Resource Details

β-catenin Signaling and Axis Specification

Randall T. Moon*

1Howard Hughes Medical Institute and Department of Pharmacology, University of Washington School of Medicine, Seattle, WA 98195, USA.


*Corresponding author. E-mail, rtmoon{at}


This animation provides a representation of the β-catenin signaling pathway in response to fertilization and the process of axis specification that occurs early in development. The process shown is based on analysis of embryos of the amphibian Xenopus. Prior to fertilization components of the Wnt/β-catenin pathway, Dishevelled (Dsh), glycogen synthase kinase-3 (GSK-3) binding protein (GBP), and β-catenin (β-CAT) are uniformly distributed in the egg and β-CAT is degraded by a ubiquitin (U)-proteasome process following phosphorylation (P) by casein kinase 1 (not shown) and GSK-3. Sperm entry causes a calcium wave and then the microtubules become oriented with the plus ends pointing away from the sperm entry point. Dsh accumulates in the side opposite sperm entry, which will become the anterior and dorsal structures, possibly by association with GBP, which in turn binds protein motors that move along the oriented microtubules. The accumulation of Dsh promotes the stabilization and dorsal accumulation of β-CAT, which then activates direct target genes, including the homeobox genes siamois and twinned. Activation of these genes on the prospective dorsal side is necessary and sufficient for formation of the gastrula organizer (Spemann Organizer), which organizes the embryonic germ layers and axes.

This animation would be useful in illustrating events that occur early in embryogenesis and how embryos become polarized as a consequence of localized signaling processes.

The animation was created by Cameron Slayden with the scientific oversight of Randall Moon.

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Educational Details

Learning Resource Type: Animation

Context: Undergraduate upper division, graduate, professional (degree program)

Intended Users: Teacher, learner

Intended Educational Use: Teach, learn

Discipline: Developmental biology, cell biology, reproductive biology

Keywords: signal transduction, cytoskeleton, reproduction, gene expression, movie

Technical Details

Format: Shockwave Flash Object (swf file)

Size: 91 kb

Requirements: Macromedia Flash 5 or higher (

Related Resources

Connections Map: R. T. Moon, Xenopus egg Wnt/beta-catenin pathway. Sci. STKE (Connections Map, as seen June 2004),;CMP_6031. [Specific Pathway]

Limits for Use

Cost: Free

Rights: This material may be downloaded, printed, linked to, and/or redistributed without modification for noncommercial, course-teaching purposes only, provided credit to STKE is included by listing the citation for the teaching resource.


Citation: R. T. Moon, β-catenin signaling and axis specification. Sci. STKE2004, tr6 (2004).

© 2004 American Association for the Advancement of Science