Wnt signal transduction pathway and apoptosis: a review

Scratch-induced disruption of cultured monolayers induces polarity in front row cells that can be visualized by spatially localized polymerization of actin at the front of the cell and reorientation of the centrosome/Golgi to face the leading edge. We previously reported that centrosomal reorientation and microtubule polarization depend on a Cdc42-regulated signal transduction pathway involving activation of the Par6/aPKC complex followed by inhibition of GSK-3β and accumulation of the adenomatous polyposis coli (APC) protein at the plus ends of leading-edge microtubules. Using monolayers of primary rodent embryo fibroblasts, we show here that dishevelled (Dvl) and axin, two major components of the Wnt signaling pathway are required for centrosome reorientation and that Wnt5a is required for activation of this pathway. We conclude that disruption of cell–cell contacts leads to the activation of a noncanonical Wnt/dishevelled signal transduction pathway that cooperates with Cdc42/Par6/aPKC to promote polarized reorganization of the microtubule cytoskeleton.

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The Wnt Signal Transduction Pathway

Signaling Networks and Cell Cycle Control ◽

10.1385/1-59259-218-x:53 ◽

2003 ◽

pp. 53-82 ◽

Cited By ~ 1

Author(s):

Grant D. Barish ◽

Bart O. Williams

Keyword(s):

Signal Transduction ◽

Signal Transduction Pathway ◽

Transduction Pathway ◽

Wnt Signal

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Dorsalizing and neuralizing properties of Xdsh, a maternally expressed Xenopus homolog of dishevelled

Development ◽

10.1242/dev.121.6.1637 ◽

1995 ◽

Vol 121 (6) ◽

pp. 1637-1647 ◽

Cited By ~ 7

Author(s):

S.Y. Sokol ◽

J. Klingensmith ◽

N. Perrimon ◽

K. Itoh

Keyword(s):

Signal Transduction ◽

Signal Transduction Pathway ◽

Neural Induction ◽

Neural Tissue ◽

Lineage Tracing ◽

Axis Formation ◽

Transduction Pathway ◽

Vertebrate Development ◽

Dorsal Axis ◽

Wnt Signal

Signaling factors of the Wnt proto-oncogene family are implicated in dorsal axis formation during vertebrate development, but the molecular mechanism of this process is not known. Studies in Drosophila have indicated that the dishevelled gene product is required for wingless (Wnt1 homolog) signal transduction. We demonstrate that injection of mRNA encoding a Xenopus homolog of dishevelled (Xdsh) into prospective ventral mesodermal cells triggers a complete dorsal axis formation in Xenopus embryos. Lineage tracing experiments show that cells derived from the injected blastomere contribute to anterior and dorsal structures of the induced axis. In contrast to its effect on mesoderm, overexpression of Xdsh mRNA in prospective ectodermal cells triggers anterior neural tissue differentiation. These studies suggest that Wnt signal transduction pathway is conserved between Drosophila and vertebrates and point to a role for maternal Xdsh product in dorsal axis formation and in neural induction.

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pygopusencodes a nuclear protein essential for Wingless/Wnt signaling

Development ◽

10.1242/dev.129.17.4089 ◽

2002 ◽

Vol 129 (17) ◽

pp. 4089-4101 ◽

Cited By ~ 2

Author(s):

Tatyana Y. Belenkaya ◽

Chun Han ◽

Henrietta J. Standley ◽

Xinda Lin ◽

Douglas W. Houston ◽

...

Keyword(s):

Signal Transduction ◽

Target Genes ◽

Nuclear Protein ◽

Signal Transduction Pathway ◽

Transduction Pathway ◽

Phd Finger ◽

Nuclear Function ◽

Evolutionarily Conserved ◽

Wnt Signal

The Wingless (Wg)/Wnt signal transduction pathway regulates many developmental processes through a complex of Armadillo(Arm)/β-catenin and the HMG-box transcription factors of the Tcf family. We report the identification of a new component, Pygopus (Pygo), that plays an essential role in the Wg/Wnt signal transduction pathway. We show that Wg signaling is diminished during embryogenesis and imaginal disc development in the absence of pygo activity. Pygo acts downstream or in parallel with Arm to regulate the nuclear function of Arm protein. pygo encodes a novel and evolutionarily conserved nuclear protein bearing a PHD finger that is essential for its activity. We further show that Pygo can form a complex with Arm in vivo and possesses a transcription activation domain(s). Finally, we have isolated a Xenopus homolog of pygo (Xpygo). Depletion of maternal Xpygo by antisense deoxyoligonucleotides leads to ventralized embryonic defects and a reduction of the expression of Wnt target genes. Together, these findings demonstrate that Pygo is an essential component in the Wg/Wnt signal transduction pathway and is likely to act as a transcription co-activator required for the nuclear function of Arm/β-catenin.

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