localized molecules in the oocyte, the mechanisms of RNA localization and novel roles for localized RNAs in axis formation are discussed. The work reviewed here provides a beginning framework for understanding the coupling of asymmetry in oogenesis with the establishment of asymmetry in the embryo.

Subject headings: Animals; Body Patterning; Microtubules, metabolism; Ovum, physiology; RNA Transport; RNA, Messenger, metabolism; Wnt Signaling Pathway; Xenopus; Embryology; Genetics; Frogs

Publication year: 2012

Journal or book title: Wiley interdisciplinary reviews. Developmental biology

Volume: 1

Pages: 371-388

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Serial number: 3741

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